CDN Interconnect Triggers
draft-murray-cdni-triggers-02
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| Authors | Rob Murray , Ben Niven-Jenkins | ||
| Last updated | 2013-02-24 | ||
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draft-murray-cdni-triggers-02
Network Working Group R. Murray
Internet-Draft B. Niven-Jenkins
Intended status: Standards Track Velocix (Alcatel-Lucent)
Expires: August 28, 2013 February 24, 2013
CDN Interconnect Triggers
draft-murray-cdni-triggers-02
Abstract
This document proposes a mechanism for a CDN to trigger activity in
an interconnected CDN that is configured to deliver content on its
behalf. The upstream CDN can use this mechanism to request that the
downstream CDN pre-positions metadata or content, or that it re-
validate or purge metadata or content. The upstream CDN can monitor
the status of activity that it has triggered in the downstream CDN.
Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
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 http://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 August 28, 2013.
Copyright Notice
Copyright (c) 2013 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
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(http://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
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described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 5
2. Model for CDNI Triggers . . . . . . . . . . . . . . . . . . . 5
2.1. Timing of Triggered Activity . . . . . . . . . . . . . . . 7
2.2. Trigger Results . . . . . . . . . . . . . . . . . . . . . 7
3. Collections of Trigger Status Resources . . . . . . . . . . . 7
4. CDNI Trigger interface . . . . . . . . . . . . . . . . . . . . 8
4.1. Creating Triggers . . . . . . . . . . . . . . . . . . . . 9
4.2. Checking Status . . . . . . . . . . . . . . . . . . . . . 10
4.2.1. Polling Trigger Status Resource collections . . . . . 11
4.2.2. Polling Trigger Status Resources . . . . . . . . . . . 11
4.3. Deleting Triggers . . . . . . . . . . . . . . . . . . . . 11
4.4. Expiry of Trigger Status Resources . . . . . . . . . . . . 12
4.5. Error Handling . . . . . . . . . . . . . . . . . . . . . . 12
5. Properties of Triggers . . . . . . . . . . . . . . . . . . . . 13
5.1. Properties of Trigger Requests . . . . . . . . . . . . . . 13
5.1.1. Content URLs . . . . . . . . . . . . . . . . . . . . . 14
5.2. Properties of Trigger Status Resources . . . . . . . . . . 14
5.3. Properties of ErrorDesc . . . . . . . . . . . . . . . . . 15
5.4. Properties of Trigger Collections . . . . . . . . . . . . 15
5.5. Trigger Resource Simple Data Type Descriptions . . . . . . 16
5.5.1. TriggerType . . . . . . . . . . . . . . . . . . . . . 16
5.5.2. TriggerStatus . . . . . . . . . . . . . . . . . . . . 16
5.5.3. URLs . . . . . . . . . . . . . . . . . . . . . . . . . 16
5.5.4. AbsoluteTime . . . . . . . . . . . . . . . . . . . . . 17
5.5.5. ErrorCode . . . . . . . . . . . . . . . . . . . . . . 17
6. JSON Encoding of Objects . . . . . . . . . . . . . . . . . . . 17
6.1. JSON Encoding of Embedded Types . . . . . . . . . . . . . 18
6.1.1. TriggerType . . . . . . . . . . . . . . . . . . . . . 18
6.1.2. TriggerStatus . . . . . . . . . . . . . . . . . . . . 18
6.1.3. PatternMatch . . . . . . . . . . . . . . . . . . . . . 18
6.1.4. ErrorDesc . . . . . . . . . . . . . . . . . . . . . . 19
6.1.5. ErrorCode . . . . . . . . . . . . . . . . . . . . . . 19
6.1.6. Relationship . . . . . . . . . . . . . . . . . . . . . 19
6.2. MIME Media Types . . . . . . . . . . . . . . . . . . . . . 20
7. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
7.1. Creating Triggers . . . . . . . . . . . . . . . . . . . . 21
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7.1.1. Preposition . . . . . . . . . . . . . . . . . . . . . 21
7.1.2. Invalidate . . . . . . . . . . . . . . . . . . . . . . 22
7.2. Examining Trigger Status . . . . . . . . . . . . . . . . . 24
7.2.1. Collection of All Triggers . . . . . . . . . . . . . . 24
7.2.2. Filtered Collections of Triggers . . . . . . . . . . . 25
7.2.3. Trigger Status Resources . . . . . . . . . . . . . . . 27
7.2.4. Polling for Change . . . . . . . . . . . . . . . . . . 29
7.2.5. Cancelling or Removing a Trigger . . . . . . . . . . . 32
7.2.6. Error Reporting . . . . . . . . . . . . . . . . . . . 34
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 35
9. Security Considerations . . . . . . . . . . . . . . . . . . . 35
10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 35
11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 35
11.1. Normative References . . . . . . . . . . . . . . . . . . . 35
11.2. Informative References . . . . . . . . . . . . . . . . . . 35
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 36
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1. Introduction
[RFC6707] introduces the Problem scope for CDN Interconnection (CDNI)
and lists the four categories of interfaces that may be used to
compose a CDNI solution (Control, Metadata, Request Routing,
Logging).
[I-D.ietf-cdni-framework] expands on the information provided in
[RFC6707] and describes each of the interfaces and the relationships
between them in more detail.
This draft concentrates on the "High" and "Medium" priority
requirements for the CDNI Control Interface identified in section 4
of [I-D.ietf-cdni-requirements], reproduced here for convenience:
CNTL-1 [HIGH] The CDNI Control interface shall allow the Upstream
CDN to request that the Downstream CDN (and, if cascaded CDNs are
supported by the solution, that the potential cascaded Downstream
CDNs) perform the following actions on an object or object set:
* Mark an object(s) and/or its CDNI metadata as "stale" and
revalidate them before they are delivered again.
* Delete an object(s) and/or its CDNI metadata from the CDN
surrogates and any storage. Only the object(s) and CDNI
metadata that pertain to the requesting Upstream CDN are
allowed to be purged.
CNTL-2 [HIGH] The CDNI Control interface shall allow the
downstream CDN to report on the completion of these actions (by
itself, and if cascaded CDNs are supported by the solution, by
potential cascaded Downstream CDNs), in a manner appropriate for
the action (e.g. synchronously or asynchronously).
CNTL-3 [HIGH] The CDNI Control interface shall support initiation
and control by the Upstream CDN of pre-positioned CDNI metadata
acquisition by the Downstream CDN.
CNTL-4 [MED] The CDNI Control interface should support initiation
and control by the Upstream CDN of pre-positioned content
acquisition by the Downstream CDN.
This document does not consider those parts of the control interface
that relate to configuration, bootstrapping or authentication of CDN
Interconnect interfaces.
o Section 2 outlines the model for the Trigger Interface at a high
level.
o Section 3 describes collections of Trigger Resources.
o Section 4 defines the RESTful web service provided by dCDN.
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o Section 5 lists properties of Trigger Requests and Status
Resources.
o Section 6 defines a JSON encoding for Trigger Requests and Status
Resources.
o Section 7 contains example messages.
1.1. Terminology
This document reuses the terminology defined in [RFC6707].
2. Model for CDNI Triggers
A trigger, sent from uCDN to dCDN, is a request for dCDN to do some
work relating to data originating from uCDN.
The trigger may request action on either metadata or content, the
following actions can be requested:
o preposition - used to instruct dCDN to fetch metadata from uCDN,
or content from any origin including uCDN.
o invalidate - used to instruct dCDN to revalidate specific metadata
or content before re-using it.
o purge - used to instruct dCDN to delete specific metadata or
content.
The CDNI trigger interface is a RESTful web service offered by dCDN.
It allows creation and deletion of triggers, and tracking of the
triggered activity. When dCDN accepts a trigger it creates a
resource describing status of the triggered activity, a Trigger
Status Resource. The uCDN may poll Trigger Status Resources to
monitor progress.
Requests to invalidate and purge metadata or content apply to all
variants of that data with a given URI.
The dCDN maintains a collection of Trigger Status Resources for each
uCDN, each uCDN only has access to its own collection and the
location of that collection is shared when CDN interconnection is
established.
To trigger activity in dCDN, uCDN will POST to the collection of
Trigger Status Resources. If dCDN accepts the trigger, it creates a
new Trigger Status Resource and returns its location to uCDN. To
monitor progress, uCDN may GET the Trigger Status Resource. To
cancel a trigger, or remove a trigger from the collection once its
activity has been completed, uCDN may DELETE the Trigger Status
Resource.
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In addition to the collection of all Trigger Status Resources for
uCDN, uCDN shall have access to filtered views of that collection.
These filtered views are defined in Section 3 and include collections
of active and completed triggers. 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 dCDN, and for uCDN to discover the status
of that activity. Only successful triggering is shown. Examples of
the messages are given in Section 7.
uCDN dCDN
| (1) POST http://dcdn.example.com/triggers/uCDN |
[ ] --------------------------------------------------> [ ]--+
| [ ] | (2)
| (3) HTTP 201 Response [ ]<-+
[ ] <-------------------------------------------------- [ ]
| Loc: http://dcdn.example.com/triggers/uCDN/123 |
| |
. . .
. . .
. . .
| |
| (4) GET http://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:
1. uCDN triggers action in dCDN by posting to a collection of
Trigger Status Resources,
"http://dcdn.example.com/triggers/uCDN". The URL of this was
given to uCDN when the trigger interface was established.
2. dCDN authenticates the request, validates the trigger and if it
accepts the request, creates a new Trigger Status Resource.
3. dCDN responds to uCDN with an HTTP 201 response status, and the
location of the Trigger Status Resource.
4. uCDN may repeatedly poll the Trigger Status Resource in dCDN.
5. dCDN responds with the Trigger Status Resource, describing
progress or results of the triggered activity.
The remainder of this document describes the messages, Trigger Status
Resources, and collections of Trigger Status Resources in more
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detail.
2.1. Timing of Triggered Activity
Timing of triggered activity is under dCDN control, including its
start-time and pacing of the activity in the network.
Invalidate and purge triggers MUST be applied to all data acquired
before the trigger was created in dCDN. The dCDN MAY apply the
triggers to data acquired after trigger creation.
If uCDN wishes to invalidate or purge content, then immediately
preposition replacement content at the same URLs, it must ensure the
dCDN has completed the invalidate/purge before initiating the
prepositioning. If it fails to do that and the requests overlap, and
dCDN passes the triggers on to a further dCDN in a cascade, that CDN
may preposition content that has not yet been invalidated/purged in
its uCDN.
2.2. Trigger Results
Each Trigger Request may operate on multiple data items. The trigger
shall be reported as "complete" only if all actions can be completed
successfully, otherwise it shall be reported as "failed". The
reasons for failure and URLs or Patterns affected shall be enumerated
in the Trigger Status Resource. For more detail, see section
Section 4.5.
If a dCDN is also acting as uCDN in a cascade, it MUST forward
triggers to any downstream CDNs that may have data affected by the
trigger. The trigger MUST NOT be reported as complete in a CDN until
it is complete in all of its downstream CDNs. A trigger MAY be
reported as failed as soon as it fails in a CDN or in any of its
downstream CDNs.
3. Collections of Trigger Status Resources
As described in Section 2, Trigger Status Resources exist in 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.
To trigger activity in dCDN, uCDN creates a new Trigger Status
Resource by posting to dCDN's collection of uCDN's Trigger Status
Resources. The URL of each Trigger Status Resource is generated by
the dCDN when it accepts the trigger, and returned to uCDN. This
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immediately enables uCDN to check the status of that trigger.
The dCDN must present a different set of Trigger Status Resources to
each interconnected uCDN, only Trigger Status Resources belonging to
a uCDN shall be visible to it. The dCDN may, for example, achieve
this by offering different collection URLs to uCDNs, or by filtering
the response based on the client uCDN.
The dCDN resource representing the collection of all uCDN's Trigger
Status Resources is accessible to uCDN. This collection lists all
uCDN triggers that have been accepted by dCDN, and have not yet been
deleted by uCDN or expired and removed by dCDN.
In order to allow uCDN to check status of multiple jobs in a single
request, dCDN shall also maintain collections representing filtered
views of the collection of all Trigger Status Resources. The
filtered collections are:
o Pending - Trigger Status Resources for triggers that have been
accepted, but not yet acted upon.
o Active - Trigger Status Resources for triggered activity that is
currently being processed in dCDN.
o Complete - Trigger Status Resources representing activity that
completed successfully.
o Failed - Trigger Status Resources representing activity that
failed.
4. CDNI Trigger interface
This section describes an interface to enable an upstream CDN to
trigger defined activities in a downstream CDN. The interface is
intended to be independent of the set of activities defined now, or
that may be defined in future.
The CDNI Trigger interface is built on the principles of RESTful web
services. Requests are made over HTTP, and the HTTP Method defines
the operation the request would like to perform. The corresponding
HTTP Response returns the status of the operation in the HTTP Status
Code and returns the current representation of the resource (if
appropriate) in the Response Body. HTTP Responses from servers
implementing the CDNI Triggers interface that contain a response body
SHOULD include an ETag to enable validation of cached versions of
returned resources.
Servers implementing the CDNI Trigger interface MUST support the HTTP
GET, HEAD, POST and DELETE methods. The only representation
specified in this document is JSON.
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Trigger Requests are POSTed to a URI in dCDN. If the trigger is
accepted by dCDN, it creates a Trigger Status Resource and returns
its URI to dCDN in an HTTP 201 response. The triggered activity can
then be monitored by uCDN using that resource and the collections
described in Section 3.
The URI that Trigger Requests should be POSTed to needs to be either
discovered by or configured in the upstream CDN. Performing a GET on
that URI retrieves a collection of the URIs of all Trigger Status
Resources. The URI of each Trigger Status Resource is also returned
to uCDN when it is created. This means all Trigger Status Resources
can be discovered, so CDNI Trigger servers are free to assign
whatever structure they desire to the URIs for CDNI Trigger
resources. CDNI Trigger clients MUST NOT make any assumptions
regarding the structure of CDNI Trigger URIs or the mapping between
CDNI Trigger objects and their associated URIs. Therefore any URIs
present in the examples below are purely illustrative and are not
intended to impose a definitive structure on CDNI Trigger interface
implementations.
The CDNI Trigger interface builds on top of HTTP, so CDNI Trigger
servers may make use of any HTTP feature when implementing the CDNI
Trigger interface. For example, a CDNI Trigger server may make use
of HTTP's caching mechanisms to indicate that the returned response/
representation has not been modified since it was last returned,
reducing the processing needed to determine whether the status of
triggered activity has changed.
This specification is neutral with regard to the transport below the
HTTP layer.
[Editor's note: It is anticipated that decisions on use of HTTPS for
other CDNI interfaces will be adopted for Triggers.]
Discovery of the CDNI Triggers Interface is outside the scope of this
document. It is anticipated that a common mechanism for discovery of
all CDNI interfaces will be defined.
The dCDN must ensure that activity triggered by uCDN only affects
metadata or content originating from that uCDN. Since only one CDN
can be authoritative for a given item of metadata or content, this
requirement means there cannot be any "loops" in trigger requests
between CDNs.
4.1. Creating Triggers
To create a new trigger, uCDN makes an HTTP POST to the unfiltered
collection of its triggers. The request body of that POST is a
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Trigger Request.
dCDN validates and authenticates that request, if it is malformed or
uCDN does not have sufficient access rights it MAY reject the request
immediately. In this case, it SHALL respond with an appropriate 4xx
HTTP error code and no resource shall be created on dCDN.
If the request is accepted, uCDN SHALL create a new Trigger Status
Resource. The HTTP response to dCDN SHALL have status code 201 and
the URI of the Trigger Status Resource in the Location header field.
The HTTP response MAY include the content of the newly created
Trigger Status Resource, this is recommended particularly in cases
where the trigger has completed immediately.
Once a Trigger Status Resource has been created dCDN MUST NOT re-use
its location, even after that resource has been removed through
deletion or expiry.
The "request" property of the Trigger Status Resource SHALL contain
the information posted in the body of the Trigger Request. Note that
this need not be a byte-for-byte copy. For example, in the JSON
representation the dCDN may re-serialise the information differently.
If the trigger is queued by dCDN for later action, the "status"
property of the Trigger Status Resource SHALL be "pending". Once
trigger processing has started the "status" SHALL be "active".
A trigger may result in no activity in dCDN if, for example, it is an
invalidate or purge request for data the dCDN has not acquired, or a
prepopulate request for data it has already acquired. In this case,
the "status" of the Trigger Status Resource shall be "complete" and
the Trigger Status Resource shall be added to the dCDN collection of
Complete Triggers.
If dCDN is not able to track triggered activity, it MAY indicate that
it has undertaken to complete the activity but will not report
completion or any further errors. To do this, it must set the
trigger status to "complete", with an estimated completion time in
the future ("etime" greater than "mtime").
Once created, Trigger Status Resources may be deleted by uCDN but not
modified. The dCDN MUST reject PUT and POST requests from uCDN to
Trigger Status Resources using HTTP status code 403.
4.2. Checking Status
The uCDN has two ways to check progress of activity it has triggered
in dCDN, described in the following sections.
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Because the triggers protocol is based on HTTP, Entity Tags may be
used by the uCDN as cache validators, as defined in section 3.11 of
[RFC2616], to check for change in status of a resource or collection
of resources without re-fetching the whole resource or collection.
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 uCDN should poll for change.
4.2.1. Polling Trigger Status Resource collections
uCDN can fetch the collection of its Trigger Status Resources, or
filtered views of that collection.
This makes it possible to poll status of all triggered activity in a
single request. If dCDN moves a Trigger Status Resource from the
Active to the Completed collection, uCDN may chose to fetch the
result of that activity.
When polling in this way, uCDN may choose to use HTTP Entity Tags to
monitor for change, rather than repeatedly fetching the whole
collection.
4.2.2. Polling Trigger Status Resources
uCDN has a reference (URI provided by the dCDN) for each Trigger
Status Resource it has created, it may fetch that resource at any
time.
This may be used to retrieve progress information, and to fetch the
result of triggered activity.
4.3. Deleting Triggers
The uCDN MAY delete Trigger Status Resources at any time, using the
HTTP DELETE method.
Once deleted, the references to a Trigger Status Resource MUST be
removed from all Trigger Status Resource collections. Subsequent
requests for the resource shall be handled as required by HTTP, and
so will receive responses with status 404 or 410.
If a "pending" Trigger Status Resource is deleted, dCDN SHOULD NOT
start processing of that activity. Deleting a "pending" trigger does
not however guarantee that it is not started because, once it has
triggered activity, uCDN cannot control the timing of that activity.
Processing may, for example, start after the DELETE is sent by uCDN
and before the DELETE is processed by dCDN.
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If an "active" Trigger Status Resource is deleted, dCDN MAY stop
processing the triggered activity. However, as with deletion of a
"pending" trigger, dCDN does not guarantee this.
Deletion of a "complete" or "failed" Trigger Status Resource requires
no processing in dCDN other than deletion of the resource.
4.4. Expiry of Trigger Status Resources
The dCDN MAY choose to automatically delete Trigger Status Resources
some time after they become completed or failed. In this case, dCDN
will remove the resource and respond to subsequent requests for it
with HTTP status 404 or 410.
If dCDN performs this housekeeping, it MUST have reported the length
of time after which completed Trigger Status Resources become stale
via a property of the collection of all Trigger Status Resources. It
is recommended that Trigger Status Resources are automatically
deleted 24 hours after they become completed or failed.
To ensure it has access to the status of its completed and failed
triggers, it is recommended that uCDN's polling interval is half the
time after which records for completed activity will be considered
stale.
4.5. Error Handling
A CDNI Triggers server may reject a trigger request using HTTP status
codes, for example 400 if the request is malformed or 401 if the
client does not have permission to create triggers or it is trying to
act on another CDN's data.
If any part of the trigger request fails the trigger shall 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 may be present while the trigger is still
"pending" or "active" if the trigger is still running for some URLs
or Patterns in the trigger request.
Once a request has been accepted, processing errors are reported in
the Trigger Status Resource using a list of "ErrorDesc". Each
ErrorDesc is used to report errors against one or more of the URLs or
Patterns in the trigger request.
If a surrogate affected by a trigger is offline in dCDN, or dCDN is
unable to pass a trigger request on to any of its affected dCDNs;
dCDN should report an error if the request is abandoned, otherwise it
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must keep the trigger in state "pending" or "active" until it's acted
upon or uCDN chooses to cancel it. Or, if the request is queued and
dCDN will not report further status, dCDN may report the trigger as
"complete" with an "etime" in the future.
Note that an "invalidate" trigger may be reported as "complete" when
surrogates that may have the data are offline, if those surrogates
will not use the affected data without first revalidating it when
they are back online. This does not apply to "preposition" or
"purge" triggers.
5. Properties of Triggers
5.1. Properties of Trigger Requests
Properties of Trigger Requests are defined in the following
subsections.
Property: type
Description: This property defines the type of the trigger:
Type: TriggerType
Mandatory: Yes
Property: metadata.urls
Description: The uCDN URL for the metadata the trigger applies
to.
Type: URLs
Mandatory: No, but at least one of 'metadata.*' or 'content.*'
MUST be present and non-empty.
Property: content.urls
Description: URLs of content data the trigger applies to, see
Section 5.1.1.
Type: URLs
Mandatory: No, but at least one of 'metadata.*' or 'content.*'
MUST be present and non-empty.
Property: metadata.patterns
Description: The metadata the trigger applies to.
Type: List of PatternMatch
Mandatory: No, but at least one of 'metadata.*' or 'content.*'
MUST be present and non-empty, and metadata.patterns MUST NOT
be present if the TriggerType is Preposition.
Property: content.patterns
Description: The content data the trigger applies to.
Type: List of PatternMatch
Mandatory: No, but at least one of 'metadata.*' or 'content.*'
MUST be present and non-empty, and content.patterns MUST NOT be
present if the TriggerType is Preposition.
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5.1.1. Content URLs
To refer to content in dCDN, uCDN must present URLs in the same form
clients will use to access content in that dCDN, after transformation
to remove any surrogate-specific parts of a 302-redirect URL form.
By definition, it is always possible to locate content based on URLs
in this form.
If content URLs are transformed by an intermediate CDN in a cascade,
that intermediate CDN must transform URLs in trigger requests it
passes to its dCDN.
[Editor's note: Design for CDNI Metadata transformation, including
discussion of URL transformation, is being undertaken as part of the
work on the metadata interface. The intention is to align with that
document or make reference to it when it's complete.]
When processing trigger requests, CDNs may ignore the URL scheme
(http or https) in comparing URLs. For example, for an invalidate or
purge trigger, content may invalidated or purged regardless of the
protocol clients use to request it.
5.2. Properties of Trigger Status Resources
Property: trigger
Description: The properties of trigger request that created
this record.
Type: TriggerRequest
Mandatory: Yes
Property: ctime
Description: Time at which the request was received by dCDN.
Time is local to dCDN, there is no requirement to synchronise
clocks between interconnected CDNs.
Type: AbsoluteTime
Mandatory: Yes
Property: mtime
Description: Time at which the resource was last modified.
Time is local to dCDN, there is no requirement to synchronise
clocks between interconnected CDNs.
Type: AbsoluteTime
Mandatory: Yes
Property: etime
Description: Estimate of the time at which dCDN expects to
complete the activity. Time is local to dCDN, there is no
requirement to synchronise clocks between interconnected CDNs.
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Type: AbsoluteTime
Mandatory: No
Property: status
Description: Current status of the triggered activity.
Type: TriggerStatus
Mandatory: Yes
Property: errors
Description: List of ErrorDesc.
Mandatory: No.
5.3. Properties of ErrorDesc
An ErrorDesc object is used to report failure for URLs and patterns
in a trigger request.
Property: error
Type: ErrorCode.
Mandatory: Yes.
Description: List of metadata.urls, content.urls,
metadata.patterns, content.patterns
Description: Metadata and content references copied from the
trigger request. Only those URLs and patterns to which the
error applies shall be included in each property, but those
URLs and patterns shall be exactly as they appear in the
request, dCDN must not generalise the URLs. (For example, if
uCDN requests prepositioning of URLs
"http://ucdn.example.com/a" and "http://ucdn.example.com/b",
dCDN may not generalise its error report to Pattern
"http://ucdn.example.com/*").
Mandatory: At least one of these properties is mandatory in
each ErrorDesc.
Property: description
Description: A String containing a human-readable description
of the error.
Mandatory: No.
5.4. Properties of Trigger Collections
Property: links
Description: References to Trigger Status Resources in the
collection.
Type: List of Relationships.
Mandatory: Yes
Property: staleresourcetime
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Description: The length of time for which dCDN guarantees to
keep a completed Trigger Status Resource. After this time,
dCDN MAY delete the resource and all references to it from
collections.
Type: Integer, time in seconds.
Mandatory: Yes, in the collection of all Trigger Status
Resources if 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.
5.5. Trigger Resource Simple Data Type Descriptions
This section describes the simpler data types that are used for
properties of Trigger Status resources.
5.5.1. TriggerType
This type defines the type of action being triggered, permitted
actions are:
o Preposition - a request for dCDN to acquire metadata or content.
o Invalidate - a request for dCDN to invalidate metadata or content.
After servicing this request the dCDN will not use the specified
data without first re-validating it using, for example, an "If-
None-Match" HTTP request. The dCDN need not erase the associated
data.
o Purge - a request for dCDN to erase metadata or content. After
servicing the request, the specified data must not be held on
dCDN.
5.5.2. TriggerStatus
This type describes the current status of a Trigger, possible values
are:
o Pending - the trigger has not yet been acted upon.
o Active - the trigger is currently being acted upon.
o Complete - the triggered activity completed successfully, or the
trigger has been accepted and no further status update will be
made.
o Failed - the triggered activity could not be completed.
5.5.3. URLs
This type describes a set of references to metadata or content, it is
simply a list of absolute URLs.
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5.5.4. AbsoluteTime
Times are expressed in seconds since the UNIX epoch.
5.5.5. ErrorCode
This type is used by dCDN to report failures in trigger processing.
o EMETA - dCDN was unable to acquire metadata required to fulfil the
request.
o ECONTENT - dCDN was unable to acquire content (preposition
triggers only).
o EPERM - uCDN does not have permission to trigger the requested
activity (for example, the data is owned by another CDN).
o EREJECT - dCDN is not willing to fulfil the request (for example,
a preposition request for content at a time when dCDN would not
accept Request Routing requests from uCDN).
o ECDN - An internal error in dCDN or one of its downstream CDNs.
6. JSON Encoding of Objects
This encoding is based on that described in [I-D.ietf-cdni-metadata],
but has been reproduced here while metadata work is in progress.
Once that work is complete, the authors would look to align with the
structure of the metadata draft and make reference to common
definitions as appropriate.
The encoding for a CDNI Trigger object is a JSON object containing a
dictionary of (key,value) pairs where the keys are the property
names, and the values are the associated property values.
The keys of the dictionary are the names of the properties associated
with the object and are therefore dependent on the specific object
being encoded (i.e. dependent on the MIME Media Type of the returned
resource). Likewise, the values associated with each key are
dependent on the specific object being encoded (i.e. dependent on the
MIME Media Type of the returned resource).
The "trigger" property of the top level JSON object lists the
requested action.
Key: trigger
Description: An object specifying the trigger type and a set of
data to act upon.
Type: A JSON object.
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Mandatory: Yes.
Object keys in JSON are case sensitive and therefore any dictionary
key defined by this document (for example the names of CDNI Triggers
object properties) MUST always be represented in lowercase.
In addition to the properties of an object, the following additional
keys may be present.
Key: base
Description: Provides a prefix for any relative URLs in the
object. This is similar to the XML base tag [XML-BASE]. If
absent, all URLs in the remainder of the document must be
absolute URLs.
Type: URI
Mandatory: No
Key: links
Description: The relationships of this object to other
addressable objects.
Type: Array of Relationships.
Mandatory: Yes
6.1. JSON Encoding of Embedded Types
6.1.1. TriggerType
Key: type
Description: One of "preposition", "invalidate" or "purge".
Type: string
6.1.2. TriggerStatus
Key: status
Description: One of "pending", "active", "failed", "complete"
Type: string
6.1.3. PatternMatch
A PatternMatch is encoded as a JSON Object containing a string to
match and flags describing the type of match.
Key: pattern
Description: A pattern for string matching. The pattern may
contain the wildcards * and ?, where * matches any sequence of
characters (including the empty string) and ? matches exactly
one character. The three literals \ , * and ? should be
escaped as \\, \* and \?
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Type: String
Mandatory: Yes
Key: case-sensitive
Description: Flag indicating whether or not case-sensitive
matching should be used.
Type: Boolean
Mandatory: No, default is case-insensitive match.
Key: match-query-string
Description: Flag indicating whether or not the query string
should be included in the pattern match.
Type: Boolean
Mandatory: No, default is not to include query.
Example of case-sensitive prefix match against
"http://www.example.com/trailers/":
{
"pattern": "http://www.example.com/trailers/*",
"case-sensitive": true
}
6.1.4. ErrorDesc
ErrorDesc shall be encoded as a JSON object with the following keys:
Key: error
Type: ErrorCode
Mandatory: Yes
Keys: metadata.urls, content.urls
Type: Array of strings
Mandatory: At least one of metadata.* or content.* must be
present.
Keys: metadata.patterns, content.patterns
Type: Array of PatternMatch
Mandatory: At least one of metadata.* or content.* must be
present.
Key: description
Type: String
Mandatory: No.
6.1.5. ErrorCode
One of the strings "EMETA", "ECONTENT", "EPERM", "EREJECT" or "ECDN".
6.1.6. Relationship
JSON: A dictionary with the following keys:
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o href - The URI of the of the addressable object being referenced.
o rel - The Relationship between the referring object and the object
it is referencing.
o type - The MIME Media Type of the referenced object. See
Section 6.2 for the MIME Media Types of objects specified in this
document.
o title - An optional title for the Relationship/link.
Note: The above structure follows the pattern of atom:link in
[RFC4287].
Example Relationship to a CDNI Trigger Resource within a CDNI Trigger
Collection:
{
"href": "http://triggers.cdni.example.com/trigger/12345",
"rel": "Trigger",
"type": "application/vnd.cdni.control.trigger.status+json"
}
The format of relationship values is expected to align with other
CDNI interfaces. For example, rather than use simple names (like
"Trigger" in this case), there may be a namespace that allows well-
known and proprietary values to co-exist.
6.2. MIME Media Types
Table 1 lists the MIME Media Type for each trigger object (resource)
that is retrievable through the CDNI Trigger interface.
Note: A prefix of "vnd.cdni" is used, however it is expected that a
more appropriate prefix will be used if the CDNI WG accepts this
document.
+-------------------+-----------------------------------------------+
| Data Object | MIME Media Type |
+-------------------+-----------------------------------------------+
| TriggerStatus | application/ |
| | vnd.cdni.control.trigger.status+json |
| TriggerCollection | application/ |
| | vnd.cdni.control.trigger.collection+json |
+-------------------+-----------------------------------------------+
Table 1: MIME Media Types for CDNI Trigger resources
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7. Examples
The following sections provide examples of different CDNI Trigger
objects encoded as JSON.
No authentication is shown in the following illustrative examples, it
is anticipated that authentication mechanisms will be aligned with
other CDNI Interfaces as and when those mechanisms are defined.
Discovery of the triggers interface is out of scope of this document.
In an implementation, all URLs are under control of dCDN and the uCDN
must not attempt to ascribe any meaning to individual elements of the
path. In examples in this section, the following URLs are used as
the location of the collections of triggers:
o Collection of all Triggers belonging to one uCDN:
http://dcdn.example.com/triggers
o Filtered collections:
Pending: http://dcdn.example.com/triggers/pending
Active: http://dcdn.example.com/triggers/active
Complete: http://dcdn.example.com/triggers/complete
Failed: http://dcdn.example.com/triggers/failed
7.1. Creating Triggers
Examples of uCDN triggering activity in dCDN:
7.1.1. Preposition
An example of a preposition request, a POST to the "AllTriggers"
collection.
Note that "metadata.patterns" and "content.patterns" are not allowed
in a preposition trigger request.
REQUEST:
POST /triggers HTTP/1.1
User-Agent: example-user-agent/0.1
Host: dcdn.example.com
Accept: */*
Content-Type: application/vnd.cdni.control.trigger.request+json
Content-Length: 315
{
"trigger" : {
"type": "preposition",
"metadata.urls" : [ "http://metadata.example.com/a/b/c" ],
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"content.urls" : [
"http://www.example.com/a/b/c/1",
"http://www.example.com/a/b/c/2",
"http://www.example.com/a/b/c/3",
"http://www.example.com/a/b/c/4"
]
}
}
RESPONSE:
HTTP/1.1 201 Created
Date: Sat, 23 Feb 2013 14:20:06 GMT
Content-Length: 472
Content-Type: application/vnd.cdni.control.trigger.status+json
Location: http://dcdn.example.com/triggers/0
Server: example-server/0.1
{
"ctime": 1361629206,
"etime": 1361629214,
"mtime": 1361629206,
"status": "pending",
"trigger": {
"content.urls": [
"http://www.example.com/a/b/c/1",
"http://www.example.com/a/b/c/2",
"http://www.example.com/a/b/c/3",
"http://www.example.com/a/b/c/4"
],
"metadata.urls": [
"http://metadata.example.com/a/b/c"
],
"type": "preposition"
}
}
7.1.2. Invalidate
An example of an invalidate request, another POST to the
"AllTriggers" collection. This instructs dCDN to re-validate the
content at "http://www.example.com/a/index.html", as well as any
metadata and content whose URLs are prefixed by
"http://metadata.example.com/a/b/" and "http://www.example.com/a/b/"
respectively, using case-insensitive matching.
REQUEST:
POST /triggers HTTP/1.1
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User-Agent: example-user-agent/0.1
Host: dcdn.example.com
Accept: */*
Content-Type: application/vnd.cdni.control.trigger.request+json
Content-Length: 352
{
"trigger" : {
"type": "invalidate",
"metadata.patterns" : [
{ "pattern" : "http://metadata.example.com/a/b/*" }
],
"content.urls" : [ "http://www.example.com/a/index.html" ],
"content.patterns" : [
{ "pattern" : "http://www.example.com/a/b/*",
"case-sensitive" : true
}
]
}
}
RESPONSE:
HTTP/1.1 201 Created
Date: Sat, 23 Feb 2013 14:20:08 GMT
Content-Length: 551
Content-Type: application/vnd.cdni.control.trigger.status+json
Location: http://dcdn.example.com/triggers/1
Server: example-server/0.1
{
"ctime": 1361629208,
"etime": 1361629216,
"mtime": 1361629208,
"status": "pending",
"trigger": {
"content.patterns": [
{
"case-sensitive": true,
"pattern": "http://www.example.com/a/b/*"
}
],
"content.urls": [
"http://www.example.com/a/index.html"
],
"metadata.patterns": [
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{
"pattern": "http://metadata.example.com/a/b/*"
}
],
"type": "invalidate"
}
}
7.2. Examining Trigger Status
Once triggers have been created, uCDN can check their status as shown
in these examples.
7.2.1. Collection of All Triggers
The uCDN can fetch the set of all the triggers it has created and
which have not yet been deleted or removed as expired. After
creation of the "preposition" and "invalidate" triggers shown above,
this collection might look as follows:
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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: 422
Expires: Sat, 23 Feb 2013 14:21:08 GMT
Server: example-server/0.1
ETag: "1484827667515030767"
Cache-Control: max-age=60
Date: Sat, 23 Feb 2013 14:20:08 GMT
Content-Type: application/vnd.cdni.control.trigger.collection+json
{
"links": [
{
"href": "http://dcdn.example.com/triggers/0",
"rel": "Trigger",
"type": "application/vnd.cdni.control.trigger.status+json"
},
{
"href": "http://dcdn.example.com/triggers/1",
"rel": "Trigger",
"type": "application/vnd.cdni.control.trigger.status+json"
}
],
"staleresourcetime": 86400
}
7.2.2. Filtered Collections of Triggers
The filtered collections are also available to uCDN. Before dCDN
starts processing the two triggers shown above, both will appear in
the collection of Pending Triggers, for example:
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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: 422
Expires: Sat, 23 Feb 2013 14:21:09 GMT
Server: example-server/0.1
ETag: "-970375801048973013"
Cache-Control: max-age=60
Date: Sat, 23 Feb 2013 14:20:09 GMT
Content-Type: application/vnd.cdni.control.trigger.collection+json
{
"links": [
{
"href": "http://dcdn.example.com/triggers/0",
"rel": "Trigger",
"type": "application/vnd.cdni.control.trigger.status+json"
},
{
"href": "http://dcdn.example.com/triggers/1",
"rel": "Trigger",
"type": "application/vnd.cdni.control.trigger.status+json"
}
],
"staleresourcetime": 86400
}
At this point, if no other triggers had been created, the other
filtered views of the triggers would be empty. For example:
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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: 53
Expires: Sat, 23 Feb 2013 14:21:09 GMT
Server: example-server/0.1
ETag: "-654105208640281650"
Cache-Control: max-age=60
Date: Sat, 23 Feb 2013 14:20:09 GMT
Content-Type: application/vnd.cdni.control.trigger.collection+json
{
"links": [],
"staleresourcetime": 86400
}
7.2.3. Trigger Status Resources
The Trigger Status Resources can also be examined for detail about
individual triggers. For example, for the "preposition" and
"invalidate" triggers from previous examples:
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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: 472
Expires: Sat, 23 Feb 2013 14:21:08 GMT
Server: example-server/0.1
ETag: "-7651038857765989381"
Cache-Control: max-age=60
Date: Sat, 23 Feb 2013 14:20:08 GMT
Content-Type: application/vnd.cdni.control.trigger.status+json
{
"ctime": 1361629206,
"etime": 1361629214,
"mtime": 1361629206,
"status": "pending",
"trigger": {
"content.urls": [
"http://www.example.com/a/b/c/1",
"http://www.example.com/a/b/c/2",
"http://www.example.com/a/b/c/3",
"http://www.example.com/a/b/c/4"
],
"metadata.urls": [
"http://metadata.example.com/a/b/c"
],
"type": "preposition"
}
}
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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: 551
Expires: Sat, 23 Feb 2013 14:21:09 GMT
Server: example-server/0.1
ETag: "-1103964172288811711"
Cache-Control: max-age=60
Date: Sat, 23 Feb 2013 14:20:09 GMT
Content-Type: application/vnd.cdni.control.trigger.status+json
{
"ctime": 1361629208,
"etime": 1361629216,
"mtime": 1361629208,
"status": "pending",
"trigger": {
"content.patterns": [
{
"case-sensitive": true,
"pattern": "http://www.example.com/a/b/*"
}
],
"content.urls": [
"http://www.example.com/a/index.html"
],
"metadata.patterns": [
{
"pattern": "http://metadata.example.com/a/b/*"
}
],
"type": "invalidate"
}
}
7.2.4. Polling for Change
The uCDN may use the Entity Tags of collections or resources when
polling for change in status, as shown in the following examples:
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REQUEST:
GET /triggers/pending HTTP/1.1
User-Agent: example-user-agent/0.1
Host: dcdn.example.com
Accept: */*
If-None-Match: "-970375801048973013"
RESPONSE:
HTTP/1.1 304 Not Modified
Content-Length: 0
Expires: Sat, 23 Feb 2013 14:21:09 GMT
Server: example-server/0.1
ETag: "-970375801048973013"
Cache-Control: max-age=60
Date: Sat, 23 Feb 2013 14:20:09 GMT
Content-Type: application/vnd.cdni.control.trigger.collection+json
REQUEST:
GET /triggers/0 HTTP/1.1
User-Agent: example-user-agent/0.1
Host: dcdn.example.com
Accept: */*
If-None-Match: "-7651038857765989381"
RESPONSE:
HTTP/1.1 304 Not Modified
Content-Length: 0
Expires: Sat, 23 Feb 2013 14:21:08 GMT
Server: example-server/0.1
ETag: "-7651038857765989381"
Cache-Control: max-age=60
Date: Sat, 23 Feb 2013 14:20:08 GMT
Content-Type: application/vnd.cdni.control.trigger.status+json
When the triggered activity is complete, the contents of the filtered
collections will be updated, along with their Entity Tags. For
example, when the two example triggers are complete, the collections
of pending and complete triggers may look like:
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REQUEST:
GET /triggers/pending HTTP/1.1
User-Agent: example-user-agent/0.1
Host: dcdn.example.com
Accept: */*
If-None-Match: "-970375801048973013"
RESPONSE:
HTTP/1.1 200 OK
Content-Length: 53
Expires: Sat, 23 Feb 2013 14:21:13 GMT
Server: example-server/0.1
ETag: "-7056231826368088123"
Cache-Control: max-age=60
Date: Sat, 23 Feb 2013 14:20:13 GMT
Content-Type: application/vnd.cdni.control.trigger.collection+json
{
"links": [],
"staleresourcetime": 86400
}
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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: 422
Expires: Sat, 23 Feb 2013 14:21:20 GMT
Server: example-server/0.1
ETag: "2013095476705515794"
Cache-Control: max-age=60
Date: Sat, 23 Feb 2013 14:20:20 GMT
Content-Type: application/vnd.cdni.control.trigger.collection+json
{
"links": [
{
"href": "http://dcdn.example.com/triggers/0",
"rel": "Trigger",
"type": "application/vnd.cdni.control.trigger.status+json"
},
{
"href": "http://dcdn.example.com/triggers/1",
"rel": "Trigger",
"type": "application/vnd.cdni.control.trigger.status+json"
}
],
"staleresourcetime": 86400
}
7.2.5. Cancelling or Removing a Trigger
To request dCDN to cancel a Trigger, uCDN may delete the Trigger
Resource. It may also delete completed and failed triggers to reduce
the size of the collections. For example, to remove the
"preposition" request from earlier examples:
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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: Sat, 23 Feb 2013 14:20:20 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 triggers
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: 239
Expires: Sat, 23 Feb 2013 14:21:20 GMT
Server: example-server/0.1
ETag: "4257416552489354137"
Cache-Control: max-age=60
Date: Sat, 23 Feb 2013 14:20:20 GMT
Content-Type: application/vnd.cdni.control.trigger.collection+json
{
"links": [
{
"href": "http://dcdn.example.com/triggers/1",
"rel": "Trigger",
"type": "application/vnd.cdni.control.trigger.status+json"
}
],
"staleresourcetime": 86400
}
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7.2.6. Error Reporting
In this example uCDN has requested prepositioning of
"http://newsite.example.com/index.html", but dCDN was unable to
locate metadata for that site:
REQUEST:
GET /triggers/2 HTTP/1.1
User-Agent: example-user-agent/0.1
Host: dcdn.example.com
Accept: */*
RESPONSE:
HTTP/1.1 200 OK
Content-Length: 505
Expires: Sat, 23 Feb 2013 14:21:28 GMT
Server: example-server/0.1
ETag: "2621489144226897896"
Cache-Control: max-age=60
Date: Sat, 23 Feb 2013 14:20:28 GMT
Content-Type: application/vnd.cdni.control.trigger.status+json
{
"ctime": 1361629220,
"errors": [
{
"content.urls": [
"http://newsite.example.com/index.html"
],
"description":
"No HostIndex entry found for newsite.example.com",
"error": "EMETA"
}
],
"etime": 1361629228,
"mtime": 1361629224,
"status": "active",
"trigger": {
"content.urls": [
"http://newsite.example.com/index.html"
],
"type": "preposition"
}
}
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8. IANA Considerations
TBD.
9. Security Considerations
The dCDN must ensure that each uCDN only has access to its own
Trigger Status Resources.
It is anticipated that a common authentication mechanism will be used
by this and other CDNI Interconnect interfaces, the mechanism must
exist but is not identified in this document.
The dCDN must ensure that activity triggered by uCDN only affects
metadata or content originating from that uCDN.
10. Acknowledgements
TBD.
11. References
11.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2616] Fielding, R., Gettys, J., Mogul, J., Frystyk, H.,
Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext
Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999.
[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
Resource Identifier (URI): Generic Syntax", STD 66,
RFC 3986, January 2005.
11.2. Informative References
[I-D.ietf-cdni-framework]
Peterson, L. and B. Davie, "Framework for CDN
Interconnection", draft-ietf-cdni-framework-03 (work in
progress), February 2013.
[I-D.ietf-cdni-metadata]
Niven-Jenkins, B., Murray, R., Watson, G., Caulfield, M.,
Leung, K., and K. Ma, "CDN Interconnect Metadata",
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draft-ietf-cdni-metadata-00 (work in progress),
October 2012.
[I-D.ietf-cdni-requirements]
Leung, K. and Y. Lee, "Content Distribution Network
Interconnection (CDNI) Requirements",
draft-ietf-cdni-requirements-05 (work in progress),
February 2013.
[RFC4287] Nottingham, M., Ed. and R. Sayre, Ed., "The Atom
Syndication Format", RFC 4287, December 2005.
[RFC6707] Niven-Jenkins, B., Le Faucheur, F., and N. Bitar, "Content
Distribution Network Interconnection (CDNI) Problem
Statement", RFC 6707, September 2012.
[XML-BASE]
Marsh, J., Ed. and R. Tobin, Ed., "XML Base (Second
Edition) - http://www.w3.org/TR/xmlbase/", January 2009.
Authors' Addresses
Rob Murray
Velocix (Alcatel-Lucent)
3 Ely Road
Milton, Cambridge CB24 6DD
UK
Email: rmurray@velocix.com
Ben Niven-Jenkins
Velocix (Alcatel-Lucent)
3 Ely Road
Milton, Cambridge CB24 6DD
UK
Email: ben@velocix.com
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