CDNI Metadata Model Extensions
draft-goldstein-cdni-metadata-model-extensions-01
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| Authors | Glenn Goldstein , Will Power , Guillaume Bichot , Alfonso Silóniz | ||
| Last updated | 2021-10-25 | ||
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draft-goldstein-cdni-metadata-model-extensions-01
Network Working Group G. Goldstein
Internet-Draft W. Power
Updates: 8006, 8008 (if approved) Lumen Technologies
Intended status: Standards Track G. Bichot
Expires: 28 April 2022 Broadpeak
A. Siloniz
Telefonica
25 October 2021
CDNI Metadata Model Extensions
draft-goldstein-cdni-metadata-model-extensions-01
Abstract
Open Caching architecture is a use case of Content Delivery Networks
Interconnection (CDNI) in which the commercial Content Delivery
Network (CDN) is the upstream CDN (uCDN) and the ISP caching layer
serves as the downstream CDN (dCDN). This document proposed
extensions to the RFC8006 Metadata Model by way of a set of
GenericMetadata objects that address extend the original CDNI
capabilities to meet the more general needs of the CDN and Open
Caching industry. Extensions to RFC8008 are also introduced to allow
a dCDN to advertise support for these extended metadata capabilities.
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-
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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 28 April 2022.
Copyright Notice
Copyright (c) 2021 IETF Trust and the persons identified as the
document authors. All rights reserved.
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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
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 5
1.2. Requirements Language . . . . . . . . . . . . . . . . . . 6
2. CDNI Additonal GenericMetadata Objects . . . . . . . . . . . 6
2.1. Auth . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.1.1. HeaderAuth . . . . . . . . . . . . . . . . . . . . . 7
2.1.2. AWSv4Auth . . . . . . . . . . . . . . . . . . . . . . 8
2.2. AllowCompress . . . . . . . . . . . . . . . . . . . . . . 9
2.3. CachePolicy . . . . . . . . . . . . . . . . . . . . . . . 10
2.4. ComputedCacheKey . . . . . . . . . . . . . . . . . . . . 11
2.5. CrossoriginPolicy . . . . . . . . . . . . . . . . . . . . 12
2.5.1. AllowOrigin . . . . . . . . . . . . . . . . . . . . . 13
2.6. NegativeCachePolicy . . . . . . . . . . . . . . . . . . . 14
2.7. CacheBypassPolicy . . . . . . . . . . . . . . . . . . . . 15
2.8. OcnSelection . . . . . . . . . . . . . . . . . . . . . . 16
2.8.1. OcnDelivery . . . . . . . . . . . . . . . . . . . . . 16
2.9. PrivateFeatureList . . . . . . . . . . . . . . . . . . . 17
2.9.1. PrivateFeature . . . . . . . . . . . . . . . . . . . 17
2.10. ProcessingStages . . . . . . . . . . . . . . . . . . . . 18
2.10.1. StageRules . . . . . . . . . . . . . . . . . . . . . 22
2.10.2. ExpressionMatch . . . . . . . . . . . . . . . . . . 22
2.10.3. StageMetadata . . . . . . . . . . . . . . . . . . . 23
2.10.4. RequestTransform . . . . . . . . . . . . . . . . . . 25
2.10.5. ResponseTransform . . . . . . . . . . . . . . . . . 25
2.10.6. SyntheticResponse . . . . . . . . . . . . . . . . . 27
2.10.7. HeaderTransform . . . . . . . . . . . . . . . . . . 28
2.10.8. HttpHeader . . . . . . . . . . . . . . . . . . . . . 29
2.11. RequestedCapacityLimits . . . . . . . . . . . . . . . . . 30
2.12. RequestRouting . . . . . . . . . . . . . . . . . . . . . 31
2.13. ServiceIDs . . . . . . . . . . . . . . . . . . . . . . . 32
2.14. SourceMetadataExtended . . . . . . . . . . . . . . . . . 33
2.14.1. SourceExtended . . . . . . . . . . . . . . . . . . . 34
2.14.2. LoadBalanceMetadata . . . . . . . . . . . . . . . . 36
2.15. StaleContentCachePolicy . . . . . . . . . . . . . . . . . 37
2.16. TrafficType . . . . . . . . . . . . . . . . . . . . . . . 38
3. CDNI Additional FCI Objects . . . . . . . . . . . . . . . . . 39
3.1. FCI.AuthTypes . . . . . . . . . . . . . . . . . . . . . . 40
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3.2. FCI.ProcessingStages . . . . . . . . . . . . . . . . . . 40
3.3. FCI.SourceMetadataExtended . . . . . . . . . . . . . . . 41
3.4. FCI.RequestRouting . . . . . . . . . . . . . . . . . . . 41
3.5. FCI.PrivateFeatures . . . . . . . . . . . . . . . . . . . 42
3.6. FCI.OcnSelection . . . . . . . . . . . . . . . . . . . . 42
3.6.1. OcnDeliveryList . . . . . . . . . . . . . . . . . . . 43
4. Metadata Expression Language . . . . . . . . . . . . . . . . 43
4.1. Expression Variables . . . . . . . . . . . . . . . . . . 45
4.2. Expression Operators and keywords . . . . . . . . . . . . 45
4.3. Expression Built-in Functions . . . . . . . . . . . . . . 47
4.3.1. Basic Functions: Type Conversions . . . . . . . . . . 47
4.3.2. Basic Functions: String Conversions . . . . . . . . . 47
4.3.3. Convenience Functions . . . . . . . . . . . . . . . . 48
4.4. Error Handling . . . . . . . . . . . . . . . . . . . . . 49
4.4.1. Compile Time Errors . . . . . . . . . . . . . . . . . 49
4.4.2. Runtime Errors . . . . . . . . . . . . . . . . . . . 50
4.5. Expression Examples . . . . . . . . . . . . . . . . . . . 50
4.5.1. ComputedCacheKey . . . . . . . . . . . . . . . . . . 50
4.5.2. ExpressionMatch . . . . . . . . . . . . . . . . . . . 50
4.5.3. ResponseTransform . . . . . . . . . . . . . . . . . . 51
4.5.4. MI.ServiceIDs . . . . . . . . . . . . . . . . . . . . 51
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 52
5.1. CDNI Payload Types . . . . . . . . . . . . . . . . . . . 52
6. Security Considerations . . . . . . . . . . . . . . . . . . . 52
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 52
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 52
8.1. Normative References . . . . . . . . . . . . . . . . . . 52
8.2. Informative References . . . . . . . . . . . . . . . . . 54
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 54
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1. Introduction
The Streaming Video Alliance [SVA] is a global association that works
to solve streaming video challenges in an effort to improve end-user
experience and adoption. The Open Caching Working Group [OCWG] of
the Streaming Video Alliance [SVA] is focused on the delegation of
video delivery requests from commerical CDNs to a caching layer at
the ISP's network. Open Caching architecture is a specific use case
of CDNI where the commercial CDN is the upstream CDN (uCDN) and the
ISP caching layer is the downstream CDN (dCDN). The interchange of
content delivery configuration metadata between the various entities
in the delivery ecosystem is essential for efficient
interoperability. The need for an industry-standard API and metadata
model becomes increasingly important as content and service providers
automate more of their operations, and as technologies, such as open
caching, require coordination of content delivery configurations. In
order to achieve this, the Open Caching Configuration Interface
Specification [OC-CI] defines an interface contemplating a set of use
cases.
The following capabilities extend the [RFC8006] Metadata Model:
* Open Caching Configuration Metadata
* Enhanced Source definitions, with load balancing, failover, and
extended authorization methods Section 2.14
* A rich set of Cache Control Policies Section 2.3 and computed
cache keys Section 2.4
* Rules for generating Dynamic CORS Headers Section 2.5
* Possibility to activate compression in the Edge independent of the
origin content Section 2.2
* Traffic Types Section 2.16
* ServiceID Metadata Section 2.13
* Processing Stage Rules Section 2.10, enabling metadata to be
applied conditionally at various stages in the CDN request/
response pipeline.
* Request URI Rewrites
* HTTP Header Modifications Section 2.10.8
* HTTP Status Modifications Section 2.10.5
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* Synthetic HTTP Responses Section 2.10.6
* An Expression Language for matching rules and synthesis of dynamic
values Section 4
* Private Features Section 2.9
For consistency with other CDNI documents this document follows the
CDNI convention of uCDN (upstream CDN) and dCDN (downstream CDN) to
represent the commercial CDN and ISP caching layer respectively.
This document defines and registers CDNI GenericMetadata objects (as
defined in section 4 of [RFC8006]), registers additional CDNI Payload
Types (section 7.1 of [RFC8006]), and adds capability objects
(extending section 5 in [RFC8008])
1.1. Terminology
The following terms are used throughout this document:
* API - Application Programming Interface
* AWS - Amazon Web Services
* CDN - Content Delivery Network
* CDNi - CDN Interconnect
* CORS - Cross-Origin Resource Sharing
* CP - Content Provider
* dCDN - Downstream CDN
* DNS - Domain Name System
* FCI - Footprint and Capabilities Advertising Interface
* HREF - Hypertext Reference (link)
* HTTP - Hypertext Transfer Protocol
* IETF - Internet Engineering Task Force
* ISP - Internet Service Provider
* JSON - JavaScript Object Notation
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* MEL - Metadata Expression Language
* Object - A collection of properties.
* OC - Open Caching
* OCN - Open Caching Node
* PatternMatch - An object which matches a string pattern
* UA - User Agent
* uCDN - Upstream CDN
* URI - Uniform Resource Identifier
* URN - Uniform Resource Name
* VOD - Video-on-Demand
* W3C - World Wide Web Consortium
Additionally, this document reuses the terminology defined in
[RFC6707], [RFC7336], [RFC8006], [RFC8007], [RFC8008], and [RFC8804].
Specifically, we use the following CDNI acronyms:
* uCDN, dCDN - Upstream CDN and Downstream CDN respectively (see
[RFC7336] )
1.2. Requirements Language
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. CDNI Additonal GenericMetadata Objects
Section 4 of [RFC8006] defines a set of GenericMetadata Object Types.
Below additional GenericMetadata Objects are defined to meet the more
general needs of the CDNs and Open Caching industry.
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Note: In the following sections, the term "mandatory-to-specify" is
used to convey which properties MUST be included when serializing a
given capability object. When mandatory-to-specify is defined as
"Yes" for an individual property, it means that if the object
containing that property is included in a message, then the
mandatory-to-specify property MUST also be included.
2.1. Auth
To meet the CDN industry requirements for origin authentication, two
new authentication types are proposed to be registered via the CDNi
Media Type Registration process, as described in [RFC7736].
auth-type: headerauth
- Description: Header based authentication is used to pass an
HTTP header secret-name and value secret-value to a uCDN when
requesting content. The header name and value are agreed upon
between parties out of band.
- auth-value: HeaderAuth object as defined in Section 2.1.1
auth-type: awsv4auth
- Description: Allows for the specification of a set of headers
to be added to requests that are forwarded to an origin to
enable Amazon Web Services AWS authentication as documented by
AWS See Specifications Standards References.
- auth-value: AWSv4Auth object specifying the access parameters
as defined in Section 2.1.2
2.1.1. HeaderAuth
The HeaderAuth metadata object is used in the auth-value property of
the Auth object, as defined in section 4.2.7 of [RFC8006], and may be
applied to any source by including or referencing it under its
authentication property. This method of authentication provides a
simple capability for a mutually agreed upon header to be added by
the CDN to all requests sent to a specific origin. Note that if a
dynamically generated header value is required, the RequestTransform
capabilities within StageProcessing (See Section 2.10) can be used.
Property: header-name
- Description: Name of the authentication header.
- Type: String
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- Mandatory-to-Specify: Yes
Property: header-value
- Description: Value of the authentication header typically a
pre-shared key. Note that this value should not be disclosed
it should be protected by some mechanism such as a secret-
sharing API which is outside the scope of this specification.
- Type: String
- Mandatory-to-Specify: Yes
2.1.2. AWSv4Auth
The AWSv4Auth metadata object is used in the auth-value property of
the Auth object as defined in RFC-8006 section 4.2.7, and may be
applied to any source by including or referencing it under its
authentication property.
AWSv4 authentication causes upstream requests to have a signature
applied, following the method described in [AWSv4Method]. A hash-
based signature is calculated over the request URI and specified
headers, and provided in an Authorization: header on the upstream
request. The signature is tied to a pre-shared secret key specific
to an AWS service, region, and key ID.
Property: access-key-id
- Description: The preconfigured ID of the pre-shared
authorization secret.
- Type: String
- Mandatory-to-Specify: Yes
Property: secret-access-key
- Description: The pre-shared authorization secret which is the
basis of building the signature. This is a secret key that
should not be disclosed it should be protected by some
mechanism such as a secret-sharing API which is outside the
scope of this specification.
- Type: String
- Mandatory-to-Specify: Yes
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Property: aws-region
- Description: The AWS region name that is hosting the service
and shares the key ID and corresponding pre-shared secret.
- Type: String
- Mandatory-to-Specify: Yes
Property: aws-service
- Description: The AWS service name that is serving the upstream
requests.
- Type: String
- Mandatory-to-Specify: No. It defaults to s3 if not specified.
Property: host-name
- Description: The host name to use as part of the signature
calculation.
- Type: String
- Mandatory-to-Specify: No. It defaults to using the value of
the Host: header of the upstream request. This property is
available in case the application needs to override that
behavior.
2.2. AllowCompress
Downstream CDNs often have the ability to compress HTTP response
bodies in cases where the client has declared that it can accept
compressed responses (via an Accept-Encoding header), but the source/
origin has returned an uncompressed response
The specific compression algorithm used by the dCDN is negotiated by
the client's Accept-Encoding header according to [RFC7694] (including
q= preferences) and the compression capabilities available on the
dCDN.
MI.AllowCompress is a new GenericMetadata object that allows the uCDN
to control the activation of response compression in the dCDN
directly, and allows content providers to disable compression in
cases where compressed responses are not handled properly by certain
streaming devices. This can be achieved using a match expression on
the user agent.
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In addition, HeaderTransform allows the uCDN to normalize, or modify,
the Accept-Encoding header to allow for fine-grain control over the
selection of the compression algorithm (e.g., gzip, compress,
deflate, br, etc.).
Properties of AllowCompress object are:
Property: allow-compress
- Description: If set to True then the dCDN will try to compress
the response to the client based on the Accept-Encoding request
header.
- Type: Boolean
- Mandatory-to-Specify: No. The default is False.
2.3. CachePolicy
MI.CachePolicy is a new GenericMetadata object that allows for the
uCDN to specify internal caching policies for the dCDN and external
caching policies advertised to clients of the dCDN. overriding any
cache control policy set in the response from the uCDN
Property: internal
- Description: Specifies the internal cache control policy to be
used by the dCDN.
- Type: Number in seconds encoded as string (e.g. 5 is a five
second cache ) and/or a list of Enumeration [as-is|no-cache|no-
store]
- Mandatory-to-Specify: No. The default is to use the cache
control policy specified in the response from the uCDN.
Property: external
- Description: Specifies the external cache control policy to be
used by clients of this dCDN.
- Type: Number in seconds encoded as string (e.g. 5 is a five
second cache ) and/or a list of Enumeration [as-is|no-cache|no-
store]
- Mandatory-to-Specify: No. The default is to use the cache
control policy specified in the response from the uCDN.
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Property: force
- Description: If set to True the metadata interface cache policy
defined in the MI.CachePolicy will override any cache control
policy set in the response from the uCDN. If set to False the
MI.CachePolicy is only used if there is no cache control policy
provided in the response from the uCDN.
- Type: Boolean
- Mandatory-to-Specify: No. The default is False which will
apply the MI.CachePolicy only if no policy is provided in the
response from the uCDN.
2.4. ComputedCacheKey
While the properties provided by the standard CDNi metadata Cache
object (See Section 4.2.6 [RFC8006]) provide some simple control over
the construction of the cache key, it is typical in advanced CDN
configurations to generate cache keys that are dynamically
constructed via lightweight processing of various properties of the
HTTP request and/or response. As an example, an origin may specify a
cache key as a value returned in a specific HTTP response header.
MI.ComputedCacheKey is a new GenericMetadata object that allows for
the specification of a cache key using the metadata expression
language. See Section 4. Typical use cases would involve the
construction of a cache key from one or more elements of the HTTP
request. In cases where both the ComputedCacheKey and the Cache
object are applied, the ComputedCacheKey will take precedence.
Property: expression
- Description: The expression that specifies how the cache key
shall be constructed.
- Type: String. An expression using CDNI-MEL (Section 4) to
dynamically construct the cache key from elements of the HTTP
request and/or response.
- Mandatory-to-Specify: Yes
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2.5. CrossoriginPolicy
Delegation of traffic between an uCDN over a dCDN based on HTTP
redirection does change the domain name in the client requests. This
represents a cross-origin request that must be managed appropriately
using Cross-Origin Resource Sharing (CORS) headers in the responses
in the dCDN.
The dynamic generation of CORS headers is typical in modern HTTP
request processing and avoids CORS validation forwarded to the uCDN
origin servers, particularly with the preflight OPTIONS requests.
The CDNI metadata model requires extensions to specify how a dCDN
should generate and evaluate these headers.
Simple CORS requests are those where both HTTP method and headers in
the request are included in the safe list defined by the World Wide
Web Consortium [W3C]. The user agent request can include an origin
header set to the URL domain of the webpage where a player runs.
Depending on the metadata configuration, the logic to apply by the
dCDN is:
1. Validation of the origin header
2. Wildcard usage
3. Set a default value for CORS response headers
When a UA makes a request that includes a method or headers that are
not included in the safe-list, the client will make a CORS preflight
request using the OPTIONS method to the resource including the origin
header. If CORS is enabled and the requests passes the origin
validation, the OCN should respond with the set of headers that
indicate what is permitted for that resource, including one or more
of the following:
1. Allowed methods
2. Allowed credentials
3. Allowed request headers
4. max-age that the OPTIONS request is valid
5. Headers that can be exposed to the client
CrossoriginPolicy allows for the specification of dynamically
generated CORS headers.
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Property: allow-origin
- Description: Validation of simple CORS requests.
- Type: Object
- Values: One element for each of the following properties.
- Mandatory-to-Specify: Yes
2.5.1. AllowOrigin
The AllowOrigin object has the following properties:
Property: allow-list
- Description: List of valid URLs only scheme and host name that
will be used to match the request origin header.
- Type: Array of PatternMatch objects (Section 4.1.5 of
[RFC8006])
- Mandatory-to-Specify: Yes
Property: wildcard-return
- Description: If True the dCDN will include a wildcard in the
Access-Control-Allow-Origin response header. If False the dCDN
will reflect the request origin header in the Access-Control-
Allow-Origin response header.
- Type: Boolean
- Mandatory-to-Specify: Yes
Property: expose-headers
- Description: A list of values the dCDN will include in the
Access-Control-Expose-Headers response header to a preflight
request.
- Type: Array of strings
- Mandatory-to-Specify: No
Property: allow-methods
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- Description: A list of values the dCDN will include in the
Access-Control-Allow-Methods response header to a preflight
request.
- Type: Array of strings
- Mandatory-to-Specify: No
Property: allow-headers:
- Description: A list of values the dCDN will include in the
Access-Control-Allow-Headers response header to a preflight
request.
- Type: Array of strings
- Mandatory-to-Specify: No
Property: allow-credentials
- Description: The value the dCDN will include in the Access-
Control-Allow-Credentials response header to a preflight
request.
- Type: Boolean
- Mandatory-to-Specify: No
Property: max-age
- Description: The value the dCDN will include in the Access-
Control-Max-Age response header to a preflight request.
- Type: Integer
- Mandatory-to-Specify: No
2.6. NegativeCachePolicy
MI.NegativeCachePolicy is a new GenericMetadata object that allows
for the specification of caching policies based on error response
codes received from the origin, allowing for fine-grained control of
the downstream caching of error responses. For example, it may be
desirable to cache error responses at the uCDN for a short period of
time to prevent an overwhelmed origin service from being flooded with
requests
Property: error-codes
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- Description: Array of HTTP response error status codes (See
Sextions 6.5 and 6.6 of [RFC7231]) that if returned from the
uCDN will be cached using the cache policy defined by the
cache-policy property.
- Type: Array of HTTP response error status codes
- Mandatory-to-Specify: No. The default is to revert to
[RFC8006] behavior.
Property: cache-policy
- Description: MI.CachePolicy to apply to the HTTP response error
status codes returned by the uCDN.
- Mandatory-to-Specify: Yes
2.7. CacheBypassPolicy
MI.CacheBypassPolicy is a new GenericMetadata object that allows a
client request to be set as non cacheable. It is expected that this
feature will be used to allow clients to bypass cache when testing
the uCDN fill path. Note, CacheBypassPolicy only applies to the
current request. In addition, any content previously cached (by
client requests that do not set CacheBypassPolicy) is not evicted.
Property: error-codes
- Description: Array of HTTP response error status codes (See
Sextions 6.5 and 6.6 of [RFC7231]) that if returned from the
uCDN will be cached using the cache policy defined by the
cache-policy property.
- Type: Array of HTTP response error status codes
- Mandatory-to-Specify: No. The default is to revert to
[RFC8006] behavior.
Property: cache-policy
- Description: MI.CachePolicy to apply to the HTTP response error
status codes returned by the uCDN.
- Mandatory-to-Specify: Yes
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2.8. OcnSelection
MI.OcnSelection is a new GenericMetadata object that allows the uCDN
to indicate to the dCDN a preference in terms of OCN selection.
Property: ocn-delivery
- Description: Instructs the dCDN to perform delegation operating
a particular medium and/or a transport arrangement.
- Type: An OcnDeliver yObject as defined in Section 2.8.1
2.8.1. OcnDelivery
An OcnDelivery object contains the following properties:
- Property: ocn-medium
o Description: Instructs the dCDN to perform delegation
operating a particular medium. The following values are
specified: SATELLITE.
o Type: String
o Mandatory-to-Specify: No. Either the ocn-medium property or
the ocn-transport property must be present.
- Property: ocn-transport
o Description: Instructs the dCDN to perform delegation
operating a particular transport arrangement. The following
values are specified: MABR.
o Type: String
o Mandatory-to-Specify: No. Either the ocn-medium property or
the ocn-transport property must be present.
o Mandatory-to-Specify: No. At least one of the two
properties ocn-type or ocn-delivery must be present.
- Property: ocn-type
o Description: Instructs the dCDN to perform delegation
operating the type of open caching nodes.
o Type: A string corresponding to one of the open caching node
types announced by the dCDN through the FCI interface.
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o Mandatory-to-Specify: No. At least one of the two
properties ocn-type or ocn-delivery must be present.
- Property: ocn-selection
o Description: This property enforces the selection of OCNs
considering the ocn-type and/or the ocn-delivery properties.
False means best-effort.
o Type: string. attempt-or-failed and attempt-or-besteffort
mean that the delegation must be attempted considering the
ocn-type and/or the ocn-delivery properties. If not
possible it is considered as an error and either fails
configuration failure or the dCDN continues with a best-
effort procedure. Last best effort means the dCDN tries its
best to fulfill the requested ocn-selection policy.
o Mandatory-to-Specify: No. Best-effort is the default OCN
selection policy.
2.9. PrivateFeatureList
MI.PrivateFeatureList is a new GenericMetadata configuration object
as a base generic object that permits the control of private
features. Note that the private features exposed by the dCDN can be
advertised through a dedicated FCI object.
Property: features
- Description: The list of feature configuration objects.
- Type: List array of MI.PrivateFeature objects .
- Mandatory-to-Specify: Yes
2.9.1. PrivateFeature
A MI.PrivateFeature object contains the following properties:
- Property: feature-oid
o Description: The owner organization that has specified that
feature.
o Type: String
o Mandatory-to-Specify: Yes
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- Property: feature-type
o Description: Indicates the typename of the private feature
configuration object.
o Type: String
o Mandatory-to-Specify: Yes
- Property: feature-value
o Description: Feature configuration object.
o Type: Format type is defined by the value of the feature-
type property above.
o Mandatory-to-Specify: Yes
2.10. ProcessingStages
A ProcessingStages object is a type of GenericMetadata that describes
the matching rules, metadata, and transformations to be applied at
specific stages in the request processing pipeline.
It is typical in CDN configurations to define matching rules and
metadata that are to be applied at specific stages in the request
processing pipeline. For example, it may be required to append a
host header prior to forwarding a request to an origin, or modify the
response returned from an origin prior to storing in the cache. The
following four processing stages are defined:
+-------+ +---------------+ +--------+
| +--->|A B+--->| |
| | | | | uCDN |
| UA | | dCDN | | |
| | | | | Source |
| |<---+D C|<---+ |
+-------+ +---------------+ +--------+
Figure 1: Rule stages
a. clientRequest - Rules run on the client request prior to further
processing.
b. originRequest - Rules run prior to making a request to the
origin.
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c. originResponse - Rules run after a response is received from the
origin and before being placed in the cache.
d. clientResponse - Rules run prior to sending the response to the
client. If the response is from the cache, rules are applied to
the response retrieved from the cache prior to sending to the
client.
Each of the four processing stages is represented by an array of
StageRules objects, with each StageRules object defining match
criteria along with metadata that should be applied if the match
applies to true. It should be noted that all of the StageRules
objects in the array are evaluated and processed in order. A
possible future extension to this processing model could allow for an
if-else structure, where processing for a stage is halted upon
matching of a StageRule match expression.
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+----------------+
|ProcessingStages|
+----------------+
(*)
|
+----------------+-------+---------+----------------+
| | | |
v v v v
+-------------+ +-------------+ +--------------+ +--------------+
|ClientRequest| |OriginRequest| |OriginResponse| |ClientResponse|
+-------------+ +-------------+ +--------------+ +--------------+
(*) (*) (*) (*)
| | | |
+---------------+----------------+----------------+
|
| +---------------+
| +-------->|ExpressionMatch|
| | +---------------+
| |
| | *****************
| (*) +--->*GenericMetadata*
| +----------+ +-------------+ | * Objects *
+--->+StageRules+--->|StageMetadata+(*)-+ *****************
+----------+ +-------------+
(*) (*)
| |
+-------+ +-----------+
| |
v v
+----------------+ +-----------------+
|RequestTransform|(*)-+ +-(*)|ResponseTransform|
+----------------+ | | +-----------------+
(*) | |
| | |
| v v
| +---------------+
| |HeaderTransform|(*)-+
| +---------------+ |
| |
v |
+-----------------+ |
|SyntheticResponse|(*)--+ v
+-----------------+ | +----------+
+----->|HTTPHeader|
+----------+
Figure 2: CDNi ProcessingStages metadata model with contained objects
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Each of the four processing stages is represented by an array of
StageRules objects, with each StageRules object defining criteria
along with metadata that should be applied if the match applies to
True. It should be noted that the StageRules objects in the array
are evaluated and processed in order. A possible future extension to
this processing model could allow for an if-else structure, where
processing for a stage is halted upon the first match of a StageRules
expression.
Property: client-request
- Description: Allows for the specification of conditional
metadata to be applied at the client request processing stages
as defined in the Rule Processing Stages section. The
StageRules in the array are evaluated in order.
- Type: Array of StageRules objects
- Mandatory-to-Specify: No
Property: origin-request
- Description: Allows for the specification of conditional
metadata to be applied at origin request processing stages as
defined in the Rule Processing Stages section. The StageRules
in the array are evaluated in order.
- Type: Array of StageRules objects
- Mandatory-to-Specify: No
Property: origin-response
- Description: Allows for the specification of conditional
metadata to be applied at origin response processing stages as
defined in the Rule Processing Stages section. The StageRules
in the array are evaluated in order.
- Type: Array of StageRules objects
- Mandatory-to-Specify: No
Property: client-response
- Description: Allows for the specification of conditional
metadata to be applied at client response processing stages as
defined in the Rule Processing Stages section. The StageRules
in the array are evaluated in order.
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- Type: Array of StageRules objects
- Mandatory-to-Specify: No
2.10.1. StageRules
A StageRules object is used within the context of ProcessingStages to
define elements in a list of match rules and stage-specific metadata
and transformations that should be applied conditionally on a rich
expression match.
Property: match
- Description: An ExpressionMatch object encapsulating a rich
expression using the CDNi Metadata Expression Language CDNI-MEL
to evaluate aspects of the HTTP request and/or response. The
stage-metadata rules are only applied if the match evaluates to
True or if no match expression is provided
- Type: ExpressionMatch object
- Mandatory-to-Specify: No. The stage-metadata rules are always
applied if no match expression is provided. This would be the
case when stage-metadata should be applied unconditionally
within the context of the higher-level host and path matches.
Property: stage-metadata
- Description: Specifies the set of StageMetadata to be applied
at the processing stage if the match expression evaluates to
True or is not present.
- Type: Array of StageMetadata objects applied in order.
- Mandatory-to-Specify: Yes
2.10.2. ExpressionMatch
CDN and open caching systems often require a rich set of matching
rules, with full regular expressions and Boolean combinations of
matching parameters for host, path, and header elements of a request.
In typical CDN implementations, this capability is provided by a rich
expression language that can be embedded in the metadata
configurations
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The ExpressionMatch object contains the rich expression that must
evaluate to True for the StageMetadata to be applied for the specific
StageRules. Defining expressions as stand-alone objects allows for
sets of reusable match expressions to be reused via metadata
reference linking.
Property: expression
- Description: A rich expression using CDNI-MEL to evaluate
aspects of the HTTP request and/or response. See documentation
on the Metadata Expression Language for details on the
expression of matching variables and syntax.
- Type: String using CDNI-MEL syntax. See Section 4
- Mandatory-to-Specify: Yes
2.10.3. StageMetadata
The StageMetadata object contains GenericMetadata and HTTP request/
response transformations that should be applied for a StageRules
match. The following table defines the processing stages where
request and response transformations are possible:
+================+===================+====================+
| Stage | request-transform | response-transform |
+================+===================+====================+
| clientRequest | Yes | Yes |
+----------------+-------------------+--------------------+
| originRequest | Yes | Yes |
+----------------+-------------------+--------------------+
| originResponse | Yes | No |
+----------------+-------------------+--------------------+
| clientResponse | Yes | No |
+----------------+-------------------+--------------------+
Table 1
Note that for the stages where both request and response
transformations are allowed, it is possible to specify both. This
may be the case if, for example, the request URI needs alteration for
cache-key generation and the response headers need to be manipulated.
Property: generic-metadata
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- Description: Specifies the set of GenericMetadata to be applied
for a StageRules match. A typical use case would be the
application of a CachePolicy or TimeWindowACL conditionally on
matching HTTP headers. Support for this capability is optional
and can be advertised via feature-flags in the FCI interface.
- Type: Array of GenericMetadata applied in order. Note that not
all GenericMetadata object types may be applicable at all
processing stages.
- Mandatory-to-Specify: No. The generic-metadata property would
not be needed when StageMetadata is used to only specify
request or response transformations such as modifications of
HTTP headers.
Property: request-transform
- Description: Specifies a transformation to be applied to the
HTTP request for a StageRules match. The transformation can be
the modification of any request header and/or the modification
of the URI. Modifications are applied such that downstream
processing stages receive the modified HTTP request as their
input. Support for this capability is optional and can be
advertised via feature-flags in the FCI interface.
- Type: RequestTransform object
- Mandatory-to-Specify: No
Property: response-transform
- Description: Specifies a transformation to be applied to the
HTTP response for a StageRules match. The transformation can
be the modification of any response header HTTP response status
code or the generation of a synthetic response. Modifications
are applied such that downstream processing stages receive the
modified HTTP response as their input. Support for this
capability is optional and can be advertised via feature-flags
in the FCI interface.
- Type: ResponseTransform object
- Mandatory-to-Specify: No
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2.10.4. RequestTransform
The RequestTransform object contains metadata for transforming the
HTTP request for a specific StageRules object. The transformation
can be the modification of any request header and/or the modification
of the URI. Modifications are applied such that downstream
processing stages receive the modified HTTP request as their input.
Property: headers
- Description: A HeaderTransform object specifying HTTP request
headers to add replace or delete.
- Type: HeaderTransform object
- Mandatory-to-Specify: No
Property: uri
- Description: Replacement value for the HTTP request.
- Type: String. Either a literal static string or an expression
using CDNI-MEL to dynamically construct a URI value from
elements of the HTTP request and/or response.
- Mandatory-to-Specify: No
Property: uri-is-expression
- Description: Flag to signal whether the URI is a static string
literal or a CDNI-MEL expression that needs to be dynamically
evaluated.
- Type: Boolean
- Mandatory-to-Specify: No. The default is False indicating that
the URI is a string literal and does not need to be evaluated.
2.10.5. ResponseTransform
The ResponseTransform object contains metadata for transforming the
HTTP response for a StageRules match. The transformation can be the
modification of any response header, HTTP response status code, or
the generation of a synthetic response. Modifications are applied
such that downstream processing stages receive the modified HTTP
response as their input.
Property: headers
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- Description: A HeaderTransform object specifying HTTP response
headers to add replace or delete.
- Type: HeaderTransform object
- Mandatory-to-Specify: No
Property: response-status
- Description: Replacement value for the HTTP response status
code.
- Type: Integer. Either a static integer or an expression using
CDNI-MEL that evaluates to an integer to dynamically generate
an HTTP status code based on elements of the HTTP request and/
or response. Expressions that do not evaluate to an integer
shall be considered invalid and result in no override of
origin-provided response status.
- Mandatory-to-Specify: No
Property: status-is-expression
- Description: Flag to signal whether the response-status is a
static integer or a CDNI-MEL expression that needs to be
dynamically evaluated to generate an HTTP response status code.
- Type: Boolean
- Mandatory-to-Specify: No. The default is False indicating that
the response-status is a static integer and does not need to be
evaluated.
Property: synthetic
- Description: Specification of a complete replacement of any
HTTP response that may have been generated in an earlier
processing stage with a synthetic response. Use of this
property to specify a synthetic response would override any
response transformations or status codes specified by other
properties.
- Type: SyntheticResponse object
- Mandatory-to-Specify: No
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2.10.6. SyntheticResponse
It is quite common in CDN configurations to specify a synthetic
response be generated based on inspection of aspects of the original
request or the origin response.
The SyntheticResponse object allows for the specification of a
synthetic response to be generated in response to the HTTP request
being processed. The synthetic response can contain a set of
response headers, a status code, and a response body, and is a
complete replacement for any HTTP response elements generated in an
earlier processing stage.
A dynamically generated Content-Length HTTP response header is
generated based on the length of the generated response body.
Property: headers
- Description: An array of HTTP header objects that specify the
full set of headers to be applied to the synthetic response.
- Type: Array of HTTP header objects
- Mandatory-to-Specify: No although it would be unusual to not
specify minimal standard response headers such as Content-Type.
Property: response-status
- Description: HTTP response status code.
- Type: Integer. Either a static integer or an expression using
CDNI-MEL that evaluates to an integer to dynamically generate
an HTTP status code based on elements of the upstream HTTP
request and/or response. Expressions that do not evaluate to
an integer shall be considered invalid and result in a 500
status for the synthetic response.
- Mandatory-to-Specify: Yes
Property: status-is-expression
- Description: Flag to signal whether the response-status is a
static integer or a CDNI-MEL expression that needs to be
dynamically evaluated to generate an HTTP response status code.
- Type: Boolean
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- Mandatory-to-Specify: No. The default is False indicating that
the response-status is a static integer and does not need to be
evaluated.
Property: body
- Description: Body for the synthetic HTTP response. The
response body can either be static or dynamically constructed
from a rich expression.
- Type: String. Either a literal static string or an expression
using CDNI-MEL to dynamically construct a response body from
elements of the HTTP request and/or response.
- Mandatory-to-Specify: No. If absent an empty HTTP response
with a zero-value Content-Length header is generated.
Property: body-is-expression
- Description: Flag to signal whether the synthetic response body
is a static string literal or a CDNI-MEL expression that needs
to be dynamically evaluated.
- Type: Boolean
- Mandatory-to-Specify: No. The default is False indicating that
the body is a string literal and does not need to be evaluated.
2.10.7. HeaderTransform
In processing HTTP requests, it is often required to modify HTTP
request or response headers at one of the processing stages,
requiring CDNi metadata to have the capability to update any field in
an HTTP request or response header. It should be noted that certain
HTTP headers (such as Set-Cookie) have multiple occurrences in a
request or response, thereby requiring that we allow for add and
replace designations for header modification.
The HeaderTransform object specifies how HTTP headers should be
added, replaced, or deleted from HTTP requests and responses.
Property: add
- Description: List of HTTP headers name/value pairs that should
be added to the HTTP request or response. Note that any
existing headers in the request or response with the same names
of those added are not affected resulting in multiple headers
with the same name.
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- Type: Array of HTTPHeader objects containing header name/value
pairs
- Mandatory-to-Specify: No
Property: replace
- Description: List of HTTP headers name/value pairs that should
be added to the HTTP request or response replacing any previous
headers with the same name.
- Type: Array of HTTPHeader objects containing header name/value
pairs
- Mandatory-to-Specify: No
Property: delete
- Description: List of names of HTTP headers that should be
deleted from the
- HTTP request or response. If a named header appears multiple
times all occurrences are deleted.
- Type: Array of strings with each string naming an HTTP header
to delete
- Mandatory-to-Specify: No
2.10.8. HttpHeader
The HTTPHeader object contains a name/value pair for an HTTP header
to add or replace in a request or response. The CDNI-MEL Section 4
expression language can be used to dynamically generate response
values.
Property: name
- Description: Name of the HTTP header.
- Type: String
- Mandatory-to-Specify: Yes
Property: value
- Description: New value of the named HTTP header.
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- Type: String. Either a static string or an expression using
CDNI-MEL to dynamically construct a header value from elements
of the HTTP request and/or response.
- Mandatory-to-Specify: Yes
Property: value-is-expression
- Description: Flag to signal whether the value is a static
string literal or a CDNI-MEL Section 4 expression that needs to
be dynamically evaluated.
- Type: Boolean
- Mandatory-to-Specify: No. The default is False indicating that
the value is a string literal and does not need to be
evaluated.
2.11. RequestedCapacityLimits
MI.RequestedCapacityLimits is a new GenericMetadata object that
allows the uCDN to communicate to the dCDN a desired change in the
advertised traffic delegation limits for a given host and footprint.
Property: requested-limits
- Description: A set of requested changes to the dCDNs advertised
FCI.CapacityLimits [capacity-insights-advertisement].
- Type: Array of RequestedCapacityLimit objects
- Mandatory-to-Specify: Yes
RequestedCapacityLimit objects contain the following properties:
- Property: limit-type
o Description: The limit type for which the change is
requested corresponding to the limit types of
FCI.CapacityLimits [capacity-insights-advertisement].
o Type: String. One of egress requests storage-size storage-
objects sessions or cache-size
o Mandatory-to-Specify: Yes
- Property: limit-value
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o Description: The requested new value for the limit. Units
of this value are dependent upon the limit-type and are
defined in the SVA Capacity Insights Interface
Specification.
o Type: Integer
o Mandatory-to-Specify: Yes
- Property: footprints
o Description: dCDN footprints with advertised
FCI.CapacityLimits [capacity-insights-advertisement] for
which this request applies.
o Type: List of CDNI footprint objects from the CDNI Metadata
Footprint Types registry of [RFC8006]
o Mandatory-to-Specify: Yes
2.12. RequestRouting
MI.RequestRouting is a new GenericMetadata object that allows the
uCDN to force the dCDN request routing mode(s) to be applied when
working in iterative redirection mode. The list of redirection modes
supported by the dCDN is advertised through the FCI.RedirectionMode
object. See Section 5.5 of [RFC8006]. The list of request routing
modes supported by the dCDN is advertised through the
FCI.RequestRouting object (Section 2.12)
Property: request-routing-modes
- Description: Instructs the dCDN to perform request routing
according to one or more preferred modes among those supported
and advertised by the dCDN through the FCI.RequestRouting
object. One must understand that forcing instead of letting
the dCDN request router select one particular request routing
mode may trigger some inefficiency in the request routing
process.
- Type: List array of iterative request routing modes, defined as
Enumeration of [DNS|HTTP|MANIFESTREWRITE] encoded as an
uppercase string
- Mandatory-to-Specify: No. By default all request routing modes
supported by the dCDN can be used by the dCDN as part of its
request routing process.
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2.13. ServiceIDs
CDN configurations typically have multiple layers of identifiers that
group configurations by customer account to facilitate logging,
billing, and support operations. The metadata model sis extended to
allow for the association service identifier metadata to a host or
path match and to allow for these IDs to be dynamically generated via
an expression language. For example, it may be necessary to extract
a portion of the Request URI path to derive a service identifier
(e.g.: /news/* maps to one serviceID and /movies/* maps to a
different serviceID)
A MI.ServiceIDs is a new GenericMetadata object that allows for the
specification of two tiers of CDN-specific identifiers and names.
The interpretation of these identifiers is implementation specific.
Property: service-id
- Description: A provider-specific identifier for the service
typically a customer account identifier.
- Type: String. Either a literal static string or an expression
using CDNI-MEL Section 4 to dynamically construct the ID from
elements of the HTTP request and/or response.
- Mandatory-to-Specify: No
Property: service-id-is-expression
- Description: Flag to signal whether the service-id is a static
string literal or a CDNI-MEL Section 4 expression that needs to
be dynamically evaluated.
- Type: Boolean
- Mandatory-to-Specify: No. The default is False indicating that
the service-id is a string literal and does not need to be
evaluated.
Property: service-name
- Description: Human-readable name for the service-id.
- Type: String
- Mandatory-to-Specify: No
Property: property-id
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- Description: A provider-specific identifier for the property
typically identifies a child configuration within the parent
service-id.
- Type: String. Either a literal static string or an expression
using CDNI-MEL Section 4 to dynamically construct the ID from
elements of the HTTP request and/or response.
- Mandatory-to-Specify: No
Property: property-id-is-expression
- Description: Flag to signal whether the property-id is a static
string literal or a CDNI-MEL Section 4 expression that needs to
be dynamically evaluated.
- Type: Boolean
- Mandatory-to-Specify: No. The default is False indicating that
the property-id is a string literal and does not need to be
evaluated.
Property: property-name
- Description: Human-readable name for the property-id.
- Type: String
- Mandatory-to-Specify: No
2.14. SourceMetadataExtended
MI.SourceMetadataExtended is an alternative to the CDNi standard
MI.SourceMetadata object (See Section 4.2.1 of [RFC8006]), which adds
a property to specify load balancing across multiple sources, as well
as a SourceExtended sub-object with additional attributes to the CDNi
standard Source object (See Section 4.2.1.1 of [RFC8006]). While
both SourceMetadataExtended and SourceMetadata can be provided for
backward compatibility, a dCDN that advertises capability for
SourceMetadataExtended will ignore SourceMetadata if both are
provided for a given host or path match.
Property: sources
- Description: Sources from which the dCDN can acquire content
listed in order of preference.
- Type: Array of SourceExtended objects
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- Mandatory-to-Specify: No. Default is to use static
configuration out-of-band from the CDNI metadata interface.
Property: load-balance
- Description: Specifies load balancing rules for the set of
sources.
- Type: LoadBalanceMetadata object
- Mandatory-to-Specify: No
2.14.1. SourceExtended
SourceExtended is an alternative to the CDNi standard Source
(Section 4.2.1.1 of [RFC8006]) object with additional metadata. Open
Caching use cases requires additional capabilities not covered in
[RFC8006] as:
1. Web root path specification for the source.
2. Support for additional forms of origin authentication
3. Validate a host header in the request different than the defined
in endpoints
4. Whether a Source response of HTTP redirect is passed through to
the user agent or followed by the dCDN to acquire a content
It inherits all the attributes of the Source object (acquistion-auth,
endpoints, and protocol), with the following additions:
Property: origin-host
- Description: HTTP host header to pass to the endpoints when
retrieving content from a uCDN. The host MUST conform to the
Domain Name System DNS syntax defined in [RFC1034] and
[RFC1123].
- Type: String
- Mandatory-to-Specify: No. The default is to use the host name
passed by the dCDN.
Property: webroot
- Description: The path element that is prepended to a resources
URI before
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- retrieving content from a uCDN.
- Type: String
- Mandatory-to-Specify: No. The default is to use the original
URI.
Property: follow-redirects
- Description: If the follow-redirects property is set to True
HTTP redirect responses returned from a uCDN will be followed
when retrieving content. Otherwise the HTTP redirect response
is returned to the client.
- Type: Boolean
- Mandatory-to-Specify: No. The default is True i.e. follow
redirect responses from the uCDN.
Property: timeout-ms
- Description: A timeout in milliseconds to apply when connecting
to a uCDN. If the connection is not established within
timeout-ms this source is abandoned and the next source in the
MI.SourceMetadataExtended sources array is tried. Once a
connection is established timeout-ms is used on subsequent
reads of data from the uCDN.
- Type: Integer
- Mandatory-to-Specify: No. The default is to revert to RFC-8006
behavior.
Property: failover-errors
- Description: Array of HTTP response error status codes (See
Sections 6.5 and 6.6 of [RFC7231]) that if returned from the
uCDN will trigger a failover to the next source in the
MI.SourceMetadataExtended (Section 2.14) sources array. If the
uCDN returns an HTTP error code that is not in the failover-
errors array that error code is returned to the client of the
dCDN.
- Type: Array of HTTP response error status codes.
- Mandatory-to-Specify: No. The default is to revert to RFC-8006
behavior.
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2.14.2. LoadBalanceMetadata
The LoadBalanceMetadata object defines how content acquisition
requests are distributed over the SourceExtended objects listed in
the SourceMetadataExtended object.
It permits the following capabilities:
1. Multi-origin failover: ability to specify a list of origins that
can act as fallbacks to the primary origin. Failure rules can
specify types of errors and timeout values that trigger failover
2. Multi-origin load balancing: The ability to specify a list of
origins that can be selected by one of several balancing rules
(round robin, content hash, IP hash).
3. Origin Shielding Definitions - The ability to designate CDN
origin shield locations associated with a specific origin
Parameters for LoadBalanceMetadata are:
Property: balance-algorithm
- Description: Specifies the algorithm to be used when
distributing content acquisition requests over the sources in a
SourceMetadataExtended object. The available algorithms are
random content-hash and ip-hash
o random: Requests are distributed over the sources in
proportion to their associated weights.
o content-hash: Requests are distributed over the sources in a
consistent fashion based on the balance-path-pattern
property.
o ip-hash: Requests are distributed over the sources in a
consistent fashion based on the IP address of the client
requestor.
- Type: Enumeration [random|content-hash|ip-hash] encoded as a
lowercase string.
- Mandatory-to-Specify: No. The default is to use sources in
preference order as defined in the SourceMetadataExtended
object.
Property: balance-weights
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- Description: This property specifies the relative frequency
that a source is used when distributing requests. For example
if there are three SourceExtended objects in a
SourceMetadataExtended object with balance-weights 1 2 1 source
1 will receive 14 of the requests source 2 will receive 24 of
the requests source 3 will receive 14 of the requests.
- Type: Array of integers
- Mandatory-to-Specify: No. The default is to use sources in
preference order as defined in the SourceMetadataExtended
object.
Property: balance-path-pattern
- Description: This property specifies a regular expression
pattern to apply to the URI when calculating the content hash
used by the balance-algorithm. For example balance-path-
pattern: prod...ts would distribute requests based on the URI
but excluding the prod prefix and the .ts segment file.
- Type: String regular expression
- Mandatory-to-Specify: No. The default is to use the original
URI.
2.15. StaleContentCachePolicy
MI.StaleContentCachePolicy is a new GenericMetadata object that
allows the uCDN to specify the policy how the dCDN should process
requests for stale content. For example, this policy allows the
content provider to specify that stale content be served from cache
for a specified time period while refreshes from the origin occur
asynchronously.
Property: stale-while-revalidating
- Description: Instructs the dCDN to serve a stale version of a
resource while refreshing the resource with the uCDN. When set
to True the dCDN will return a previously cached version of a
resource while the resource is refreshed with the uCDN in the
background.
- Type: Boolean
- Mandatory-to-Specify: No. The default is False which waits for
the uCDN to refresh a resource before responding to the client.
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Property: stale-if-error
- Description: Instructs the dCDN to serve a stale version of a
resource if an error was received when trying to refresh the
resource with the uCDN. When set the dCDN will return a
previously cached version of a resource instead of caching the
error response. Per [RFC5861] Section 4 an error is any
situation that would result in a 500 502 503 or 504 HTTP
response status code being returned
- Type: Array of HTTP response error status codes
- Mandatory-to-Specify: No. The default is to cache the error
response received from the uCDN.
Property: failed-refresh-ttl
- Description: Instructs the dCDN to serve a stale version of a
resource for the number of seconds specified in failed-refresh-
ttl before trying to revalidate the resource with the uCDN.
Use of failed-refresh-ttl allows the load to be reduced on the
uCDN during times of system stress.
- Type: Integer
- Mandatory-to-Specify: No
2.16. TrafficType
Content delivery networks often apply different infrastructure,
network routes, and internal metadata for different types of traffic.
Knowing those differences, a dCDN provider can implement specific
strategies that will maximize performance and thereby provide more
available capacity to the upstream provider. it should be noted that
the dCDNs handling of the traffic types is implementation-specific
and not prescribed here.
TrafficType metadata defines a set of descriptors that characterize
either the type or usage of the traffic, enabling dCDNs to apply any
internal configuration rules without exposing an unnecessary amount
of internal details.
Property: traffic-type
- Description: A literal that defines the traffic type. uCDN will
use the literal that is most representative of the traffic
being delegated. The following literals can be specified:
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o vod
o live
o object-download
- Type: String
- Mandatory-to-Specify: Yes
Property: hints
- Description: Other traffic characteristics that the uCDN can
indicate to the dCDN as suggestions for service optimization.
Accepts free-form unconstrained values.
- Type: Array of strings
- Mandatory-to-Specify: No
3. CDNI Additional FCI Objects
Section 5 of [RFC8008] describes the FCI Capability Advertisement
Object, which includes a CDNI Capability Object as well as the
capability object type (a CDNI Payload Type). The section also
defines the Capability Objects per such type. Below we define
additional Capability Objects.
In most cases, the presence or absence of a GenericMetadata object
name in FCI.Metadata (as described above), is sufficient to convey
support for a capability. There are cases, however, where more fine-
grained capabilities declarations are required. Specifically, a dCDN
may support some, but not all, of the capabilities specified by one
of the new GenericMetadata objects. In these cases, new FCI objects
are created to allow a dCDN to express these fine-grained
capabilities.
Note: In the following sections, the term "mandatory-to-specify" is
used to convey which properties MUST be included when serializing a
given capability object. When mandatory-to-specify is defined as
"Yes" for an individual property, it means that if the object
containing that property is included in an FCI message, then the
mandatory-to-specify property MUST also be included.
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3.1. FCI.AuthTypes
This object is used to to indicate the support of authentication
methods to be used for content acquisition (while interacting with an
origin server) and authorization methods to be used for content
delivery.
This documents defines two new authentication methods (See
Section 2.1), while there is one other authorization method under
specification in CDNI called URI signing [URI.signing]
Property: authe-types
- Description: List of supported authentication methods possibly
required for content acquisition
- Type: List of supported authentication methods (e.g. as defined
in Section 2.1)
- Mandatory-to-Specify: No. No authentication method is
supported in this case.
Property: autho-types
- Description: List of supported authorization methods possibly
required for content delivery
- Type: List of supported authorization methods (e.g. URI
signing [URI.signing])
- Mandatory-to-Specify: No. No authorization method is supported
in this case.
3.2. FCI.ProcessingStages
This object is used to signal the set of features that are supported
in relation with the ProcessingStages (Section 2.10) configuration
object. Those optional features depend on the CDNI-MEL language
(Section 4) support.
Property: features
- Description: List of supported optional processing stages
features. Note that these features all have some dependencies
on support of the CDNi MEL expression language.
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- Type: Enumeration
[ExpressionMatch|RequestTransform|ResponseTransform] encoded as
string
- Mandatory-to-Specify: No. None of these optional features are
supported in this case.
3.3. FCI.SourceMetadataExtended
This object is used to signal the supported features related to the
SourceMetadataExtended configuration object.
Property: load-balance
- Description: List of supported load balancing algorithms in
relation to the SourceMetadataExtended configuration object see
GenericMetadata: SourceMetadataExtended
- Type: Enumeration [random|content-hash|ip-hash] encoded as
lowercase strings
- Mandatory-to-Specify: No. load balancing is not supported among
sources.
If the FCI.SourceMetadataExtended object is not exposed neither
advertised or if the load-balance array is empty, the dCDN does
not support the usage of the load-balance property attached to the
SourceMetadataExtended configuration object (see
SourceMetadataExtended (Section 2.14)).
3.4. FCI.RequestRouting
This object is used by the dCDN to signal/announce the supported
request routing modes. This can be optionally used by the uCDN to
further select a subset of those modes when operating one of the
iterative delegation modes. See Section 2.12
Property: request-routing-modes
- Description: List of supported request routing modes by the
dCDN. This information is useful when the uCDN decides to
perform a delegation in iterative mode.
- Type: Enumeration [DNS|HTTP-R|MANIFESTREWRITE] encoded as
uppercase strings
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- Mandatory-to-Specify: No. If the dCDN does not advertise the
supported request routing modes they are all supported by
default.
3.5. FCI.PrivateFeatures
This object is used by the dCDN to signal/announce the list of
supported private features. See Section 2.9
Property: features
- Description: The list of supported private feature
- Type: List array of nested objects each containing the
following properties:
o Property: feature-oid
+ Description: The owner/organization that has specified
the feature.
+ Type: String
+ Mandatory-to-Specify: Yes
o Property: feature-type
+ Description: Indicates the typename of the private
feature configuration object.
+ Type: String
+ Mandatory-to-Specify: Yes
3.6. FCI.OcnSelection
This object is used by the dCDN to signal/announce the supported OCN
types and/or their transport arrangement and/or medium supported by
OCNs.
Property: ocn-delivery-list
- Description: List of supported medium and/or transport
arrangements.
- Type: List of OcnDeliveryList objects Section 3.6.1
Property: ocn-type-list
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- oDescription: List of supported OCN types. Examples include:
HOME or EDGE.
- oType: Array of strings
- oMandatory-to-Specify: No
3.6.1. OcnDeliveryList
Property: ocn-medium
- Description: This property lists the supported mediums.
- Type: List of strings. The following values are specified:
SATELLITE
- Mandatory-to-Specify: No
Property: ocn-transport
- Description: Instructs the dCDN to perform delegation operating
a particular transport arrangement. The following values are
specified: MABR.
- Type: List of strings
- Mandatory-to-Specify: No
4. Metadata Expression Language
The CDNI Metadata Expression Language provides a syntax with a rich
set of variables, operators, and built-in functions to facilitate use
cases within the extended CDNi metadata model.
Enables expression matching to dynamically determine if
StageMetadata (Section 2.10.3) should be applied at a StageRules
match.
Enables the dynamic construction of a value to be used in
scenarios such as constructing a service identifier or cache key,
setting an HTTP header, rewriting a request URI, setting a
response status code, or dynamically generating a response body
for a SyntheticResponse.
Expressions can evaluate to a Boolean, string, or integer, depending
on the use case:
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+=============================+=================+==================+
| Usage | Description | Evaluation |
| | | Results |
+=============================+=================+==================+
| ExpressionMatch.expression | Dynamically | Boolean. |
| | determines if | Expressions that |
| | StageMetadata | do not evaluate |
| | should be | to True or False |
| | applied at a | shall be |
| | specific | considered as |
| | StageRules. | False. |
+-----------------------------+-----------------+------------------+
| RequestTransform.uri | Rewrites | String |
| | request URI | |
| | that will be | |
| | presented to | |
| | all downstream | |
| | stages. | |
+-----------------------------+-----------------+------------------+
| ResponseTransform.response- | Dynamically | Integer (HTTP |
| status | sets a response | status code) |
| | status code to | |
| | replace the | |
| | status-code | |
| | returned by the | |
| | origin. | |
+-----------------------------+-----------------+------------------+
| SyntheticResponse.response- | Dynamically | Integer (HTTP |
| status | sets a response | status code) |
| | status code for | |
| | a synthetically | |
| | constructed | |
| | response. | |
+-----------------------------+-----------------+------------------+
| SyntheticResponse.body | Dynamically | String |
| | constructs a | |
| | response body. | |
+-----------------------------+-----------------+------------------+
| HTTPHeader.value | Dynamically | String |
| | constructs a | |
| | header value. | |
+-----------------------------+-----------------+------------------+
| ComputedCacheKey.expression | Dynamically | String |
| | constructs a | |
| | cache key. | |
+-----------------------------+-----------------+------------------+
| ServiceIDs.properry- | Dynamically | String |
| id,ServiceIDs.service-id | constructs | |
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| | service and | |
| | property | |
| | identifiers. | |
+-----------------------------+-----------------+------------------+
Table 2: CDNI MEL expressions
4.1. Expression Variables
+=====================+====================================+
| Variable | Meaning |
+=====================+====================================+
| req.h.<name> | Request header <name> |
+---------------------+------------------------------------+
| req.uri | Request URI (includes query string |
| | and fragment identifier, if any) |
+---------------------+------------------------------------+
| req.uri.path | Request URI path |
+---------------------+------------------------------------+
| req.uri.pathquery | Request path and query string |
+---------------------+------------------------------------+
| req.uri.query | Request query string |
+---------------------+------------------------------------+
| req.uri.query.<key> | Request query string value |
| | associated with <key> |
+---------------------+------------------------------------+
| req.method | Request HTTP method (GET, POST, |
| | others) |
+---------------------+------------------------------------+
| resp.h.<name> | Response header <name> |
+---------------------+------------------------------------+
| resp.status | Response status code |
+---------------------+------------------------------------+
Table 3: CDNI MEL variables
4.2. Expression Operators and keywords
+==========+==========+==========+=================================+
| Operator | Type | Result | Meaning |
| | | Type | |
+==========+==========+==========+=================================+
| == | infix | Boolean | Equality test |
+----------+----------+----------+---------------------------------+
| != | infix | Boolean | Inequality test |
+----------+----------+----------+---------------------------------+
| ! | infix | Boolean | Logical NOT operator |
+----------+----------+----------+---------------------------------+
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| > | infix | Boolean | Greater than test |
+----------+----------+----------+---------------------------------+
| < | infix | Boolean | Less than test |
+----------+----------+----------+---------------------------------+
| >= | infix | Boolean | Greater than or equal test |
+----------+----------+----------+---------------------------------+
| <= | infix | Boolean | Less than or equal |
+----------+----------+----------+---------------------------------+
| *= | infix | Boolean | Glob style match |
+----------+----------+----------+---------------------------------+
| ~= | infix | Boolean | Regular expression match (see |
| | | | https://www.pcre.org/ for |
| | | | details on PCRE RegEx matching) |
+----------+----------+----------+---------------------------------+
| ipmatch | infix | Boolean | Match against IP address or |
| | | | CIDR (IPv4 and IPv6) |
+----------+----------+----------+---------------------------------+
| + | infix | Numeric | Addition |
+----------+----------+----------+---------------------------------+
| - | infix | Numeric | Subtraction |
+----------+----------+----------+---------------------------------+
| * | infix | Numeric | Multiplication |
+----------+----------+----------+---------------------------------+
| / | infix | Numeric | Division |
+----------+----------+----------+---------------------------------+
| % | infix | Unsigned | Modulus |
| | | or | |
| | | Integer | |
+----------+----------+----------+---------------------------------+
| . | infix | String | Concatenation |
+----------+----------+----------+---------------------------------+
| ? : | ternary | * | Conditional operator: <e> ? |
| | | | <v1> : <v2> Evaluates <v1> if |
| | | | <e> is true, <v2> otherwise. |
+----------+----------+----------+---------------------------------+
| ( ) | grouping | | Used to override precedence and |
| | | | for function calls. |
+----------+----------+----------+---------------------------------+
Table 4: CDNI MEL expression operators
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+=========+=======================================+
| Keyword | Meaning |
+=========+=======================================+
| and | Logical AND |
+---------+---------------------------------------+
| or | Logical OR |
+---------+---------------------------------------+
| not | Logical NOT (see also the ! operator) |
+---------+---------------------------------------+
| nil | No value (distinct from empty value) |
+---------+---------------------------------------+
| true | Boolean constant: true |
+---------+---------------------------------------+
| false | Boolean constant: false |
+---------+---------------------------------------+
Table 5: CDNI MEL expression keywords
4.3. Expression Built-in Functions
4.3.1. Basic Functions: Type Conversions
+============+=====================+=============+=========+
| Function | Action | Argument(s) | Returns |
+============+=====================+=============+=========+
| integer(e) | Converts expression | 1 | integer |
| | to integer. | | |
+------------+---------------------+-------------+---------+
| real(e) | Converts expression | 1 | real |
| | to real. | | |
+------------+---------------------+-------------+---------+
| string(e) | Converts expression | 1 | string |
| | to string. | | |
+------------+---------------------+-------------+---------+
| boolean(e) | Converts expression | 1 | Boolean |
| | to Boolean. | | |
+------------+---------------------+-------------+---------+
Table 6: CDNI MEL type conversions
4.3.2. Basic Functions: String Conversions
+==========+==============================+=============+=========+
| Function | Action | Argument(s) | Returns |
+==========+==============================+=============+=========+
| upper(e) | Converts a string to | 1 | string |
| | uppercase. Useful for case- | | |
| | insensitive comparisons. | | |
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+----------+------------------------------+-------------+---------+
| lower(e) | Converts a string to | 1 | string |
| | lowercase. Useful for case- | | |
| | insensitive comparisons. | | |
+----------+------------------------------+-------------+---------+
Table 7: CDNI MEL string conversions
4.3.3. Convenience Functions
+====================+======================================+===========+=======+
|Function |Action |Argument(s)|Returns|
+====================+======================================+===========+=======+
|match(string Input, |Regular expression Match is applied to|2 |string |
|string Match) |Input and the matching element (if | | |
| |any) is returned. Empty string is | | |
| |returned if there is no match. See | | |
| |https://www.pcre.org/ for details on | | |
| |PCRE RegEx matching. | | |
+--------------------+--------------------------------------+-----------+-------+
|match_replace(string|Regular expression Match is applied to|3 |string |
|Input, string Match,|Input arg and replaced with the | | |
|string Replace) |Replace arg upon successful match. | | |
| |Returns updated (replaced) version of | | |
| |Input. | | |
+--------------------+--------------------------------------+-----------+-------+
|add_query(string |Add query string element q with value |2 |string |
|Input, string q, |v to the Input string. If v is nil, | | |
|string v) |then just add the query string element| | |
| |q. The query element q and value v | | |
| |must conform to the format defined in:| | |
| |https://datatracker.ietf.org/doc/html/| | |
| |rfc3986 | | |
+--------------------+--------------------------------------+-----------+-------+
|remove_query(string |Remove (all occurrences of) query |2 |string |
|Input, string q) |string element q from the Input | | |
| |string. | | |
+--------------------+--------------------------------------+-----------+-------+
|path_element(string |Return the path element n from Input. |2 |string |
|Input, integer n) |-1 returns the last element. | | |
+--------------------+--------------------------------------+-----------+-------+
|path_element(string |Return the path elements from position|3 |string |
|Input, integer n, |n to m. | | |
|integer m) | | | |
+--------------------+--------------------------------------+-----------+-------+
Table 8: CDNI MEL convenience functions
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4.4. Error Handling
4.4.1. Compile Time Errors
To ensure reliable service, all CDNI Metadata configurations MUST be
validated for syntax errors before they are ingested into a dCDN.
That is, existing configurations should be kept as the live running
configuration until the new configuration has passed validation. If
errors are detected in a new configuration, the configuration MUST be
rejected. A HTTP 500 Internal Server Error should be returned with a
message that indicates the source of the error (line number, and
configuration element that caused the error).
Examples of compile-time errors:
1. Configuration does not parse relative to the CDNI Metadata JSON
schema
2. Unknown CDNI Metadata object referenced in the configuration
3. CDNI Metadata object parse error
a. Missing mandatory CDNI Metadata property
b. Unknown CDNI Metadata property
c. Incorrect type for a CDNI Metadata property value
4. CDNI-MEL
a. Unknown CDNI-MEL variable name referenced in an expression
b. Unknown CDNI-MEL operator, key-word, or functions referenced
in an expression
c. Incorrect number of arguments used in a CDNI-MEL expression
operator or function
d. Incorrect type of argument used in a CDNI-MEL expression
operator or function
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4.4.2. Runtime Errors
If a runtime error is detected when processing a request, the request
should be terminated, and a HTTP 500 'Internal Server Error' returned
to the caller. To avoid security leaks, sensitive information MUST
be removed from the error message before it is returned to an
external client. In addition to returning the HTTP 500 error, the
dCDN SHOULD log additional diagnostics information to assist in
troubleshooting.
Examples of runtime errors:
1. Failure to allocate memory (or other server resources) when
evaluating a CDNI-MEL expression
2. Incorrect runtime argument type in a CDNI-MEL expression. E.g.,
trying to convert a non-numeric string to a number
4.5. Expression Examples
4.5.1. ComputedCacheKey
Sets the MI.ComputedCacheKey to the value of the X-Cache-Key header
from the client request.
{
"generic-metadata-type": "MI.ComputedCacheKey",
"generic-metadata-value": {
"expression": "$req.h.x-cache-key"
}
}
Sets the MI.ComputedCacheKey to the lowercase version of the URI.
{
"generic-metadata-type": "MI.ComputedCacheKey",
"generic-metadata-value": {
"expression": "$lower(req.uri)"
}
}
4.5.2. ExpressionMatch
ExpressionMatch where the expression is true if the user-agent (glob)
matches *Safari* and the referrer equals www.example.com.
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{
"expression": "req.h.user-agent *= '*Safari*'
and req.h.referrer == 'www.example.com'"
}
4.5.3. ResponseTransform
Adds X-custom-response-header with a value equal to the value of
user-agent - host header.
{
"response-transform": {
"headers": {
"add": [
{
"name": "X-custom-response-header",
"value": "$req.h.user-agent - $req.h.host",
"value-is-expression": true
}
],
"response-status": "403"
}
}
}
Adds a Set-Cookie header with a dynamically computed cookie value
(concatenating user agent and host name) and forces a 403 response.
{
"response-transform":{
"headers":{
"add":[
{
"name":"Set-Cookie",
"value":"$req.h.user-agent - $req.h.host",
"value-is-expression":true
}
]
}
}
}
4.5.4. MI.ServiceIDs
Extracts the first path element from the URI. For example, if the
URI = /789/second/third/test.txt, property-id is set to the first-
path (789).
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{
"generic-metadata-type":"MI.ServiceIDs",
"generic-metadata-value":{
"service-id":"12345",
"service-name":"My Streaming Service",
"property-id":"$path_element(req.uri, 1)",
"property-id-is-expression":true
}
}
5. IANA Considerations
5.1. CDNI Payload Types
TBD. Two new auth-types will be introduced for use with
SourceMetadataExtended: AWSv4Auth and HeaderAuth
6. Security Considerations
This specification is in accordance with the CDNI Request Routing:
Footprint and Capabilities Semantics. As such, it is subject to the
security and privacy considerations as defined in Section 8 of
[RFC8006] and in Section 7 of [RFC8008] respectively.
MORE - TBD
7. Acknowledgements
The authors would like to express their gratitude to the members of
the Streaming Video Alliance Open Caching Working Group for their
guidance / contribution / reviews ...)
8. References
8.1. Normative References
[capacity-insights-advertisement]
Ryan, A., Rosenblum, B., and N. Sopher, "CDNI Capacity
Insights Capability Advertisment Extensions", 5 July 2021,
<https://www.ietf.org/id/draft-ryan-cdni-capacity-
insights-extensions-00.txt>.
[RFC1034] Mockapetris, P., "Domain names - concepts and facilities",
STD 13, RFC 1034, DOI 10.17487/RFC1034, November 1987,
<https://www.rfc-editor.org/info/rfc1034>.
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[RFC1123] Braden, R., Ed., "Requirements for Internet Hosts -
Application and Support", STD 3, RFC 1123,
DOI 10.17487/RFC1123, October 1989,
<https://www.rfc-editor.org/info/rfc1123>.
[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>.
[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>.
[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>.
[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>.
[RFC8008] Seedorf, J., Peterson, J., Previdi, S., van Brandenburg,
R., and K. Ma, "Content Delivery Network Interconnection
(CDNI) Request Routing: Footprint and Capabilities
Semantics", RFC 8008, DOI 10.17487/RFC8008, December 2016,
<https://www.rfc-editor.org/info/rfc8008>.
[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>.
[RFC8804] Finkelman, O. and S. Mishra, "Content Delivery Network
Interconnection (CDNI) Request Routing Extensions",
RFC 8804, DOI 10.17487/RFC8804, September 2020,
<https://www.rfc-editor.org/info/rfc8804>.
[URI.signing]
van Brandenburg, R., Leung, K., and P. Sorber, "URI
Signing for CDN Interconnection (CDNI)", 8 October 2019,
<http://www.ietf.org/internet-drafts/draft-ietf-cdni-uri-
signing-19.txt>.
[W3C] "Cross-Origin Resource Sharing",
<https://www.w3.org/TR/2020/SPSD-cors-20200602/>.
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8.2. Informative References
[AWSv4Method]
"Authenticating Requests (AWS Signature Version 4)",
<https://docs.aws.amazon.com/AmazonS3/latest/API/sig-v4-
authenticating-requests.html>.
[OC-CI] Goldstein, G., Ed., Power, W., Bichot, G., and A. Siloniz,
"Open Caching - Configuration Interface Functional
Specification (Parts 1,2,3)", Version 0.1, 2 July 2021.
[OCWG] "Open Caching Home Page",
<https://www.streamingvideoalliance.org/technical-groups/
open-caching/>.
[RFC5861] Nottingham, M., "HTTP Cache-Control Extensions for Stale
Content", RFC 5861, DOI 10.17487/RFC5861, May 2010,
<https://www.rfc-editor.org/info/rfc5861>.
[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>.
[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>.
[RFC7694] Reschke, J., "Hypertext Transfer Protocol (HTTP) Client-
Initiated Content-Encoding", RFC 7694,
DOI 10.17487/RFC7694, November 2015,
<https://www.rfc-editor.org/info/rfc7694>.
[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>.
[SVA] "Streaming Video Alliance Home Page",
<https://www.streamingvideoalliance.org>.
Authors' Addresses
Glenn Goldstein
Lumen Technologies
United States of America
Email: glenng1215@gmail.com
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Will Power
Lumen Technologies
United States of America
Email: wrpower@gmail.com
Guillaume Bichot
Broadpeak
France
Email: guillaume.bichot@gmail.com
Alfonso Siloniz
Telefonica
Spain
Email: alfonsosiloniz@gmail.com
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