Internet DRAFT - draft-ietf-cdni-metadata
draft-ietf-cdni-metadata
Network Working Group B. Niven-Jenkins
Internet-Draft R. Murray
Intended status: Standards Track Velocix (Alcatel-Lucent)
Expires: November 21, 2016 M. Caulfield
Cisco Systems
K. Ma
Ericsson
May 20, 2016
CDN Interconnection Metadata
draft-ietf-cdni-metadata-17
Abstract
The Content Delivery Networks Interconnection (CDNI) metadata
interface enables interconnected Content Delivery Networks (CDNs) to
exchange content distribution metadata in order to enable content
acquisition and delivery. The CDNI metadata associated with a piece
of content provides a downstream CDN with sufficient information for
the downstream CDN to service content requests on behalf of an
upstream CDN. This document describes both a base set of CDNI
metadata and the protocol for exchanging that metadata.
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 November 21, 2016.
Niven-Jenkins, et al. Expires November 21, 2016 [Page 1]
Internet-Draft CDN Interconnection Metadata May 2016
Copyright Notice
Copyright (c) 2016 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
(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
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 5
1.2. Supported Metadata Capabilities . . . . . . . . . . . . . 5
2. Design Principles . . . . . . . . . . . . . . . . . . . . . . 6
3. CDNI Metadata object model . . . . . . . . . . . . . . . . . 7
3.1. HostIndex, HostMatch, HostMetadata, PathMatch,
PatternMatch and PathMetadata objects . . . . . . . . . . 8
3.2. Generic CDNI Metadata Objects . . . . . . . . . . . . . . 10
3.3. Metadata Inheritance and Override . . . . . . . . . . . . 13
4. CDNI Metadata objects . . . . . . . . . . . . . . . . . . . . 14
4.1. Definitions of the CDNI structural metadata objects . . . 15
4.1.1. HostIndex . . . . . . . . . . . . . . . . . . . . . . 15
4.1.2. HostMatch . . . . . . . . . . . . . . . . . . . . . . 16
4.1.3. HostMetadata . . . . . . . . . . . . . . . . . . . . 17
4.1.4. PathMatch . . . . . . . . . . . . . . . . . . . . . . 18
4.1.5. PatternMatch . . . . . . . . . . . . . . . . . . . . 19
4.1.6. PathMetadata . . . . . . . . . . . . . . . . . . . . 20
4.1.7. GenericMetadata . . . . . . . . . . . . . . . . . . . 21
4.2. Definitions of the initial set of CDNI Generic Metadata
objects . . . . . . . . . . . . . . . . . . . . . . . . . 23
4.2.1. SourceMetadata . . . . . . . . . . . . . . . . . . . 23
4.2.1.1. Source . . . . . . . . . . . . . . . . . . . . . 24
4.2.2. LocationACL Metadata . . . . . . . . . . . . . . . . 25
4.2.2.1. LocationRule . . . . . . . . . . . . . . . . . . 27
4.2.2.2. Footprint . . . . . . . . . . . . . . . . . . . . 27
4.2.3. TimeWindowACL . . . . . . . . . . . . . . . . . . . . 28
4.2.3.1. TimeWindowRule . . . . . . . . . . . . . . . . . 29
4.2.3.2. TimeWindow . . . . . . . . . . . . . . . . . . . 30
4.2.4. ProtocolACL Metadata . . . . . . . . . . . . . . . . 31
4.2.4.1. ProtocolRule . . . . . . . . . . . . . . . . . . 32
4.2.5. DeliveryAuthorization Metadata . . . . . . . . . . . 32
Niven-Jenkins, et al. Expires November 21, 2016 [Page 2]
Internet-Draft CDN Interconnection Metadata May 2016
4.2.6. Cache . . . . . . . . . . . . . . . . . . . . . . . . 33
4.2.7. Auth . . . . . . . . . . . . . . . . . . . . . . . . 34
4.2.8. Grouping . . . . . . . . . . . . . . . . . . . . . . 35
4.3. CDNI Metadata Simple Data Type Descriptions . . . . . . . 35
4.3.1. Link . . . . . . . . . . . . . . . . . . . . . . . . 35
4.3.2. Protocol . . . . . . . . . . . . . . . . . . . . . . 37
4.3.3. Endpoint . . . . . . . . . . . . . . . . . . . . . . 37
4.3.4. Time . . . . . . . . . . . . . . . . . . . . . . . . 38
4.3.5. IPv4CIDR . . . . . . . . . . . . . . . . . . . . . . 38
4.3.6. IPv6CIDR . . . . . . . . . . . . . . . . . . . . . . 38
4.3.7. ASN . . . . . . . . . . . . . . . . . . . . . . . . . 38
4.3.8. CountryCode . . . . . . . . . . . . . . . . . . . . . 39
5. CDNI Metadata Capabilities . . . . . . . . . . . . . . . . . 39
6. CDNI Metadata interface . . . . . . . . . . . . . . . . . . . 39
6.1. Transport . . . . . . . . . . . . . . . . . . . . . . . . 40
6.2. Retrieval of CDNI Metadata resources . . . . . . . . . . 41
6.3. Bootstrapping . . . . . . . . . . . . . . . . . . . . . . 42
6.4. Encoding . . . . . . . . . . . . . . . . . . . . . . . . 42
6.5. Extensibility . . . . . . . . . . . . . . . . . . . . . . 43
6.6. Metadata Enforcement . . . . . . . . . . . . . . . . . . 44
6.7. Metadata Conflicts . . . . . . . . . . . . . . . . . . . 44
6.8. Versioning . . . . . . . . . . . . . . . . . . . . . . . 45
6.9. Media Types . . . . . . . . . . . . . . . . . . . . . . . 45
6.10. Complete CDNI Metadata Example . . . . . . . . . . . . . 46
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 50
7.1. CDNI Payload Types . . . . . . . . . . . . . . . . . . . 50
7.1.1. CDNI MI HostIndex Payload Type . . . . . . . . . . . 50
7.1.2. CDNI MI HostMatch Payload Type . . . . . . . . . . . 51
7.1.3. CDNI MI HostMetadata Payload Type . . . . . . . . . . 51
7.1.4. CDNI MI PathMatch Payload Type . . . . . . . . . . . 51
7.1.5. CDNI MI PatternMatch Payload Type . . . . . . . . . . 51
7.1.6. CDNI MI PathMetadata Payload Type . . . . . . . . . . 51
7.1.7. CDNI MI SourceMetadata Payload Type . . . . . . . . . 52
7.1.8. CDNI MI Source Payload Type . . . . . . . . . . . . . 52
7.1.9. CDNI MI LocationACL Payload Type . . . . . . . . . . 52
7.1.10. CDNI MI LocationRule Payload Type . . . . . . . . . . 52
7.1.11. CDNI MI Footprint Payload Type . . . . . . . . . . . 52
7.1.12. CDNI MI TimeWindowACL Payload Type . . . . . . . . . 53
7.1.13. CDNI MI TimeWindowRule Payload Type . . . . . . . . . 53
7.1.14. CDNI MI TimeWindow Payload Type . . . . . . . . . . . 53
7.1.15. CDNI MI ProtocolACL Payload Type . . . . . . . . . . 53
7.1.16. CDNI MI ProtocolRule Payload Type . . . . . . . . . . 53
7.1.17. CDNI MI DeliveryAuthorization Payload Type . . . . . 54
7.1.18. CDNI MI Cache Payload Type . . . . . . . . . . . . . 54
7.1.19. CDNI MI Auth Payload Type . . . . . . . . . . . . . . 54
7.1.20. CDNI MI Grouping Payload Type . . . . . . . . . . . . 54
7.2. CDNI Metadata Footprint Types Registry . . . . . . . . . 54
7.3. CDNI Metadata Protocol Types Registry . . . . . . . . . . 55
Niven-Jenkins, et al. Expires November 21, 2016 [Page 3]
Internet-Draft CDN Interconnection Metadata May 2016
7.4. CDNI Metadata Auth Types Registry . . . . . . . . . . . . 56
8. Security Considerations . . . . . . . . . . . . . . . . . . . 56
8.1. Authentication . . . . . . . . . . . . . . . . . . . . . 56
8.2. Confidentiality . . . . . . . . . . . . . . . . . . . . . 57
8.3. Integrity . . . . . . . . . . . . . . . . . . . . . . . . 57
8.4. Privacy . . . . . . . . . . . . . . . . . . . . . . . . . 57
8.5. Securing the CDNI Metadata interface . . . . . . . . . . 58
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 58
10. Contributing Authors . . . . . . . . . . . . . . . . . . . . 58
11. References . . . . . . . . . . . . . . . . . . . . . . . . . 59
11.1. Normative References . . . . . . . . . . . . . . . . . . 59
11.2. Informative References . . . . . . . . . . . . . . . . . 60
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 61
1. Introduction
Content Delivery Networks Interconnection (CDNI) [RFC6707] enables a
downstream Content Delivery Network (dCDN) to service content
requests on behalf of an upstream CDN (uCDN).
The CDNI metadata interface is discussed in [RFC7336] along with four
other interfaces that can be used to compose a CDNI solution (CDNI
Control interface, CDNI Request Routing Redirection interface, CDNI
Footprint & Capabilities Advertisement interface and CDNI Logging
interface). [RFC7336] describes each interface and the relationships
between them. The requirements for the CDNI metadata interface are
specified in [RFC7337].
The CDNI metadata associated with a piece of content (or with a set
of content) provides a dCDN with sufficient information for servicing
content requests on behalf of an uCDN, in accordance with the
policies defined by the uCDN.
This document defines the CDNI metadata interface which enables a
dCDN to obtain CDNI metadata from an uCDN so that the dCDN can
properly process and respond to:
o Redirection requests received over the CDNI Request Routing
Redirection interface [I-D.ietf-cdni-redirection].
o Content requests received directly from User Agents.
Specifically, this document specifies:
o A data structure for mapping content requests and redirection
requests to CDNI metadata objects (Section 3 and Section 4.1).
o An initial set of CDNI Generic metadata objects (Section 4.2).
Niven-Jenkins, et al. Expires November 21, 2016 [Page 4]
Internet-Draft CDN Interconnection Metadata May 2016
o A HTTP web service for the transfer of CDNI metadata (Section 6).
1.1. Terminology
This document reuses the terminology defined in [RFC6707].
Additionally, the following terms are used throughout this document
and are defined as follows:
o Object - a collection of properties.
o Property - a key and value pair where the key is a property name
and the value is the property value or another object.
This document uses the phrase "[Object] A contains [Object] B" for
simplicity when a strictly accurate phrase would be "[Object] A
contains or references (via a Link object) [Object] B".
1.2. Supported Metadata Capabilities
Only the metadata for a small set of initial capabilities is
specified in this document. This set provides the minimum amount of
metadata for basic CDN interoperability while still meeting the
requirements set forth by [RFC7337].
The following high-level functionality can be configured via the CDNI
metadata objects specified in Section 4:
o Acquisition Source: Metadata for allowing a dCDN to fetch content
from a uCDN.
o Delivery Access Control: Metadata for restricting (or permitting)
access to content based on any of the following factors:
* Location
* Time Window
* Delivery Protocol
o Delivery Authorization: Metadata for authorizing dCDN user agent
requests.
o Cache Control: Metadata for controlling cache behavior of the
dCDN.
The metadata encoding described by this document is extensible in
order to allow for future additions to this list.
Niven-Jenkins, et al. Expires November 21, 2016 [Page 5]
Internet-Draft CDN Interconnection Metadata May 2016
The set of metadata specified in this document covers the initial
capabilities above. It is only intended to support CDN
interconnection for the delivery of content by a dCDN using HTTP/1.1
[RFC7230] and for a dCDN to be able to acquire content from a uCDN
using either HTTP/1.1 or HTTP/1.1 over TLS [RFC2818].
Supporting CDN interconnection for the delivery of content using
unencrypted HTTP/2 [RFC7540] (as well as for a dCDN to acquire
content using unencrypted HTTP/2 or HTTP/2 over TLS) requires the
registration of these protocol names in the CDNI Metadata Protocol
Types registry Section 7.3.
Supporting CDN interconnection for the delivery of content using
HTTP/1.1 over TLS or HTTP/2 over TLS requires specifying additional
metadata objects to carry the properties required to establish a TLS
session, for example metadata to describe the certificate to use as
part of the TLS handshake.
2. Design Principles
The CDNI metadata interface was designed to achieve the following
objectives:
1. Cacheability of CDNI metadata objects;
2. Deterministic mapping from redirection requests and content
requests to CDNI metadata properties;
3. Support for DNS redirection as well as application-specific
redirection (for example HTTP redirection);
4. Minimal duplication of CDNI metadata; and
5. Leveraging of existing protocols.
Cacheability can decrease the latency of acquiring metadata while
maintaining its freshness, and therefore decrease the latency of
serving content requests and redirection requests, without
sacrificing accuracy. The CDNI metadata interface uses HTTP and its
existing caching mechanisms to achieve CDNI metadata cacheability.
Deterministic mappings from content to metadata properties eliminates
ambiguity and ensures that policies are applied consistently by all
dCDNs.
Support for both HTTP and DNS redirection ensures that the CDNI
metadata meets the same design principles for both HTTP and DNS based
redirection schemes.
Niven-Jenkins, et al. Expires November 21, 2016 [Page 6]
Internet-Draft CDN Interconnection Metadata May 2016
Minimal duplication of CDNI metadata improves storage efficiency in
the CDNs.
Leveraging existing protocols avoids reinventing common mechanisms
such as data structure encoding (by leveraging I-JSON [RFC7493]) and
data transport (by leveraging HTTP [RFC7230]).
3. CDNI Metadata object model
The CDNI metadata object model describes a data structure for mapping
redirection requests and content requests to metadata properties.
Metadata properties describe how to acquire content from an uCDN,
authorize access to content, and deliver content from a dCDN. The
object model relies on the assumption that these metadata properties
can be aggregated based on the hostname of the content and
subsequently on the resource path (URI) of the content. The object
model associates a set of CDNI metadata properties with a Hostname to
form a default set of metadata properties for content delivered on
behalf of that Hostname. That default set of metadata properties can
be overridden by properties that apply to specific paths within a
URI.
Different Hostnames and URI paths will be associated with different
sets of CDNI metadata properties in order to describe the required
behaviour when a dCDN surrogate or request router is processing User
Agent requests for content at that Hostname and URI path. As a
result of this structure, significant commonality could exist between
the CDNI metadata properties specified for different Hostnames,
different URI paths within a Hostname and different URI paths on
different Hostnames. For example the definition of which User Agent
IP addresses should be grouped together into a single network or
geographic location is likely to be common for a number of different
Hostnames; although a uCDN is likely to have several different
policies configured to express geo-blocking rules, it is likely that
a single geo-blocking policy could be applied to multiple Hostnames
delivered through the CDN.
In order to enable the CDNI metadata for a given Hostname and URI
Path to be decomposed into reusable sets of CDNI metadata properties,
the CDNI metadata interface splits the CDNI metadata into separate
objects. Efficiency is improved by enabling a single CDNI metadata
object (that is shared across Hostname and/or URI paths) to be
retrieved and stored by a dCDN once, even if it is referenced by the
CDNI metadata for multiple Hostnames and/or URI paths.
Important Note: Any CDNI metadata object A that contains another CDNI
metadata object B can include a Link object specifying a URI that can
be used to retrieve object B, instead of embedding object B within
Niven-Jenkins, et al. Expires November 21, 2016 [Page 7]
Internet-Draft CDN Interconnection Metadata May 2016
object A. The remainder of this document uses the phrase "[Object] A
contains [Object] B" for simplicity when a strictly accurate phrase
would be "[Object] A contains or references (via a Link object)
[Object] B". It is generally a deployment choice for the uCDN
implementation to decide when to embed CDNI metadata objects and when
to reference separate resources via Link objects.
Section 3.1 introduces a high level description of the HostIndex,
HostMatch, HostMetadata, PathMatch, PatternMatch and PathMetadata
objects, and describes the relationships between them.
Section 3.2 introduces a high level description of the CDNI
GenericMetadata object which represents the level at which CDNI
metadata override occurs between HostMetadata and PathMetadata
objects.
Section 4 describes in detail the specific CDNI metadata objects and
properties specified by this document which can be contained within a
CDNI GenericMetadata object.
3.1. HostIndex, HostMatch, HostMetadata, PathMatch, PatternMatch and
PathMetadata objects
The relationships between the HostIndex, HostMatch, HostMetadata,
PathMatch, PatternMatch and PathMetadata objects are described in
Figure 1.
+---------+ +---------+ +------------+
|HostIndex+-(*)->|HostMatch+-(1)->|HostMetadata+-------(*)------+
+---------+ +---------+ +------+-----+ |
| |
(*) |
| V
--> Contains or References V ******************
(1) One and only one +---------+ *Generic Metadata*
(*) Zero or more +--->|PathMatch| * Objects *
| +----+---++ ******************
| | | ^
(*) (1) (1) +------------+ |
| | +->|PatternMatch| |
| V +------------+ |
| +------------+ |
+--+PathMetadata+-------(*)------+
+------------+
Figure 1: Relationships between CDNI Metadata Objects (Diagram
Representation)
Niven-Jenkins, et al. Expires November 21, 2016 [Page 8]
Internet-Draft CDN Interconnection Metadata May 2016
A HostIndex object (see Section 4.1.1) contains a list of HostMatch
objects (see Section 4.1.2) that contain Hostnames (and/or IP
addresses) for which content requests might be delegated to the dCDN.
The HostIndex is the starting point for accessing the uCDN CDNI
metadata data store. It enables the dCDN to deterministically
discover which CDNI metadata objects it requires in order to deliver
a given piece of content.
The HostIndex links Hostnames (and/or IP addresses) to HostMetadata
objects (see Section 4.1.3) via HostMatch objects. A HostMatch
object defines a Hostname (or IP address) to match against a
requested host and contains a HostMetadata object.
HostMetadata objects contain the default GenericMetadata objects (see
Section 4.1.7) required to serve content for that host. When looking
up CDNI metadata, the dCDN looks up the requested Hostname (or IP
address) against the HostMatch entries in the HostIndex, from there
it can find HostMetadata which describes the default metadata
properties for each host as well as PathMetadata objects (see
Section 4.1.6), via PathMatch objects (see Section 4.1.4). PathMatch
objects define patterns, contained inside PatternMatch objects (see
Section 4.1.5), to match against the requested URI path.
PatternMatch objects contain the pattern strings and flags that
describe the URI path that a PathMatch applies to. PathMetadata
objects contain the GenericMetadata objects that apply to content
requests matching the defined URI path pattern. PathMetadata
properties override properties previously defined in HostMetadata or
less specific PathMatch paths. PathMetadata objects can contain
additional PathMatch objects to recursively define more specific URI
paths to which GenericMetadata properties might be applied.
A GenericMetadata object contains individual CDNI metadata objects
which define the specific policies and attributes needed to properly
deliver the associated content. For example, a GenericMetadata
object could describe the source from which a CDN can acquire a piece
of content. The GenericMetadata object is an atomic unit that can be
referenced by HostMetadata or PathMetadata objects.
For example, if "example.com" is a content provider, a HostMatch
object could include an entry for "example.com" with the URI of the
associated HostMetadata object. The HostMetadata object for
"example.com" describes the metadata properties which apply to
"example.com" and could contain PathMatches for "example.com/
movies/*" and "example.com/music/*", which in turn reference
corresponding PathMetadata objects that contain the properties for
those more specific URI paths. The PathMetadata object for
"example.com/movies/*" describes the properties which apply to that
URI path. It could also contain a PathMatch object for
Niven-Jenkins, et al. Expires November 21, 2016 [Page 9]
Internet-Draft CDN Interconnection Metadata May 2016
"example.com/movies/hd/*" which would reference the corresponding
PathMetadata object for the "example.com/movies/hd/" path prefix.
The relationships in Figure 1 are also represented in tabular format
in Table 1 below.
+--------------+----------------------------------------------------+
| Data Object | Objects it contains or references |
+--------------+----------------------------------------------------+
| HostIndex | 0 or more HostMatch objects. |
| HostMatch | 1 HostMetadata object. |
| HostMetadata | 0 or more PathMatch objects. 0 or more |
| | GenericMetadata objects. |
| PathMatch | 1 PatternMatch object. 1 PathMetadata object. |
| PatternMatch | Does not contain or reference any other objects. |
| PathMetadata | 0 or more PathMatch objects. 0 or more |
| | GenericMetadata objects. |
+--------------+----------------------------------------------------+
Table 1: Relationships between CDNI Metadata Objects
(Table Representation)
3.2. Generic CDNI Metadata Objects
The HostMetadata and PathMetadata objects contain other CDNI metadata
objects that contain properties which describe how User Agent
requests for content should be processed, for example where to
acquire the content from, authorization rules that should be applied,
geo-blocking restrictions, and so on. Each such CDNI metadata object
is a specialization of a CDNI GenericMetadata object. The
GenericMetadata object abstracts the basic information required for
metadata override and metadata distribution, from the specifics of
any given property (i.e., property semantics, enforcement options,
etc.).
The GenericMetadata object defines the properties contained within it
as well as whether or not the properties are "mandatory-to-enforce".
If the dCDN does not understand or support a "mandatory-to-enforce"
property, the dCDN MUST NOT serve the content. If the property is
not "mandatory-to-enforce", then that GenericMetadata object can be
safely ignored and the dCDN MUST process the content request in
accordance with the rest of the CDNI metadata.
Although a CDN MUST NOT serve content to a User Agent if a
"mandatory-to-enforce" property cannot be enforced, it could still be
"safe-to-redistribute" that metadata to another CDN without
modification. For example, in the cascaded CDN case, a transit CDN
(tCDN) could pass through "mandatory-to-enforce" metadata to a dCDN.
Niven-Jenkins, et al. Expires November 21, 2016 [Page 10]
Internet-Draft CDN Interconnection Metadata May 2016
For metadata which does not require customization or translation
(i.e., metadata that is "safe-to-redistribute"), the data
representation received off the wire MAY be stored and redistributed
without being understood or supported by the transit CDN. However,
for metadata which requires translation, transparent redistribution
of the uCDN metadata values might not be appropriate. Certain
metadata can be safely, though perhaps not optimally, redistributed
unmodified. For example, source acquisition address might not be
optimal if transparently redistributed, but it might still work.
Redistribution safety MUST be specified for each GenericMetadata
property. If a CDN does not understand or support a given
GenericMetadata property that is not "safe-to-redistribute", the CDN
MUST set the "incomprehensible" flag to true for that GenericMetadata
object before redistributing the metadata. The "incomprehensible"
flag signals to a dCDN that the metadata was not properly transformed
by the transit CDN. A CDN MUST NOT attempt to use metadata that has
been marked as "incomprehensible" by a uCDN.
Transit CDNs MUST NOT change the value of "mandatory-to-enforce" or
"safe-to-redistribute" when propagating metadata to a dCDN. Although
a transit CDN can set the value of "incomprehensible" to true, a
transit CDN MUST NOT change the value of "incomprehensible" from true
to false.
Table 2 describes the action to be taken by a transit CDN (tCDN) for
the different combinations of "mandatory-to-enforce" (MtE) and "safe-
to-redistribute" (StR) properties, when the tCDN either does or does
not understand the metadata in question:
Niven-Jenkins, et al. Expires November 21, 2016 [Page 11]
Internet-Draft CDN Interconnection Metadata May 2016
+-------+-------+------------+--------------------------------------+
| MtE | StR | Metadata | Action |
| | | Understood | |
| | | by tCDN | |
+-------+-------+------------+--------------------------------------+
| False | True | True | Can serve and redistribute. |
| False | True | False | Can serve and redistribute. |
| False | False | False | Can serve. MUST set |
| | | | "incomprehensible" to True when |
| | | | redistributing. |
| False | False | True | Can serve. Can redistribute after |
| | | | transforming the metadata (if the |
| | | | CDN knows how to do so safely), |
| | | | otherwise MUST set |
| | | | "incomprehensible" to True when |
| | | | redistributing. |
| True | True | True | Can serve and redistribute. |
| True | True | False | MUST NOT serve but can redistribute. |
| True | False | True | Can serve. Can redistribute after |
| | | | transforming the metadata (if the |
| | | | CDN knows how to do so safely), |
| | | | otherwise MUST set |
| | | | "incomprehensible" to True when |
| | | | redistributing. |
| True | False | False | MUST NOT serve. MUST set |
| | | | "incomprehensible" to True when |
| | | | redistributing. |
+-------+-------+------------+--------------------------------------+
Table 2: Action to be taken by a tCDN for the different combinations
of MtE and StR properties
Table 3 describes the action to be taken by a dCDN for the different
combinations of "mandatory-to-enforce" (MtE) and "incomprehensible"
(Incomp) properties, when the dCDN either does or does not understand
the metadata in question:
Niven-Jenkins, et al. Expires November 21, 2016 [Page 12]
Internet-Draft CDN Interconnection Metadata May 2016
+-------+--------+--------------+-----------------------------------+
| MtE | Incomp | Metadata | Action |
| | | Understood | |
| | | by dCDN | |
+-------+--------+--------------+-----------------------------------+
| False | False | True | Can serve. |
| False | True | True | Can serve but MUST NOT |
| | | | interpret/apply any metadata |
| | | | marked incomprehensible. |
| False | False | False | Can serve. |
| False | True | False | Can serve but MUST NOT |
| | | | interpret/apply any metadata |
| | | | marked incomprehensible. |
| True | False | True | Can serve. |
| True | True | True | MUST NOT serve. |
| True | False | False | MUST NOT serve. |
| True | True | False | MUST NOT serve. |
+-------+--------+--------------+-----------------------------------+
Table 3: Action to be taken by a dCDN for the different combinations
of MtE and Incomp properties
3.3. Metadata Inheritance and Override
In the metadata object model, a HostMetadata object can contain
multiple PathMetadata objects (via PathMatch objects). Each
PathMetadata object can in turn contain other PathMetadata objects.
HostMetadata and PathMetadata objects form an inheritance tree where
each node in the tree inherits or overrides the property values set
by its parent.
GenericMetadata objects of a given type override all GenericMetadata
objects of the same type previously defined by any parent object in
the tree. GenericMetadata objects of a given type previously defined
by a parent object in the tree are inherited when no object of the
same type is defined by the child object. For example, if
HostMetadata for the host "example.com" contains GenericMetadata
objects of type LocationACL and TimeWindowACL, while a PathMetadata
object which applies to "example.com/movies/*" defines an alternate
GenericMetadata object of type TimeWindowACL, then:
o the TimeWindowACL defined in the PathMetadata would override the
TimeWindowACL defined in the HostMetadata for all User Agent
requests for content under "example.com/movies/", and
o the LocationACL defined in the HostMetadata would be inherited for
all User Agent requests for content under "example.com/movies/".
Niven-Jenkins, et al. Expires November 21, 2016 [Page 13]
Internet-Draft CDN Interconnection Metadata May 2016
A single HostMetadata or PathMetadata object MUST NOT contain
multiple GenericMetadata objects of the same type. If a list of
GenericMetadata contains objects of duplicate types, the receiver
MUST ignore all but the first object of each type.
4. CDNI Metadata objects
Section 4.1 provides the definitions of each metadata object type
introduced in Section 3. These metadata objects are described as
structural metadata objects as they provide the structure for host
and URI path-based inheritance and identify which GenericMetadata
objects apply to a given User Agent content request.
Section 4.2 provides the definitions for a base set of core metadata
objects which can be contained within a GenericMetadata object.
These metadata objects govern how User Agent requests for content are
handled. GenericMetadata objects can contain other GenericMetadata
as properties; these can be referred to as sub-objects). As with all
CDNI metadata objects, the value of the GenericMetadata sub-objects
can be either a complete serialized representation of the sub-object,
or a Link object that contains a URI that can be dereferenced to
retrieve the complete serialized representation of the property sub-
object.
Section 6.5 discusses the ability to extend the base set of
GenericMetadata objects specified in this document with additional
standards-based or vendor specific GenericMetadata objects that might
be defined in the future in separate documents.
dCDNs and tCDNs MUST support parsing of all CDNI metadata objects
specified in this document. A dCDN does not have to implement the
underlying functionality represented by non-structural
GenericMetadata objects (though that might restrict the content that
a given dCDN will be able to serve). uCDNs as generators of CDNI
metadata only need to support generating the CDNI metadata that they
need in order to express the policies required by the content they
are describing.
CDNI metadata objects MUST be encoded as I-JSON objects [RFC7493]
containing a dictionary of (key,value) pairs where the keys are the
property names and the values are the associated property values.
See Section 6.4 for more details of the specific encoding rules for
CDNI metadata objects.
Note: In the following sections, the term "mandatory-to-specify" is
used to convey which properties MUST be included for a given
structural or GenericMetadata object. When mandatory-to-specify is
specified as "Yes" for an individual property, it means that if the
Niven-Jenkins, et al. Expires November 21, 2016 [Page 14]
Internet-Draft CDN Interconnection Metadata May 2016
object containing that property is included in a metadata response,
then the mandatory-to-specify property MUST also be included
(directly or by reference) in the response, e.g., a HostMatch
property object without a host to match against does not make sense,
therefore, the host property is mandatory-to-specify inside a
HostMatch object.
4.1. Definitions of the CDNI structural metadata objects
Each of the sub-sections below describe the structural objects
introduced in Section 3.1.
4.1.1. HostIndex
The HostIndex object is the entry point into the CDNI metadata
hierarchy. It contains a list of HostMatch objects. An incoming
content request is checked against the Hostname (or IP address)
specified by each of the listed HostMatch objects to find the
HostMatch object which applies to the request.
Property: hosts
Description: List of HostMatch objects. Hosts (HostMatch
objects) MUST be evaluated in the order they appear and the
first HostMatch object that matches the content request being
processed MUST be used.
Type: List of HostMatch objects
Mandatory-to-Specify: Yes.
Example HostIndex object containing two HostMatch objects, where the
first HostMatch object is embedded and the second HostMatch object is
referenced:
{
"hosts": [
{
<Properties of embedded HostMatch object>
},
{
"type": "MI.HostMatch",
"href": "http://metadata.ucdn.example/hostmatch1234"
}
]
}
Niven-Jenkins, et al. Expires November 21, 2016 [Page 15]
Internet-Draft CDN Interconnection Metadata May 2016
4.1.2. HostMatch
The HostMatch object contains a Hostname or IP address to match
against content requests. The HostMatch object also contains a
HostMetadata object to apply if a match is found.
Property: host
Description: Hostname or IP address to match against the
requested host. In order for a Hostname or IP address in a
content request to match the Hostname or IP address in the host
property the value from the content request when converted to
lowercase MUST be identical to the value of the host property
when converted to lowercase.
Type: Endpoint
Mandatory-to-Specify: Yes.
Property: host-metadata
Description: CDNI metadata to apply when delivering content
that matches this host.
Type: HostMetadata
Mandatory-to-Specify: Yes.
Example HostMatch object with an embedded HostMetadata object:
{
"host": "video.example.com",
"host-metadata" : {
<Properties of embedded HostMetadata object>
}
}
Example HostMatch object referencing (via a Link object, see
Section 4.3.1) a HostMetadata object:
{
"host": "video.example.com",
"host-metadata" : {
"type": "MI.HostMetadata",
"href": "http://metadata.ucdn.example/host1234"
}
}
Niven-Jenkins, et al. Expires November 21, 2016 [Page 16]
Internet-Draft CDN Interconnection Metadata May 2016
4.1.3. HostMetadata
A HostMetadata object contains the CDNI metadata properties for
content served for a particular host (defined in the HostMatch
object) and possibly child PathMatch objects.
Property: metadata
Description: List of host related metadata.
Type: List of GenericMetadata objects
Mandatory-to-Specify: Yes.
Property: paths
Description: Path specific rules. Path patterns (PathMatch
objects) MUST be evaluated in the order they appear and the
first PathMatch object that matches the content request being
processed MUST be used.
Type: List of PathMatch objects
Mandatory-to-Specify: No.
Example HostMetadata object containing a number of embedded
GenericMetadata objects that will describe the default metadata for
the host and an embedded PathMatch object that contains a path for
which metadata exists that overrides the default metadata for the
host:
Niven-Jenkins, et al. Expires November 21, 2016 [Page 17]
Internet-Draft CDN Interconnection Metadata May 2016
{
"metadata": [
{
<Properties of 1st embedded GenericMetadata object>
},
{
<Properties of 2nd embedded GenericMetadata object>
},
...
{
<Properties of Nth embedded GenericMetadata object>
}
],
"paths": [
{
<Properties of embedded PathMatch object>
}
]
}
4.1.4. PathMatch
A PathMatch object contains PatternMatch object with a path to match
against a resource's URI path, as well as a PathMetadata object with
GenericMetadata to apply if the resource's URI path matches the
pattern within the PatternMatch object.
Property: path-pattern
Description: Pattern to match against the requested resource's
URI path, i.e., against the [RFC3986] path-absolute.
Type: PatternMatch
Mandatory-to-Specify: Yes.
Property: path-metadata
Description: CDNI metadata to apply when delivering content
that matches the associated PatternMatch.
Type: PathMetadata
Mandatory-to-Specify: Yes.
Niven-Jenkins, et al. Expires November 21, 2016 [Page 18]
Internet-Draft CDN Interconnection Metadata May 2016
Example PathMatch object referencing the PathMetadata object to use
for URIs that match the case-sensitive URI path pattern "/movies/*"
(contained within an embedded PatternMatch object):
{
"path-pattern": {
"pattern": "/movies/*",
"case-sensitive": true
},
"path-metadata": {
"type": "MI.PathMetadata",
"href": "http://metadata.ucdn.example/host1234/pathDCE"
}
}
4.1.5. PatternMatch
A PatternMatch object contains the pattern string and flags that
describe the pattern expression.
Property: pattern
Description: A pattern for string matching. The pattern can
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 $?. All other characters are treated as literals.
Type: String
Mandatory-to-Specify: Yes.
Property: case-sensitive
Description: Flag indicating whether or not case-sensitive
matching should be used.
Type: Boolean
Mandatory-to-Specify: No. Default is case-insensitive match.
Property: ignore-query-string
Description: List of query parameters which should be ignored
when searching for a pattern match. Matching against query
parameters to ignore MUST be case-insensitive. If all query
parameters should be ignored then the list MUST be empty.
Niven-Jenkins, et al. Expires November 21, 2016 [Page 19]
Internet-Draft CDN Interconnection Metadata May 2016
Type: List of String
Mandatory-to-Specify: No. Default is to include query strings
when matching.
Example PatternMatch object that matches the case-sensitive URI path
pattern "/movies/*". All query parameters will be ignored when
matching URIs requested from surrogates by content clients against
this path pattern:
{
"pattern": "/movies/*",
"case-sensitive": true,
"ignore-query-string": []
}
Example PatternMatch object that matches the case-sensitive URI path
pattern "/movies/*". The query parameter "sessionid" will be ignored
when matching URIs requested from surrogates by content clients
against this path pattern:
{
"pattern": "/movies/*",
"case-sensitive": true,
"ignore-query-string": ["sessionid"]
}
4.1.6. PathMetadata
A PathMetadata object contains the CDNI metadata properties for
content requests that match against the associated URI path (defined
in a PathMatch object).
Note that if DNS-based redirection is employed, then a dCDN will be
unable to evaulate any metadata at the PathMetadata level or below
because only the hostname of the content request is available at
request routing time. dCDNs SHOULD still process all PathMetadata for
the host before responding to the redirection request to detect if
any unsupported metadata is specifed. If any metadata not supported
by the dCDN is marked as "mandatory-to-enforce", the dCDN SHOULD NOT
accept the content redirection request, in order to avoid receiving
content requests that it will not be able to satisfy/serve.
Property: metadata
Description: List of path related metadata.
Type: List of GenericMetadata objects
Niven-Jenkins, et al. Expires November 21, 2016 [Page 20]
Internet-Draft CDN Interconnection Metadata May 2016
Mandatory-to-Specify: Yes.
Property: paths
Description: Path specific rules. First match applies.
Type: List of PathMatch objects
Mandatory-to-Specify: No.
Example PathMetadata object containing a number of embedded
GenericMetadata objects that describe the metadata to apply for the
URI path defined in the parent PathMatch object, as well as a more
specific PathMatch object.
{
"metadata": [
{
<Properties of 1st embedded GenericMetadata object>
},
{
<Properties of 2nd embedded GenericMetadata object>
},
...
{
<Properties of Nth embedded GenericMetadata object>
}
],
"paths": [
{
<Properties of embedded PathMatch object>
}
]
}
4.1.7. GenericMetadata
A GenericMetadata object is a wrapper for managing individual CDNI
metadata properties in an opaque manner.
Property: generic-metadata-type
Description: Case-insensitive CDNI metadata object type.
Niven-Jenkins, et al. Expires November 21, 2016 [Page 21]
Internet-Draft CDN Interconnection Metadata May 2016
Type: String containing the CDNI Payload Type [RFC7736] of the
object contained in the generic-metadata-value property (see
Table 4).
Mandatory-to-Specify: Yes.
Property: generic-metadata-value
Description: CDNI metadata object.
Type: Format/Type is defined by the value of generic-metadata-
type property above. Note: generic-metadata-values MUST NOT
name any properties "href" (see Section 4.3.1).
Mandatory-to-Specify: Yes.
Property: mandatory-to-enforce
Description: Flag identifying whether or not the enforcement of
the property metadata is required.
Type: Boolean
Mandatory-to-Specify: No. Default is to treat metadata as
mandatory to enforce (i.e., a value of True).
Property: safe-to-redistribute
Description: Flag identifying whether or not the property
metadata can be safely redistributed without modification.
Type: Boolean
Mandatory-to-Specify: No. Default is allow transparent
redistribution (i.e., a value of True).
Property: incomprehensible
Description: Flag identifying whether or not any CDN in the
chain of delegation has failed to understand and/or failed to
properly transform this metadata object. Note: This flag only
applies to metadata objects whose safe-to-redistribute property
has a value of False.
Type: Boolean
Mandatory-to-Specify: No. Default is comprehensible (i.e., a
value of False).
Niven-Jenkins, et al. Expires November 21, 2016 [Page 22]
Internet-Draft CDN Interconnection Metadata May 2016
Example GenericMetadata object containing a metadata object that
applies to the applicable URI path and/or host (within a parent
PathMetadata and/or HostMetadata object, respectively):
{
"mandatory-to-enforce": true,
"safe-to-redistribute": true,
"incomprehensible": false,
"generic-metadata-type": <CDNI Payload Type of this metadata object>,
"generic-metadata-value":
{
<Properties of this metadata object>
}
}
4.2. Definitions of the initial set of CDNI Generic Metadata objects
The objects defined below are intended to be used in the
GenericMetadata object generic-metadata-value field as defined in
Section 4.1.7 and their generic-metadata-type property MUST be set to
the appropriate CDNI Payload Type as defined in Table 4.
4.2.1. SourceMetadata
Source metadata provides the dCDN with information about content
acquisition, i.e., how to contact an uCDN Surrogate or an Origin
Server to obtain the content to be served. The sources are not
necessarily the actual Origin Servers operated by the CSP but might
be a set of Surrogates in the uCDN.
Property: sources
Description: Sources from which the dCDN can acquire content,
listed in order of preference.
Type: List of Source objects (see Section 4.2.1.1)
Mandatory-to-Specify: No. Default is to use static
configuration, out-of-band from the metadata interface.
Example SourceMetadata object (which contains two Source objects)
that describes which servers the dCDN should use for acquiring
content for the applicable URI path and/or host:
Niven-Jenkins, et al. Expires November 21, 2016 [Page 23]
Internet-Draft CDN Interconnection Metadata May 2016
{
"generic-metadata-type": "MI.SourceMetadata",
"generic-metadata-value":
{
"sources": [
{
"endpoints": [
"a.service123.ucdn.example",
"b.service123.ucdn.example"
],
"protocol": "http/1.1"
},
{
"endpoints": ["origin.service123.example"],
"protocol": "http/1.1"
}
]
}
}
4.2.1.1. Source
A Source object describes the source to be used by the dCDN for
content acquisition (e.g., a Surrogate within the uCDN or an
alternate Origin Server), the protocol to be used, and any
authentication method to be used when contacting that source.
Endpoints within a Source object MUST be treated as equivalent/equal.
A uCDN can specify a list of sources in preference order within a
SourceMetadata objecct, and then for each preference ranked Source
object, a uCDN can specify a list of endpoints that are equivalent
(e.g., a pool of servers that are not behind a load balancer).
Property: acquisition-auth
Description: Authentication method to use when requesting
content from this source.
Type: Auth (see Section 4.2.7)
Mandatory-to-Specify: No. Default is no authentication
required.
Property: endpoints
Description: Origins from which the dCDN can acquire content.
If multiple endpoints are specified they are all equal, i.e.,
Niven-Jenkins, et al. Expires November 21, 2016 [Page 24]
Internet-Draft CDN Interconnection Metadata May 2016
the list is not in preference order (e.g., a pool of servers
behind a load balancer).
Type: List of Endpoint objects (See Section 4.3.3)
Mandatory-to-Specify: Yes.
Property: protocol
Description: Network retrieval protocol to use when requesting
content from this source.
Type: Protocol (see Section 4.3.2)
Mandatory-to-Specify: Yes.
Example Source object that describes a pair of endpoints (servers)
the dCDN can use for acquiring content for the applicable host and/or
URI path:
{
"endpoints": [
"a.service123.ucdn.example",
"b.service123.ucdn.example"
],
"protocol": "http/1.1"
}
4.2.2. LocationACL Metadata
LocationACL metadata defines which locations a User Agent needs to be
in, in order to be able to receive the associated content.
A LocationACL which does not include a locations property results in
an action of allow all, meaning that delivery can be performed
regardless of the User Agent's location, otherwise a CDN MUST take
the action from the first footprint to match against the User Agent's
location. If two or more footprints overlap, the first footprint
that matches against the User Agent's location determines the action
a CDN MUST take. If the locations property is included but is empty,
or if none of the listed footprints matches the User Agent's
location, then the result is an action of deny.
Although the LocationACL, TimeWindowACL (see Section 4.2.3), and
ProtocolACL (see Section 4.2.4) are independent GenericMetadata
objects, they can provide conflicting information to a dCDN, e.g., a
content request which is simultaneously allowed based on the
LocationACL and denied based on the TimeWindowACL. The dCDN MUST use
Niven-Jenkins, et al. Expires November 21, 2016 [Page 25]
Internet-Draft CDN Interconnection Metadata May 2016
the logical AND of all ACLs (where 'allow' is true and 'deny' is
false) to determine whether or not a request should be allowed.
Property: locations
Description: Access control list which allows or denies
(blocks) delivery based on the User Agent's location.
Type: List of LocationRule objects (see Section 4.2.2.1)
Mandatory-to-Specify: No. Default is allow all locations.
Example LocationACL object that allows the dCDN to deliver content to
any location/IP address:
{
"generic-metadata-type": "MI.LocationACL",
"generic-metadata-value":
{
}
}
Example LocationACL object (which contains a LocationRule object
which itself contains a Footprint object) that only allows the dCDN
to deliver content to User Agents in the USA:
{
"generic-metadata-type": "MI.LocationACL",
"generic-metadata-value":
{
"locations": [
{
"action": "allow",
"footprints": [
{
"footprint-type": "countrycode",
"footprint-value": ["us"]
}
]
}
]
}
}
Niven-Jenkins, et al. Expires November 21, 2016 [Page 26]
Internet-Draft CDN Interconnection Metadata May 2016
4.2.2.1. LocationRule
A LocationRule contains or references a list of Footprint objects and
the corresponding action.
Property: footprints
Description: List of footprints to which the rule applies.
Type: List of Footprint objects (see Section 4.2.2.2)
Mandatory-to-Specify: Yes.
Property: action
Description: Defines whether the rule specifies locations to
allow or deny.
Type: Enumeration [allow|deny] encoded as a lowercase string
Mandatory-to-Specify: No. Default is deny.
Example LocationRule object (which contains a Footprint object) that
allows the dCDN to deliver content to clients in the USA:
{
"action": "allow",
"footprints": [
{
"footprint-type": "countrycode",
"footprint-value": ["us"]
}
]
}
}
4.2.2.2. Footprint
A Footprint object describes the footprint to which a LocationRule
can be applied to, e.g., an IPv4 address range or a geographic
location.
Property: footprint-type
Description: Registered footprint type (see Section 7.2). The
footprint types specified by this document are: "ipv4cidr"
(IPv4CIDR, see Section 4.3.5), "ipv6cidr" (IPv6CIDR, see
Section 4.3.6), "asn" (Autonomous System Number, see
Niven-Jenkins, et al. Expires November 21, 2016 [Page 27]
Internet-Draft CDN Interconnection Metadata May 2016
Section 4.3.7) and "countrycode" (Country Code, see
Section 4.3.8).
Type: Lowercase String
Mandatory-to-Specify: Yes.
Property: footprint-value
Description: List of footprint values conforming to the
specification associated with the registered footprint type.
Footprint values can be simple strings (e.g., IPv4CIDR,
IPv6CIDR, ASN, and CountryCode), however, other Footprint
objects can be defined in the future, along with a more complex
encoding (e.g., GPS coordinate tuples).
Type: List of footprints
Mandatory-to-Specify: Yes.
Example Footprint object describing a footprint covering the USA:
{
"footprint-type": "countrycode",
"footprint-value": ["us"]
}
Example Footprint object describing a footprint covering the IP
address ranges 192.0.2.0/24 and 198.51.100.0/24:
{
"footprint-type": "ipv4cidr",
"footprint-value": ["192.0.2.0/24", "198.51.100.0/24"]
}
4.2.3. TimeWindowACL
TimeWindowACL metadata defines time-based restrictions.
A TimeWindowACL which does not include a times property results in an
action of allow all, meaning that delivery can be performed
regardless of the time of the User Agent's request, otherwise a CDN
MUST take the action from the first window to match against the
current time. If two or more windows overlap, the first window that
matches against the current time determines the action a CDN MUST
take. If the times property is included but is empty, or if none of
the listed windows matches the current time, then the result is an
action of deny.
Niven-Jenkins, et al. Expires November 21, 2016 [Page 28]
Internet-Draft CDN Interconnection Metadata May 2016
Although the LocationACL (see Section 4.2.2), TimeWindowACL, and
ProtocolACL (see Section 4.2.4) are independent GenericMetadata
objects, they can provide conflicting information to a dCDN, e.g., a
content request which is simultaneously allowed based on the
LocationACL and denied based on the TimeWindowACL. The dCDN MUST use
the logical AND of all ACLs (where 'allow' is true and 'deny' is
false) to determine whether or not a request should be allowed.
Property: times
Description: Access control list which allows or denies
(blocks) delivery based on the time of a User Agent's request.
Type: List of TimeWindowRule objects (see Section 4.2.3.1)
Mandatory-to-Specify: No. Default is allow all time windows.
Example TimeWIndowACL object (which contains a TimeWindowRule object
which itself contains a TimeWIndow object) that only allows the dCDN
to deliver content to clients between 09:00 01/01/2000 UTC and 17:00
01/01/2000 UTC:
{
"generic-metadata-type": "MI.TimeWindowACL",
"generic-metadata-value":
{
"times": [
{
"action": "allow",
"windows": [
{
"start": 946717200,
"end": 946746000
}
]
}
]
}
}
4.2.3.1. TimeWindowRule
A TimeWindowRule contains or references a list of TimeWindow objects
and the corresponding action.
Property: windows
Description: List of time windows to which the rule applies.
Niven-Jenkins, et al. Expires November 21, 2016 [Page 29]
Internet-Draft CDN Interconnection Metadata May 2016
Type: List of TimeWindow objects (see Section 4.2.3.2)
Mandatory-to-Specify: Yes.
Property: action
Description: Defines whether the rule specifies time windows to
allow or deny.
Type: Enumeration [allow|deny] encoded as a lowercase string
Mandatory-to-Specify: No. Default is deny.
Example TimeWIndowRule object (which contains a TimeWIndow object)
that only allows the dCDN to deliver content to clients between 09:00
01/01/2000 UTC and 17:00 01/01/2000 UTC:
{
"action": "allow",
"windows": [
{
"start": 946717200,
"end": 946746000
}
]
}
4.2.3.2. TimeWindow
A TimeWindow object describes a time range which can be applied by an
TimeWindowACL, e.g., start 946717200 (i.e., 09:00 01/01/2000 UTC),
end: 946746000 (i.e., 17:00 01/01/2000 UTC).
Property: start
Description: The start time of the window.
Type: Time (see Section 4.3.4)
Mandatory-to-Specify: Yes.
Property: end
Description: The end time of the window.
Type: Time (see Section 4.3.4)
Mandatory-to-Specify: Yes.
Niven-Jenkins, et al. Expires November 21, 2016 [Page 30]
Internet-Draft CDN Interconnection Metadata May 2016
Example TimeWIndow object that describes a time window from 09:00
01/01/2000 UTC to 17:00 01/01/2000 UTC:
{
"start": 946717200,
"end": 946746000
}
4.2.4. ProtocolACL Metadata
ProtocolACL metadata defines delivery protocol restrictions.
A ProtocolACL which does not include a protocol-acl property results
in an action of allow all, meaning that delivery can be performed
regardless of the protocol in the User Agent's request, otherwise a
CDN MUST take the action from the first protocol to match against the
request protocol. If two or more request protocols overlap, the
first protocol that matches the request protocol determines the
action a CDN MUST take. If the protocol-acl property is included but
is empty, or if none of the listed protocol matches the request
protocol, then the result is an action of deny.
Although the LocationACL, TimeWindowACL, and ProtocolACL are
independent GenericMetadata objects, they can provide conflicting
information to a dCDN, e.g., a content request which is
simultaneously allowed based on the ProtocolACL and denied based on
the TimeWindowACL. The dCDN MUST use the logical AND of all ACLs
(where 'allow' is true and 'deny' is false) to determine whether or
not a request should be allowed.
Property: protocol-acl
Description: Description: Access control list which allows or
denies (blocks) delivery based on delivery protocol.
Type: List of ProtocolRule objects (see Section 4.2.4.1)
Mandatory-to-Specify: No. Default is allow all protocols.
Example ProtocolACL object (which contains a ProtocolRule object)
that only allows the dCDN to deliver content using HTTP/1.1:
Niven-Jenkins, et al. Expires November 21, 2016 [Page 31]
Internet-Draft CDN Interconnection Metadata May 2016
{
"generic-metadata-type": "MI.ProtocolACL",
"generic-metadata-value":
{
"protocol-acl": [
{
"action": "allow",
"protocols": ["http/1.1"]
}
]
}
}
4.2.4.1. ProtocolRule
A ProtocolRule contains or references a list of Protocol objects and
the corresponding action.
Property: protocols
Description: List of protocols to which the rule applies.
Type: List of Protocols (see Section 4.3.2)
Mandatory-to-Specify: Yes.
Property: action
Description: Defines whether the rule specifies protocols to
allow or deny.
Type: Enumeration [allow|deny] encoded as a lowercase string
Mandatory-to-Specify: No. Default is deny.
Example ProtocolRule object (which contains a ProtocolRule object)
that allows the dCDN to deliver content using HTTP/1.1:
{
"action": "allow",
"protocols": ["http/1.1"]
}
4.2.5. DeliveryAuthorization Metadata
Delivery Authorization defines authorization methods for the delivery
of content to User Agents.
Niven-Jenkins, et al. Expires November 21, 2016 [Page 32]
Internet-Draft CDN Interconnection Metadata May 2016
Property: delivery-auth-methods
Description: Options for authorizing content requests.
Delivery for a content request is authorized if any of the
authorization methods in the list is satisfied for that
request.
Type: List of Auth objects (see Section 4.2.7)
Mandatory-to-Specify: No. Default is no authorization
required.
Example DeliveryAuthorization object (which contains an Auth object):
{
"generic-metadata-type": "MI.DeliveryAuthorization",
"generic-metadata-value":
{
"delivery-auth-methods": [
{
"auth-type": <CDNI Payload Type of this Auth object>,
"auth-value":
{
<Properties of this Auth object>
}
}
]
}
}
4.2.6. Cache
A Cache object describes the cache control parameters to be applied
to the content by intermediate caches.
Property: ignore-query-string
Description: Allows a Surrogate to ignore URI query string
parameters when comparing the requested URI against the URIs in
its cache for equivalence. Matching query parameters to ignore
MUST be case-insensitive. Each query parameter to ignore is
specified in the list. If all query parameters should be
ignored, then the list MUST be specified and MUST be empty.
Type: List of String
Mandatory-to-Specify: No. Default is to consider query string
parameters when comparing URIs.
Niven-Jenkins, et al. Expires November 21, 2016 [Page 33]
Internet-Draft CDN Interconnection Metadata May 2016
Example Cache object that instructs the dCDN to ignore all query
parameters:
{
"generic-metadata-type": "MI.Cache",
"generic-metadata-value":
{
"ignore-query-string": []
}
}
Example Cache object that instructs the dCDN to ignore the (case-
insensitive) query parameters named "sessionid" and "random":
{
"generic-metadata-type": "MI.Cache",
"generic-metadata-value":
{
"ignore-query-string": ["sessionid", "random"]
}
}
4.2.7. Auth
An Auth object defines authentication and authorization methods to be
used during content acquisition and content delivery, respectively.
Property: auth-type
Description: Registered Auth type (Section 7.4).
Type: String
Mandatory-to-Specify: Yes.
Property: auth-value
Description: An object conforming to the specification
associated with the Registered Auth type.
Type: GenericMetadata Object
Mandatory-to-Specify: Yes.
Example Auth object:
Niven-Jenkins, et al. Expires November 21, 2016 [Page 34]
Internet-Draft CDN Interconnection Metadata May 2016
{
"generic-metadata-type": "MI.Auth",
"generic-metadata-value":
{
"auth-type": <CDNI Payload Type of this Auth object>,
"auth-value":
{
<Properties of this Auth object>
}
}
}
4.2.8. Grouping
A Grouping object identifies a group of content to which a given
asset belongs.
Property: ccid
Description: Content Collection identifier for an application-
specific purpose such as logging aggregation.
Type: String
Mandatory-to-Specify: No. Default is an empty string.
Example Grouping object that specifies a Content Collection
Identifier for the content associated with the Grouping object's
parent HostMetdata and PathMetadata:
{
"generic-metadata-type": "MI.Grouping",
"generic-metadata-value":
{
"ccid": "ABCD"
}
}
4.3. CDNI Metadata Simple Data Type Descriptions
This section describes the simple data types that are used for
properties of CDNI metadata objects.
4.3.1. Link
A Link object can be used in place of any of the objects or
properties described above. Link objects can be used to avoid
duplication if the same metadata information is repeated within the
Niven-Jenkins, et al. Expires November 21, 2016 [Page 35]
Internet-Draft CDN Interconnection Metadata May 2016
metadata tree. When a Link object replaces another object, its href
property is set to the URI of the resource and its type property is
set to the CDNI Payload Type of the object it is replacing.
dCDNs can detect the presence of a Link object by detecting the
presence of a property named "href" within the object. This means
that GenericMetadata types MUST NOT contain a property named "href"
because doing so would conflict with the ability for dCDNs to detect
Link objects being used to reference a GenericMetadata object.
Property: href
Description: The URI of the addressable object being
referenced.
Type: String
Mandatory-to-Specify: Yes.
Property: type
Description: The type of the object being referenced.
Type: String
Mandatory-to-Specify: No. If the container specifies the type
(e.g., the HostIndex object contains a list of HostMatch
objects, so a Link object in the list of HostMatch objects must
reference a HostMatch), then it is not necessary to explicitly
specify a type.
Example Link object referencing a HostMatch object:
{
"type": "MI.HostMatch",
"href": "http://metadata.ucdn.example/hostmatch1234"
}
Example Link object referencing a HostMatch object, without an
explicit type, inside a HostIndex object:
Niven-Jenkins, et al. Expires November 21, 2016 [Page 36]
Internet-Draft CDN Interconnection Metadata May 2016
{
"hosts": [
{
<Properties of embedded HostMatch object>
},
{
"href": "http://metadata.ucdn.example/hostmatch1234"
}
]
}
4.3.2. Protocol
Protocol objects are used to specify registered protocols for content
acquisition or delivery (see Section 7.3).
Type: String
Example:
"http/1.1"
4.3.3. Endpoint
A Hostname (with optional port) or an IP address (with optional
port).
Note: All implementations MUST support IPv4 addresses encoded as
specified by the 'IPv4address' rule in Section 3.2.2 of [RFC3986].
IPv6 addresses MUST be encoded in one of the IPv6 address formats
specified in [RFC5952] although receivers MUST support all IPv6
address formats specified in [RFC4291].
Type: String
Example Hostname:
"metadata.ucdn.example"
Example IPv4 address:
"192.0.2.1"
Example IPv6 address (with port number):
"[2001:db8::1]:81"
Niven-Jenkins, et al. Expires November 21, 2016 [Page 37]
Internet-Draft CDN Interconnection Metadata May 2016
4.3.4. Time
A time value expressed in seconds since the Unix epoch in the UTC
timezone.
Type: Integer
Example Time representing 09:00 01/01/2000 UTC:
946717200
4.3.5. IPv4CIDR
An IPv4address CIDR block encoded as specified by the 'IPv4address'
rule in Section 3.2.2 of [RFC3986] followed by a / followed by an
unsigned integer representing the leading bits of the routing prefix
(i.e., IPv4 CIDR notation). Single IP addresses can be expressed as
/32.
Type: String
Example IPv4 CIDR:
"192.0.2.0/24"
4.3.6. IPv6CIDR
An IPv6address CIDR block encoded in one of the IPv6 address formats
specified in [RFC5952] followed by a / followed by an unsigned
integer representing the leading bits of the routing prefix (i.e.,
IPv6 CIDR notation). Single IP addresses can be expressed as /128.
Type: String
Example IPv6 CIDR:
"2001:db8::/32"
4.3.7. ASN
An Autonomous System Number encoded as a string consisting of the
characters "as" (in lowercase) followed by the Autonomous System
number.
Type: String
Example ASN:
Niven-Jenkins, et al. Expires November 21, 2016 [Page 38]
Internet-Draft CDN Interconnection Metadata May 2016
"as64496"
4.3.8. CountryCode
An ISO 3166-1 alpha-2 code [ISO3166-1] in lowercase.
Type: String
Example Country Code representing the USA:
"us"
5. CDNI Metadata Capabilities
CDNI metadata is used to convey information pertaining to content
delivery from uCDN to dCDN. For optional metadata, it can be useful
for the uCDN to know if the dCDN supports the underlying
functionality described by the metadata, prior to delegating any
content requests to the dCDN. If some metadata is "mandatory-to-
enforce", and the dCDN does not support it, any delegated requests
for content that requires that metadata will fail. The uCDN will
likely want to avoid delegating those requests to that dCDN.
Likewise, for any metadata which might be assigned optional values,
it could be useful for the uCDN to know which values a dCDN supports,
prior to delegating any content requests to that dCDN. If the
optional value assigned to a given piece of content's metadata is not
supported by the dCDN, any delegated requests for that content can
fail, so again the uCDN is likely to want to avoid delegating those
requests to that dCDN.
The CDNI Footprint and Capabilities Interface (FCI) provides a means
of advertising capabilities from dCDN to uCDN [RFC7336]. Support for
optional metadata types and values can be advertised using the FCI.
6. CDNI Metadata interface
This section specifies an interface to enable a dCDN to retrieve CDNI
metadata objects from a uCDN.
The interface can be used by a dCDN to retrieve CDNI metadata objects
either:
o Dynamically as required by the dCDN to process received requests.
For example in response to a query from an uCDN over the CDNI
Request Routing Redirection interface (RI)
[I-D.ietf-cdni-redirection] or in response to receiving a request
for content from a User Agent. Or;
Niven-Jenkins, et al. Expires November 21, 2016 [Page 39]
Internet-Draft CDN Interconnection Metadata May 2016
o In advance of being required. For example in the case of pre-
positioned CDNI metadata acquisition, initiated through the "CDNI
Control interface / Triggers" (CI/T) interface
[I-D.ietf-cdni-control-triggers].
The CDNI metadata interface is built on the principles of HTTP web
services. In particular, this means that requests and responses over
the interface are built around the transfer of representations of
hyperlinked resources. A resource in the context of the CDNI
metadata interface is any object in the object model (as described in
Section 3 and Section 4).
To retrieve CDNI metadata, a CDNI metadata client (i.e., a client in
the dCDN) first makes a HTTP GET request for the URI of the HostIndex
which provides the CDNI metadata client with a list of Hostnames for
which the uCDN can delegate content delivery to the dCDN. The CDNI
metadata client can then obtain any other CDNI metadata objects by
making a HTTP GET requests for any linked metadata objects it
requires.
CDNI metadata servers (i.e., servers in the uCDN) are free to assign
whatever structure they desire to the URIs for CDNI metadata objects
and CDNI metadata clients MUST NOT make any assumptions regarding the
structure of CDNI metadata URIs or the mapping between CDNI metadata
objects and their associated URIs. Therefore any URIs present in the
examples in this document are purely illustrative and are not
intended to impose a definitive structure on CDNI metadata interface
implementations.
6.1. Transport
The CDNI metadata interface uses HTTP as the underlying protocol
transport.
The HTTP Method in the request defines the operation the request
would like to perform. A server implementation of the CDNI metadata
interface MUST support the HTTP GET and HEAD methods.
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 that
contain a response body SHOULD include an ETag to enable validation
of cached versions of returned resources.
The CDNI metadata interface specified in this document is a read-only
interface. Therefore support for other HTTP methods such as PUT,
POST, DELETE, etc. is not specified. A server implementation of the
Niven-Jenkins, et al. Expires November 21, 2016 [Page 40]
Internet-Draft CDN Interconnection Metadata May 2016
CDNI metadata interface SHOULD reject all methods other than GET and
HEAD.
As the CDNI metadata interface builds on top of HTTP, CDNI metadata
server implementations MAY make use of any HTTP feature when
implementing the CDNI metadata interface, for example, a CDNI
metadata server MAY make use of HTTP's caching mechanisms to indicate
that the returned response/representation can be reused without re-
contacting the CDNI metadata server.
6.2. Retrieval of CDNI Metadata resources
In the general case, a CDNI metadata server makes CDNI metadata
objects available via a unique URIs and thus, in order to retrieve
CDNI metadata, a CDNI metadata client first makes a HTTP GET request
for the URI of the HostIndex which provides a list of Hostnames for
which the uCDN can delegate content delivery to the dCDN.
In order to retrieve the CDNI metadata for a particular request the
CDNI metadata client processes the received HostIndex object and
finds the corresponding HostMetadata entry (by matching the hostname
in the request against the hostnames listed in the HostMatch
objects). If the HostMetadata is linked (rather than embedded), the
CDNI metadata client then makes a GET request for the URI specified
in the href property of the Link object which points to the
HostMetadata object itself.
In order to retrieve the most specific metadata for a particular
request, the CDNI metadata client inspects the HostMetadata for
references to more specific PathMetadata objects (by matching the URI
path in the request against the path-patterns in any PathMatch
objects listed in the HostMetadata object). If any PathMetadata are
found to match (and are linked rather than embedded), the CDNI
metadata client makes another GET request for the PathMetadata. Each
PathMetadata object can also include references to yet more specific
metadata. If this is the case, the CDNI metadata client continues
requesting PathMatch and PathMetadata objects recursively. The CDNI
metadata client repeats this approach of processing metadata objects
and retrieving (via HTTP GETs) any linked objects until it has all
the metadata objects it requires in order to process the redirection
request from an uCDN or the content request from a User Agent.
In cases where a dCDN is not able to retrieve the entire set of CDNI
metadata associated with a User Agent request, for example because
the uCDN is unreachable or returns a HTTP 4xx or 5xx status in
response to some or all of the dCDN's CDNI metadata requests, the
dCDN MUST NOT serve the requested content unless the dCDN has stale
versions of all the required metadata and the stale-if-error Cache-
Niven-Jenkins, et al. Expires November 21, 2016 [Page 41]
Internet-Draft CDN Interconnection Metadata May 2016
Control extension [RFC5861] was included in all previous responses
that are required but cannot currently be retrieved. The dCDN can
continue to serve other content for which it can retrieve (or for
which it has fresh responses cached) all the required metadata even
if some non-applicable part of the metadata tree is missing.
Where a dCDN is interconnected with multiple uCDNs, the dCDN needs to
determine which uCDN's CDNI metadata should be used to handle a
particular User Agent request.
When application level redirection (e.g., HTTP 302 redirects) is
being used between CDNs, it is expected that the dCDN will be able to
determine the uCDN that redirected a particular request from
information contained in the received request (e.g., via the URI).
With knowledge of which uCDN routed the request, the dCDN can choose
the correct uCDN from which to obtain the HostIndex. Note that the
HostIndexes served by each uCDN can be unique.
In the case of DNS redirection there is not always sufficient
information carried in the DNS request from User Agents to determine
the uCDN that redirected a particular request (e.g., when content
from a given host is redirected to a given dCDN by more than one
uCDN) and therefore dCDNs will have to apply local policy when
deciding which uCDN's metadata to apply.
6.3. Bootstrapping
The URI for the HostIndex object of a given uCDN needs to be either
configured in, or discovered by, the dCDN. All other objects/
resources are then discoverable from the HostIndex object by
following any links in the HostIndex object and through the
referenced HostMetadata and PathMetadata objects and their
GenericMetadata sub-objects.
If the URI for the HostIndex object is not manually configured in the
dCDN then the HostIndex URI could be discovered. A mechanism
allowing the dCDN to discover the URI of the HostIndex is outside the
scope of this document.
6.4. Encoding
CDNI metadata objects MUST be encoded as I-JSON objects [RFC7493]
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 CDNI Payload Type of the
Niven-Jenkins, et al. Expires November 21, 2016 [Page 42]
Internet-Draft CDN Interconnection Metadata May 2016
returned resource). Likewise, the values associated with each
property (dictionary key) are dependent on the specific object being
encoded (i.e., dependent on the CDNI Payload Type of the returned
resource).
Dictionary keys (properties) in I-JSON are case sensitive. By
convention, any dictionary key (property) defined by this document
(for example, the names of CDNI metadata object properties) MUST be
lowercase.
6.5. Extensibility
The set of GenericMetadata objects can be extended with additional
(standards based or vendor specific) metadata objects through the
specification of new GenericMetadata objects. The GenericMetadata
object defined in Section 4.1.7 specifies a type field and a type-
specific value field that allows any metadata to be included in
either the HostMetadata or PathMetadata lists.
As with the initial GenericMetadata types defined in Section 4.2,
future GenericMetadata types MUST specify the information necessary
for constructing and decoding the GenericMetadata object.
Any document which defines a new GenericMetadata type MUST:
1. Specify and register the CDNI Payload Type [RFC7736] used to
identify the new GenericMetadata type being specified.
2. Define the set of properties associated with the new
GenericMetadata object. GenericMetadata MUST NOT contain a
property named "href" because doing so would conflict with the
ability to detect Link objects (see Section 4.3.1).
3. Define a name, description, type, and whether or not the property
is mandatory-to-specify.
4. Describe the semantics of the new type including its purpose and
example of a use case to which it applies including an example
encoded in I-JSON.
Note: In the case of vendor specific extensions, vendor-identifying
CDNI Payload Type names will decrease the possibility of
GenericMetadata type collisions.
Niven-Jenkins, et al. Expires November 21, 2016 [Page 43]
Internet-Draft CDN Interconnection Metadata May 2016
6.6. Metadata Enforcement
At any given time, the set of GenericMetadata types supported by the
uCDN might not match the set of GenericMetadata types supported by
the dCDN.
In cases where a uCDN sends metadata containing a GenericMetadata
type that a dCDN does not support, the dCDN MUST enforce the
semantics of the "mandatory-to-enforce" property. If a dCDN does not
understand or is unable to perform the functions associated with any
"mandatory-to-enforce" metadata, the dCDN MUST NOT service any
requests for the corresponding content.
Note: Ideally, uCDNs would not delegate content requests to a dCDN
that does not support the "mandatory-to-enforce" metadata associated
with the content being requested. However, even if the uCDN has a
priori knowledge of the metadata supported by the dCDN (e.g., via the
FCI or through out-of-band negotiation between CDN operators),
metadata support can fluctuate or be inconsistent (e.g., due to mis-
communication, mis-configuration, or temporary outage). Thus, the
dCDN MUST always evaluate all metadata associated with redirection
and content requests and reject any requests where "mandatory-to-
enforce" metadata associated with the content cannot be enforced.
6.7. Metadata Conflicts
It is possible that new metadata definitions will obsolete or
conflict with existing GenericMetadata (e.g., a future revision of
the CDNI metadata interface could redefine the Auth GenericMetadata
object or a custom vendor extension could implement an alternate Auth
metadata option). If multiple metadata (e.g., MI.Auth.v2,
vendor1.Auth, and vendor2.Auth) all conflict with an existing
GenericMetadata object (i.e., MI.Auth) and all are marked as
"mandatory-to-enforce", it could be ambiguous which metadata should
be applied, especially if the functionality of the metadata overlap.
As described in Section 3.3, metadata override only applies to
metadata objects of the same exact type found in HostMetadata and
nested PathMetadata structures. The CDNI metadata interface does not
support enforcement of dependencies between different metadata types.
It is the responsibility of the CSP and the CDN operators to ensure
that metadata assigned to a given piece of content do not conflict.
Note: Because metadata is inherently ordered in HostMetadata and
PathMetadata lists, as well as in the PathMatch hierarchy, multiple
conflicting metadata types MAY be used, however, metadata hierarchies
SHOULD ensure that independent PathMatch root objects are used to
prevent ambiguous or conflicting metadata definitions.
Niven-Jenkins, et al. Expires November 21, 2016 [Page 44]
Internet-Draft CDN Interconnection Metadata May 2016
6.8. Versioning
The version of CDNI metadata objects is conveyed inside the CDNI
Payload Type that is included in the HTTP Content-Type header, for
example: "Content-Type: application/cdni; ptype=MI.HostIndex". We
intentionally omit the ".v1" on the initial versions of metadata, for
simplicity. Subsequent versions of those metadata MUST postpend a
version string (e.g., ".v2"). Upon responding to a request for an
object, a CDNI metadata server MUST include a Content-Type header
with the CDNI Payload Type containing the version number (or
implicitly, version 1) of the object. HTTP requests sent to a
metadata server SHOULD include an Accept header with the CDNI Payload
Type (which includes the version) of the expected object. Metadata
clients can specify multiple CDNI Payload Types in the Accept header,
for example if a metadata client is capable of processing two
different versions of the same type of object (defined by different
CDNI Payload Types) it might decide to include both in the Accept
header.
6.9. Media Types
All CDNI metadata objects use the Media Type "application/cdni". The
CDNI Payload Type for each object then contains the object name of
that object as defined by this document, prefixed with "MI.".
Table 4 lists the CDNI Paylod Type for the metadata objects
(resources) specified in this document.
Niven-Jenkins, et al. Expires November 21, 2016 [Page 45]
Internet-Draft CDN Interconnection Metadata May 2016
+-----------------------+--------------------------+
| Data Object | CDNI Payload Type |
+-----------------------+--------------------------+
| HostIndex | MI.HostIndex |
| HostMatch | MI.HostMatch |
| HostMetadata | MI.HostMetadata |
| PathMatch | MI.PathMatch |
| PatternMatch | MI.PatternMatch |
| PathMetadata | MI.PathMetadata |
| SourceMetadata | MI.SourceMetadata |
| Source | MI.Source |
| LocationACL | MI.LocationACL |
| LocationRule | MI.LocationRule |
| Footprint | MI.Footprint |
| TimeWindowACL | MI.TimeWindowACL |
| TimeWindowRule | MI.TimeWindowRule |
| TimeWindow | MI.TineWindow |
| ProtocolACL | MI.ProtocolACL |
| ProtocolRule | MI.ProtocolRule |
| DeliveryAuthorization | MI.DeliveryAuthorization |
| Cache | MI.Cache |
| Auth | MI.Auth |
| Grouping | MI.Grouping |
+-----------------------+--------------------------+
Table 4: CDNI Payload Types for CDNI Metadata objects
6.10. Complete CDNI Metadata Example
A dCDN requests the HostIndex and receive the following object with a
CDNI payload type of "MI.HostIndex":
Niven-Jenkins, et al. Expires November 21, 2016 [Page 46]
Internet-Draft CDN Interconnection Metadata May 2016
{
"hosts": [
{
"host": "video.example.com",
"host-metadata" : {
"type": "MI.HostMetadata",
"href": "http://metadata.ucdn.example/host1234"
}
},
{
"host": "images.example.com",
"host-metadata" : {
"type": "MI.HostMetadata",
"href": "http://metadata.ucdn.example/host5678"
}
}
]
}
If the incoming request has a Host header with "video.example.com"
then the dCDN would fetch the HostMetadata object from
"http://metadata.ucdn.example/host1234" expecting a CDNI payload type
of "MI.HostMetadata":
{
"metadata": [
{
"generic-metadata-type": "MI.SourceMetadata",
"generic-metadata-value": {
"sources": [
{
"endpoint": "acq1.ucdn.example",
"protocol": "http/1.1"
},
{
"endpoint": "acq2.ucdn.example",
"protocol": "http/1.1"
}
]
}
},
{
"generic-metadata-type": "MI.LocationACL",
"generic-metadata-value": {
"locations": [
{
"footprints": [
{
Niven-Jenkins, et al. Expires November 21, 2016 [Page 47]
Internet-Draft CDN Interconnection Metadata May 2016
"footprint-type": "IPv4CIDR",
"footprint-value": "192.0.2.0/24"
}
],
"action": "deny"
}
]
}
},
{
"generic-metadata-type": "MI.ProtocolACL",
"generic-metadata-value": {
"protocol-acl": [
{
"protocols": [
"http/1.1"
],
"action": "allow"
}
]
}
}
],
"paths": [
{
"path-pattern": {
"pattern": "/video/trailers/*"
},
"path-metadata": {
"type": "MI.PathMetadata",
"href": "http://metadata.ucdn.example/host1234/pathABC"
}
},
{
"path-pattern": {
"pattern": "/video/movies/*"
},
"path-metadata": {
"type": "MI.PathMetadata",
"href": "http://metadata.ucdn.example/host1234/pathDEF"
}
}
]
}
Suppose the path of the requested resource matches the "/video/
movies/*" pattern, the next metadata requested would be for
Niven-Jenkins, et al. Expires November 21, 2016 [Page 48]
Internet-Draft CDN Interconnection Metadata May 2016
"http://metadata.ucdn.example/host1234/pathDCE" with an expected CDNI
payload type of "MI.PathMetadata":
{
"metadata": [],
"paths": [
{
"path-pattern": {
"pattern": "/videos/movies/hd/*"
},
"path-metadata": {
"type": "MI.PathMetadata",
"href":
"http://metadata.ucdn.example/host1234/pathDEF/path123"
}
}
]
}
Finally, if the path of the requested resource also matches the
"/videos/movies/hd/*" pattern, the dCDN would also fetch the
following object from "http://metadata.ucdn.example/host1234/pathDEF/
path123" with CDNI payload type "MI.PathMetadata":
{
"metadata": [
{
"generic-metadata-type": "MI.TimeWindowACL",
"generic-metadata-value": {
"times": [
"windows": [
{
"start": "1213948800",
"end": "1327393200"
}
],
"action": "allow"
]
}
}
]
}
The final set of metadata which applies to the requested resource
includes a SourceMetadata, a LocationACL, a ProtocolACL, and a
TimeWindowACL.
Niven-Jenkins, et al. Expires November 21, 2016 [Page 49]
Internet-Draft CDN Interconnection Metadata May 2016
7. IANA Considerations
7.1. CDNI Payload Types
This document requests the registration of the following CDNI Payload
Types under the IANA CDNI Payload Type registry:
+--------------------------+---------------+
| Payload Type | Specification |
+--------------------------+---------------+
| MI.HostIndex | RFCthis |
| MI.HostMatch | RFCthis |
| MI.HostMetadata | RFCthis |
| MI.PathMatch | RFCthis |
| MI.PatternMatch | RFCthis |
| MI.PathMetadata | RFCthis |
| MI.SourceMetadata | RFCthis |
| MI.Source | RFCthis |
| MI.LocationACL | RFCthis |
| MI.LocationRule | RFCthis |
| MI.Footprint | RFCthis |
| MI.TimeWindowACL | RFCthis |
| MI.TimeWindowRule | RFCthis |
| MI.TimeWindow | RFCthis |
| MI.ProtocolACL | RFCthis |
| MI.ProtocolRule | RFCthis |
| MI.DeliveryAuthorization | RFCthis |
| MI.Cache | RFCthis |
| MI.Auth | RFCthis |
| MI.Grouping | RFCthis |
+--------------------------+---------------+
[RFC Editor: Please replace RFCthis with the published RFC number for
this document.]
7.1.1. CDNI MI HostIndex Payload Type
Purpose: The purpose of this payload type is to distinguish HostIndex
MI objects (and any associated capabilitiy advertisement)
Interface: MI/FCI
Encoding: see Section 4.1.1
Niven-Jenkins, et al. Expires November 21, 2016 [Page 50]
Internet-Draft CDN Interconnection Metadata May 2016
7.1.2. CDNI MI HostMatch Payload Type
Purpose: The purpose of this payload type is to distinguish HostMatch
MI objects (and any associated capabilitiy advertisement)
Interface: MI/FCI
Encoding: see Section 4.1.2
7.1.3. CDNI MI HostMetadata Payload Type
Purpose: The purpose of this payload type is to distinguish
HostMetadata MI objects (and any associated capabilitiy
advertisement)
Interface: MI/FCI
Encoding: see Section 4.1.3
7.1.4. CDNI MI PathMatch Payload Type
Purpose: The purpose of this payload type is to distinguish PathMatch
MI objects (and any associated capabilitiy advertisement)
Interface: MI/FCI
Encoding: see Section 4.1.4
7.1.5. CDNI MI PatternMatch Payload Type
Purpose: The purpose of this payload type is to distinguish
PatternMatch MI objects (and any associated capabilitiy
advertisement)
Interface: MI/FCI
Encoding: see Section 4.1.5
7.1.6. CDNI MI PathMetadata Payload Type
Purpose: The purpose of this payload type is to distinguish
PathMetadata MI objects (and any associated capabilitiy
advertisement)
Interface: MI/FCI
Encoding: see Section 4.1.6
Niven-Jenkins, et al. Expires November 21, 2016 [Page 51]
Internet-Draft CDN Interconnection Metadata May 2016
7.1.7. CDNI MI SourceMetadata Payload Type
Purpose: The purpose of this payload type is to distinguish
SourceMetadata MI objects (and any associated capabilitiy
advertisement)
Interface: MI/FCI
Encoding: see Section 4.2.1
7.1.8. CDNI MI Source Payload Type
Purpose: The purpose of this payload type is to distinguish Source MI
objects (and any associated capabilitiy advertisement)
Interface: MI/FCI
Encoding: see Section 4.2.1.1
7.1.9. CDNI MI LocationACL Payload Type
Purpose: The purpose of this payload type is to distinguish
LocationACL MI objects (and any associated capabilitiy advertisement)
Interface: MI/FCI
Encoding: see Section 4.2.2
7.1.10. CDNI MI LocationRule Payload Type
Purpose: The purpose of this payload type is to distinguish
LocationRule MI objects (and any associated capabilitiy
advertisement)
Interface: MI/FCI
Encoding: see Section 4.2.2.1
7.1.11. CDNI MI Footprint Payload Type
Purpose: The purpose of this payload type is to distinguish Footprint
MI objects (and any associated capabilitiy advertisement)
Interface: MI/FCI
Encoding: see Section 4.2.2.2
Niven-Jenkins, et al. Expires November 21, 2016 [Page 52]
Internet-Draft CDN Interconnection Metadata May 2016
7.1.12. CDNI MI TimeWindowACL Payload Type
Purpose: The purpose of this payload type is to distinguish
TimeWindowACL MI objects (and any associated capabilitiy
advertisement)
Interface: MI/FCI
Encoding: see Section 4.2.3
7.1.13. CDNI MI TimeWindowRule Payload Type
Purpose: The purpose of this payload type is to distinguish
TimeWindowRule MI objects (and any associated capabilitiy
advertisement)
Interface: MI/FCI
Encoding: see Section 4.2.3.1
7.1.14. CDNI MI TimeWindow Payload Type
Purpose: The purpose of this payload type is to distinguish
TimeWindow MI objects (and any associated capabilitiy advertisement)
Interface: MI/FCI
Encoding: see Section 4.2.3.2
7.1.15. CDNI MI ProtocolACL Payload Type
Purpose: The purpose of this payload type is to distinguish
ProtocolACL MI objects (and any associated capabilitiy advertisement)
Interface: MI/FCI
Encoding: see Section 4.2.4
7.1.16. CDNI MI ProtocolRule Payload Type
Purpose: The purpose of this payload type is to distinguish
ProtocolRule MI objects (and any associated capabilitiy
advertisement)
Interface: MI/FCI
Encoding: see Section 4.2.4.1
Niven-Jenkins, et al. Expires November 21, 2016 [Page 53]
Internet-Draft CDN Interconnection Metadata May 2016
7.1.17. CDNI MI DeliveryAuthorization Payload Type
Purpose: The purpose of this payload type is to distinguish
DeliveryAuthorization MI objects (and any associated capabilitiy
advertisement)
Interface: MI/FCI
Encoding: see Section 4.2.5
7.1.18. CDNI MI Cache Payload Type
Purpose: The purpose of this payload type is to distinguish Cache MI
objects (and any associated capabilitiy advertisement)
Interface: MI/FCI
Encoding: see Section 4.2.6
7.1.19. CDNI MI Auth Payload Type
Purpose: The purpose of this payload type is to distinguish Auth MI
objects (and any associated capabilitiy advertisement)
Interface: MI/FCI
Encoding: see Section 4.2.7
7.1.20. CDNI MI Grouping Payload Type
Purpose: The purpose of this payload type is to distinguish Grouping
MI objects (and any associated capabilitiy advertisement)
Interface: MI/FCI
Encoding: see Section 4.2.8
7.2. CDNI Metadata Footprint Types Registry
The IANA is requested to create a new "CDNI Metadata Footprint Types"
subregistry in the "Content Delivery Networks Interconnection (CDNI)
Parameters" registry. The "CDNI Metadata Footprint Types" namespace
defines the valid Footprint object type values used by the Footprint
object in Section 4.2.2.2. Additions to the Footprint type namespace
conform to the "Specification Required" policy as defined in
[RFC5226]. The designated expert will verify that new type
definitions do not duplicate existing type definitions and prevent
gratuitous additions to the namespace. New registrations are
Niven-Jenkins, et al. Expires November 21, 2016 [Page 54]
Internet-Draft CDN Interconnection Metadata May 2016
required to provide a clear description of how to interpret new
footprint types.
The following table defines the initial Footprint Registry values:
+----------------+-------------------------------+---------------+
| Footprint Type | Description | Specification |
+----------------+-------------------------------+---------------+
| ipv4cidr | IPv4 CIDR address block | RFCthis |
| ipv6cidr | IPv6 CIDR address block | RFCthis |
| asn | Autonomous System (AS) Number | RFCthis |
| countrycode | ISO 3166-1 alpha-2 code | RFCthis |
+----------------+-------------------------------+---------------+
[RFC Editor: Please replace RFCthis with the published RFC number for
this document.]
7.3. CDNI Metadata Protocol Types Registry
The IANA is requested to create a new "CDNI Metadata Protocol Types"
subregistry in the "Content Delivery Networks Interconnection (CDNI)
Parameters" registry. The "CDNI Metadata Protocol Types" namespace
defines the valid Protocol object values in Section 4.3.2, used by
the SourceMetadata and ProtocolACL objects. Additions to the
Protocol namespace conform to the "Specification Required" policy as
defined in [RFC5226], where the specification defines the Protocol
Type and the protocol to which it is associated. The designated
expert will verify that new protocol definitions do not duplicate
existing protocol definitions and prevent gratuitous additions to the
namespace.
The following table defines the initial Protocol values corresponding
to the HTTP and HTTPS protocols:
+-----------+----------------------+---------------+----------------+
| Protocol | Description | Type | Protocol |
| Type | | Specification | Specification |
+-----------+----------------------+---------------+----------------+
| http/1.1 | Hypertext Transfer | RFCthis | RFC7230 |
| | Protocol -- HTTP/1.1 | | |
| https/1.1 | HTTP/1.1 Over TLS | RFCthis | RFC2818 |
+-----------+----------------------+---------------+----------------+
[RFC Editor: Please replace RFCthis with the published RFC number for
this document.]
Niven-Jenkins, et al. Expires November 21, 2016 [Page 55]
Internet-Draft CDN Interconnection Metadata May 2016
7.4. CDNI Metadata Auth Types Registry
The IANA is requested to create a new "CDNI Metadata Auth Types"
subregistry in the "Content Delivery Networks Interconnection (CDNI)
Parameters" registry. The "CDNI Metadata Auth Type" namespace
defines the valid Auth object types used by the Auth object in
Section 4.2.7. Additions to the Auth Type namespace conform to the
"Specification Required" policy as defined in [RFC5226]. The
designated expert will verify that new type definitions do not
duplicate existing type definitions and prevent gratuitous additions
to the namespace. New registrations are required to provide a clear
description of what information the uCDN is required to provide to
the dCDN, as well as the procedures the dCDN is required to perform
to authorize and/or authenticate content requests.
The registry will initially be unpopulated:
+-----------+-------------+---------------+
| Auth Type | Description | Specification |
+-----------+-------------+---------------+
+-----------+-------------+---------------+
8. Security Considerations
8.1. Authentication
Unauthorized access to metadata could result in denial of service. A
malicious metadata server, proxy server, or an attacker performing a
"man in the middle" attack could provide malicious metadata to a dCDN
that either:
o Denies service for one or more pieces of content to one or more
User Agents; or
o Directs dCDNs to contact malicious origin servers instead of the
actual origin servers.
Unauthorized access to metadata could also enable a malicious
metadata client to continuously issue metadata requests in order to
overload a uCDN's metadata server(s).
Unauthorized access to metadata could result in leakage of private
information. A malicious metadata client could request metadata in
order to gain access to origin servers, as well as information
pertaining to content restrictions.
An implementation of the CDNI metadata interface SHOULD use mutual
authentication to prevent unauthorized access to metadata.
Niven-Jenkins, et al. Expires November 21, 2016 [Page 56]
Internet-Draft CDN Interconnection Metadata May 2016
8.2. Confidentiality
Unauthorized viewing of metadata could result in leakage of private
information. A third party could intercept metadata transactions in
order to gain access to origin servers, as well as information
pertaining to content restrictions.
An implementation of the CDNI metadata interface SHOULD use strong
encryption to prevent unauthorized interception of metadata.
8.3. Integrity
Unauthorized modification of metadata could result in denial of
service. A malicious metadata server, proxy server, or an attacker
performing a "man in the middle" attack could modify metadata
destined to a dCDN in order to deny service for one or more pieces of
content to one or more user agents. A malicious metadata server,
proxy server, or an attacker performing a "Man in the middle" attack
could also modify metadata so that dCDNs are directed to contact to
malicious origin servers instead of the actual origin servers.
An implementation of the CDNI metadata interface SHOULD use strong
encryption and mutual authentication to prevent unauthorized
modification of metadata.
8.4. Privacy
Content provider origin and policy information is conveyed through
the CDNI metadata interface. The distribution of this information to
another CDN could introduce potential privacy concerns for some
content providers, for example, dCDNs accepting content requests for
a content provider's content might be able to obtain additional
information and usage patterns relating to the users of a content
provider's services. Content providers with such concerns can
instruct their CDN partners not to use CDN interconnects when
delivering that content provider's content.
An attacker performing a "man in the middle" attack could monitor
metadata in order to obtain usage patterns relating to the users of a
content provider's services.
An implementation of the CDNI metadata interface SHOULD use strong
encryption and mutual authentication to prevent unauthorized
monitoring of metadata.
Niven-Jenkins, et al. Expires November 21, 2016 [Page 57]
Internet-Draft CDN Interconnection Metadata May 2016
8.5. Securing the CDNI Metadata interface
An implementation of the CDNI metadata interface MUST support TLS
transport as per [RFC2818] and [RFC7230]. The use of TLS for
transport of the CDNI metadata interface messages allows:
o The dCDN and uCDN to authenticate each other.
and, once they have mutually authenticated each other, it allows:
o The dCDN and uCDN to authorize each other (to ensure they are
transmitting/receiving CDNI metadata requests and responses from
an authorized CDN);
o CDNI metadata interface requests and responses to be transmitted
with confidentiality; and
o The integrity of the CDNI metadata interface requests and
responses to be protected during the exchange.
In an environment where any such protection is required, TLS MUST be
used (including authentication of the remote end) by the server-side
(uCDN) and the client-side (dCDN) of the CDNI metadata interface
unless alternate methods are used for ensuring the confidentiality of
the information in the CDNI metadata interface requests and responses
(such as setting up an IPsec tunnel between the two CDNs or using a
physically secured internal network between two CDNs that are owned
by the same corporate entity).
When TLS is used, the general TLS usage guidance in [RFC7525] MUST be
followed.
9. Acknowledgements
The authors would like to thank David Ferguson, Francois Le Faucheur,
Jan Seedorf and Matt Miller for their valuable comments and input to
this document.
10. Contributing Authors
[RFC Editor Note: Please move the contents of this section to the
Authors' Addresses section prior to publication as an RFC.]
Niven-Jenkins, et al. Expires November 21, 2016 [Page 58]
Internet-Draft CDN Interconnection Metadata May 2016
Grant Watson
Velocix (Alcatel-Lucent)
3 Ely Road
Milton, Cambridge CB24 6AA
UK
Email: gwatson@velocix.com
Kent Leung
Cisco Systems
3625 Cisco Way
San Jose, 95134
USA
Email: kleung@cisco.com
11. References
11.1. Normative References
[ISO3166-1]
"https://www.iso.org/obp/ui/#search".
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.
[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
Resource Identifier (URI): Generic Syntax", STD 66,
RFC 3986, DOI 10.17487/RFC3986, January 2005,
<http://www.rfc-editor.org/info/rfc3986>.
[RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing
Architecture", RFC 4291, DOI 10.17487/RFC4291, February
2006, <http://www.rfc-editor.org/info/rfc4291>.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226,
DOI 10.17487/RFC5226, May 2008,
<http://www.rfc-editor.org/info/rfc5226>.
[RFC5861] Nottingham, M., "HTTP Cache-Control Extensions for Stale
Content", RFC 5861, DOI 10.17487/RFC5861, May 2010,
<http://www.rfc-editor.org/info/rfc5861>.
Niven-Jenkins, et al. Expires November 21, 2016 [Page 59]
Internet-Draft CDN Interconnection Metadata May 2016
[RFC5952] Kawamura, S. and M. Kawashima, "A Recommendation for IPv6
Address Text Representation", RFC 5952,
DOI 10.17487/RFC5952, August 2010,
<http://www.rfc-editor.org/info/rfc5952>.
[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, <http://www.rfc-editor.org/info/rfc6707>.
[RFC7230] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
Protocol (HTTP/1.1): Message Syntax and Routing",
RFC 7230, DOI 10.17487/RFC7230, June 2014,
<http://www.rfc-editor.org/info/rfc7230>.
[RFC7493] Bray, T., Ed., "The I-JSON Message Format", RFC 7493,
DOI 10.17487/RFC7493, March 2015,
<http://www.rfc-editor.org/info/rfc7493>.
[RFC7525] Sheffer, Y., Holz, R., and P. Saint-Andre,
"Recommendations for Secure Use of Transport Layer
Security (TLS) and Datagram Transport Layer Security
(DTLS)", BCP 195, RFC 7525, DOI 10.17487/RFC7525, May
2015, <http://www.rfc-editor.org/info/rfc7525>.
11.2. Informative References
[I-D.ietf-cdni-control-triggers]
Murray, R. and B. Niven-Jenkins, "CDNI Control Interface /
Triggers", draft-ietf-cdni-control-triggers-15 (work in
progress), May 2016.
[I-D.ietf-cdni-redirection]
Niven-Jenkins, B. and R. Brandenburg, "Request Routing
Redirection interface for CDN Interconnection", draft-
ietf-cdni-redirection-18 (work in progress), April 2016.
[RFC2818] Rescorla, E., "HTTP Over TLS", RFC 2818,
DOI 10.17487/RFC2818, May 2000,
<http://www.rfc-editor.org/info/rfc2818>.
[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, <http://www.rfc-editor.org/info/rfc7336>.
Niven-Jenkins, et al. Expires November 21, 2016 [Page 60]
Internet-Draft CDN Interconnection Metadata May 2016
[RFC7337] Leung, K., Ed. and Y. Lee, Ed., "Content Distribution
Network Interconnection (CDNI) Requirements", RFC 7337,
DOI 10.17487/RFC7337, August 2014,
<http://www.rfc-editor.org/info/rfc7337>.
[RFC7540] Belshe, M., Peon, R., and M. Thomson, Ed., "Hypertext
Transfer Protocol Version 2 (HTTP/2)", RFC 7540,
DOI 10.17487/RFC7540, May 2015,
<http://www.rfc-editor.org/info/rfc7540>.
[RFC7736] Ma, K., "Content Delivery Network Interconnection (CDNI)
Media Type Registration", RFC 7736, DOI 10.17487/RFC7736,
December 2015, <http://www.rfc-editor.org/info/rfc7736>.
Authors' Addresses
Ben Niven-Jenkins
Velocix (Alcatel-Lucent)
3 Ely Road
Milton, Cambridge CB24 6AA
UK
Email: ben@velocix.com
Rob Murray
Velocix (Alcatel-Lucent)
3 Ely Road
Milton, Cambridge CB24 6AA
UK
Email: rmurray@velocix.com
Matt Caulfield
Cisco Systems
1414 Massachusetts Avenue
Boxborough, MA 01719
USA
Phone: +1 978 936 9307
Email: mcaulfie@cisco.com
Niven-Jenkins, et al. Expires November 21, 2016 [Page 61]
Internet-Draft CDN Interconnection Metadata May 2016
Kevin J. Ma
Ericsson
43 Nagog Park
Acton, MA 01720
USA
Phone: +1 978-844-5100
Email: kevin.j.ma@ericsson.com
Niven-Jenkins, et al. Expires November 21, 2016 [Page 62]
