Content Delivery Network Interconnection (CDNI) Control Interface / Triggers 2nd Edition
draft-ietf-cdni-ci-triggers-rfc8007bis-11
| Document | Type | Active Internet-Draft (cdni WG) | |
|---|---|---|---|
| Authors | Nir Baruch Sopher , Ori Finkelman , Sanjay Mishra , Jay K. Robertson | ||
| Last updated | 2024-03-04 | ||
| Replaces | draft-ietf-cdni-triggers-extensions, draft-sopher-cdni-ci-triggers-rfc8007bis | ||
| RFC stream | Internet Engineering Task Force (IETF) | ||
| Intended RFC status | (None) | ||
| Formats | |||
| Additional resources | Mailing list discussion | ||
| Stream | WG state | WG Document | |
| Associated WG milestone |
|
||
| Document shepherd | (None) | ||
| IESG | IESG state | I-D Exists | |
| Consensus boilerplate | Unknown | ||
| Telechat date | (None) | ||
| Responsible AD | (None) | ||
| Send notices to | (None) |
draft-ietf-cdni-ci-triggers-rfc8007bis-11
Network Working Group N.B. Sopher
Internet-Draft O. Finkelman
Obsoletes: 8007 (if approved) Qwilt
Intended status: Standards Track S. Mishra
Expires: 5 September 2024 Verizon
J.K. Robertson
Qwilt
4 March 2024
Content Delivery Network Interconnection (CDNI) Control Interface /
Triggers 2nd Edition
draft-ietf-cdni-ci-triggers-rfc8007bis-11
Abstract
This document obsoletes RFC8007. The document describes the part of
Content Delivery Network Interconnection (CDNI) Control interface
that allows a CDN to trigger activity in an interconnected CDN that
is configured to deliver content on its behalf. The upstream CDN MAY
use this mechanism to request that the downstream CDN pre-position
metadata or content as well as request that it invalidate or purge
metadata or content. The upstream CDN MAY monitor the status of
activity that it has triggered in the downstream CDN.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on 5 September 2024.
Copyright Notice
Copyright (c) 2024 IETF Trust and the persons identified as the
document authors. All rights reserved.
Sopher, et al. Expires 5 September 2024 [Page 1]
Internet-Draft CDN Interconnect Triggers March 2024
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents (https://trustee.ietf.org/
license-info) in effect on the date of publication of this document.
Please review these documents carefully, as they describe your rights
and restrictions with respect to this document. Code Components
extracted from this document must include Revised BSD License text as
described in Section 4.e of the Trust Legal Provisions and are
provided without warranty as described in the Revised BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 5
2. Model for CDNI Triggers . . . . . . . . . . . . . . . . . . . 5
2.1. Timing of Triggered Activity . . . . . . . . . . . . . . 8
2.2. Scope of Triggered Activity . . . . . . . . . . . . . . . 8
2.2.1. Multiple Interconnected CDNs . . . . . . . . . . . . 9
2.3. Trigger Results . . . . . . . . . . . . . . . . . . . . . 10
3. Trigger Specification . . . . . . . . . . . . . . . . . . . . 10
3.1. Trigger Action . . . . . . . . . . . . . . . . . . . . . 10
3.2. Trigger Spec . . . . . . . . . . . . . . . . . . . . . . 11
3.2.1. Trigger Subject . . . . . . . . . . . . . . . . . . . 12
3.2.2. Content URLs . . . . . . . . . . . . . . . . . . . . 13
3.3. Trigger Extensibility . . . . . . . . . . . . . . . . . . 13
4. Collections of Trigger Status Resources . . . . . . . . . . . 14
5. CDNI Trigger Interface . . . . . . . . . . . . . . . . . . . 15
5.1. Creating Triggers . . . . . . . . . . . . . . . . . . . . 16
5.2. Checking Status . . . . . . . . . . . . . . . . . . . . . 17
5.2.1. Polling Trigger Status Resource Collections . . . . . 18
5.2.2. Polling Trigger Status Resources . . . . . . . . . . 18
5.3. Cancelling Triggers . . . . . . . . . . . . . . . . . . . 18
5.4. Deleting Triggers . . . . . . . . . . . . . . . . . . . . 19
5.5. Expiry of Trigger Status Resources . . . . . . . . . . . 20
5.6. Loop Detection and Prevention . . . . . . . . . . . . . . 20
5.7. Error Handling . . . . . . . . . . . . . . . . . . . . . 21
5.7.1. Error propagation . . . . . . . . . . . . . . . . . . 22
6. CI/T Object Properties and Encoding . . . . . . . . . . . . . 25
6.1. CI/T Objects . . . . . . . . . . . . . . . . . . . . . . 25
6.1.1. CI/T Trigger Command . . . . . . . . . . . . . . . . 25
6.1.2. CI/T Cancel Command . . . . . . . . . . . . . . . . . 26
6.1.3. Trigger Status Resources . . . . . . . . . . . . . . 26
6.1.4. Trigger Collections . . . . . . . . . . . . . . . . . 27
6.2. Properties of CI/T Objects . . . . . . . . . . . . . . . 30
6.2.1. Trigger.v2 Specification . . . . . . . . . . . . . . 30
6.2.2. Generic Trigger Specs . . . . . . . . . . . . . . . . 31
6.2.3. CI/T Trigger Extensions . . . . . . . . . . . . . . . 32
6.2.4. Absolute Time . . . . . . . . . . . . . . . . . . . . 37
6.2.5. Error.v2 Description . . . . . . . . . . . . . . . . 37
Sopher, et al. Expires 5 September 2024 [Page 2]
Internet-Draft CDN Interconnect Triggers March 2024
6.2.6. Trigger Status . . . . . . . . . . . . . . . . . . . 39
6.2.7. Error Code . . . . . . . . . . . . . . . . . . . . . 41
7. Trigger Spec Objects . . . . . . . . . . . . . . . . . . . . 42
7.1. URLs Spec . . . . . . . . . . . . . . . . . . . . . . . . 42
7.2. CCIDs Spec . . . . . . . . . . . . . . . . . . . . . . . 43
7.3. URI Pattern Match Spec . . . . . . . . . . . . . . . . . 43
7.3.1. UriPatternMatch . . . . . . . . . . . . . . . . . . . 43
7.4. URI Regex Match Spec . . . . . . . . . . . . . . . . . . 44
7.4.1. RegexMatch . . . . . . . . . . . . . . . . . . . . . 45
7.5. Content Playlist Spec . . . . . . . . . . . . . . . . . . 46
7.5.1. Playlist . . . . . . . . . . . . . . . . . . . . . . 46
7.5.2. MediaProtocol . . . . . . . . . . . . . . . . . . . . 47
8. Trigger Extension Objects . . . . . . . . . . . . . . . . . . 48
8.1. LocationPolicy extension . . . . . . . . . . . . . . . . 48
8.2. TimePolicy Extension . . . . . . . . . . . . . . . . . . 50
8.2.1. UTCWindow . . . . . . . . . . . . . . . . . . . . . . 51
8.2.2. LocalTimeWindow . . . . . . . . . . . . . . . . . . . 52
8.2.3. DateLocalTime . . . . . . . . . . . . . . . . . . . . 53
9. Footprint and Capabilities . . . . . . . . . . . . . . . . . 55
9.1. CI/T Objects Versions Capability Object . . . . . . . . . 55
9.1.1. CI/T Objects Versions Capability Object
Serialization . . . . . . . . . . . . . . . . . . . . 55
9.2. CI/T Trigger Scope Capability Object . . . . . . . . . . 56
9.2.1. CI/T Trigger Scope Capability Object Serialization . 57
9.3. CI/T Playlist Protocol Capability Object . . . . . . . . 58
9.3.1. CI/T Playlist Protocol Capability Object
Serialization . . . . . . . . . . . . . . . . . . . . 59
10. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . 59
10.1. Creating Triggers . . . . . . . . . . . . . . . . . . . 59
10.1.1. Preposition . . . . . . . . . . . . . . . . . . . . 59
10.1.2. Invalidate . . . . . . . . . . . . . . . . . . . . . 61
10.1.3. Invalidation with Regex . . . . . . . . . . . . . . 63
10.1.4. Preposition with Playlists . . . . . . . . . . . . . 65
10.2. Examining Trigger Status . . . . . . . . . . . . . . . . 66
10.2.1. Collection of All Triggers . . . . . . . . . . . . . 66
10.2.2. Filtered Collections of Trigger Status Resources . . 67
10.2.3. Individual Trigger Status Resources . . . . . . . . 69
10.2.4. Polling for Changes in Status . . . . . . . . . . . 71
10.2.5. Deleting Trigger Status Resources . . . . . . . . . 74
10.2.6. Extensions with Error Propagation . . . . . . . . . 75
11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 78
11.1. CDNI Payload Type Parameter Registrations . . . . . . . 78
11.1.1. CDNI ci-trigger-command.trigger.v2 Payload Type . . 79
11.1.2. CDNI ci-trigger-command.cancel Payload Type . . . . 79
11.1.3. CDNI ci-trigger-status.v2 Payload Type . . . . . . . 79
11.1.4. CDNI FCI CI/T Payload Types . . . . . . . . . . . . 79
11.2. "CDNI CI/T Trigger Types" Registry For Trigger
Actions . . . . . . . . . . . . . . . . . . . . . . . . 80
Sopher, et al. Expires 5 September 2024 [Page 3]
Internet-Draft CDN Interconnect Triggers March 2024
11.3. "CDNI CI/T Trigger Specs" Registry . . . . . . . . . . . 80
11.4. "CDNI CI/T Trigger Subjects" Registry . . . . . . . . . 81
11.5. CDNI CI/T Playlist Spec MediaProtocols . . . . . . . . . 81
11.6. "CDNI CI/T Trigger Extensions" Registry . . . . . . . . 81
11.7. "CDNI CI/T Error Codes" Registry . . . . . . . . . . . . 82
12. Security Considerations . . . . . . . . . . . . . . . . . . . 82
12.1. Authentication, Authorization, Confidentiality, Integrity
Protection . . . . . . . . . . . . . . . . . . . . . . . 83
12.2. Denial of Service . . . . . . . . . . . . . . . . . . . 84
12.3. Privacy . . . . . . . . . . . . . . . . . . . . . . . . 84
13. References . . . . . . . . . . . . . . . . . . . . . . . . . 84
13.1. Normative References . . . . . . . . . . . . . . . . . . 84
13.2. Informative References . . . . . . . . . . . . . . . . . 86
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 87
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 87
1. Introduction
[RFC6707] introduces the problem scope for Content Delivery Network
Interconnection (CDNI) and lists the four categories of interfaces
that may be used to compose a CDNI solution (Control, Metadata,
Request Routing, and Logging).
[RFC7336] expands on the information provided in [RFC6707] and
describes each of the interfaces and the relationships between them
in more detail.
The CDNI Control Interface / Triggers 1st edition [RFC8007],
deprecated by this document describes the "CI/T" interface -- "CDNI
Control interface / Triggers". It does not consider those parts of
the Control interface that relate to configuration, bootstrapping, or
authentication of CDN Interconnect interfaces. Section 4 of
[RFC7337] identifies the requirements specific to the CI/T interface;
requirements applicable to the CI/T interface are CI-1 to CI-6.
This document is a second edition for the CDNI Control Interface /
Triggers, which define a new version, "v2", of the interface objects.
The new objects replace the trigger interface’s main objects, the
"ci-trigger-command" object and its matching "ci-trigger-status"
object, and improve the interface’s flexibility and extensibility.
The document also provides a Trigger Extension mechanism that MAY be
used to provide further instruction on the trigger execution.
Additionally, this second edition includes cascaded CDN error
propagation for improved trigger execution monitoring. Note that the
trigger interface mechanism itself is not changed by this new
edition.
Sopher, et al. Expires 5 September 2024 [Page 4]
Internet-Draft CDN Interconnect Triggers March 2024
* Section 2 outlines the model for the CI/T interface at a high
level.
* Section 3 describes the trigger attributes used for specifying the
trigger's targets and for controlling the trigger's execution.
* Section 4 describes collections of Trigger Status Resources.
* Section 5 defines the web service provided by the downstream CDN.
* Section 6 lists properties of CI/T Commands and Status Resources.
* Section 7 describes the Trigger's Spec object.
* Section 8 describes the Trigger's Extensions object.
* Section 9 describes the FCI capabilities objects used to inform on
the supported CI/T related capabilities.
* Section 10 contains example messages.
1.1. Terminology
This document reuses the terminology defined in [RFC6707] and uses
"uCDN" and "dCDN" as shorthand for "upstream CDN" and "downstream
CDN", respectively.
Additionally, the following terms are used throughout this document
and are defined as follows:
* HLS - HTTP Live Streaming
* DASH - Dynamic Adaptive Streaming Over HTTP
* MSS - Microsoft Smooth Streaming
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
2. Model for CDNI Triggers
A CI/T Command, sent from the uCDN to the dCDN, is a request for the
dCDN to do some work (an "action") relating to data associated with
content requests originating from the uCDN.
Sopher, et al. Expires 5 September 2024 [Page 5]
Internet-Draft CDN Interconnect Triggers March 2024
There are two types of CI/T Commands: CI/T Trigger Commands and CI/T
Cancel Commands. The CI/T Cancel Command can be used to request
cancellation of an earlier CI/T Trigger Command.
A CI/T Trigger Action is of one of the following:
* preposition - used to instruct the dCDN to fetch metadata from the
uCDN or content from any origin including the uCDN.
* invalidate - used to instruct the dCDN to revalidate specific
metadata or content before reusing it.
* purge - used to instruct the dCDN to delete specific metadata or
content.
Note that additional CI/T Trigger Actions can be defined and
registered in the future.
The CI/T interface is a web service offered by the dCDN. It allows
CI/T Commands to be issued and allows triggered activity to be
tracked. The CI/T interface builds on top of HTTP/1.1 [RFC7230].
References to URL in this document relate to HTTP/HTTPS URIs, as
defined in Section 2.7 of [RFC7230].
When the dCDN accepts a CI/T Command, it creates a resource
describing the status of the triggered activity -- a Trigger Status
Resource. The uCDN can poll Trigger Status Resources to monitor
progress.
The dCDN maintains at least one collection of Trigger Status
Resources for each uCDN. Each uCDN only has access to its own
collections, the locations of which are shared when CDNI is
established.
To trigger activity in the dCDN, the uCDN POSTs a CI/T Command to the
collection of Trigger Status Resources. If the dCDN accepts the CI/T
Command, it creates a new Trigger Status Resource and returns its
location to the uCDN. To monitor progress, the uCDN can GET the
Trigger Status Resource. To request cancellation of a CI/T Trigger
Command, the uCDN can POST to the collection of Trigger Status
Resources or simply DELETE the Trigger Status Resource.
Note that the CI/T Command objects POSTed by the uCDN, and CI/T
Status Resource objects generated and reported by the dCDN, are
matched by their version, i.e., sending a [RFC8007] "ci-trigger-
command" object as the command generates a "ci-trigger-status"
structured resource to be reported, while sending a "ci-trigger-
command.trigger.v2" object generates a "ci-trigger-status.v2" object.
Sopher, et al. Expires 5 September 2024 [Page 6]
Internet-Draft CDN Interconnect Triggers March 2024
In addition to the collection of all Trigger Status Resources for the
uCDN, the dCDN can maintain filtered views of that collection. These
filtered views are defined in Section 4 and include collections of
Trigger Status Resources corresponding to active and completed CI/T
Trigger Commands. These collections provide a mechanism for polling
the status of multiple jobs.
Figure 1 is an example showing the basic message flow used by the
uCDN to trigger activity in the dCDN and for the uCDN to discover the
status of that activity. Only successful triggering is shown.
Examples of the messages are shown in Section 10.
uCDN dCDN
| (1) POST https://dcdn.example.com/triggers/uCDN |
[ ] --------------------------------------------------> [ ]--+
| [ ] | (2)
| (3) HTTP 201 Response [ ]<-+
[ ] <-------------------------------------------------- [ ]
| Loc: https://dcdn.example.com/triggers/uCDN/123 |
| |
. . .
. . .
. . .
| |
| (4) GET https://dcdn.example.com/triggers/uCDN/123 |
[ ] --------------------------------------------------> [ ]
| [ ]
| (5) HTTP 200 Trigger Status Resource [ ]
[ ] <-------------------------------------------------- [ ]
| |
| |
Figure 1: Basic CDNI Message Flow for Triggers
The steps in Figure 1 are as follows:
1. The uCDN triggers action in the dCDN by POSTing a CI/T Command to
a collection of Trigger Status Resources --
"https://dcdn.example.com/triggers/uCDN". This URL was given to
the uCDN when the CI/T interface was established.
2. The dCDN authenticates the request, validates the CI/T Command,
and, if it accepts the request, creates a new Trigger Status
Resource.
3. The dCDN responds to the uCDN with an HTTP 201 response status
and the location of the Trigger Status Resource.
Sopher, et al. Expires 5 September 2024 [Page 7]
Internet-Draft CDN Interconnect Triggers March 2024
4. The uCDN MAY query, possibly repeatedly, the Trigger Status
Resource in the dCDN.
5. The dCDN responds to each query with the Trigger Status Resource,
describing the progress or results of the CI/T Trigger Command.
The remainder of this document describes the messages, Trigger Status
Resources, and collections of Trigger Status Resources in more
detail.
2.1. Timing of Triggered Activity
Timing of the execution of CI/T Commands is under the dCDN's control,
including its start time and pacing of the activity in the network.
Instructions regarding this timing may be included in the trigger
using one of the Trigger Extension Objects defined in Section 8.
CI/T "invalidate" and "purge" commands MUST be applied to all data
acquired before the command was accepted by the dCDN. The dCDN
SHOULD NOT apply CI/T "invalidate" and "purge" commands to data
acquired after the CI/T Command was accepted, but this may not always
be achievable, so the uCDN cannot count on that.
If the uCDN wishes to invalidate or purge content and then
immediately pre-position replacement content at the same URLs, it
SHOULD ensure that the dCDN has completed the invalidate/purge before
initiating the pre-positioning. Otherwise, there is a risk that the
dCDN pre-positions the new content, then immediately invalidates or
purges it (as a result of the two uCDN requests running in parallel).
Because the CI/T Command timing is under the dCDN's control, the dCDN
implementation can choose whether to apply CI/T "invalidate" and
"purge" commands to content acquisition that has already started when
the command is received.
2.2. Scope of Triggered Activity
Each CI/T Command can operate on multiple metadata and content
elements, usually referred to by their URLs. These elements are
targeted by specifying both their subject (i.e., "metadata" or
"content") as well as specification method (e.g., URL Regexes) and
value.
Multiple representations of an HTTP resource may share the same URL.
CI/T Trigger Commands that invalidate or purge metadata or content
apply to all resource representations with matching URLs.
Sopher, et al. Expires 5 September 2024 [Page 8]
Internet-Draft CDN Interconnect Triggers March 2024
2.2.1. Multiple Interconnected CDNs
In a network of interconnected CDNs, a single uCDN will originate a
given item of metadata and associated content. It would possibly
distribute that metadata and content to more than one dCDN, which in
turn distribute that metadata and content to additional CDNs located
further downstream.
An intermediate CDN is a dCDN that passes on CDNI Metadata and
content to dCDNs located further downstream.
A "diamond" configuration is one where a dCDN can acquire metadata
and content originated in one uCDN from that uCDN itself and an
intermediate CDN, or via more than one intermediate CDN.
CI/T Commands originating in the single source uCDN affect metadata
and content in all dCDNs; however, in a diamond configuration, it may
not be possible for the dCDN to determine from which uCDN it acquired
content. In this case, a dCDN MUST allow each uCDN from which it may
have acquired the content to act upon that content using CI/T
Commands.
In all other cases, a dCDN MUST reject CI/T Commands from a uCDN that
attempts to act on another uCDN's content by using, for example,
responding with an HTTP 403 ("Forbidden").
Security considerations are discussed further in Section 12.
The diamond configuration may lead to inefficient interactions, but
the interactions are otherwise harmless. For example:
* When the uCDN issues an "invalidate" CI/T Command, a dCDN will
receive that command from multiple directly connected uCDNs. The
dCDN may schedule multiple such commands separately, and the last
scheduled command may affect content already revalidated following
execution of the "invalidate" command that was scheduled first.
* If one of a dCDN's directly connected uCDNs loses its rights to
distribute content, it may issue a CI/T "purge" command. That
purge may affect content the dCDN could retain because it's
distributed by another directly connected uCDN. But, that content
can be reacquired by the dCDN from the remaining uCDN.
* When the uCDN originating an item of content issues a CI/T purge
followed by a pre-position, two directly connected uCDNs will pass
those commands to a dCDN. That dCDN implementation need not merge
those operations or notice the repetition, in which case the purge
issued by one uCDN will complete before the other. The first uCDN
Sopher, et al. Expires 5 September 2024 [Page 9]
Internet-Draft CDN Interconnect Triggers March 2024
to finish its purge may then forward the "preposition" trigger,
and content pre-positioned as a result might be affected by the
still-running purge issued by the other uCDN. However, the dCDN
will reacquire that content as needed, or when it's asked to pre-
position the content by the second uCDN. A dCDN implementation
could avoid this interaction by knowing which uCDN it acquired the
content from, or it could minimize the consequences by recording
the time at which the "invalidate"/"purge" command was received
and not applying it to content acquired after that time.
2.3. Trigger Results
Possible states for a Trigger Status Resource are defined in
Section 6.2.6.
The CI/T Trigger Command MUST NOT be reported as "complete" until all
operations have been completed successfully. The reasons for
failure, and URLs or patterns affected, SHOULD be enumerated in the
Trigger Status Resource. For more details, see Section 5.7.
If a dCDN is also acting as a uCDN in a cascade, it MUST forward CI/T
Commands to any dCDNs that may be affected. The CI/T Trigger Command
MUST NOT be reported as "complete" in a CDN until it is "complete" in
all of its dCDNs. If a CI/T Trigger Command is reported as
"processed" in any dCDN, intermediate CDNs MUST NOT report
"complete"; instead, they MUST also report "processed". A CI/T
Command MAY be reported as "failed" as soon as it fails in a CDN or
in any of its dCDNs. A cancelled CI/T Trigger Command MUST be
reported as "cancelling" until it has been reported as "cancelled",
"complete", or "failed" by all dCDNs in a cascade.
3. Trigger Specification
The following attributes are defining the trigger execution.
3.1. Trigger Action
Trigger Action is used in a Trigger Specification to describe trigger
actions. It was initially referred to in [RFC8007] as "Trigger
Type".
All trigger actions MUST be registered in the IANA "CDNI CI/T Trigger
Types" registry (see Section 11.2).
Sopher, et al. Expires 5 September 2024 [Page 10]
Internet-Draft CDN Interconnect Triggers March 2024
A dCDN receiving a request containing a trigger action it does not
recognize or does not support MUST reject the request by creating a
Trigger Status Resource with a status of "failed" and the "errors"
array containing an Error.v2 Description with error "eunsupported"
(see Section 6.2.7).
The following trigger actions are defined by this document:
+=============+===============================================+
| JSON String | Description |
+=============+===============================================+
| preposition | A request for the dCDN to acquire metadata or |
| | content. |
+-------------+-----------------------------------------------+
| invalidate | A request for the dCDN to invalidate metadata |
| | or content. After servicing this request, |
| | the dCDN will not use the specified data |
| | without first revalidating it using, for |
| | example, an "If-None-Match" HTTP request. |
| | The dCDN need not erase the associated data. |
+-------------+-----------------------------------------------+
| purge | A request for the dCDN to erase metadata or |
| | content. After servicing the request, the |
| | specified data MUST NOT be held on the dCDN |
| | (the dCDN should reacquire the metadata or |
| | content from the uCDN if it needs it). |
+-------------+-----------------------------------------------+
Table 1
3.2. Trigger Spec
The CDNI Control Interface / Triggers 1st edition [RFC8007] defines a
set of properties and objects used by the trigger commands in order
to specify the targets upon which the trigger is applied. This
document modifies the trigger interface objects so it has a list of
trigger specs. Such structure improves the interface's extensibility
and flexibility. Furthermore, the document defines a generic trigger
spec object that acts as a wrapper for managing individual CDNI
trigger specs in an opaque manner, allowing future extension of the
interface.
All trigger specs MUST be registered in the IANA "CDNI CI/T Trigger
Specs" registry (see Section 11.3).
Sopher, et al. Expires 5 September 2024 [Page 11]
Internet-Draft CDN Interconnect Triggers March 2024
A dCDN receiving a request containing a trigger spec it does not
recognize or does not support MUST reject the request by creating a
Trigger Status Resource with a status of "failed" and the "errors"
array containing an Error.v2 Description with error "espec" (see
Section 6.2.7).
This document also defines an initial set of trigger spec objects and
registers them in the IANA "CDNI CI/T Trigger Specs" registry:
+===================+========================================+
| JSON String | Description |
+===================+========================================+
| urls | Allowing the specification of trigger |
| | targets via URLs. |
+-------------------+----------------------------------------+
| ccids | Allowing the specification of trigger |
| | targets via CCIDs content grouping, as |
| | defined in section 4.2.8 [RFC8006]. |
+-------------------+----------------------------------------+
| uri-pattern-match | Allowing the specification of trigger |
| | targets via [RFC3986] URI patterns. |
+-------------------+----------------------------------------+
| uri-regex-match | Allowing the specification of trigger |
| | targets via regexes matching their |
| | URI, as defined in Section 7.4. |
+-------------------+----------------------------------------+
| content-playlist | Allowing the specification of trigger |
| | targets via a playlist URI and a media |
| | protocol identifier. |
+-------------------+----------------------------------------+
Table 2
3.2.1. Trigger Subject
As the scope of the trigger may relate to either metadata as well as
content, the "trigger spec object" also specifies the trigger's
target subject (i.e., metadata or content) against which to match.
All trigger subjects MUST be registered in the IANA "CDNI CI/T
Trigger Subjects" registry (see Section 11.4).
A dCDN receiving a request containing a trigger subject it does not
recognize or does not support MUST reject the request by creating a
Trigger Status Resource with a status of "failed" and the "errors"
array containing an Error.v2 Description with error "esubject" (see
Section 6.2.7).
Sopher, et al. Expires 5 September 2024 [Page 12]
Internet-Draft CDN Interconnect Triggers March 2024
This document also defines an initial set of trigger subject values
and registers them in the IANA "CDNI CI/T Trigger Subjects" registry:
+=============+====================================================+
| JSON String | Description |
+=============+====================================================+
| metadata | Indicating the trigger target specification refers |
| | to Metadata object, as defined at [RFC8006]. |
+-------------+----------------------------------------------------+
| content | Indicating the trigger target specification refers |
| | to client facing content. |
+-------------+----------------------------------------------------+
Table 3
3.2.2. Content URLs
Each CI/T Command usually refers to the targets by the target URLs,
using a "urls" trigger spec object or some aggregating spec such as
the "url-regex-match". If content URLs are transformed by an
intermediate CDN in a cascade, that intermediate CDN MUST similarly
transform URLs in CI/T Commands it passes to its dCDN.
When processing Trigger Specifications, CDNs MUST ignore the URL
scheme (HTTP or HTTPS) in comparing URLs. For example, for a CI/T
"invalidate" or "purge" command, content MUST be invalidated or
purged regardless of the protocol clients used to request it.
3.3. Trigger Extensibility
The CDNI Control Interface / Triggers 1st edition [RFC8007] defines a
set of properties and objects used by the trigger commands. This 2nd
edition defines an extension mechanism to the triggers interface that
enables applications to add instructions for finer control over the
trigger execution, for example indicating a time window in which to
execute the trigger. This document specifies a generic trigger
extension object wrapper for managing individual CDNI trigger
extensions in an opaque manner.
All trigger extensions are optional, and it is thus the
responsibility of the extension specification to define a consistent
default behavior for the case the extension is not present.
All trigger extensions MUST be registered in the IANA "CDNI CI/T
Trigger Extensions" registry (see Section 11.6).
Sopher, et al. Expires 5 September 2024 [Page 13]
Internet-Draft CDN Interconnect Triggers March 2024
This document also defines an initial set of trigger extension
objects and registers them in the IANA "CDNI CI/T Trigger Extensions"
registry:
+=================+=========================================+
| JSON String | Description |
+=================+=========================================+
| location-policy | Allowing the control over the locations |
| | in which the trigger is executed. |
+-----------------+-----------------------------------------+
| time-policy | Allowing the scheduling of a trigger to |
| | run in a specific time window. |
+-----------------+-----------------------------------------+
Table 4
Example use cases
* Pre-position with cache location policy
* Purge content with cache location policy
* Pre-position at a specific time
* Purge by content acquisition time (e.g., purge all content
acquired in the past X hours)
4. Collections of Trigger Status Resources
As described in Section 2, Trigger Status Resources exist in the dCDN
to report the status of activity triggered by each uCDN.
A collection of Trigger Status Resources is a resource that contains
a reference to each Trigger Status Resource in that collection. Note
that the collection may possibly refer to Trigger Status Resources of
triggers from several CI/T objects versions, i.e., a subsequent call
for the retrieval of the relevant trigger status may provide objects
of various MIME media types: ci-trigger-status as defined in
[RFC8007], ci-trigger-status.v2 defined in this document, or objects
of future CI/T objects versions, based on the CI/T command version
used for the creation of the trigger.
The dCDN MUST make a collection of a uCDN's Trigger Status Resources
available to that uCDN. This collection includes all of the Trigger
Status Resources created for CI/T Commands from the uCDN that have
been accepted by the dCDN and have not yet been deleted by the uCDN
or expired and removed by the dCDN (as described in Section 5.4).
Trigger Status Resources belonging to a uCDN MUST NOT be visible to
Sopher, et al. Expires 5 September 2024 [Page 14]
Internet-Draft CDN Interconnect Triggers March 2024
any other CDN. The dCDN could, for example, achieve this by offering
different collection URLs to each uCDN and by filtering the response
based on the uCDN with which the HTTP client is associated.
To trigger an activity in a dCDN or to cancel a triggered activity,
the uCDN POSTs a CI/T Command to the dCDN's collection of the uCDN's
Trigger Status Resources.
In order to allow the uCDN to check the status of multiple jobs in a
single request, the dCDN MAY also maintain collections representing
filtered views of the collection of all Trigger Status Resources.
These filtered collections are "optional-to-implement", but if they
are implemented, the dCDN MUST include links to them in the
collection of all Trigger Status Resources. The filtered collections
are:
* Pending - Trigger Status Resources for CI/T Trigger Commands that
have been accepted but not yet acted upon.
* Active - Trigger Status Resources for CI/T Trigger Commands that
are currently being processed in the dCDN.
* Complete - Trigger Status Resources representing activity that
completed successfully, and "processed" CI/T Trigger Commands for
which no further status updates will be made by the dCDN.
* Failed - Trigger Status Resources representing CI/T Commands that
failed or were cancelled by the uCDN.
5. CDNI Trigger Interface
This section describes an interface to enable a uCDN to trigger
activity in a dCDN.
The CI/T interface builds on top of HTTP, so dCDNs may make use of
any HTTP feature when implementing the CI/T interface. For example,
a dCDN SHOULD make use of HTTP's caching mechanisms to indicate that
a requested response/representation has not been modified, reducing
the uCDN's processing needed to determine whether the status of
triggered activity has changed.
All dCDNs implementing CI/T MUST support the HTTP GET, HEAD, POST,
and DELETE methods as defined in [RFC7231].
The only representation specified in this document is JSON [RFC8259].
It MUST be supported by the uCDN and by the dCDN.
Sopher, et al. Expires 5 September 2024 [Page 15]
Internet-Draft CDN Interconnect Triggers March 2024
The URL of the dCDN's collection of all Trigger Status Resources
needs to be either discovered by or configured in the uCDN. The
mechanism for discovery of that URL is outside the scope of this
document.
CI/T Commands are POSTed to the dCDN's collection of all Trigger
Status Resources. If a CI/T Trigger Command is accepted by the dCDN,
the dCDN creates a new Trigger Status Resource and returns its URI to
the uCDN in an HTTP 201 response. The triggered activity can then be
monitored by the uCDN using that resource and the collections
described in Section 4.
The URI of each Trigger Status Resource is returned to the uCDN when
it is created, and URIs of all Trigger Status Resources are listed in
the dCDN's collection of all Trigger Status Resources. This means
all Trigger Status Resources can be discovered by the uCDN, so dCDNs
are free to assign whatever structure they desire to the URIs for CI/
T resources. Therefore, uCDNs MUST NOT make any assumptions
regarding the structure of CI/T URIs or the mapping between CI/T
objects and their associated URIs. URIs present in the examples in
this document are purely illustrative and are not intended to impose
a definitive structure on CI/T interface implementations.
5.1. Creating Triggers
To issue a CI/T Command, the uCDN makes an HTTP POST to the dCDN's
collection of all of the uCDN's Trigger Status Resources. The
request body of that POST is a CI/T Command, as described in
Section 6.1.1.
The dCDN validates the CI/T Command. If the command is malformed or
the uCDN does not have sufficient access rights, the dCDN MUST either
respond with an appropriate 4xx HTTP error code and not create a
Trigger Status Resource or create a "failed" Trigger Status Resource
containing an appropriate Error.v2 Description.
When a CI/T Trigger Command is accepted, the dCDN MUST create a new
Trigger Status Resource that will convey a specification of the CI/T
Command and its current status. The HTTP response to the uCDN MUST
have status code 201 and MUST convey the URI of the Trigger Status
Resource in the Location header field [RFC7231]. The HTTP response
SHOULD include the content of the newly created Trigger Status
Resource. This is particularly important in cases where the CI/T
Trigger Command has completed immediately.
Once a Trigger Status Resource has been created, the dCDN MUST NOT
reuse its URI, even after that Trigger Status Resource has been
removed.
Sopher, et al. Expires 5 September 2024 [Page 16]
Internet-Draft CDN Interconnect Triggers March 2024
The dCDN SHOULD track and report on the progress of CI/T Trigger
Commands using a Trigger Status Resource (Section 6.1.3). If the
dCDN is not able to do that, it MUST indicate that it has accepted
the request but will not be providing further status updates. To do
this, it sets the status of the Trigger Status Resource to
"processed". In this case, CI/T processing should continue as for a
"complete" request, so the Trigger Status Resource MUST be added to
the dCDN's collection of complete Trigger Status Resources. The dCDN
SHOULD also provide an estimated completion time for the request by
using the "etime" property of the Trigger Status Resource. This will
allow the uCDN to schedule pre-positioning after an earlier delete of
the same URLs is expected to have finished.
If the dCDN is able to track the execution of CI/T Commands and a CI/
T Command is queued by the dCDN for later action, the "status"
property of the Trigger Status Resource MUST be "pending". Once
processing has started, the status MUST be "active". Finally, once
the CI/T Command is complete, the status MUST be set to "complete" or
"failed".
A CI/T Trigger Command may result in no activity in the dCDN if, for
example, it is an "invalidate" or "purge" request for data the dCDN
has not yet acquired, or a "preposition" request for data that it has
already acquired and that is still valid. In this case, the status
of the Trigger Status Resource MUST be "processed" or "complete", and
the Trigger Status Resource MUST be added to the dCDN's collection of
complete Trigger Status Resources.
Once created, Trigger Status Resources can be cancelled or deleted by
the uCDN, but not modified. The dCDN MUST reject PUT and POST
requests from the uCDN to Trigger Status Resources by responding with
an appropriate HTTP status code -- for example, 405 ("Method Not
Allowed").
5.2. Checking Status
The uCDN has two ways to check the progress of CI/T Commands it has
issued to the dCDN, as described in Sections Section 5.2.1 and
Section 5.2.2.
To allow the uCDN to check for changes in the status of a Trigger
Status Resource or collection of Trigger Status Resources without
refetching the whole resource or collection, the dCDN SHOULD include
entity-tags (ETags) for the uCDN to use as cache validators, as
defined in [RFC7232].
Sopher, et al. Expires 5 September 2024 [Page 17]
Internet-Draft CDN Interconnect Triggers March 2024
The dCDN SHOULD use the cache control headers for responses to GETs
for Trigger Status Resources and Collections to indicate the
frequency at which it recommends that the uCDN should poll for
change.
5.2.1. Polling Trigger Status Resource Collections
The uCDN can fetch the collection of its Trigger Status Resources or
filtered views of that collection.
This makes it possible to poll the status of all CI/T Trigger
Commands in a single request. If the dCDN moves a Trigger Status
Resource from the active to the completed collection, the uCDN can
fetch the result of that activity.
When polling in this way, the uCDN SHOULD use HTTP ETags to monitor
for change, rather than repeatedly fetching the whole collection. An
example of this is given in Section 10.2.4.
5.2.2. Polling Trigger Status Resources
The uCDN has a URI provided by the dCDN for each Trigger Status
Resource it has created. It may fetch that Trigger Status Resource
at any time.
This can be used to retrieve progress information and to fetch the
result of the CI/T Command.
When polling in this way, the uCDN SHOULD use HTTP ETags to monitor
for change, rather than repeatedly fetching the Trigger Status
Resource.
5.3. Cancelling Triggers
The uCDN can request cancellation of a CI/T Trigger Command by
POSTing a CI/T Cancel Command (see Section 6.1.2) to the specific
trigger's Trigger Status Resource URL.
The dCDN is required to accept and respond to the CI/T Cancel
Command, but the actual cancellation of a CI/T Trigger Command is
optional-to-implement.
The dCDN MUST respond to the CI/T Cancel Command appropriately -- for
example, with HTTP status code 200 ("OK") if the cancellation has
been processed and the CI/T Command is inactive, 202 ("Accepted") if
the command has been accepted but the CI/T Command remains active,
404 ("Not Found") when the Trigger Status Resource does not exist, or
501 ("Not Implemented") if cancellation is not supported by the dCDN.
Sopher, et al. Expires 5 September 2024 [Page 18]
Internet-Draft CDN Interconnect Triggers March 2024
If cancellation of a "pending" Trigger Status Resource is accepted by
the dCDN, the dCDN SHOULD NOT start the processing of that activity.
Issuing a CI/T Cancel Command for a "pending" Trigger Status Resource
does not, however, guarantee that the corresponding activity will not
be started, because the uCDN cannot control the timing of that
activity. Processing could, for example, start after the POST is
sent by the uCDN but before that request is processed by the dCDN.
If cancellation of an "active" or "processed" Trigger Status Resource
is accepted by the dCDN, the dCDN SHOULD stop processing the CI/T
Command. However, as with cancellation of a "pending" CI/T Command,
the dCDN does not guarantee this.
If the CI/T Command cannot be stopped immediately, the status in the
corresponding Trigger Status Resource MUST be set to "cancelling",
and the Trigger Status Resource MUST remain in the collection of
Trigger Status Resources for active CI/T Commands. If processing is
stopped before normal completion, the status value in the Trigger
Status Resource MUST be set to "cancelled", and the Trigger Status
Resource MUST be included in the collection of failed CI/T Trigger
Commands.
Cancellation of a "complete" or "failed" Trigger Status Resource
requires no processing in the dCDN. Its status MUST NOT be changed
to "cancelled".
5.4. Deleting Triggers
The uCDN can delete Trigger Status Resources at any time using the
HTTP DELETE method. As defined in the CDNI Control Interface /
Triggers 1st edition [RFC8007], the effect is similar to
cancellation, but no Trigger Status Resource remains afterwards.
Note that in cases where the trigger's status prior to the deletion
is not a terminal status (i.e., "completed", "failed" or
"cancelled"), the uCDN would not have the ability to further monitor
the cancellation process and the final status of the trigger. For
this reason, it is recommended that the cancellation command (see
Section 6.1.2) is used prior to trigger deletion, and deletion is
only used on triggers with a terminal status.
Once deleted, the references to a Trigger Status Resource MUST be
removed from all Trigger Status Resource collections. Subsequent
requests to GET the deleted Trigger Status Resource SHOULD be
rejected by the dCDN with an HTTP error.
If a "pending" Trigger Status Resource is deleted, the dCDN SHOULD
NOT start the processing of that activity. Deleting a "pending"
Trigger Status Resource does not, however, guarantee that it has not
Sopher, et al. Expires 5 September 2024 [Page 19]
Internet-Draft CDN Interconnect Triggers March 2024
started, because the uCDN cannot control the timing of that activity.
Processing may, for example, start after the DELETE is sent by the
uCDN but before that request is processed by the dCDN.
If an "active" or "processed" Trigger Status Resource is deleted, the
dCDN SHOULD stop processing the CI/T Command. However, as with
deletion of a "pending" Trigger Status Resource, the dCDN does not
guarantee this.
Deletion of a "complete" or "failed" Trigger Status Resource requires
no processing in the dCDN other than deletion of the Trigger Status
Resource.
5.5. Expiry of Trigger Status Resources
The dCDN can choose to automatically delete Trigger Status Resources
some time after they become "complete", "processed", "failed", or
"cancelled". In this case, the dCDN will remove the Trigger Status
Resource and respond to subsequent requests for it with an HTTP
error.
If the dCDN does remove Trigger Status Resources automatically, it
MUST report the length of time after which it will do so, using a
property of the collection of all Trigger Status Resources. It is
RECOMMENDED that Trigger Status Resources are not automatically
deleted by the dCDN for at least 24 hours after they become
"complete", "processed", "failed", or "cancelled".
To ensure that it is able to get the status of its Trigger Status
Resources for completed and failed CI/T Commands, it is RECOMMENDED
that the uCDN polling interval is less than the time after which
records for completed activity will be deleted.
5.6. Loop Detection and Prevention
Given three CDNs, A, B, and C, if CDNs B and C delegate delivery of
CDN A's content to each other, CDN A's CI/T Commands could be passed
between CDNs B and C in a loop. More complex networks of CDNs could
contain similar loops involving more hops.
In order to prevent and detect such CI/T loops, each CDN uses a CDN
Provider ID (PID) to uniquely identify itself. In every CI/T Command
it originates or cascades, each CDN MUST append an array element
containing its CDN PID to a JSON array under an entry named "cdn-
path". When receiving CI/T Commands, a dCDN MUST check the cdn-path
and reject any CI/T Command that already contains its own CDN PID in
the cdn-path. Transit CDNs MUST check the cdn-path and not cascade
the CI/T Command to dCDNs that are already listed in the cdn-path.
Sopher, et al. Expires 5 September 2024 [Page 20]
Internet-Draft CDN Interconnect Triggers March 2024
The CDN PID consists of the two characters "AS" followed by the CDN
provider's Autonomous System number [RFC1930], then a colon (":") and
an additional qualifier that is used to guarantee uniqueness in case
a particular AS has multiple independent CDNs deployed -- for
example, "AS64496:0".
If the CDN provider has multiple ASes, the same AS number SHOULD be
used in all messages from that CDN provider, unless there are
multiple distinct CDNs.
If the CDNI Request Routing Redirection interface (RI) described in
[RFC7975] is implemented by the dCDN, the CI/T interface and the RI
SHOULD use the same CDN PID.
5.7. Error Handling
A dCDN can signal rejection of a CI/T Command using HTTP status codes
-- for example, 400 ("Bad Request") if the request is malformed, or
403 ("Forbidden") or 404 ("Not Found") if the uCDN does not have
permission to issue CI/T Commands or it is trying to act on another
CDN's data.
If any part of the CI/T Trigger Command fails, the trigger SHOULD be
reported as "failed" once its activity is complete or if no further
errors will be reported. The "errors" property in the Trigger Status
Resource will be used to enumerate which actions failed and the
reasons for failure, and can be present while the Trigger Status
Resource is still "pending" or "active", if the CI/T Trigger Command
is still running for some URLs or patterns in the Trigger
Specification.
Once a request has been accepted, processing errors are reported in
the Trigger Status Resource using a list of Error.v2 Descriptions.
Each Error.v2 Description is used to report errors against one or
more of the URLs or patterns in the Trigger Specification.
If a Surrogate affected by a CI/T Trigger Command is offline in the
dCDN or the dCDN is unable to pass a CI/T Command on to any of its
cascaded dCDNs:
* If the CI/T Command is abandoned by the dCDN, the dCDN SHOULD
report an error.
* A CI/T "invalidate" command may be reported as "complete" when
Surrogates that may have the data are offline. In this case,
Surrogates MUST NOT use the affected data without first
revalidating it when they are back online.
Sopher, et al. Expires 5 September 2024 [Page 21]
Internet-Draft CDN Interconnect Triggers March 2024
* CI/T "preposition" and "purge" commands can be reported as
"processed" if affected caches are offline and the activity will
complete when they return to service.
* Otherwise, the dCDN SHOULD keep the Trigger Status Resource in
state "pending" or "active" until either the CI/T Command is acted
upon or the uCDN chooses to cancel it.
5.7.1. Error propagation
This subsection explains the mechanism for enabling the uCDN to trace
an error back to the dCDN in which it occurred. CDNI triggers may be
propagated over a chain of downstream CDNs. For example, an upstream
CDN A (uCDN-A) that is delegating to a downstream CDN B (dCDN-B) and
dCDN-B is delegating to a downstream CDN C (dCDN-C). Triggers sent
from uCDN-A to dCDN-B may be redistributed from dCDN-B to dCDN-C, and
errors can occur anywhere along the path. Therefore, it might be
essential for uCDN-A that sets the trigger, be able to trace back an
error to the downstream CDN where it occurred. This document adds a
mechanism to propagate the PID of the dCDN where the fault occurred,
back to the uCDN by adding the PID to the error.v2 description. When
dCDN-B propagates a trigger further to the downstream dCDN-C, it MUST
also propagate back the errors received in the trigger status
resource from dCDN-C by adding them to the errors array in its own
status resource to be sent back to the originating uCDN-A. While
propagating back the errors dCDN-B MAY also specify the dCDN-C PID,
indicating to which CDN the error specifically relates. The trigger
originating upstream CDN then receives an array built of the errors
that occurred in all the CDNs along the execution path, where each
error MAY be carrying its own CDN identifier.
Figure 2 below is an example showing the message flow used by uCDN-A
to trigger activity in the dCDN-B, followed by dCDN-C, as well as the
discovery of the status of that activity, including the Error
Propagation.
uCDN-A dCDN-B dCDN-C
| | |
| (1) POST | |
| https://dcdn-b.example.com | |
| /triggers/uCDN-A | |
[ ]--------------------------->[ ]--+ |
| [ ] | (2) |
| [ ]<-+ |
| (3) HTTP 201 Response. [ ] |
|<----------------------------[ ] |
| Loc: [ ] |
| https://dcdn-b.example.com [ ] (4) POST |
Sopher, et al. Expires 5 September 2024 [Page 22]
Internet-Draft CDN Interconnect Triggers March 2024
| /triggers/uCDN-A/123 [ ] https://dcdn-c.example.com |
| [ ] /triggers/dCDN-B | (5)
| [ ]--------------------------->[ ]--+
| | [ ] |
| | [ ]<-+
| | (6) HTTP 201 Response. [ ]
| [ ]<---------------------------[ ]
| | Loc: |
| | https://dcdn-c.example.com |
| | /triggers/dCDN-B/456 |
| | |
| [ ]--+ |
| [ ] | (7.1) |
| [ ]<-+ [ ]--+
| | (7.2) [ ] |
| | [ ]<-+
| | |
. . .
. . .
. . .
| | (8) GET |
| | https://dcdn-c.example.com |
| | /triggers/dCDN-B/456 |
| [ ]--------------------------->[ ]
| | [ ]
| | (9) HTTP 200 [ ]
| | Trigger Status Resource [ ]
| [ ]<---------------------------[ ]
| | |
. . .
. . .
. . .
| (10) GET | |
| https://dcdn-b.example.com | |
| /triggers/uCDN-A/123 | |
[ ]--------------------------->[ ] |
| [ ] |
| (11) HTTP 200 [ ] |
| Trigger Status Resource [ ] |
[ ]<---------------------------[ ] |
Figure 2: CDNI Message Flow for Triggers, Including Error Propagation
The steps in Figure 2 are as follows:
Sopher, et al. Expires 5 September 2024 [Page 23]
Internet-Draft CDN Interconnect Triggers March 2024
1. The uCDN-A triggers action in the dCDN-B by POSTing a CI/T
Command to a collection of Trigger Status Resources
"https://dcdn-b.example.com/triggers/uCDN-A". This URL was
given to the uCDN-A when the CI/T interface was established.
2. The dCDN-B authenticates the request, validates the CI/T
Command, and, if it accepts the request, creates a new Trigger
Status Resource.
3. The dCDN-B responds to the uCDN-A with an HTTP 201 response
status and the location of the Trigger Status Resource.
4. The dCDN-B triggers the action in the dCDN-C by POSTing a CI/T
Command to a collection of Trigger Status Resources
"https://dcdn-c.example.com/triggers/dCDN-B". This URL was
given to the dCDN-B when the CI/T interface was established.
5. The dCDN-C authenticates the request, validates the CI/T
Command, and, if it accepts the request, creates a new Trigger
Status Resource.
6. The dCDN-C responds to the dCDN-B with an HTTP 201 response
status and the location of the Trigger Status Resource.
7. The dCDN-C acts upon the CI/T Command. However, the command
fails at dCDN-C as, for example, the Trigger Specification
contains an "action type" that is not supported by dCDN-C.
dCDN-C's action is depicted by 7.2 in the diagram, while 7.1
shows dCDN-B acting on its own command.
8. The dCDN-B queries, possibly repeatedly, the Trigger Status
Resource in dCDN-C.
9. The dCDN-C responds with the Trigger Status Resource, describing
the progress or results of the CI/T Trigger Command. In the
described flow, the returned Status is "failed", with an
Error.v2 Description Object holding an "eunsupported" Error Code
reflecting the status response.
10. The uCDN-A queries, possibly repeatedly, the Trigger Status
Resource in dCDN-B.
Sopher, et al. Expires 5 September 2024 [Page 24]
Internet-Draft CDN Interconnect Triggers March 2024
11. The dCDN-B responds with the Trigger Status Resource, describing
the progress or results of the CI/T Trigger Command. In the
flow described above, the returned Status is "failed", and the
"eunsupported" error received in the trigger status resource
from dCDN-C is propagated along with dCDN-C PID by adding it to
the errors array in dCDN-B's own status resource to be sent back
to the originating uCDN-A.
6. CI/T Object Properties and Encoding
The CI/T Trigger Command, CI/T Cancel Command, Trigger Status
Resources, and Trigger Collections, as well as their properties, are
encoded using JSON, as defined in Sections Section 6.1.1,
Section 6.1.2, Section 6.1.3, and Section 6.1.4, respectively. They
MUST use the MIME media type "application/cdni", with parameter
"ptype" values as defined below and in Section 11.1.
Names in JSON are case sensitive. The names and literal values
specified in the present document MUST always use lowercase.
JSON types, including "object", "array", "number", and "string", are
defined in [RFC8259].
Unrecognized name/value pairs in JSON objects SHOULD NOT be treated
as an error by either the uCDN or dCDN. They SHOULD be ignored
during processing and passed on by the dCDN to any further dCDNs in a
cascade.
6.1. CI/T Objects
The top-level objects defined by the CI/T interface are described in
this section.
The encoding of values used by these objects is described in
Section 6.2.
6.1.1. CI/T Trigger Command
CI/T Trigger Command, which is used to create a new trigger, MUST use
a MIME media type of "application/cdni; ptype=ci-trigger-
command.trigger.v2".
A CI/T Trigger Command is encoded as a JSON object containing the
following name/value pairs.
Name: trigger
Description: A specification of the trigger action and a set of
targets upon which to act.
Sopher, et al. Expires 5 September 2024 [Page 25]
Internet-Draft CDN Interconnect Triggers March 2024
Value: A Trigger.v2 Specification, as defined in Section 6.2.1.
Mandatory: Yes.
Name: cdn-path
Description: The CDN PIDs of CDNs that have already issued the
CI/T Command to their dCDNs.
Value: A non-empty JSON array of JSON strings, where each
string is a CDN PID as defined in Section 5.6.
Mandatory: Yes.
6.1.2. CI/T Cancel Command
CI/T Cancel Command, which is used to cancel an existing trigger,
MUST use a MIME media type of "application/cdni; ptype=ci-trigger-
command.cancel".
A CI/T Cancel Command is encoded as an empty JSON object.
6.1.3. Trigger Status Resources
Trigger Status Resources MUST use a MIME media type of "application/
cdni; ptype=ci-trigger-status.v2".
A Trigger Status Resource is encoded as a JSON object containing the
following name/value pairs.
Name: trigger
Description: The Trigger Specification POSTed in the body of
the CI/T Command. Note that this need not be a byte-for-byte
copy. For example, in the JSON representation the dCDN may re-
serialize the information differently.
Value: A Trigger.v2 Specification, as defined in Section 6.2.1.
Mandatory: Yes.
Name: ctime
Description: Time at which the CI/T Command was received by the
dCDN. Time is determined by the dCDN; there is no requirement
to synchronize clocks between interconnected CDNs.
Value: Absolute Time, as defined in Section 6.2.4.
Mandatory: Yes.
Sopher, et al. Expires 5 September 2024 [Page 26]
Internet-Draft CDN Interconnect Triggers March 2024
Name: mtime
Description: Time at which the Trigger Status Resource was last
modified. Time is determined by the dCDN; there is no
requirement to synchronize clocks between interconnected CDNs.
Value: Absolute Time, as defined in Section 6.2.4.
Mandatory: Yes.
Name: etime
Description: Estimate of the time at which the dCDN expects to
complete the activity. Time is determined by the dCDN; there
is no requirement to synchronize clocks between interconnected
CDNs.
Value: Absolute Time, as defined in Section 6.2.4.
Mandatory: No.
Name: status
Description: Current status of the triggered activity.
Value: Trigger Status, as defined in Section 6.2.6.
Mandatory: Yes.
Name: status-reason
Description: A human-readable explanation for the object
status.
Value: A JSON string, the human-readable status reason.
Mandatory: No.
Name: errors
Description: Descriptions of errors that have occurred while
processing a Trigger Command.
Value: An array of Error.v2 Descriptions, as defined in
Section 6.2.5. An empty array is allowed and is equivalent to
omitting "errors" from the object.
Mandatory: No.
6.1.4. Trigger Collections
Trigger Collections MUST use a MIME media type of "application/cdni;
ptype=ci-trigger-collection".
Sopher, et al. Expires 5 September 2024 [Page 27]
Internet-Draft CDN Interconnect Triggers March 2024
A Trigger Collection is encoded as a JSON object containing the
following name/value pairs.
Name: triggers
Description: Links to Trigger Status Resources in the
collection.
Value: A JSON array of zero or more URLs, represented as JSON
strings.
Mandatory: Yes.
Name: staleresourcetime
Description: The length of time for which the dCDN guarantees
to keep a completed Trigger Status Resource. After this time,
the dCDN SHOULD delete the Trigger Status Resource and all
references to it from collections.
Value: A JSON number, which must be a positive integer,
representing time in seconds.
Mandatory: Yes, in the collection of all Trigger Status
Resources if the dCDN deletes stale entries. If the property
is present in the filtered collections, it MUST have the same
value as in the collection of all Trigger Status Resources.
Name: coll-all
Description: Link to a Trigger Collection representing all
Trigger Status Resources.
Value: A URL represented as a JSON string.
Mandatory: Links to all of the filtered collections are
mandatory in the collection of all Trigger Status Resources, if
the dCDN implements the filtered collections. Otherwise,
optional.
Name: coll-pending
Description: Link to a Trigger Collection representing Trigger
Status Resources that have been accepted but not yet acted
upon.
Value: A URL represented as a JSON string.
Mandatory: Links to all of the filtered collections are
mandatory in the collection of all Trigger Status Resources, if
the dCDN implements the filtered collections. Otherwise,
optional.
Sopher, et al. Expires 5 September 2024 [Page 28]
Internet-Draft CDN Interconnect Triggers March 2024
Name: coll-active
Description: Link to a Trigger Collection representing Trigger
Status Resources that are currently being processed in the
dCDN.
Value: A URL represented as a JSON string.
Mandatory: Links to all of the filtered collections are
mandatory in the collection of all Trigger Status Resources, if
the dCDN implements the filtered collections. Otherwise,
optional.
Name: coll-complete
Description: Link to a Trigger Collection representing Trigger
Status Resources that completed successfully.
Value: A URL represented as a JSON string.
Mandatory: Links to all of the filtered collections are
mandatory in the collection of all Trigger Status Resources, if
the dCDN implements the filtered collections. Otherwise,
optional.
Name: coll-failed
Description: Link to a Trigger Collection representing Trigger
Status Resources that failed or were cancelled by the uCDN.
Value: A URL represented as a JSON string.
Mandatory: Links to all of the filtered collections are
mandatory in the collection of all Trigger Status Resources, if
the dCDN implements the filtered collections. Otherwise,
optional.
Name: cdn-id
Description: The CDN PID of the dCDN.
Value: A JSON string, the dCDN's CDN PID, as defined in
Section 5.6.
Mandatory: Only in the collection of all Trigger Status
Resources, if the dCDN implements the filtered collections.
Optional in the filtered collections (the uCDN can always find
the dCDN's cdn-id in the collection of all Trigger Status
Resources, but the dCDN can choose to repeat that information
in its implementation of filtered collections).
Sopher, et al. Expires 5 September 2024 [Page 29]
Internet-Draft CDN Interconnect Triggers March 2024
6.2. Properties of CI/T Objects
This section defines the values that can appear in the top-level
objects described in Section 6.1 and their encodings.
6.2.1. Trigger.v2 Specification
A Trigger.v2 Specification is encoded as a JSON object containing the
following name/value pairs.
An unrecognized name/value pair in the Trigger Specification object
contained in a CI/T Command SHOULD be preserved in the Trigger
Specification of any Trigger Status Resource it creates. Note that
the preferred method for extending the CI/T capabilities is by
defining new related trigger specs and/or trigger extensions, rather
than adding new properties to the Trigger.v2 object.
Name: action
Description: Defines the type of the CI/T Trigger Action.
Value: Trigger Action Type, as defined in Section 3.1.
Mandatory: Yes.
Name: specs
Description: Array of trigger specs representing trigger's
targets.
Value: Array of GenericTriggerSpec objects (see
Section 6.2.2.1).
Mandatory: Yes. Furthermore, the list MUST NOT be empty.
Name: extensions
Description: Array of trigger extensions.
Value:Array of GenericTriggerExtension objects (see
Section 6.2.3.2).
Mandatory: No. The default is no extensions.
Sopher, et al. Expires 5 September 2024 [Page 30]
Internet-Draft CDN Interconnect Triggers March 2024
6.2.2. Generic Trigger Specs
A "trigger.v2" object, as defined in Section 6.2.1, includes an array
of trigger spec objects. Each trigger spec object contains
properties that are used as trigger target selection directives for
the dCDN when executing the trigger command, e.g., content URLs or
metadata URI patterns. Each such CDNI Trigger Spec is a
specialization of a CDNI GenericTriggerSpec object. The
GenericTriggerSpec object abstracts the basic information required
for trigger distribution from the specifics of any given property
(i.e., property semantics, enforcement options, etc.).
The semantics of the Trigger Specs list is additive, i.e., the
trigger applies to any object matching one of the listed specs.
6.2.2.1. Generic Spec Object
A GenericSpecObject object is a wrapper for managing individual CDNI
Trigger specs in an opaque manner.
Property: trigger-subject
Description: Case-insensitive CDNI Trigger subject.
Type: String containing the type of the subject matching the
generic-trigger-spec-value property, such as "content" or
"metadata" as define in Section 3.2.1.
Mandatory: Yes.
Property: generic-trigger-spec-type
Description: Case-insensitive CDNI Trigger spec type.
Type: String containing the spec type of the object contained
in the generic-trigger-spec-value property (see table in
Section 3.2).
Mandatory: Yes.
Property: generic-trigger-spec-value
Description:A CDNI Trigger spec object.
Type: Format/Type is defined by the value of the generic-
trigger-spec-type property.
Mandatory: Yes.
Sopher, et al. Expires 5 September 2024 [Page 31]
Internet-Draft CDN Interconnect Triggers March 2024
The structure of a JSON serialized GenericTriggerSpec object,
containing a specific trigger spec is illustrated below:
{
"generic-trigger-spec-type":
<Type of this trigger spec>,
"generic-trigger-spec-value":
{
<properties of this trigger spec object>
},
"generic-trigger-spec-subject":
<Category of this trigger spec subject>
}
6.2.3. CI/T Trigger Extensions
A "trigger.v2" object, as defined in Section 6.2.1 includes an
optional array of trigger extension objects. A trigger extension
contains properties that are used as directives for the dCDN when
executing the trigger command, e.g., location policies, time
policies, and so on. Each such CDNI Trigger extension is a
specialization of a CDNI GenericTriggerExtension object. The
GenericTriggerExtension object abstracts the basic information
required for trigger distribution from the specifics of any given
property (i.e., property semantics, enforcement options, etc.). All
trigger extensions are optional, and it is thus the responsibility of
the extension specification to define a consistent default behavior
for extensions supported by a dCDN when not specified by the uCDN.
6.2.3.1. Enforcement Options
The trigger enforcement options concept is in accordance with the
metadata enforcement options as defined in Section 3.2 of [RFC8006].
The GenericTriggerExtension object defines the properties contained
within it as well as whether or not the properties are "mandatory-to-
enforce". If the dCDN does not understand or support a mandatory-to-
enforce property, the dCDN MUST NOT execute the trigger command. If
the extension is not mandatory-to-enforce, then that
GenericTriggerExtension object can be safely ignored and the trigger
command can be processed in accordance with the rest of the CDNI
Trigger spec.
Although a CDN MUST NOT execute a trigger command if a mandatory-to-
enforce extension cannot be enforced, it could still be safe to
redistribute that trigger (the "safe-to-redistribute" property) to
Sopher, et al. Expires 5 September 2024 [Page 32]
Internet-Draft CDN Interconnect Triggers March 2024
another CDN without modification. For example, in the cascaded CDN
case, a transit CDN (tCDN) could convey mandatory-to-enforce trigger
extension to a dCDN. For a trigger extension that does not require
customization or translation (i.e., trigger extension that is safe-
to-redistribute), the data representation received off the wire MAY
be stored and redistributed without being understood or supported by
the tCDN. However, for trigger extension that requires translation,
transparent redistribution of the uCDN trigger values might not be
appropriate. Certain triggers extensions can be safely, though
perhaps not optimally, redistributed unmodified. For example, pre-
position command might be executed in suboptimal times for some
geographies if transparently redistributed, but it might still work.
Redistribution safety MUST be specified for each
GenericTriggerExtension listed. If a CDN does not understand or
support a given GenericTriggerExtension object that is not safe-to-
redistribute, the CDN MUST set the "incomprehensible" flag to true
for that GenericTriggerExtension object before redistributing it.
The "incomprehensible" flag signals to a dCDN that trigger metadata
was not properly transformed by the tCDN. A CDN MUST NOT attempt to
execute a trigger with an extension that has been marked as
"incomprehensible" by a uCDN.
tCDNs MUST NOT change the value of mandatory-to-enforce or safe-to-
redistribute when propagating a trigger to a dCDN. Although a tCDN
can set the value of "incomprehensible" to true, a tCDN MUST NOT
change the value of "incomprehensible" from true to false.
Table 5 describes the action to be taken by a tCDN for the different
combinations of mandatory-to-enforce ("MtE") and safe-to-redistribute
("StR") properties when the tCDN either does or does not understand
the trigger extension object in question:
Sopher, et al. Expires 5 September 2024 [Page 33]
Internet-Draft CDN Interconnect Triggers March 2024
+=======+=======+============+=================================+
| MtE | StR | Extension | Trigger action |
| | | object | |
| | | understood | |
| | | by tCDN | |
+=======+=======+============+=================================+
| False | True | True | Can execute and redistribute. |
+-------+-------+------------+---------------------------------+
| False | True | False | Can execute and redistribute. |
+-------+-------+------------+---------------------------------+
| False | False | False | Can execute. MUST set |
| | | | "incomprehensible" to true when |
| | | | redistributing. |
+-------+-------+------------+---------------------------------+
| False | False | True | Can execute. Can redistribute |
| | | | after transforming the trigger |
| | | | extension (if the CDN knows how |
| | | | to do so safely); otherwise, |
| | | | MUST set "incomprehensible" to |
| | | | true when redistributing. |
+-------+-------+------------+---------------------------------+
| True | True | True | Can execute and redistribute. |
+-------+-------+------------+---------------------------------+
| True | True | False | MUST NOT execute but can |
| | | | redistribute. |
+-------+-------+------------+---------------------------------+
| True | False | True | Can execute. Can redistribute |
| | | | after transforming the trigger |
| | | | extension (if the CDN knows how |
| | | | to do so safely); otherwise, |
| | | | MUST set "incomprehensible" to |
| | | | true when redistributing. |
+-------+-------+------------+---------------------------------+
| True | False | False | MUST NOT serve. MUST set |
| | | | "incomprehensible" to true when |
| | | | redistributing. |
+-------+-------+------------+---------------------------------+
Table 5: Action to be taken by a tCDN for the different
combinations of MtE and StR properties
Table 6 describes the action to be taken by a dCDN for the different
combinations of mandatory-to-enforce and "incomprehensible"
("Incomp") properties, when the dCDN either does or does not
understand the trigger extension object in question:
Sopher, et al. Expires 5 September 2024 [Page 34]
Internet-Draft CDN Interconnect Triggers March 2024
+=======+========+==================+==========================+
| MtE | Incomp | Extension object | Trigger action |
| | | understood by | |
| | | dCDN | |
+=======+========+==================+==========================+
| False | False | True | Can execute. |
+-------+--------+------------------+--------------------------+
| False | True | True | Can execute but MUST NOT |
| | | | interpret/apply any |
| | | | trigger extension marked |
| | | | as "incomprehensible". |
+-------+--------+------------------+--------------------------+
| False | False | False | Can execute. |
+-------+--------+------------------+--------------------------+
| False | True | False | Can execute but MUST NOT |
| | | | interpret/apply any |
| | | | trigger extension marked |
| | | | as "incomprehensible". |
+-------+--------+------------------+--------------------------+
| True | False | True | Can execute. |
+-------+--------+------------------+--------------------------+
| True | True | True | MUST NOT execute. |
+-------+--------+------------------+--------------------------+
| True | False | False | MUST NOT execute. |
+-------+--------+------------------+--------------------------+
| True | True | False | MUST NOT execute. |
+-------+--------+------------------+--------------------------+
Table 6: Action to be taken by a dCDN for the different
combinations of MtE and Incomp properties
6.2.3.2. GenericExtensionObject
A GenericTriggerExtension object is a wrapper for managing individual
CDNI Trigger extensions in an opaque manner.
Property: generic-trigger-extension-type
Description: Case-insensitive CDNI Trigger extension object
type.
Type: String containing the CDNI Extension Type [RFC7736] of
the object contained in the generic-trigger-extension-value
property (see table in Section 3.3).
Mandatory: Yes.
Property: generic-trigger-extension-value
Sopher, et al. Expires 5 September 2024 [Page 35]
Internet-Draft CDN Interconnect Triggers March 2024
Description: CDNI Trigger extension object.
Type: Format/Type is defined by the value of the generic-
trigger-extension-type property above.
Mandatory: Yes.
Property: mandatory-to-enforce
Description: Flag identifying whether or not the enforcement of
this trigger extension is mandatory.
Type: Boolean
Mandatory: No. Default is to treat the trigger extension as
mandatory-to-enforce (i.e., a value of True).
Property: safe-to-redistribute
Description: Flag identifying whether or not this trigger
extension can be safely redistributed without modification,
even if the CDN fails to understand the extension.
Type: Boolean
Mandatory: No. Default is to allow transparent redistribution
(i.e., a value of True).
Property: incomprehensible
Description: Flag identifying whether or not any CDN in the
chain of delegation has failed to understand and/or failed to
properly transform this trigger extension object. Note: This
flag only applies to trigger extension objects whose safe-to-
redistribute property has a value of False.
Type: Boolean
Mandatory: No. Default is comprehensible (i.e., a value of
False).
The structure of a JSON serialized GenericTriggerExtension object
containing a specific trigger extension object is illustrated below:
Sopher, et al. Expires 5 September 2024 [Page 36]
Internet-Draft CDN Interconnect Triggers March 2024
{
"generic-trigger-extension-type":
<Type of this trigger extension object>,
"generic-trigger-extension-value":
{
<properties of this trigger extension object>
},
"mandatory-to-enforce": <bool>,
"safe-to-redistribute": <bool>,
"incomprehensible": <bool>
}
6.2.4. Absolute Time
A JSON number, seconds since the UNIX epoch (00:00:00 UTC on 1
January 1970).
6.2.5. Error.v2 Description
An Error.v2 Description is used to report the failure of a CI/T
Command or failure in the activity it triggered. It is encoded as a
JSON object with the following name/value pairs:
Name: error
Value: Error Code, as defined in Section 6.2.7.
Mandatory: Yes.
Name: description
Description: A human-readable description of the error.
Value: A JSON string, the human-readable description.
Mandatory: No.
Name: specs
Description: Array of trigger spec objects from the
corresponding "specs" array at the Trigger Specification. Only
those spec to which the error applies are listed.
Value: Array Trigger Specifications, as defined in
Section 6.2.1, where each spec object MUST be exactly as they
appear in the request.
Mandatory: Yes.
Name: extensions
Sopher, et al. Expires 5 September 2024 [Page 37]
Internet-Draft CDN Interconnect Triggers March 2024
Description: Array of trigger extension objects copied from the
corresponding "extensions" array from the Trigger
Specification. Only those extensions to which the error
applies are included, but those extensions MUST be exactly as
they appear in the request.
Value: Array of GenericTriggerExtension objects, where each
extension object is copied from the "extensions" array values
in the Trigger Specification.
Mandatory: No. The "extensions" array SHOULD be used only if
the error relates to extension objects. Property omission
should be interpreted as "the error is not related to any
extension".
Name: cdn-id
Description: The CDN PID of the CDN where the error occurred.
The "cdn-id" property is used by the originating uCDN or by the
propagating dCDN in order to distinguish in which CDN the error
occurred.
Value: A non-empty JSON string, where the string is a CDN PID
as defined in Section Section 5.6
Mandatory: Yes. The dCDN may use its own CDN PID if it does not
want to expose the CDN PIDs of dCDNs.
Example of a JSON serialized Error.v2 Description object reporting a
malformed Playlist:
{
"error": "econtent",
"description": "Failed to parse HLS playlist",
"specs": [
{
"trigger-subject": "content",
"generic-trigger-spec-type": "content-playlist",
"generic-trigger-spec-value": {
"playlist": "https://www.example.com/hls/title/index.m3u8",
"media-protocol": "hls"
}
}
],
"cdn": "AS64500:0"
},
Example of a JSON serialized Error.v2 Description object reporting an
unsupported extension object:
Sopher, et al. Expires 5 September 2024 [Page 38]
Internet-Draft CDN Interconnect Triggers March 2024
{
"errors": [
{
"error": "eextension",
"description": "unrecognized extension <type>",
"specs": [
{
"trigger-subject": "content",
"generic-trigger-spec-type": "urls",
"generic-trigger-spec-value": {
"urls": [
"https://www.example.com/a/b/c/1",
"https://www.example.com/a/b/c/2"
]
}
}
],
"extensions": [
{
"generic-trigger-extension-type":
<Type of this erroneous trigger extension object>,
"generic-trigger-extension-value":
{
<properties of this erroneous trigger extension object>
},
}
],
"cdn": "AS64500:0"
},
]
}
6.2.6. Trigger Status
Trigger Status describes the current status of the triggered
activity. It MUST be one of the JSON strings in the following table:
Sopher, et al. Expires 5 September 2024 [Page 39]
Internet-Draft CDN Interconnect Triggers March 2024
+=============+==============================+
| JSON String | Description |
+=============+==============================+
| pending | The CI/T Trigger Command has |
| | not yet been acted upon. |
+-------------+------------------------------+
| active | The CI/T Trigger Command is |
| | currently being acted |
+-------------+------------------------------+
| | upon. |
+-------------+------------------------------+
| complete | The CI/T Trigger Command |
| | completed successfully. |
+-------------+------------------------------+
| processed | The CI/T Trigger Command has |
| | been accepted, and no |
+-------------+------------------------------+
| | further status update will |
| | be made (can be used in |
+-------------+------------------------------+
| | cases where completion |
| | cannot be confirmed). |
+-------------+------------------------------+
| failed | The CI/T Trigger Command |
| | could not be completed. |
+-------------+------------------------------+
| cancelling | Processing of the CI/T |
| | Trigger Command is still in |
+-------------+------------------------------+
| | progress, but the CI/T |
| | Trigger Command has been |
+-------------+------------------------------+
| | cancelled by the uCDN. |
+-------------+------------------------------+
| cancelled | The CI/T Trigger Command was |
| | cancelled by the uCDN. |
+-------------+------------------------------+
Table 7
Along with the Trigger Status, the Trigger Status Resource object
includes a Status Reason property, allowing the dCDN to provide
additional information for the trigger status. For example, the dCDN
may indicate that the trigger status is "pending" due to one of the
execution prerequisites not being fulfilled. Such a prerequisite may
possibly be specified via one of the extensions.
Sopher, et al. Expires 5 September 2024 [Page 40]
Internet-Draft CDN Interconnect Triggers March 2024
6.2.7. Error Code
This type is used by the dCDN to report failures in trigger
processing. All Error Codes MUST be registered in the IANA "CDNI CI/
T Error Codes" registry (see Section 11.7). Unknown Error Codes MUST
be treated as fatal errors, and the request MUST NOT be automatically
retried without modification.
The following Error Codes are defined by this document and MUST be
supported by an implementation of the CI/T interface utilizing the
ci-trigger-command.trigger.v2 and the ci-trigger-status.v2 objects.
+==============+====================================+==============+
| Error Code | Description | Registration |
+==============+====================================+==============+
| emeta | The dCDN was unable to acquire | RFCthis |
| | metadata required to fulfill the | |
| | request. | |
+--------------+------------------------------------+--------------+
| econtent | The dCDN was unable to acquire | RFCthis |
| | content (CI/T "preposition" | |
| | commands only). | |
+--------------+------------------------------------+--------------+
| eperm | The uCDN does not have permission | RFCthis |
| | to issue the CI/T Command (for | |
| | example, the data is owned by | |
| | another CDN). | |
+--------------+------------------------------------+--------------+
| ereject | The dCDN is not willing to fulfill | RFCthis |
| | the CI/T Command (for example, a | |
| | "preposition" request for content | |
| | at a time when the dCDN would not | |
| | accept Request Routing requests | |
| | from the uCDN). | |
+--------------+------------------------------------+--------------+
| ecdn | An internal error in the dCDN or | RFCthis |
| | one of its dCDNs. | |
+--------------+------------------------------------+--------------+
| ecancelled | The uCDN cancelled the request. | RFCthis |
+--------------+------------------------------------+--------------+
| eunsupported | The Trigger Specification | RFCthis |
| | contained an "action type" that is | |
| | not supported by the dCDN. No | |
| | action was taken by the dCDN other | |
| | than to create a Trigger Status | |
| | Resource in state "failed". | |
+--------------+------------------------------------+--------------+
| espec | An error occurred while parsing a | RFCthis |
Sopher, et al. Expires 5 September 2024 [Page 41]
Internet-Draft CDN Interconnect Triggers March 2024
| | generic trigger spec, or that the | |
| | specific trigger spec is not | |
| | supported by the CDN. | |
+--------------+------------------------------------+--------------+
| esubject | An error occurred while parsing a | RFCthis |
| | trigger subject, or that the | |
| | specific trigger subject is not | |
| | supported by the CDN. | |
+--------------+------------------------------------+--------------+
| eextension | An error occurred while parsing a | RFCthis |
| | generic trigger extension, or that | |
| | the specific extension is not | |
| | supported by the CDN. | |
+--------------+------------------------------------+--------------+
Table 8
7. Trigger Spec Objects
The objects defined below are intended to be used in the
GenericTriggerSpec object's generic-trigger-spec-value field as
defined in Section Section 6.2.2.1. As such all these trigger specs
are registered in the IANA "CDNI CI/T Trigger Specs" registry (see
Section 11.3).
7.1. URLs Spec
The urls spec type allows the uCDN to manage uCDN content or metadata
objects held by the dCDN based on the objects' URLs.
Spec object specification
Property: urls
Description: An array of URLs over which the trigger MUST be
executed.
Value: A JSON array of URLs represented as JSON strings.
Mandatory: Yes.
Below is an example of a JSON serialized generic trigger spec object,
matching the metadata at metadata.example.com/a/b/c.
Sopher, et al. Expires 5 September 2024 [Page 42]
Internet-Draft CDN Interconnect Triggers March 2024
{
"trigger-subject": "metadata",
"generic-trigger-spec-type": "urls",
"generic-trigger-spec-value": {
"urls": [
"https://metadata.example.com/a/b/c"
]
}
}
7.2. CCIDs Spec
The content-ccids spec type allows the uCDN to specify the Content
Collection IDentifier of content to which the trigger applies. The
"ccid" is a grouping of content as defined by [RFC8006]. The ccid
spec type is valid only for the content spec subject (see
Section 3.2.1).
Spec object specification
Property: ccids
Description: An array of Content Collection IDentifiers over
which the trigger MUST be executed.
Value: A JSON array of strings, where each string is a Content
Collection IDentifier.
Mandatory: Yes.
7.3. URI Pattern Match Spec
The uri-pattern match spec type allows the uCDN to manage uCDN
content or metadata objects held by the dCDN based on the objects'
URI pattern. The value is a UriPatternMatch object, as defined in
Section 7.3.1.
7.3.1. UriPatternMatch
A UriPatternMatch consists of a string pattern to match against a
URI, and flags describing the type of match.
It is encoded as a JSON object with the following name/value
pairs:
Name: pattern
Description: A pattern for URI matching.
Sopher, et al. Expires 5 September 2024 [Page 43]
Internet-Draft CDN Interconnect Triggers March 2024
Value: A JSON string representing the pattern. The pattern can
contain the wildcards * and ?, where * matches any sequence of
[RFC3986] pchar or "/" characters (including the empty string) and
? matches exactly one [RFC3986] pchar character. The three
literals $, * and ? MUST be escaped as $$, $* and $? (where $ is
the designated escape character). All other characters are
treated as literals.
Mandatory: Yes.
Name: case-sensitive
Description: Flag indicating whether or not case-sensitive
matching should be used.
Value: One of the JSON values "true" (the matching is case
sensitive) or "false" (the matching is case insensitive).
Mandatory: No; default is "false", i.e., a case-insensitive
match.
Name: match-query-string
Description: Flag indicating whether to include the query part
of the URI when comparing against the pattern.
Value: One of the JSON values "true" (the full URI, including
the query part, should be compared against the given pattern)
or "false" (the query part of the URI should be dropped before
comparison with the given pattern).
Mandatory: No; default is "false". The query part of the URI
should be dropped before comparison with the given pattern.
Example of case-sensitive prefix match against
"https://www.example.com/trailers/":
{
"pattern": "https://www.example.com/trailers/*",
"case-sensitive": true
}
7.4. URI Regex Match Spec
The content-uri-regexes spec type allows the uCDN to manage content
or metadata objects held by the dCDN based on the objects' URI regex.
Sopher, et al. Expires 5 September 2024 [Page 44]
Internet-Draft CDN Interconnect Triggers March 2024
7.4.1. RegexMatch
A RegexMatch consists of a regular expression string a URI is matched
against, and flags describing the type of match. It is encoded as a
JSON object with following properties:
Property: regex
Description: A regular expression for URI matching.
Type: A regular expression to match against the URI, i.e.,
against the path-absolute and the query string parameters
[RFC3986]. The regular expression string MUST be compatible
with POSIX [POSIX.1] Section 9 Extended Regular Expressions.
This regular expression MUST be evaluated in the POSIX locate
(POSIX [POSIX.1] Section 7.2).
Note: Because '\' has a special meaning in JSON [RFC8259] as
the escape character within JSON strings, the regular
expression character '\' MUST be escaped as '\\'.
Mandatory: Yes.
Property: case-sensitive
Description: Flag indicating whether or not case-sensitive
matching should be used.
Type: JSON boolean. Either "true" (the matching is case
sensitive) or "false" (the matching is case insensitive).
Mandatory: No; default is “false”, i.e., a case-insensitive
match.
Property: match-query-string
Description: Flag indicating whether to include the query part
of the URI when comparing against the regex.
Type: JSON boolean. Either "true" (the full URI, including the
query part, should be compared against the regex) or "false"
(the query part of the URI should be dropped before comparison
with the given regex).
Mandatory: No; default is "false". The query part of the URI
MUST be dropped before comparison with the given regex. This
makes the regular expression simpler and safer for cases in
which the query parameters are not relevant for the match.
Sopher, et al. Expires 5 September 2024 [Page 45]
Internet-Draft CDN Interconnect Triggers March 2024
Example of a case sensitive, no query parameters, regex match
against:
"^(https:\/\/video\.example\.com)\/([a-z])\/
movie1\/([1-7])\/*(index.m3u8|\d{3}.ts)$"
{
"regex": "^(https:\\/\\/video\\.example\\.com)\\/([a-z])\\/movie1\
\/([1-7])\\/*(index.m3u8|\\d{3}.ts)$",
"case-sensitive": true,
"match-query-string": false
}
This regex matches URLs of domain video.example.com where the path
structure is /(single lower case letter)/(name-of-title)/(single
digit between 1 to 7)/(index.m3u8 or a 3 digit number with ts
extension). For example:
https://video.example.com/d/movie1/5/index.m3u8
or
https://video.example.com/k/movie1/4/013.ts
7.5. Content Playlist Spec
The content-playlist spec type allows the uCDN to manage content held
by the dCDN based on the content's playlist. The content-playlist
spec type is valid only for the content spec subject (see
Section 3.2.1).
7.5.1. Playlist
A Playlist consists of a full URL and a media protocol identifier.
An implementation that supports a specific playlist media protocol
MUST be able to parse playlist files of that protocol type and
extract, possibly recursively, the URLs to all media objects and/or
sub playlist files, and apply the trigger to each one of them
separately.
Playlist is encoded as a JSON object with following properties:
Property: playlist
Description: A URL to the playlist file.
Type: A URL represented as a JSON string.
Mandatory: Yes.
Sopher, et al. Expires 5 September 2024 [Page 46]
Internet-Draft CDN Interconnect Triggers March 2024
Property: media-protocol
Description: Media protocol to be used when parsing and
interpreting this playlist.
Type: MediaProtocol (see Section 7.5.2).
Mandatory: Yes.
Example of a JSON serialized HLS playlist object:
{
"playlist": "https://www.example.com/hls/title/index.m3u8",
"media-protocol": "hls"
}
7.5.2. MediaProtocol
Media Protocol objects are used to specify registered type of media
protocol (see Section 11.5) used for protocol related operations like
pre-position according to playlist.
The following table defines the initial MediaProtocol JSON string
values corresponding to the HLS, MSS, and DASH protocols:
+========+==================+===============+===============+
| JSON | Description | Specification | Protocol |
| string | | | Specification |
+========+==================+===============+===============+
| hls | HTTP Live | RFCthis | RFC 8216 |
| | Streaming | | [RFC8216] |
+--------+------------------+---------------+---------------+
| mss | Microsoft Smooth | RFCthis | MSS [MSS] |
| | Streaming | | |
+--------+------------------+---------------+---------------+
| dash | Dynamic Adaptive | RFCthis | MPEG-DASH |
| | Streaming over | | [MPEG-DASH] |
| | HTTP (MPEG-DASH) | | |
+--------+------------------+---------------+---------------+
Table 9
[RFC Editor: Please replace RFCthis with the published RFC number for
this document.]
Sopher, et al. Expires 5 September 2024 [Page 47]
Internet-Draft CDN Interconnect Triggers March 2024
8. Trigger Extension Objects
The objects defined below are intended to be used in the
GenericTriggerExtension object's generic-trigger-extension-value
field as defined in Section 6.2.3.2, and their generic-trigger-
extension-type property MUST be set to the appropriate Extension Type
as defined in Section 3.3 .
8.1. LocationPolicy extension
A content operation may be relevant for a specific geographical
region, or need to be excluded from a specific region. In this case,
the trigger should be applied only to parts of the network that are
either "included" or "not excluded" by the location policy. Note
that the restrictions here are on the cache location rather than the
client location.
The LocationPolicy object defines which CDN or cache locations for
which the trigger command is relevant.
Example use cases:
* Pre-position: Certain contracts allow for pre-positioning or
availability of contract in all regions except for certain
excluded regions in the world, including caches. For example,
some content cannot ever knowingly touch servers in a specific
country, including cached content. Therefore, these regions MUST
be excluded from a pre-positioning operation.
* Purge: In certain cases, content may have been located on servers
in regions where the content must not reside. In such cases, a
purge operation to remove content specifically from that region is
required.
Object specification
Property: locations
Description: An Access List that allows or denies (blocks) the
trigger execution per cache location.
Type: Array of LocationRule objects (see Section 4.2.2.1 of
[RFC8006])
Mandatory: Yes.
Sopher, et al. Expires 5 September 2024 [Page 48]
Internet-Draft CDN Interconnect Triggers March 2024
If a location policy object is not listed within the trigger command,
the default behavior is to execute the trigger in all available
caches and locations of the dCDN.
The trigger command is allowed, or denied, for a specific cache
location according to the action of the first location whose
footprint matches against that cache's location. If two or more
footprints overlap, the first footprint that matches against the
cache's location determines the action a CDN MUST take. If the
"locations" property is an empty list or if none of the listed
footprints match the location of a specific cache location, then the
result is equivalent to a "deny" action.
Following is an example of a JSON serialized generic trigger
extension object containing a location policy object that allows the
trigger execution in the US but blocks its execution in Canada:
{
"generic-trigger-extension-type": "location-policy",
"generic-trigger-extension-value":
{
"locations": [
{
"action": "allow",
"footprints": [
{
"footprint-type": "countrycode",
"footprint-value": ["us"]
}
]
},
{
"action": "deny",
"footprints": [
{
"footprint-type": "countrycode",
"footprint-value": ["ca"]
}
]
}
]
},
"mandatory-to-enforce": true,
"safe-to-redistribute": true,
"incomprehensible": false
}
Sopher, et al. Expires 5 September 2024 [Page 49]
Internet-Draft CDN Interconnect Triggers March 2024
8.2. TimePolicy Extension
A uCDN may wish to perform content management operations on the dCDN
on a specific schedule. The TimePolicy extensions allows the uCDN to
instruct the dCDN to execute the trigger command in a desired time
window. For example, a content provider that wishes to pre-populate
a new episode at off-peak time so that it would be ready on caches at
prime time when the episode is released for viewing. A scheduled
operation enables the uCDN to direct the dCDN in what time frame to
execute the trigger.
A uCDN may wish to schedule a trigger such that the dCDN will execute
it in local time, as it is measured in each region. For example, a
uCDN may wish the dCDN to pull the content at off-peak hours, between
2AM-4AM, however, as a CDN is distributed across multiple time zones,
the UTC definition of 2AM depends on the actual location.
We define two alternatives for localized scheduling:
* Regional schedule: When used in conjunction with the Location
Policy defined in Section 8.1, the uCDN can trigger separate
commands for different geographical regions, for each region using
a different schedule. This allows the uCDN to control the
execution time per region.
* Local Time schedule: We introduce a "local time" version for
Internet timestamps that follows the notation for local time as
defined in Section 4.2.2 of [ISO8601]. When local time is used,
that dCDN SHOULD execute the triggers at different absolute times,
according the local time of each execution location.
Object specification
Property: unix-time-window
Description: A UNIX epoch time window in which the trigger
SHOULD be executed.
Type: TimeWindow object using UNIX epoch timestamps (see
Section 4.2.3.2 of [RFC8006])
Mandatory: No, but exactly one of "unixEpochWindow",
"utcWindow" or "localTimeWindow" MUST be present.
Property: utc-window
Description: A UTC time window in which the trigger SHOULD be
executed.
Sopher, et al. Expires 5 September 2024 [Page 50]
Internet-Draft CDN Interconnect Triggers March 2024
Type: UTCWindow object as defined in Section 8.2.1.
Mandatory: No, but exactly one of "unixEpochWindow",
"utcWindow" or "localTimeWindow" MUST be present.
Property: local-time-window
Description: A local time window. The dCDN SHOULD execute the
trigger at the defined time frame, interpreted as the the local
time per location.
Type: LocalTimeWindow object as defined in Section 8.2.2.
Mandatory: No, but exactly one of "unixEpochWindow",
"utcWindow" or "localTimeWindow" MUST be present.
If a time policy object is not listed within the trigger command, the
default behavior is to execute the trigger in a time frame most
suitable to the dCDN taking under consideration other constraints and
/ or obligations.
Example of a JSON serialized generic trigger extension object
containing a time policy object that schedules the trigger execution
to a window between 09:00 01/01/2000 UTC and 17:00 01/01/2000 UTC,
using the "unix-time-window" property:
{
"generic-trigger-extension-type": "time-policy",
"generic-trigger-extension-value":
{
"unix-time-window": {
"start": 946717200,
"end": 946746000
}
},
"mandatory-to-enforce": true,
"safe-to-redistribute": true,
"incomprehensible": false
}
8.2.1. UTCWindow
A UTCWindow object describes a time range in UTC or UTC and a zone
offset that can be applied by a TimePolicy.
Property: start
Description: The start time of the window.
Sopher, et al. Expires 5 September 2024 [Page 51]
Internet-Draft CDN Interconnect Triggers March 2024
Type: Internet date and time as defined in [RFC3339].
Mandatory: No, but at least one of "start" or "end" MUST be
present and non-empty.
Property: end
Description: The end time of the window.
Type: Internet date and time as defined in [RFC3339].
Mandatory: No, but at least one of "start" or "end" MUST be
present and non-empty.
Example JSON serialized UTCWindow object that describes a time window
from 02:30 01/01/2000 UTC to 04:30 01/01/2000 UTC:
{
"start": "2000-01-01T02:30:00.00Z",
"end": "2000-01-01T04:30:00.00Z"
}
Example JSON serialized UTCWindow object that describes a time window
in New York time zone offset UTC-05:00 from 02:30 01/01/2000 to 04:30
01/01/2000:
{
"start": "2000-01-01T02:30:00.00-05:00",
"end": "2000-01-01T04:30:00.00-05:00"
}
8.2.2. LocalTimeWindow
A LocalTimeWindow object describes a time range in local time. The
reader of this object MUST interpret it as "the local time at the
location of execution". For example, if the time window states 2AM
to 4AM local time then a dCDN that has presence in both London (UTC)
and New York (UTC-05:00) will execute the trigger at 2AM-4AM UTC in
London and at 2AM-4AM UTC-05:00 in New York.
Property: start
Description: The start time of the window.
Type: JSON string formatted as DateLocalTime as defined in
Section 8.2.3.
Sopher, et al. Expires 5 September 2024 [Page 52]
Internet-Draft CDN Interconnect Triggers March 2024
Mandatory: No, but at least one of "start" or "end" MUST be
present and non-empty.
Property: end
Description: The end time of the window.
Type: JSON string formatted as DateLocalTime as defined in
Section 8.2.3.
Mandatory: No, but at least one of "start" or "end" MUST be
present and non-empty.
Example JSON serialized LocalTimeWindow object that describes a local
time window from 02:30 01/01/2000 to 04:30 01/01/2000.
{
"start": "2000-01-01T02:30:00.00",
"end": "2000-01-01T04:30:00.00"
}
8.2.3. DateLocalTime
DateLocalTime is a timestamp that follows the date and local time
notation in Section 4.3.2 of [ISO8601] as a complete date and time
extended representation, where the time zone designator is omitted.
In addition, for simplicity and as exact accuracy is not an objective
in this case, this specification does not support the decimal
fractions of seconds, and does not take leap second into
consideration.
Type: JSON string using the format "date-local-time" as defined in
Section 8.2.3.1.
8.2.3.1. Date and Local Time Format
The Date and Local Time format is specified here using the syntax
description notation defined in [ABNF].
Sopher, et al. Expires 5 September 2024 [Page 53]
Internet-Draft CDN Interconnect Triggers March 2024
date-fullyear = 4DIGIT
date-month = 2DIGIT ; 01-12
date-mday = 2DIGIT ; 01-28, 01-29, 01-30, 01-31 based on
; month/year
time-hour = 2DIGIT ; 00-23
time-minute = 2DIGIT ; 00-59
time-second = 2DIGIT ; 00-59 leap seconds are not supported
local-time = time-hour ":" time-minute ":" time-second
full-date = date-fullyear "-" date-month "-" date-mday
date-local-time = full-date "T" local-time
Example time representing 09:00AM on 01/01/2000 local time:
2000-01-01T09:00:00.00
NOTE: Per [ABNF] and [ISO8601], the "T" character in this syntax
may alternatively be lower case "t". For simplicity, Applications
that generate the "date-local-time" format defined here, SHOULD
only use the upper case letter "T".
8.2.3.2. Restrictions
The grammar element date-mday represents the day number within the
current month. The maximum value varies based on the month and year
as follows:
Month Number Month/Year Maximum value of date-mday
------------ ---------- --------------------------
01 January 31
02 February, normal 28
02 February, leap year 29
03 March 31
04 April 30
05 May 31
06 June 30
07 July 31
08 August 31
09 September 30
10 October 31
11 November 30
12 December 31
See Appendix C of [RFC3339] for a sample C code that determines if a
year is a leap year.
Sopher, et al. Expires 5 September 2024 [Page 54]
Internet-Draft CDN Interconnect Triggers March 2024
The grammar element time-second may have the values 0-59. The value
of 60 that is used in [ISO8601] to represent a leap second MUST NOT
be used.
Although [ISO8601] permits the hour to be "24", this profile of
[ISO8601] only allows values between "00" and "23" for the hour in
order to reduce confusion.
9. Footprint and Capabilities
This section covers the FCI objects required for advertisement of the
specs, extensions, and properties introduced in this document.
9.1. CI/T Objects Versions Capability Object
The CI/T objects versions capability object is used to indicate
support for one or more CI/T objects versions. Capability type is
"FCI.CITObjectsVersion". For simplicity, it is recommended to
minimize the set of supported versions declared by the dCDN. For
example, one way to minimize supported versions is to support only
objects of version 2. Version 1, as originally defined in [RFC8007],
is the default if this capability is not explicitly declared.
Property: versions
Description: A list of version numbers.
Type: An array of JSON strings
Mandatory: No. The default is version 1. A missing or an
empty versions list means that only version 1 of the interface
and objects is supported.
9.1.1. CI/T Objects Versions Capability Object Serialization
The following shows an example of CI/T Objects Versions Capability
object serialization for a dCDN that supports versions 2 and 2.1 of
the CI/T interface.
Sopher, et al. Expires 5 September 2024 [Page 55]
Internet-Draft CDN Interconnect Triggers March 2024
{
"capabilities": [
{
"capability-type": "FCI.CITVersion",
"capability-value": {
"versions": [ "1", "2", "2.1" ]
},
"footprints": [
<Footprint objects>
]
}
]
}
9.2. CI/T Trigger Scope Capability Object
The CI/T supports several trigger actions for different trigger's
subjects as defined at Section 3.1 and Section 3.2.1. Additional
actions, as well as subjects, may be defined in the future. The
Trigger Scope capability object is used to indicate support of a
Trigger Action for a subject. It further specifies the Trigger
Generic Spec types that may be used for selecting the targets the
triggers are applied on, along with the supported Trigger Generic
Extension types.
The trigger-scope-capability object matching the "FCI.TriggerScope"
capability type, is defined as follows:
Property: trigger-action
Description: The supported CDNI CI/T Trigger Action.
Type: A string corresponding to an entry from the "CDNI CI/T
Trigger Types" registry Section 11.2, that corresponds to a
CDNI CI/T Trigger Action.
Mandatory: Yes.
Property: trigger-subject
Description: The supported CDNI CI/T Trigger Subject.
Type: A string corresponding to an entry from the "CDNI CI/T
Trigger Subjects" registry Section 11.4 that corresponds to a
CDNI CI/T Trigger Subject.
Mandatory: Yes.
Sopher, et al. Expires 5 September 2024 [Page 56]
Internet-Draft CDN Interconnect Triggers March 2024
Property: trigger-specs
Description: A list of supported CDNI CI/T GenericSpecObject
types for the Trigger Action and Subject.
Type: List of strings corresponding to entries from the "CDNI
CI/T Trigger Specs" registry Section 11.3, that corresponds to
a CDNI CI/T GenericSpecObject objects.
Mandatory: No. The default, in case of a missing or an empty
list, MUST be interpreted as "no GenericExtensionObject types
are supported". A non-empty list MUST be interpreted as
containing "the only GenericExtensionObject types that are
supported".
Property: trigger-extensions
Description: A list of supported CDNI CI/T
GenericExtensionObject types for the Trigger Action and
Subject.
Type: List of strings corresponding to entries from the "CDNI
CI/T Trigger Extension" registry Section 11.6, that corresponds
to a CDNI CI/T GenericExtensionObject objects.
Mandatory: No. The default, in case of a missing or an empty
list, MUST be interpreted as "no GenericExtensionObject types
are supported". A non-empty list MUST be interpreted as
containing "the only GenericExtensionObject types that are
supported".
9.2.1. CI/T Trigger Scope Capability Object Serialization
The following shows an example of a JSON serialized CI/T Trigger
Scope Capability object serialization for a dCDN that supports the
preposition and invalidation of content, using "urls" and "ccids"
Generic Spec types, with "time-policy" but only for the "preposition"
action. Note that in this example, purge is not supported neigher
any operation on metadata.
Sopher, et al. Expires 5 September 2024 [Page 57]
Internet-Draft CDN Interconnect Triggers March 2024
{
"capabilities": [
{
"capability-type": "FCI.TriggerScope",
"capability-value": {
"trigger-scope-capabilities": [
{
"trigger-action": "preposition",
"trigger-subject": "content",
"trigger-specs": ["urls", "ccids"],
"trigger-extensions": ["time-policy"]
},
{
"trigger-action": "invalidate",
"trigger-subject": "content",
"trigger-specs": ["urls", "ccids"]
}
]
},
"footprints": [
<Footprint objects>
]
}
]
}
9.3. CI/T Playlist Protocol Capability Object
Given a content-playlist being supported by the dCDN, the CI/T
Playlist Protocol capability object is used to indicate support for
one or more MediaProtocol types listed in Section 11.5 by the
playlists property of the "trigger.v2" object. Capability type is
"FCI.TriggerSpecPlaylistProtocol".
Property: media-protocols
Description: A list of media protocols.
Type: A list of MediaProtocol (from the CDNI Triggers media
protocol types Section 11.5)
Mandatory: No. The default, in case of a missing or an empty
list, is none supported.
Sopher, et al. Expires 5 September 2024 [Page 58]
Internet-Draft CDN Interconnect Triggers March 2024
9.3.1. CI/T Playlist Protocol Capability Object Serialization
The following shows an example of a JSON serialized CI/T Playlist
Protocol Capability object serialization for a dCDN that supports
"hls" and "dash".
{
"capabilities": [
{
"capability-type": "FCI.TriggerSpecPlaylistProtocol",
"capability-value": {
"media-protocols": ["hls", "dash"]
},
"footprints": [
<Footprint objects>
]
}
]
}
10. Examples
The following subsections provide examples of different CI/T objects
encoded as JSON.
Discovery of the CI/T interface is out of scope for this document.
In an implementation, all CI/T URLs are under the control of the
dCDN. The uCDN MUST NOT attempt to ascribe any meaning to individual
elements of the path.
In examples in this section, the URL "https://dcdn.example.com/
triggers" is used as the location of the collection of all Trigger
Status Resources, and the CDN PID of the uCDN is "AS64496:1".
10.1. Creating Triggers
Examples of the uCDN triggering activity in the dCDN:
10.1.1. Preposition
Below is an example of a CI/T "preposition" command -- a POST to the
collection of all Trigger Status Resources.
Note that pattern based specs like “UriPatternMatch” and
“UrisRegexMatch”, are not allowed in a pre-position Trigger
Specification, where the dCDN has to have a clear list of objects to
obtain.
Sopher, et al. Expires 5 September 2024 [Page 59]
Internet-Draft CDN Interconnect Triggers March 2024
REQUEST:
POST /triggers HTTP/1.1
User-Agent: example-user-agent/0.1
Host: dcdn.example.com
Accept: */*
Content-Type: application/cdni; ptype=ci-trigger-command.trigger.v2
Content-Length: 352
{
"trigger": {
"action": "preposition",
"specs": [
{
"trigger-subject": "metadata",
"generic-trigger-spec-type": "urls",
"generic-trigger-spec-value": {
"urls": [
"https://metadata.example.com/a/b/c"
]
}
},
{
"trigger-subject": "content",
"generic-trigger-spec-type": "urls",
"generic-trigger-spec-value": {
"urls": [
"https://www.example.com/a/b/c/1",
"https://www.example.com/a/b/c/2",
"https://www.example.com/a/b/c/3",
"https://www.example.com/a/b/c/4"
]
}
}
],
},
"cdn-path": [ "AS64496:1" ]
}
RESPONSE:
HTTP/1.1 201 Created
Date: Wed, 04 May 2016 08:48:10 GMT
Content-Length: 467
Content-Type: application/cdni; ptype=ci-trigger-status.v2
Location: https://dcdn.example.com/triggers/0
Server: example-server/0.1
Sopher, et al. Expires 5 September 2024 [Page 60]
Internet-Draft CDN Interconnect Triggers March 2024
{
"ctime": 1462351690,
"etime": 1462351698,
"mtime": 1462351690,
"status": "pending",
"trigger": {
"action": "preposition"
"specs": [
{
"trigger-subject": "metadata",
"generic-trigger-spec-type": "urls",
"generic-trigger-spec-value": {
"urls": [
"https://metadata.example.com/a/b/c"
]
}
},
{
"trigger-subject": "content",
"generic-trigger-spec-type": "urls",
"generic-trigger-spec-value": {
"urls": [
"https://www.example.com/a/b/c/1",
"https://www.example.com/a/b/c/2",
"https://www.example.com/a/b/c/3",
"https://www.example.com/a/b/c/4"
]
}
}
]
}
}
10.1.2. Invalidate
Below is an example of a CI/T "invalidate" command -- another POST to
the collection of all Trigger Status Resources. This instructs the
dCDN to revalidate the content at "https://www.example.com/a/
index.html", as well as any metadata and content whose URLs are
prefixed by "https://metadata.example.com/a/b/" using case-
insensitive matching, and "https://www.example.com/a/b/" using case-
sensitive matching, respectively.
Sopher, et al. Expires 5 September 2024 [Page 61]
Internet-Draft CDN Interconnect Triggers March 2024
REQUEST:
POST /triggers HTTP/1.1
User-Agent: example-user-agent/0.1
Host: dcdn.example.com
Accept: */*
Content-Type: application/cdni; ptype=ci-trigger-command.trigger.v2
Content-Length: 387
{
"trigger": {
"action": "invalidate",
"specs": [
{
"trigger-subject": "metadata",
"generic-trigger-spec-type": "uri-pattern-match",
"generic-trigger-spec-value": {
"pattern": "https://metadata.example.com/a/b/*"
}
},
{
"trigger-subject": "content",
"generic-trigger-spec-type": "urls",
"generic-trigger-spec-value": {
"urls": [
"https://www.example.com/a/index.html"
]
}
},
{
"trigger-subject": "content",
"generic-trigger-spec-type": "uri-pattern-match",
"generic-trigger-spec-value": {
"pattern": "https://www.example.com/a/b/*",
"case-sensitive": true
}
}
]
},
"cdn-path": [ "AS64496:1" ]
}
RESPONSE:
HTTP/1.1 201 Created
Date: Wed, 04 May 2016 08:48:11 GMT
Content-Length: 545
Content-Type: application/cdni; ptype=ci-trigger-status.v2
Sopher, et al. Expires 5 September 2024 [Page 62]
Internet-Draft CDN Interconnect Triggers March 2024
Location: https://dcdn.example.com/triggers/1
Server: example-server/0.1
{
"ctime": 1462351691,
"etime": 1462351699,
"mtime": 1462351691,
"status": "pending",
"trigger": {
"action": "invalidate",
"specs": [
{
"trigger-subject": "metadata",
"generic-trigger-spec-type": "uri-pattern-match",
"generic-trigger-spec-value": {
"pattern": "https://metadata.example.com/a/b/*"
}
},
{
"trigger-subject": "content",
"generic-trigger-spec-type": "urls",
"generic-trigger-spec-value": {
"urls": [
"https://www.example.com/a/index.html"
]
}
},
{
"trigger-subject": "content",
"generic-trigger-spec-type": "uri-pattern-match",
"generic-trigger-spec-value": {
"pattern": "https://www.example.com/a/b/*",
"case-sensitive": true
}
}
]
}
}
10.1.3. Invalidation with Regex
In the following example a CI/T "invalidate" command uses the Regex
property to specify the range of content objects for invalidation,
the command is rejected by the dCDN due to regex complexity, and an
appropriate error is reflected in the status response.
Sopher, et al. Expires 5 September 2024 [Page 63]
Internet-Draft CDN Interconnect Triggers March 2024
REQUEST:
POST /triggers HTTP/1.1
User-Agent: example-user-agent/0.1
Host: triggers.dcdn.example.com
Accept: */*
Content-Type: application/cdni; ptype=ci-trigger-command.trigger.v2
{
"trigger": {
"action": "invalidate",
"specs": [
{
"trigger-subject": "content",
"generic-trigger-spec-type": "uri-regex-match",
"generic-trigger-spec-value": {
"regex": "^(https:\\/\\/video\\.example\\.com)\\/
([a-z])\\/movie1\\/([1-7])\\/*(index.m3u8|\\d{3}.ts)$",
"case-sensitive": true,
"match-query-string": false
}
}
]
},
"cdn-path": [ "AS64496:0" ]
}
RESPONSE:
HTTP/1.1 201 Created
Date: Wed, 04 May 2016 08:48:10 GMT
Content-Length: 467
Content-Type: application/cdni; ptype=ci-trigger-status.v2
Location: https://triggers.dcdn.example.com/triggers/2
Server: example-server/0.1
{
"errors": [
{
"specs": [
{
"trigger-subject": "content",
"generic-trigger-spec-type": "uri-regex-match",
"generic-trigger-spec-value": {
"regex": "^(https:\\/\\/video\\.example\\.com)\\/
([a-z])\\/movie1\\/([1-7])\\/*(index.m3u8|\\d{3}.ts)$",
"case-sensitive": true,
"match-query-string": false
}
Sopher, et al. Expires 5 September 2024 [Page 64]
Internet-Draft CDN Interconnect Triggers March 2024
}
],
"description": "The dCDN rejected a regex due to complexity",
"error": "ereject",
"cdn": "AS64500:0"
},
],
"ctime": 1462351690,
"etime": 1462351698,
"mtime": 1462351690,
"status": "failed",
"trigger": { <content of trigger.v2 object from the command> }
}
10.1.4. Preposition with Playlists
In the following example a CI/T "preposition" command uses the
Playlist property to specify the full media library of a specific
content. The command fails due to playlist parse error and an
appropriate error is reflected in the status response.
REQUEST:
POST /triggers HTTP/1.1
User-Agent: example-user-agent/0.1
Host: triggers.dcdn.example.com
Accept: */*
Content-Type: application/cdni; ptype=ci-trigger-command.trigger.v2
{
"trigger": {
"action": "preposition",
"specs": [
{
"trigger-subject": "content",
"generic-trigger-spec-type": "contentPlaylist",
"generic-trigger-spec-value": {
"playlist": "https://www.example.com/hls/title/index.m3u8",
"media-protocol": "hls"
}
}
]
},
"cdn-path": [ "AS64496:0" ]
}
RESPONSE:
HTTP/1.1 201 Created
Sopher, et al. Expires 5 September 2024 [Page 65]
Internet-Draft CDN Interconnect Triggers March 2024
Date: Wed, 04 May 2016 08:48:10 GMT
Content-Length: 467
Content-Type: application/cdni; ptype=ci-trigger-status.v2
Location: https://triggers.dcdn.example.com/triggers/3
Server: example-server/0.1
{
"errors": [
{
"specs": [
{
"trigger-subject": "content",
"generic-trigger-spec-type": "contentPlaylist",
"generic-trigger-spec-value": {
"playlist": "https://www.example.com/hls/title/index.m3u8",
"media-protocol": "hls"
}
}
],
"description": "The dCDN was not able to parse the playlist",
"error": "econtent",
"cdn": "AS64500:0"
},
],
"ctime": 1462351690,
"etime": 1462351698,
"mtime": 1462351690,
"status": "failed",
"trigger": { <content of trigger.v2 object from the command> }
}
10.2. Examining Trigger Status
Once Trigger Status Resources have been created, the uCDN can check
their status as shown in the following examples.
10.2.1. Collection of All Triggers
The uCDN can fetch the collection of all Trigger Status Resources it
has created that have not yet been deleted or removed or expired.
After creation of the "preposition" and "invalidate" triggers shown
above, this collection might look as follows:
Sopher, et al. Expires 5 September 2024 [Page 66]
Internet-Draft CDN Interconnect Triggers March 2024
REQUEST:
GET /triggers HTTP/1.1
User-Agent: example-user-agent/0.1
Host: dcdn.example.com
Accept: */*
RESPONSE:
HTTP/1.1 200 OK
Content-Length: 341
Expires: Wed, 04 May 2016 08:49:11 GMT
Server: example-server/0.1
ETag: "-936094426920308378"
Cache-Control: max-age=60
Date: Wed, 04 May 2016 08:48:11 GMT
Content-Type: application/cdni; ptype=ci-trigger-collection
{
"cdn-id": "AS64496:0",
"coll-active": "/triggers/active",
"coll-complete": "/triggers/complete",
"coll-failed": "/triggers/failed",
"coll-pending": "/triggers/pending",
"staleresourcetime": 86400,
"triggers": [
"https://dcdn.example.com/triggers/0",
"https://dcdn.example.com/triggers/1"
]
}
10.2.2. Filtered Collections of Trigger Status Resources
The filtered collections are also available to the uCDN. Before the
dCDN starts processing the two CI/T Trigger Commands shown above,
both will appear in the collection of pending triggers. For example:
Sopher, et al. Expires 5 September 2024 [Page 67]
Internet-Draft CDN Interconnect Triggers March 2024
REQUEST:
GET /triggers/pending HTTP/1.1
User-Agent: example-user-agent/0.1
Host: dcdn.example.com
Accept: */*
RESPONSE:
HTTP/1.1 200 OK
Content-Length: 152
Expires: Wed, 04 May 2016 08:49:11 GMT
Server: example-server/0.1
ETag: "4331492443626270781"
Cache-Control: max-age=60
Date: Wed, 04 May 2016 08:48:11 GMT
Content-Type: application/cdni; ptype=ci-trigger-collection
{
"staleresourcetime": 86400,
"triggers": [
"https://dcdn.example.com/triggers/0",
"https://dcdn.example.com/triggers/1"
]
}
At this point, if no other Trigger Status Resources had been created,
the other filtered views would be empty. For example:
Sopher, et al. Expires 5 September 2024 [Page 68]
Internet-Draft CDN Interconnect Triggers March 2024
REQUEST:
GET /triggers/complete HTTP/1.1
User-Agent: example-user-agent/0.1
Host: dcdn.example.com
Accept: */*
RESPONSE:
HTTP/1.1 200 OK
Content-Length: 54
Expires: Wed, 04 May 2016 08:49:11 GMT
Server: example-server/0.1
ETag: "7958041393922269003"
Cache-Control: max-age=60
Date: Wed, 04 May 2016 08:48:11 GMT
Content-Type: application/cdni; ptype=ci-trigger-collection
{
"staleresourcetime": 86400,
"triggers": []
}
10.2.3. Individual Trigger Status Resources
The Trigger Status Resources can also be examined for details about
individual CI/T Trigger Commands. For example, for the CI/T
"preposition" and "invalidate" commands from previous examples:
REQUEST:
GET /triggers/0 HTTP/1.1
User-Agent: example-user-agent/0.1
Host: dcdn.example.com
Accept: */*
RESPONSE:
HTTP/1.1 200 OK
Content-Length: 467
Expires: Wed, 04 May 2016 08:49:10 GMT
Server: example-server/0.1
ETag: "6990548174277557683"
Cache-Control: max-age=60
Date: Wed, 04 May 2016 08:48:10 GMT
Content-Type: application/cdni; ptype=ci-trigger-status.v2
{
Sopher, et al. Expires 5 September 2024 [Page 69]
Internet-Draft CDN Interconnect Triggers March 2024
"ctime": 1462351690,
"etime": 1462351698,
"mtime": 1462351690,
"status": "pending",
"trigger": {
"action": "preposition",
"specs": [
{
"trigger-subject": "metadata",
"generic-trigger-spec-type": "urls",
"generic-trigger-spec-value": {
"urls": [
"https://metadata.example.com/a/b/c"
]
}
},
{
"trigger-subject": "content",
"generic-trigger-spec-type": "urls",
"generic-trigger-spec-value": {
"urls": [
"https://www.example.com/a/b/c/1",
"https://www.example.com/a/b/c/2",
"https://www.example.com/a/b/c/3",
"https://www.example.com/a/b/c/4"
]
}
}
]
}
}
REQUEST:
GET /triggers/1 HTTP/1.1
User-Agent: example-user-agent/0.1
Host: dcdn.example.com
Accept: */*
RESPONSE:
HTTP/1.1 200 OK
Content-Length: 545
Expires: Wed, 04 May 2016 08:49:11 GMT
Server: example-server/0.1
ETag: "-554385204989405469"
Cache-Control: max-age=60
Date: Wed, 04 May 2016 08:48:11 GMT
Sopher, et al. Expires 5 September 2024 [Page 70]
Internet-Draft CDN Interconnect Triggers March 2024
Content-Type: application/cdni; ptype=ci-trigger-status.v2
{
"ctime": 1462351691,
"etime": 1462351699,
"mtime": 1462351691,
"status": "pending",
"trigger": {
"action": "invalidate",
"specs": [
{
"trigger-subject": "metadata",
"generic-trigger-spec-type": "uri-pattern-match",
"generic-trigger-spec-value": {
"pattern": "https://metadata.example.com/a/b/*"
}
},
{
"trigger-subject": "content",
"generic-trigger-spec-type": "urls",
"generic-trigger-spec-value": {
"urls": [
"https://www.example.com/a/index.html"
]
}
},
{
"trigger-subject": "content",
"generic-trigger-spec-type": "uri-pattern-match",
"generic-trigger-spec-value": {
"pattern": "https://www.example.com/a/b/*",
"case-sensitive": true
}
}
]
}
}
10.2.4. Polling for Changes in Status
The uCDN SHOULD use the ETags of collections or Trigger Status
Resources when polling for changes in status, as shown in the
following examples:
Sopher, et al. Expires 5 September 2024 [Page 71]
Internet-Draft CDN Interconnect Triggers March 2024
REQUEST:
GET /triggers/pending HTTP/1.1
User-Agent: example-user-agent/0.1
Host: dcdn.example.com
Accept: */*
If-None-Match: "4331492443626270781"
RESPONSE:
HTTP/1.1 304 Not Modified
Content-Length: 0
Expires: Wed, 04 May 2016 08:49:11 GMT
Server: example-server/0.1
ETag: "4331492443626270781"
Cache-Control: max-age=60
Date: Wed, 04 May 2016 08:48:11 GMT
Content-Type: application/cdni; ptype=ci-trigger-collection
REQUEST:
GET /triggers/0 HTTP/1.1
User-Agent: example-user-agent/0.1
Host: dcdn.example.com
Accept: */*
If-None-Match: "6990548174277557683"
RESPONSE:
HTTP/1.1 304 Not Modified
Content-Length: 0
Expires: Wed, 04 May 2016 08:49:10 GMT
Server: example-server/0.1
ETag: "6990548174277557683"
Cache-Control: max-age=60
Date: Wed, 04 May 2016 08:48:10 GMT
Content-Type: application/cdni; ptype=ci-trigger-status.v2
When the CI/T Trigger Command is complete, the contents of the
filtered collections will be updated along with their ETags. For
example, when the two example CI/T Trigger Commands are complete, the
collections of pending and complete Trigger Status Resources might
look like:
Sopher, et al. Expires 5 September 2024 [Page 72]
Internet-Draft CDN Interconnect Triggers March 2024
REQUEST:
GET /triggers/pending HTTP/1.1
User-Agent: example-user-agent/0.1
Host: dcdn.example.com
Accept: */*
RESPONSE:
HTTP/1.1 200 OK
Content-Length: 54
Expires: Wed, 04 May 2016 08:49:15 GMT
Server: example-server/0.1
ETag: "1337503181677633762"
Cache-Control: max-age=60
Date: Wed, 04 May 2016 08:48:15 GMT
Content-Type: application/cdni; ptype=ci-trigger-collection
{
"staleresourcetime": 86400,
"triggers": []
}
REQUEST:
GET /triggers/complete HTTP/1.1
User-Agent: example-user-agent/0.1
Host: dcdn.example.com
Accept: */*
RESPONSE:
HTTP/1.1 200 OK
Content-Length: 152
Expires: Wed, 04 May 2016 08:49:22 GMT
Server: example-server/0.1
ETag: "4481489539378529796"
Cache-Control: max-age=60
Date: Wed, 04 May 2016 08:48:22 GMT
Content-Type: application/cdni; ptype=ci-trigger-collection
{
"staleresourcetime": 86400,
"triggers": [
"https://dcdn.example.com/triggers/0",
"https://dcdn.example.com/triggers/1"
]
}
Sopher, et al. Expires 5 September 2024 [Page 73]
Internet-Draft CDN Interconnect Triggers March 2024
10.2.5. Deleting Trigger Status Resources
The uCDN can delete completed and failed Trigger Status Resources to
reduce the size of the collections, as described in Section 5.4. For
example, to delete the "preposition" request from earlier examples:
REQUEST:
DELETE /triggers/0 HTTP/1.1
User-Agent: example-user-agent/0.1
Host: dcdn.example.com
Accept: */*
RESPONSE:
HTTP/1.1 204 No Content
Date: Wed, 04 May 2016 08:48:22 GMT
Content-Length: 0
Content-Type: text/html; charset=UTF-8
Server: example-server/0.1
This would, for example, cause the collection of completed Trigger
Status Resources shown in the example above to be updated to:
REQUEST:
GET /triggers/complete HTTP/1.1
User-Agent: example-user-agent/0.1
Host: dcdn.example.com
Accept: */*
RESPONSE:
HTTP/1.1 200 OK
Content-Length: 105
Expires: Wed, 04 May 2016 08:49:22 GMT
Server: example-server/0.1
ETag: "-6938620031669085677"
Cache-Control: max-age=60
Date: Wed, 04 May 2016 08:48:22 GMT
Content-Type: application/cdni; ptype=ci-trigger-collection
{
"staleresourcetime": 86400,
"triggers": [
"https://dcdn.example.com/triggers/1"
]
}
Sopher, et al. Expires 5 September 2024 [Page 74]
Internet-Draft CDN Interconnect Triggers March 2024
10.2.6. Extensions with Error Propagation
In the following example a CI/T "preposition" command is using two
extensions to control the way the trigger is executed. In this
example the receiving dCDN, identified as "AS64500:0", does not
support the first extension in the extensions array. dCDN "AS64500:0"
further distributes this trigger to another downstream CDN that is
identified as "AS64501:0", which does not support the second
extension in the extensions array. The error is propagated from
"AS64501:0" to "AS64500:0" and the errors.v2 array reflects both
errors.
REQUEST:
POST /triggers HTTP/1.1
User-Agent: example-user-agent/0.1
Host: triggers.dcdn.example.com
Accept: */*
Content-Type: application/cdni; ptype=ci-trigger-command.trigger.v2
{
"trigger": {
"action": "preposition",
"specs": [
{
"trigger-subject": "content",
"generic-trigger-spec-type": "contentPlaylist",
"generic-trigger-spec-value": {
"playlist": "https://www.example.com/hls/title/index.m3u8",
"media-protocol": "hls"
}
}
],
"extensions": [
{
"generic-trigger-extension-type": "location-policy",
"generic-trigger-extension-value":
{
"locations": [
{
"action": "allow",
"footprints": [
{
"footprint-type": "countrycode",
"footprint-value": ["us"]
}
]
},
{
Sopher, et al. Expires 5 September 2024 [Page 75]
Internet-Draft CDN Interconnect Triggers March 2024
"action": "deny",
"footprints": [
{
"footprint-type": "countrycode",
"footprint-value": ["ca"]
}
]
}
]
},
"mandatory-to-enforce": true,
"safe-to-redistribute": true
},
{
"generic-trigger-extension-type": "time-policy",
"generic-trigger-extension-value":
{
"unix-time-window": {
"start": 946717200,
"end": 946746000
}
},
"mandatory-to-enforce": true,
"safe-to-redistribute": true
}
],
},
"cdn-path": [ "AS64496:0" ]
}
RESPONSE:
HTTP/1.1 201 Created
Date: Wed, 04 May 2016 08:48:10 GMT
Content-Length: 467
Content-Type: application/cdni; ptype=ci-trigger-status.v2
Location: https://triggers.dcdn.example.com/triggers/0
Server: example-server/0.1
{
"errors": [
{
"extensions": [
{
"generic-trigger-extension-type": "location-policy",
"generic-trigger-extension-value":
{
"locations": [
Sopher, et al. Expires 5 September 2024 [Page 76]
Internet-Draft CDN Interconnect Triggers March 2024
{
"action": "allow",
"footprints": [
{
"footprint-type": "countrycode",
"footprint-value": ["us"]
}
]
},
{
"action": "deny",
"footprints": [
{
"footprint-type": "countrycode",
"footprint-value": ["ca"]
}
]
}
]
},
"mandatory-to-enforce": true,
"safe-to-redistribute": true
},
],
"description": "unrecognized extension <type>",
"error": "eextension",
"cdn": "AS64500:0"
},
{
"extensions": [
{
"generic-trigger-extension-type": "time-policy",
"generic-trigger-extension-value":
{
"unix-time-window": {
"start": 946717200,
"end": 946746000
}
},
"mandatory-to-enforce": true,
"safe-to-redistribute": true
}
],
"description": "unrecognized extension <type>",
"error": "eextension",
"cdn": "AS64501:0"
}
],
Sopher, et al. Expires 5 September 2024 [Page 77]
Internet-Draft CDN Interconnect Triggers March 2024
"ctime": 1462351690,
"etime": 1462351698,
"mtime": 1462351690,
"status": "failed",
"trigger": { <content of trigger.v2 object from the command> }
}
11. IANA Considerations
11.1. CDNI Payload Type Parameter Registrations
All references to RFC 8007 in the IANA registries should be replaced
with references to this document, apart from references associated
with the the following registrations:
+=======================+===============+
| Payload Type | Specification |
+=======================+===============+
| ci-trigger-command | RFC 8007 |
+-----------------------+---------------+
| ci-trigger-status | RFC 8007 |
+-----------------------+---------------+
| ci-trigger-collection | RFC 8007 |
+-----------------------+---------------+
Table 10
The IANA is requested to register the following new Payload Types in
the "CDNI Payload Types" registry defined by [RFC7736], for use with
the "application/cdni" MIME media type.
+=================================+===============+
| Payload Type | Specification |
+=================================+===============+
| ci-trigger-command.trigger.v2 | RFCthis |
+---------------------------------+---------------+
| ci-trigger-command.cancel | RFCthis |
+---------------------------------+---------------+
| ci-trigger-status.v2 | RFCthis |
+---------------------------------+---------------+
| FCI.CITObjectsVersion | RFCthis |
+---------------------------------+---------------+
| FCI.TriggerScope | RFCthis |
+---------------------------------+---------------+
| FCI.TriggerSpecPlaylistProtocol | RFCthis |
+---------------------------------+---------------+
Table 11
Sopher, et al. Expires 5 September 2024 [Page 78]
Internet-Draft CDN Interconnect Triggers March 2024
[RFC Editor: Please replace RFCthis with the published RFC number for
this document.]
11.1.1. CDNI ci-trigger-command.trigger.v2 Payload Type
Purpose: The purpose of this payload type is to distinguish version 2
of the CI/T trigger command object (and any associated capability
advertisement)
Interface: CI/T
Encoding: see Section 6.1.1
11.1.2. CDNI ci-trigger-command.cancel Payload Type
Purpose: The purpose of this payload type is to distinguish the CI/T
cancel command object (and any associated capability advertisement)
Interface: CI/T
Encoding: see Section 6.1.2
11.1.3. CDNI ci-trigger-status.v2 Payload Type
Purpose: The purpose of this payload type is to distinguish version 2
of the CI/T status resource response object (and any associated
capability advertisement)
Interface: CI/T
Encoding: see Section 6.1.3
11.1.4. CDNI FCI CI/T Payload Types
11.1.4.1. CDNI FCI CI/T Objects Versions Payload Type
Purpose: The purpose of this payload type is to distinguish FCI
advertisement objects for CI/T Objects Versions objects
Interface: FCI
Encoding: see Section 9.1.1
11.1.4.2. CDNI FCI CI/T Trigger Scope Payload Type
Purpose: The purpose of this payload type is to distinguish FCI
advertisement objects for CI/T Trigger Scope
Sopher, et al. Expires 5 September 2024 [Page 79]
Internet-Draft CDN Interconnect Triggers March 2024
Interface: FCI
Encoding: see Section 9.2.1
11.1.4.3. CDNI FCI CI/T Playlist Protocol Payload Type
Purpose: The purpose of this payload type is to distinguish FCI
advertisement objects for CI/T Playlist Protocol objects
Interface: FCI
Encoding: see Section 9.3.1
11.2. "CDNI CI/T Trigger Types" Registry For Trigger Actions
In [RFC8007] the IANA was requested to create a new "CDNI CI/T
Trigger Types" registry under the "Content Delivery Network
Interconnection (CDNI) Parameters" registry group.
Additions to the "CDNI CI/T Trigger Types" registry are made via the
RFC Required policy as defined in [RFC8126].
In this second edition of the interface, trigger types are referred
to as "trigger actions". The "Trigger Types" registry is used for
actions definitions. Furthermore, this document, and specifically
Section 3.1, reuses the definition of “trigger types” as defined in
[RFC8007] as trigger actions, and provide their specifications, with
no modification comparing to [RFC8007].
11.3. "CDNI CI/T Trigger Specs" Registry
The IANA is requested to create a new "CDNI CI/T Trigger Specs"
registry in the "Content Delivery Networks Interconnection (CDNI)
Parameters" registry group. The "CDNI CI/T Trigger Specs" namespace
defines the valid trigger targets' spec values in Section 3.2, used
by the Trigger Spec object.
Additions to the "CDNI CI/T Trigger Specs" registry are made via the
RFC Required policy as defined in [RFC8126].
The initial contents of the "CDNI CI/T Trigger Specs" registry
comprise the names and descriptions listed in Section 3.2, with this
document acting as the specification.
Sopher, et al. Expires 5 September 2024 [Page 80]
Internet-Draft CDN Interconnect Triggers March 2024
11.4. "CDNI CI/T Trigger Subjects" Registry
The IANA is requested to create a new "CDNI CI/T Trigger Subjects"
registry in the "Content Delivery Networks Interconnection (CDNI)
Parameters" registry group. The "CDNI CI/T Trigger Subjects"
namespace defines the valid trigger targets' subject values in
Section 3.2.1, used by the Trigger Spec object.
Additions to the "CDNI CI/T Trigger Subjects" registry are made via
the RFC Required policy as defined in [RFC8126].
The initial contents of the "CDNI CI/T Trigger Subjects" registry
comprise the names and descriptions listed in Section 3.2.1, with
this document acting as the specification.
11.5. CDNI CI/T Playlist Spec MediaProtocols
The IANA is requested to create a new "CDNI CI/T Playlist Spec
MediaProtocols" registry in the "Content Delivery Networks
Interconnection (CDNI) Parameters" registry group. The "CDNI CI/T
Playlist Spec MediaProtocols" namespace defines the valid trigger
targets' extension values in Section 7.5.2, used by the Trigger Spec
object.
Additions to the "CDNI Playlist Spec MediaProtocols" registry are
made via the RFC Required policy as defined in [RFC8126].
The initial contents of the "CDNI CI/T Trigger Extensions" registry
comprise the names and descriptions listed in Section 7.5.2, with
this document acting as the specification.
11.6. "CDNI CI/T Trigger Extensions" Registry
The IANA is requested to create a new "CDNI CI/T Trigger Extensions"
registry in the "Content Delivery Networks Interconnection (CDNI)
Parameters" registry group. The "CDNI CI/T Trigger Extensions"
namespace defines the valid trigger targets' extension values in
Section 3.3, used by the Trigger Spec object.
Additions to the "CDNI CI/T Trigger Extensions" registry are made via
the RFC Required policy as defined in [RFC8126].
The initial contents of the "CDNI CI/T Trigger Extensions" registry
comprise the names and descriptions listed in Section 3.3, with this
document acting as the specification.
Sopher, et al. Expires 5 September 2024 [Page 81]
Internet-Draft CDN Interconnect Triggers March 2024
11.7. "CDNI CI/T Error Codes" Registry
In [RFC8007] the IANA was requested to create a new "CDNI CI/T Error
Codes" registry under the "Content Delivery Network Interconnection
(CDNI) Parameters" registry group.
Additions to the "CDNI CI/T Error Codes" registry are made via the
Specification Required policy as defined in [RFC8126]. The
Designated Expert will verify that new Error Code registrations do
not duplicate existing Error Code definitions (in name or
functionality), prevent gratuitous additions to the namespace, and
prevent any additions to the namespace that would impair the
interoperability of CDNI implementations.
In this second edition of the interface, we list and repeat the
definition of the Error Codes from [RFC8007] - acting as the entities
specification with no modification compared to [RFC8007].
Additionally, the IANA is requested to register three additional
error codes, "espec", "esubject" and "eextension", with specification
as defined at Section 6.2.7.
12. Security Considerations
The CI/T interface provides a mechanism to allow a uCDN to generate
requests into the dCDN and to inspect its own CI/T requests and their
current states. The CI/T interface does not allow access to, or
modification of, the uCDN or dCDN metadata relating to content
delivery or to the content itself. It can only control the presence
of that metadata in the dCDN, and the processing work and network
utilization involved in ensuring that presence.
By examining "preposition" requests to a dCDN, and correctly
interpreting content and metadata URLs, an attacker could learn the
uCDN's or content owner's predictions for future content popularity.
By examining "invalidate" or "purge" requests, an attacker could
learn about changes in the content owner's catalog.
By injecting CI/T Commands, an attacker or a misbehaving uCDN would
generate work in the dCDN and uCDN as they process those requests.
So would a man-in-the-middle attacker modifying valid CI/T Commands
generated by the uCDN. In both cases, that would decrease the dCDN's
caching efficiency by causing it to unnecessarily acquire or
reacquire content metadata and/or content.
A dCDN implementation of CI/T MUST restrict the actions of a uCDN to
the data corresponding to that uCDN. Failure to do so would allow
uCDNs to detrimentally affect each other's efficiency by generating
unnecessary acquisition or reacquisition load.
Sopher, et al. Expires 5 September 2024 [Page 82]
Internet-Draft CDN Interconnect Triggers March 2024
An origin that chooses to delegate its delivery to a CDN is trusting
that CDN to deliver content on its behalf; the interconnection of
CDNs is an extension of that trust to dCDNs. That trust relationship
is a commercial arrangement, outside the scope of the CDNI protocols.
So, while a malicious CDN could deliberately generate load on a dCDN
using the CI/T interface, the protocol does not otherwise attempt to
address malicious behavior between interconnected CDNs.
12.1. Authentication, Authorization, Confidentiality, Integrity
Protection
A CI/T implementation MUST support Transport Layer Security (TLS)
transport for HTTP (HTTPS) as per [RFC2818] and [RFC7230].
TLS MUST be used by the server side (dCDN) and the client side (uCDN)
of the CI/T interface, including authentication of the remote end,
unless alternate methods are used for ensuring the security of the
information in the CI/T interface requests and responses (such as
setting up an IPsec tunnel between the two CDNs or using a physically
secured internal network between two CDNs that are owned by the same
corporate entity).
The use of TLS for transport of the CI/T interface allows the dCDN
and the uCDN to authenticate each other using TLS client
authentication and TLS server authentication.
Once the dCDN and the uCDN have mutually authenticated each other,
TLS allows:
* The dCDN and the uCDN to authorize each other (to ensure that they
are receiving CI/T Commands from, or reporting status to, an
authorized CDN).
* CDNI commands and responses to be transmitted with
confidentiality.
* Protection of the integrity of CDNI commands and responses.
When TLS is used, the general TLS usage guidance in [RFC7525] MUST be
followed.
The mechanisms for access control are dCDN-specific and are not
standardized as part of this CI/T specification.
Sopher, et al. Expires 5 September 2024 [Page 83]
Internet-Draft CDN Interconnect Triggers March 2024
HTTP requests that attempt to access or operate on CI/T data
belonging to another CDN MUST be rejected using, for example, HTTP
403 ("Forbidden") or 404 ("Not Found"). This is intended to prevent
unauthorized users from generating unnecessary load in dCDNs or uCDNs
due to revalidation, reacquisition, or unnecessary acquisition.
When deploying a network of interconnected CDNs, the possible
inefficiencies related to the diamond configuration discussed in
Section 2.2.1 should be considered.
12.2. Denial of Service
This document does not define a specific mechanism to protect against
Denial-of-Service (DoS) attacks on the CI/T interface. However, CI/T
endpoints can be protected against DoS attacks through the use of TLS
transport and/or via mechanisms outside the scope of the CI/T
interface, such as firewalling or the use of Virtual Private Networks
(VPNs).
Depending on the implementation, triggered activity may consume
significant processing and bandwidth in the dCDN. A malicious or
faulty uCDN could use this to generate unnecessary load in the dCDN.
The dCDN should consider mechanisms to avoid overload -- for example,
by rate-limiting acceptance or processing of CI/T Commands, or by
performing batch processing.
12.3. Privacy
The CI/T protocol does not carry any information about individual end
users of a CDN; there are no privacy concerns for end users.
The CI/T protocol does carry information that could be considered
commercially sensitive by CDN operators and content owners. The use
of mutually authenticated TLS to establish a secure session for the
transport of CI/T data, as discussed in Section 12.1, provides
confidentiality while the CI/T data is in transit and prevents
parties other than the authorized dCDN from gaining access to that
data. The dCDN MUST ensure that it only exposes CI/T data related to
a uCDN to clients it has authenticated as belonging to that uCDN.
13. References
13.1. Normative References
[ABNF] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", STD 68, RFC 5234,
DOI 10.17487/RFC5234, January 2008,
<https://www.rfc-editor.org/info/rfc5234>.
Sopher, et al. Expires 5 September 2024 [Page 84]
Internet-Draft CDN Interconnect Triggers March 2024
[RFC1930] Hawkinson, J. and T. Bates, "Guidelines for creation,
selection, and registration of an Autonomous System (AS)",
BCP 6, RFC 1930, DOI 10.17487/RFC1930, March 1996,
<https://www.rfc-editor.org/info/rfc1930>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC3339] Klyne, G. and C. Newman, "Date and Time on the Internet:
Timestamps", RFC 3339, DOI 10.17487/RFC3339, July 2002,
<https://www.rfc-editor.org/info/rfc3339>.
[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
Resource Identifier (URI): Generic Syntax", STD 66,
RFC 3986, DOI 10.17487/RFC3986, January 2005,
<https://www.rfc-editor.org/info/rfc3986>.
[RFC7230] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
Protocol (HTTP/1.1): Message Syntax and Routing",
RFC 7230, DOI 10.17487/RFC7230, June 2014,
<https://www.rfc-editor.org/info/rfc7230>.
[RFC7231] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
Protocol (HTTP/1.1): Semantics and Content", RFC 7231,
DOI 10.17487/RFC7231, June 2014,
<https://www.rfc-editor.org/info/rfc7231>.
[RFC7232] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
Protocol (HTTP/1.1): Conditional Requests", RFC 7232,
DOI 10.17487/RFC7232, June 2014,
<https://www.rfc-editor.org/info/rfc7232>.
[RFC7525] Sheffer, Y., Holz, R., and P. Saint-Andre,
"Recommendations for Secure Use of Transport Layer
Security (TLS) and Datagram Transport Layer Security
(DTLS)", RFC 7525, DOI 10.17487/RFC7525, May 2015,
<https://www.rfc-editor.org/info/rfc7525>.
[RFC8006] Niven-Jenkins, B., Murray, R., Caulfield, M., and K. Ma,
"Content Delivery Network Interconnection (CDNI)
Metadata", RFC 8006, DOI 10.17487/RFC8006, December 2016,
<https://www.rfc-editor.org/info/rfc8006>.
Sopher, et al. Expires 5 September 2024 [Page 85]
Internet-Draft CDN Interconnect Triggers March 2024
[RFC8007] Murray, R. and B. Niven-Jenkins, "Content Delivery Network
Interconnection (CDNI) Control Interface / Triggers",
RFC 8007, DOI 10.17487/RFC8007, December 2016,
<https://www.rfc-editor.org/info/rfc8007>.
[RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for
Writing an IANA Considerations Section in RFCs", BCP 26,
RFC 8126, DOI 10.17487/RFC8126, June 2017,
<https://www.rfc-editor.org/info/rfc8126>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8259] Bray, T., Ed., "The JavaScript Object Notation (JSON) Data
Interchange Format", STD 90, RFC 8259,
DOI 10.17487/RFC8259, December 2017,
<https://www.rfc-editor.org/info/rfc8259>.
13.2. Informative References
[ISO8601] ISO, "Data elements and interchange formats -- Information
interchange -- Representation of dates and times",
ISO 8601:2004, Edition 3, December 2004,
<https://www.iso.org/standard/40874.html>.
[MPEG-DASH]
ISO, "Information technology -- Dynamic adaptive streaming
over HTTP (DASH) -- Part 1: Media presentation description
and segment format", ISO/IEC 23009-1:2014, Edition 2, May
2014, <https://www.iso.org/standard/65274.html>.
[MSS] Microsoft, "[MS-SSTR]: Smooth Streaming Protocol",
Protocol Revision 8.0, September 2017,
<https://msdn.microsoft.com/en-us/library/ff469518.aspx>.
[POSIX.1] "The Open Group Base Specifications Issue 7", IEEE
Std 1003.1 2018 Edition, 31 January 2018,
<http://pubs.opengroup.org/onlinepubs/9699919799/>.
[RFC2818] Rescorla, E., "HTTP Over TLS", RFC 2818,
DOI 10.17487/RFC2818, May 2000,
<https://www.rfc-editor.org/info/rfc2818>.
[RFC6707] Niven-Jenkins, B., Le Faucheur, F., and N. Bitar, "Content
Distribution Network Interconnection (CDNI) Problem
Statement", RFC 6707, DOI 10.17487/RFC6707, September
2012, <https://www.rfc-editor.org/info/rfc6707>.
Sopher, et al. Expires 5 September 2024 [Page 86]
Internet-Draft CDN Interconnect Triggers March 2024
[RFC7336] Peterson, L., Davie, B., and R. van Brandenburg, Ed.,
"Framework for Content Distribution Network
Interconnection (CDNI)", RFC 7336, DOI 10.17487/RFC7336,
August 2014, <https://www.rfc-editor.org/info/rfc7336>.
[RFC7337] Leung, K., Ed. and Y. Lee, Ed., "Content Distribution
Network Interconnection (CDNI) Requirements", RFC 7337,
DOI 10.17487/RFC7337, August 2014,
<https://www.rfc-editor.org/info/rfc7337>.
[RFC7736] Ma, K., "Content Delivery Network Interconnection (CDNI)
Media Type Registration", RFC 7736, DOI 10.17487/RFC7736,
December 2015, <https://www.rfc-editor.org/info/rfc7736>.
[RFC7975] Niven-Jenkins, B., Ed. and R. van Brandenburg, Ed.,
"Request Routing Redirection Interface for Content
Delivery Network (CDN) Interconnection", RFC 7975,
DOI 10.17487/RFC7975, October 2016,
<https://www.rfc-editor.org/info/rfc7975>.
[RFC8216] Pantos, R., Ed. and W. May, "HTTP Live Streaming",
RFC 8216, DOI 10.17487/RFC8216, August 2017,
<https://www.rfc-editor.org/info/rfc8216>.
Acknowledgments
The authors thank Kevin Ma for his input, and Carsten Bormann for his
review and formalization of the JSON data.
Authors' Addresses
Nir B. Sopher
Qwilt
6, Ha'harash
Hod HaSharon 4524079
Israel
Email: nir@apache.org
Ori Finkelman
Qwilt
6, Ha'harash
Hod HaSharon 4524079
Israel
Email: ori.finkelman.ietf@gmail.com
Sopher, et al. Expires 5 September 2024 [Page 87]
Internet-Draft CDN Interconnect Triggers March 2024
Sanjay Mishra
Verizon
13100 Columbia Pike
Silver Spring, MD 20904
United States of America
Email: sanjay.mishra@verizon.com
Jay K. Robertson
Qwilt
275 Shoreline Dr Ste 510
Redwood City, CA 94065
United States of America
Email: jayrobertson@acm.org
Sopher, et al. Expires 5 September 2024 [Page 88]