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rfc:rfc8007

Internet Engineering Task Force (IETF) R. Murray Request for Comments: 8007 B. Niven-Jenkins Category: Standards Track Nokia ISSN: 2070-1721 December 2016

          Content Delivery Network Interconnection (CDNI)
                    Control Interface / Triggers

Abstract

 This document describes the part of the Content Delivery Network
 Interconnection (CDNI) Control interface that allows a CDN to trigger
 activity in an interconnected CDN that is configured to deliver
 content on its behalf.  The upstream CDN can use this mechanism to
 request that the downstream CDN pre-position metadata or content or
 to request that it invalidate or purge metadata or content.  The
 upstream CDN can monitor the status of activity that it has triggered
 in the downstream CDN.

Status of This Memo

 This is an Internet Standards Track document.
 This document is a product of the Internet Engineering Task Force
 (IETF).  It represents the consensus of the IETF community.  It has
 received public review and has been approved for publication by the
 Internet Engineering Steering Group (IESG).  Further information on
 Internet Standards is available in Section 2 of RFC 7841.
 Information about the current status of this document, any errata,
 and how to provide feedback on it may be obtained at
 http://www.rfc-editor.org/info/rfc8007.

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.

Murray & Niven-Jenkins Standards Track [Page 1] RFC 8007 CDN Interconnect Triggers December 2016

Table of Contents

 1. Introduction ....................................................3
    1.1. Terminology ................................................4
 2. Model for CDNI Triggers .........................................4
    2.1. Timing of Triggered Activity ...............................6
    2.2. Scope of Triggered Activity ................................7
         2.2.1. Multiple Interconnected CDNs ........................7
    2.3. Trigger Results ............................................8
 3. Collections of Trigger Status Resources .........................9
 4. CDNI Trigger Interface .........................................10
    4.1. Creating Triggers .........................................11
    4.2. Checking Status ...........................................12
         4.2.1. Polling Trigger Status Resource Collections ........12
         4.2.2. Polling Trigger Status Resources ...................13
    4.3. Canceling Triggers ........................................13
    4.4. Deleting Triggers .........................................14
    4.5. Expiry of Trigger Status Resources ........................14
    4.6. Loop Detection and Prevention .............................15
    4.7. Error Handling ............................................15
    4.8. Content URLs ..............................................16
 5. CI/T Object Properties and Encoding ............................17
    5.1. CI/T Objects ..............................................17
         5.1.1. CI/T Commands ......................................17
         5.1.2. Trigger Status Resources ...........................18
         5.1.3. Trigger Collections ................................20
    5.2. Properties of CI/T Objects ................................21
         5.2.1. Trigger Specification ..............................21
         5.2.2. Trigger Type .......................................23
         5.2.3. Trigger Status .....................................24
         5.2.4. PatternMatch .......................................24
         5.2.5. Absolute Time ......................................25
         5.2.6. Error Description ..................................26
         5.2.7. Error Code .........................................26
 6. Examples .......................................................27
    6.1. Creating Triggers .........................................28
         6.1.1. Preposition ........................................28
         6.1.2. Invalidate .........................................30
    6.2. Examining Trigger Status ..................................32
         6.2.1. Collection of All Triggers .........................32
         6.2.2. Filtered Collections of Trigger Status Resources ...33
         6.2.3. Individual Trigger Status Resources ................34
         6.2.4. Polling for Changes in Status ......................36
         6.2.5. Deleting Trigger Status Resources ..................38
         6.2.6. Error Reporting ....................................39

Murray & Niven-Jenkins Standards Track [Page 2] RFC 8007 CDN Interconnect Triggers December 2016

 7. IANA Considerations ............................................40
    7.1. CDNI Payload Type Parameter Registrations .................40
    7.2. "CDNI CI/T Trigger Types" Registry ........................41
    7.3. "CDNI CI/T Error Codes" Registry ..........................41
 8. Security Considerations ........................................41
    8.1. Authentication, Authorization, Confidentiality,
         Integrity Protection ......................................42
    8.2. Denial of Service .........................................43
    8.3. Privacy ...................................................44
 9. References .....................................................44
    9.1. Normative References ......................................44
    9.2. Informative References ....................................45
 Appendix A. Formalization of the JSON Data ........................47
 Acknowledgments ...................................................49
 Authors' Addresses ................................................49

1. Introduction

 [RFC6707] introduces the problem scope for Content Delivery Network
 Interconnection (CDNI) and lists the four categories of interfaces
 that may be used to compose a CDNI solution (Control, Metadata,
 Request Routing, and Logging).
 [RFC7336] expands on the information provided in [RFC6707] and
 describes each of the interfaces and the relationships between them
 in more detail.
 This document describes the "CI/T" interface -- "CDNI Control
 interface / Triggers".  It does not consider those parts of the
 Control interface that relate to configuration, bootstrapping, or
 authentication of CDN Interconnect interfaces.  Section 4 of
 [RFC7337] identifies the requirements specific to the CI/T interface;
 requirements applicable to the CI/T interface are CI-1 to CI-6.
 o  Section 2 outlines the model for the CI/T interface at a high
    level.
 o  Section 3 describes collections of Trigger Status Resources.
 o  Section 4 defines the web service provided by the downstream CDN.
 o  Section 5 lists properties of CI/T Commands and Status Resources.
 o  Section 6 contains example messages.

Murray & Niven-Jenkins Standards Track [Page 3] RFC 8007 CDN Interconnect Triggers December 2016

1.1. Terminology

 This document reuses the terminology defined in [RFC6707] and uses
 "uCDN" and "dCDN" as shorthand for "upstream CDN" and "downstream
 CDN", respectively.
 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].

2. Model for CDNI Triggers

 A CI/T Command, sent from the uCDN to the dCDN, is a request for the
 dCDN to do some work relating to data associated with content
 requests originating from the uCDN.
 There are two types of CI/T Commands: CI/T Trigger Commands and CI/T
 Cancel Commands.  The CI/T Cancel Command can be used to request
 cancellation of an earlier CI/T Trigger Command.  A CI/T Trigger
 Command is of one of the following types:
 o  preposition - used to instruct the dCDN to fetch metadata from the
    uCDN, or content from any origin including the uCDN.
 o  invalidate - used to instruct the dCDN to revalidate specific
    metadata or content before reusing it.
 o  purge - used to instruct the dCDN to delete specific metadata or
    content.
 The CI/T interface is a web service offered by the dCDN.  It allows
 CI/T Commands to be issued and allows triggered activity to be
 tracked.  The CI/T interface builds on top of HTTP/1.1 [RFC7230].
 References to URL in this document relate to HTTP/HTTPS URIs, as
 defined in Section 2.7 of [RFC7230].
 When the dCDN accepts a CI/T Command, it creates a resource
 describing the status of the triggered activity -- a Trigger Status
 Resource.  The uCDN can poll Trigger Status Resources to monitor
 progress.
 The dCDN maintains at least one collection of Trigger Status
 Resources for each uCDN.  Each uCDN only has access to its own
 collections, the locations of which are shared when CDNI is
 established.

Murray & Niven-Jenkins Standards Track [Page 4] RFC 8007 CDN Interconnect Triggers December 2016

 To trigger activity in the dCDN, the uCDN POSTs a CI/T Command to the
 collection of Trigger Status Resources.  If the dCDN accepts the CI/T
 Command, it creates a new Trigger Status Resource and returns its
 location to the uCDN.  To monitor progress, the uCDN can GET the
 Trigger Status Resource.  To request cancellation of a CI/T Trigger
 Command, the uCDN can POST to the collection of Trigger Status
 Resources or simply delete the Trigger Status Resource.
 In addition to the collection of all Trigger Status Resources for the
 uCDN, the dCDN can maintain filtered views of that collection.  These
 filtered views are defined in Section 3 and include collections of
 Trigger Status Resources corresponding to active and completed CI/T
 Trigger Commands.  These collections provide a mechanism for polling
 the status of multiple jobs.
 Figure 1 is an example showing the basic message flow used by the
 uCDN to trigger activity in the dCDN and for the uCDN to discover the
 status of that activity.  Only successful triggering is shown.
 Examples of the messages are given in Section 6.
    uCDN                                                   dCDN
     |    (1) POST https://dcdn.example.com/triggers/uCDN    |
    [ ] --------------------------------------------------> [ ]--+
     |                                                      [ ]  | (2)
     |    (3) HTTP 201 Response                             [ ]<-+
    [ ] <-------------------------------------------------- [ ]
     |     Loc: https://dcdn.example.com/triggers/uCDN/123   |
     |                                                       |
     .                           .                           .
     .                           .                           .
     .                           .                           .
     |                                                       |
     |   (4) GET https://dcdn.example.com/triggers/uCDN/123  |
    [ ] --------------------------------------------------> [ ]
     |                                                      [ ]
     |   (5) HTTP 200 Trigger Status Resource               [ ]
    [ ] <-------------------------------------------------- [ ]
     |                                                       |
     |                                                       |
            Figure 1: Basic CDNI Message Flow for Triggers

Murray & Niven-Jenkins Standards Track [Page 5] RFC 8007 CDN Interconnect Triggers December 2016

 The steps in Figure 1 are as follows:
 1.  The uCDN triggers action in the dCDN by POSTing a CI/T Command to
     a collection of Trigger Status Resources --
     "https://dcdn.example.com/triggers/uCDN".  This URL was given to
     the uCDN when the CI/T interface was established.
 2.  The dCDN authenticates the request, validates the CI/T Command,
     and, if it accepts the request, creates a new Trigger Status
     Resource.
 3.  The dCDN responds to the uCDN with an HTTP 201 response status
     and the location of the Trigger Status Resource.
 4.  The uCDN can poll, possibly repeatedly, the Trigger Status
     Resource in the dCDN.
 5.  The dCDN responds with the Trigger Status Resource, describing
     the progress or results of the CI/T Trigger Command.
 The remainder of this document describes the messages, Trigger Status
 Resources, and collections of Trigger Status Resources in more
 detail.

2.1. Timing of Triggered Activity

 Timing of the execution of CI/T Commands is under the dCDN's control,
 including its start time and pacing of the activity in the network.
 CI/T "invalidate" and "purge" commands MUST be applied to all data
 acquired before the command was accepted by the dCDN.  The dCDN
 SHOULD NOT apply CI/T "invalidate" and "purge" commands to data
 acquired after the CI/T Command was accepted, but this may not always
 be achievable, so the uCDN cannot count on that.
 If the uCDN wishes to invalidate or purge content and then
 immediately pre-position replacement content at the same URLs, it
 SHOULD ensure that the dCDN has completed the invalidate/purge before
 initiating the pre-positioning.  Otherwise, there is a risk that the
 dCDN pre-positions the new content, then immediately invalidates or
 purges it (as a result of the two uCDN requests running in parallel).
 Because the CI/T Command timing is under the dCDN's control, the dCDN
 implementation can choose whether to apply CI/T "invalidate" and
 "purge" commands to content acquisition that has already started when
 the command is received.

Murray & Niven-Jenkins Standards Track [Page 6] RFC 8007 CDN Interconnect Triggers December 2016

2.2. Scope of Triggered Activity

 Each CI/T Command can operate on multiple metadata and content URLs.
 Multiple representations of an HTTP resource may share the same URL.
 CI/T Trigger Commands that invalidate or purge metadata or content
 apply to all resource representations with matching URLs.

2.2.1. Multiple Interconnected CDNs

 In a network of interconnected CDNs, a single uCDN will originate a
 given item of metadata and associated content.  It may distribute
 that metadata and content to more than one dCDN, which may in turn
 distribute that metadata and content to CDNs located further
 downstream.
 An intermediate CDN is a dCDN that passes on CDNI Metadata and
 content to dCDNs located further downstream.
 A "diamond" configuration is one where a dCDN can acquire metadata
 and content originated in one uCDN from that uCDN itself and an
 intermediate CDN, or via more than one intermediate CDN.
 CI/T Commands originating in the single source uCDN affect metadata
 and content in all dCDNs; however, in a diamond configuration, it may
 not be possible for the dCDN to determine which uCDN it acquired
 content from.  In this case, a dCDN MUST allow each uCDN from which
 it may have acquired the content to act upon that content using CI/T
 Commands.
 In all other cases, a dCDN MUST reject CI/T Commands from a uCDN that
 attempts to act on another uCDN's content by using, for example,
 HTTP 403 ("Forbidden").
 Security considerations are discussed further in Section 8.
 The diamond configuration may lead to inefficient interactions, but
 the interactions are otherwise harmless.  For example:
 o  When the uCDN issues an "invalidate" CI/T Command, a dCDN will
    receive that command from multiple directly connected uCDNs.  The
    dCDN may schedule multiple such commands separately, and the last
    scheduled command may affect content already revalidated following
    execution of the "invalidate" command that was scheduled first.

Murray & Niven-Jenkins Standards Track [Page 7] RFC 8007 CDN Interconnect Triggers December 2016

 o  If one of a dCDN's directly connected uCDNs loses its rights to
    distribute content, it may issue a CI/T "purge" command.  That
    purge may affect content the dCDN could retain because it's
    distributed by another directly connected uCDN.  But, that content
    can be reacquired by the dCDN from the remaining uCDN.
 o  When the uCDN originating an item of content issues a CI/T purge
    followed by a pre-position, two directly connected uCDNs will pass
    those commands to a dCDN.  That dCDN implementation need not merge
    those operations or notice the repetition, in which case the purge
    issued by one uCDN will complete before the other.  The first uCDN
    to finish its purge may then forward the "preposition" trigger,
    and content pre-positioned as a result might be affected by the
    still-running purge issued by the other uCDN.  However, the dCDN
    will reacquire that content as needed, or when it's asked to
    pre-position the content by the second uCDN.  A dCDN
    implementation could avoid this interaction by knowing which uCDN
    it acquired the content from, or it could minimize the
    consequences by recording the time at which the
    "invalidate"/"purge" command was received and not applying it to
    content acquired after that time.

2.3. Trigger Results

 Possible states for a Trigger Status Resource are defined in
 Section 5.2.3.
 The CI/T Trigger Command MUST NOT be reported as "complete" until all
 actions have been completed successfully.  The reasons for failure,
 and URLs or patterns affected, SHOULD be enumerated in the Trigger
 Status Resource.  For more details, see Section 4.7.
 If a dCDN is also acting as a uCDN in a cascade, it MUST forward CI/T
 Commands to any dCDNs that may be affected.  The CI/T Trigger Command
 MUST NOT be reported as "complete" in a CDN until it is "complete" in
 all of its dCDNs.  If a CI/T Trigger Command is reported as
 "processed" in any dCDN, intermediate CDNs MUST NOT report
 "complete"; instead, they MUST also report "processed".  A CI/T
 Command MAY be reported as "failed" as soon as it fails in a CDN or
 in any of its dCDNs.  A canceled CI/T Trigger Command MUST be
 reported as "cancelling" until it has been reported as "cancelled",
 "complete", or "failed" by all dCDNs in a cascade.

Murray & Niven-Jenkins Standards Track [Page 8] RFC 8007 CDN Interconnect Triggers December 2016

3. Collections of Trigger Status Resources

 As described in Section 2, Trigger Status Resources exist in the dCDN
 to report the status of activity triggered by each uCDN.
 A collection of Trigger Status Resources is a resource that contains
 a reference to each Trigger Status Resource in that collection.
 The dCDN MUST make a collection of a uCDN's Trigger Status Resources
 available to that uCDN.  This collection includes all of the Trigger
 Status Resources created for CI/T Commands from the uCDN that have
 been accepted by the dCDN, and have not yet been deleted by the uCDN,
 or expired and removed by the dCDN (as described in Section 4.4).
 Trigger Status Resources belonging to a uCDN MUST NOT be visible to
 any other CDN.  The dCDN could, for example, achieve this by offering
 different collection URLs to each uCDN and by filtering the response
 based on the uCDN with which the HTTP client is associated.
 To trigger activity in a dCDN or to cancel triggered activity, the
 uCDN POSTs a CI/T Command to the dCDN's collection of the uCDN's
 Trigger Status Resources.
 In order to allow the uCDN to check the status of multiple jobs in a
 single request, the dCDN MAY also maintain collections representing
 filtered views of the collection of all Trigger Status Resources.
 These filtered collections are "optional-to-implement", but if they
 are implemented, the dCDN MUST include links to them in the
 collection of all Trigger Status Resources.  The filtered
 collections are:
 o  Pending - Trigger Status Resources for CI/T Trigger Commands that
    have been accepted but not yet acted upon.
 o  Active - Trigger Status Resources for CI/T Trigger Commands that
    are currently being processed in the dCDN.
 o  Complete - Trigger Status Resources representing activity that
    completed successfully, and "processed" CI/T Trigger Commands for
    which no further status updates will be made by the dCDN.
 o  Failed - Trigger Status Resources representing CI/T Commands that
    failed or were canceled by the uCDN.

Murray & Niven-Jenkins Standards Track [Page 9] RFC 8007 CDN Interconnect Triggers December 2016

4. CDNI Trigger Interface

 This section describes an interface to enable a uCDN to trigger
 activity in a dCDN.
 The CI/T interface builds on top of HTTP, so dCDNs may make use of
 any HTTP feature when implementing the CI/T interface.  For example,
 a dCDN SHOULD make use of HTTP's caching mechanisms to indicate that
 a requested response/representation has not been modified, reducing
 the uCDN's processing needed to determine whether the status of
 triggered activity has changed.
 All dCDNs implementing CI/T MUST support the HTTP GET, HEAD, POST,
 and DELETE methods as defined in [RFC7231].
 The only representation specified in this document is JSON [RFC7159].
 It MUST be supported by the uCDN and by the dCDN.
 The URL of the dCDN's collection of all Trigger Status Resources
 needs to be either discovered by or configured in the uCDN.  The
 mechanism for discovery of that URL is outside the scope of this
 document.
 CI/T Commands are POSTed to the dCDN's collection of all Trigger
 Status Resources.  If a CI/T Trigger Command is accepted by the dCDN,
 the dCDN creates a new Trigger Status Resource and returns its URI to
 the uCDN in an HTTP 201 response.  The triggered activity can then be
 monitored by the uCDN using that resource and the collections
 described in Section 3.
 The URI of each Trigger Status Resource is returned to the uCDN when
 it is created, and URIs of all Trigger Status Resources are listed in
 the dCDN's collection of all Trigger Status Resources.  This means
 all Trigger Status Resources can be discovered by the uCDN, so dCDNs
 are free to assign whatever structure they desire to the URIs for
 CI/T resources.  Therefore, uCDNs MUST NOT make any assumptions
 regarding the structure of CI/T URIs or the mapping between CI/T
 objects and their associated URIs.  URIs present in the examples in
 this document are purely illustrative and are not intended to impose
 a definitive structure on CI/T interface implementations.

Murray & Niven-Jenkins Standards Track [Page 10] RFC 8007 CDN Interconnect Triggers December 2016

4.1. Creating Triggers

 To issue a CI/T Command, the uCDN makes an HTTP POST to the dCDN's
 collection of all of the uCDN's Trigger Status Resources.  The
 request body of that POST is a CI/T Command, as described in
 Section 5.1.1.
 The dCDN validates the CI/T Command.  If the command is malformed or
 the uCDN does not have sufficient access rights, the dCDN MUST either
 respond with an appropriate 4xx HTTP error code and not create a
 Trigger Status Resource or create a "failed" Trigger Status Resource
 containing an appropriate Error Description.
 When a CI/T Trigger Command is accepted, the uCDN MUST create a new
 Trigger Status Resource that will convey a specification of the CI/T
 Command and its current status.  The HTTP response to the dCDN MUST
 have status code 201 and MUST convey the URI of the Trigger Status
 Resource in the Location header field [RFC7231].  The HTTP response
 SHOULD include the content of the newly created Trigger Status
 Resource.  This is particularly important in cases where the CI/T
 Trigger Command has completed immediately.
 Once a Trigger Status Resource has been created, the dCDN MUST NOT
 reuse its URI, even after that Trigger Status Resource has been
 removed.
 The dCDN SHOULD track and report on the progress of CI/T Trigger
 Commands using a Trigger Status Resource (Section 5.1.2).  If the
 dCDN is not able to do that, it MUST indicate that it has accepted
 the request but will not be providing further status updates.  To do
 this, it sets the status of the Trigger Status Resource to
 "processed".  In this case, CI/T processing should continue as for a
 "complete" request, so the Trigger Status Resource MUST be added to
 the dCDN's collection of complete Trigger Status Resources.  The dCDN
 SHOULD also provide an estimated completion time for the request by
 using the "etime" property of the Trigger Status Resource.  This will
 allow the uCDN to schedule pre-positioning after an earlier delete of
 the same URLs is expected to have finished.
 If the dCDN is able to track the execution of CI/T Commands and a
 CI/T Command is queued by the dCDN for later action, the "status"
 property of the Trigger Status Resource MUST be "pending".  Once
 processing has started, the status MUST be "active".  Finally, once
 the CI/T Command is complete, the status MUST be set to "complete" or
 "failed".

Murray & Niven-Jenkins Standards Track [Page 11] RFC 8007 CDN Interconnect Triggers December 2016

 A CI/T Trigger Command may result in no activity in the dCDN if, for
 example, it is an "invalidate" or "purge" request for data the dCDN
 has not yet acquired, or a "preposition" request for data that it has
 already acquired and that is still valid.  In this case, the status
 of the Trigger Status Resource MUST be "processed" or "complete", and
 the Trigger Status Resource MUST be added to the dCDN's collection of
 complete Trigger Status Resources.
 Once created, Trigger Status Resources can be canceled or deleted by
 the uCDN, but not modified.  The dCDN MUST reject PUT and POST
 requests from the uCDN to Trigger Status Resources by responding with
 an appropriate HTTP status code -- for example, 405 ("Method Not
 Allowed").

4.2. Checking Status

 The uCDN has two ways to check the progress of CI/T Commands it has
 issued to the dCDN, as described in Sections 4.2.1 and 4.2.2.
 To allow the uCDN to check for changes in the status of a Trigger
 Status Resource or collection of Trigger Status Resources without
 refetching the whole resource or collection, the dCDN SHOULD include
 entity-tags (ETags) for the uCDN to use as cache validators, as
 defined in [RFC7232].
 The dCDN SHOULD use the cache control headers for responses to GETs
 for Trigger Status Resources and Collections to indicate the
 frequency at which it recommends that the uCDN should poll for
 change.

4.2.1. Polling Trigger Status Resource Collections

 The uCDN can fetch the collection of its Trigger Status Resources or
 filtered views of that collection.
 This makes it possible to poll the status of all CI/T Trigger
 Commands in a single request.  If the dCDN moves a Trigger Status
 Resource from the active to the completed collection, the uCDN can
 fetch the result of that activity.
 When polling in this way, the uCDN SHOULD use HTTP ETags to monitor
 for change, rather than repeatedly fetching the whole collection.  An
 example of this is given in Section 6.2.4.

Murray & Niven-Jenkins Standards Track [Page 12] RFC 8007 CDN Interconnect Triggers December 2016

4.2.2. Polling Trigger Status Resources

 The uCDN has a URI provided by the dCDN for each Trigger Status
 Resource it has created.  It may fetch that Trigger Status Resource
 at any time.
 This can be used to retrieve progress information and to fetch the
 result of the CI/T Command.
 When polling in this way, the uCDN SHOULD use HTTP ETags to monitor
 for change, rather than repeatedly fetching the Trigger Status
 Resource.

4.3. Canceling Triggers

 The uCDN can request cancellation of a CI/T Trigger Command by
 POSTing a CI/T Cancel Command to the collection of all Trigger Status
 Resources.
 The dCDN is required to accept and respond to the CI/T Cancel
 Command, but the actual cancellation of a CI/T Trigger Command is
 optional-to-implement.
 The dCDN MUST respond to the CI/T Cancel Command appropriately -- for
 example, with HTTP status code 200 ("OK") if the cancellation has
 been processed and the CI/T Command is inactive, 202 ("Accepted") if
 the command has been accepted but the CI/T Command remains active, or
 501 ("Not Implemented") if cancellation is not supported by the dCDN.
 If cancellation of a "pending" Trigger Status Resource is accepted by
 the dCDN, the dCDN SHOULD NOT start the processing of that activity.
 Issuing a CI/T Cancel Command for a "pending" Trigger Status Resource
 does not, however, guarantee that the corresponding activity will not
 be started, because the uCDN cannot control the timing of that
 activity.  Processing could, for example, start after the POST is
 sent by the uCDN but before that request is processed by the dCDN.
 If cancellation of an "active" or "processed" Trigger Status Resource
 is accepted by the dCDN, the dCDN SHOULD stop processing the CI/T
 Command.  However, as with cancellation of a "pending" CI/T Command,
 the dCDN does not guarantee this.
 If the CI/T Command cannot be stopped immediately, the status in the
 corresponding Trigger Status Resource MUST be set to "cancelling",
 and the Trigger Status Resource MUST remain in the collection of
 Trigger Status Resources for active CI/T Commands.  If processing is
 stopped before normal completion, the status value in the Trigger

Murray & Niven-Jenkins Standards Track [Page 13] RFC 8007 CDN Interconnect Triggers December 2016

 Status Resource MUST be set to "cancelled", and the Trigger Status
 Resource MUST be included in the collection of failed CI/T Trigger
 Commands.
 Cancellation of a "complete" or "failed" Trigger Status Resource
 requires no processing in the dCDN.  Its status MUST NOT be changed
 to "cancelled".

4.4. Deleting Triggers

 The uCDN can delete Trigger Status Resources at any time, using the
 HTTP DELETE method.  The effect is similar to cancellation, but no
 Trigger Status Resource remains afterwards.
 Once deleted, the references to a Trigger Status Resource MUST be
 removed from all Trigger Status Resource collections.  Subsequent
 requests to GET the deleted Trigger Status Resource SHOULD be
 rejected by the dCDN with an HTTP error.
 If a "pending" Trigger Status Resource is deleted, the dCDN
 SHOULD NOT start the processing of that activity.  Deleting a
 "pending" Trigger Status Resource does not, however, guarantee that
 it has not started, because the uCDN cannot control the timing of
 that activity.  Processing may, for example, start after the DELETE
 is sent by the uCDN but before that request is processed by the dCDN.
 If an "active" or "processed" Trigger Status Resource is deleted, the
 dCDN SHOULD stop processing the CI/T Command.  However, as with
 deletion of a "pending" Trigger Status Resource, the dCDN does not
 guarantee this.
 Deletion of a "complete" or "failed" Trigger Status Resource requires
 no processing in the dCDN other than deletion of the Trigger Status
 Resource.

4.5. Expiry of Trigger Status Resources

 The dCDN can choose to automatically delete Trigger Status Resources
 some time after they become "complete", "processed", "failed", or
 "cancelled".  In this case, the dCDN will remove the Trigger Status
 Resource and respond to subsequent requests for it with an HTTP
 error.
 If the dCDN does remove Trigger Status Resources automatically, it
 MUST report the length of time after which it will do so, using a
 property of the collection of all Trigger Status Resources.  It is

Murray & Niven-Jenkins Standards Track [Page 14] RFC 8007 CDN Interconnect Triggers December 2016

 RECOMMENDED that Trigger Status Resources are not automatically
 deleted by the dCDN for at least 24 hours after they become
 "complete", "processed", "failed", or "cancelled".
 To ensure that it is able to get the status of its Trigger Status
 Resources for completed and failed CI/T Commands, it is RECOMMENDED
 that the uCDN polling interval is less than the time after which
 records for completed activity will be deleted.

4.6. Loop Detection and Prevention

 Given three CDNs, A, B, and C, if CDNs B and C delegate delivery of
 CDN A's content to each other, CDN A's CI/T Commands could be passed
 between CDNs B and C in a loop.  More complex networks of CDNs could
 contain similar loops involving more hops.
 In order to prevent and detect such CI/T loops, each CDN uses a CDN
 Provider ID (PID) to uniquely identify itself.  In every CI/T Command
 it originates or cascades, each CDN MUST append an array element
 containing its CDN PID to a JSON array under an entry named
 "cdn-path".  When receiving CI/T Commands, a dCDN MUST check the
 cdn-path and reject any CI/T Command that already contains its own
 CDN PID in the cdn-path.  Transit CDNs MUST check the cdn-path and
 not cascade the CI/T Command to dCDNs that are already listed in the
 cdn-path.
 The CDN PID consists of the two characters "AS" followed by the CDN
 provider's Autonomous System number [RFC1930], then a colon (":") and
 an additional qualifier that is used to guarantee uniqueness in case
 a particular AS has multiple independent CDNs deployed -- for
 example, "AS64496:0".
 If the CDN provider has multiple ASes, the same AS number SHOULD be
 used in all messages from that CDN provider, unless there are
 multiple distinct CDNs.
 If the CDNI Request Routing Redirection interface (RI) described in
 [RFC7975] is implemented by the dCDN, the CI/T interface and the RI
 SHOULD use the same CDN PID.

4.7. Error Handling

 A dCDN can signal rejection of a CI/T Command using HTTP status codes
 -- for example, 400 ("Bad Request") if the request is malformed, or
 403 ("Forbidden") or 404 ("Not Found") if the uCDN does not have
 permission to issue CI/T Commands or it is trying to act on another
 CDN's data.

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 If any part of the CI/T Trigger Command fails, the trigger SHOULD be
 reported as "failed" once its activity is complete or if no further
 errors will be reported.  The "errors" property in the Trigger Status
 Resource will be used to enumerate which actions failed and the
 reasons for failure, and can be present while the Trigger Status
 Resource is still "pending" or "active", if the CI/T Trigger Command
 is still running for some URLs or patterns in the Trigger
 Specification.
 Once a request has been accepted, processing errors are reported in
 the Trigger Status Resource using a list of Error Descriptions.  Each
 Error Description is used to report errors against one or more of the
 URLs or patterns in the Trigger Specification.
 If a Surrogate affected by a CI/T Trigger Command is offline in the
 dCDN or the dCDN is unable to pass a CI/T Command on to any of its
 cascaded dCDNs:
 o  If the CI/T Command is abandoned by the dCDN, the dCDN SHOULD
    report an error.
 o  A CI/T "invalidate" command may be reported as "complete" when
    Surrogates that may have the data are offline.  In this case,
    Surrogates MUST NOT use the affected data without first
    revalidating it when they are back online.
 o  CI/T "preposition" and "purge" commands can be reported as
    "processed" if affected caches are offline and the activity will
    complete when they return to service.
 o  Otherwise, the dCDN SHOULD keep the Trigger Status Resource in
    state "pending" or "active" until either the CI/T Command is acted
    upon or the uCDN chooses to cancel it.

4.8. Content URLs

 If content URLs are transformed by an intermediate CDN in a cascade,
 that intermediate CDN MUST similarly transform URLs in CI/T Commands
 it passes to its dCDN.
 When processing Trigger Specifications, CDNs MUST ignore the URL
 scheme (HTTP or HTTPS) in comparing URLs.  For example, for a CI/T
 "invalidate" or "purge" command, content MUST be invalidated or
 purged regardless of the protocol clients used to request it.

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5. CI/T Object Properties and Encoding

 The CI/T Commands, Trigger Status Resources, and Trigger Collections,
 as well as their properties, are encoded using JSON, as defined in
 Sections 5.1.1, 5.1.2, and 5.1.3.  They MUST use the MIME media type
 "application/cdni", with parameter "ptype" values as defined below
 and in Section 7.1.
 Names in JSON are case sensitive.  The names and literal values
 specified in the present document MUST always use lowercase.
 JSON types, including "object", "array", "number", and "string", are
 defined in [RFC7159].
 Unrecognized name/value pairs in JSON objects SHOULD NOT be treated
 as an error by either the uCDN or dCDN.  They SHOULD be ignored
 during processing and passed on by the dCDN to any further dCDNs in a
 cascade.

5.1. CI/T Objects

 The top-level objects defined by the CI/T interface are described in
 this section.
 The encoding of values used by these objects is described in
 Section 5.2.

5.1.1. CI/T Commands

 CI/T Commands MUST use a MIME media type of "application/cdni;
 ptype=ci-trigger-command".
 A CI/T Command is encoded as a JSON object containing the following
 name/value pairs.
    Name: trigger
       Description: A specification of the trigger type and a set of
       data to act upon.
       Value: A Trigger Specification, as defined in Section 5.2.1.
       Mandatory: No, but exactly one of "trigger" or "cancel" MUST be
       present in a CI/T Command.

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    Name: cancel
       Description: The URLs of Trigger Status Resources for CI/T
       Trigger Commands that the uCDN wants to cancel.
       Value: A non-empty JSON array of URLs represented as JSON
       strings.
       Mandatory: No, but exactly one of "trigger" or "cancel" MUST be
       present in a CI/T Command.
    Name: cdn-path
       Description: The CDN PIDs of CDNs that have already issued the
       CI/T Command to their dCDNs.
       Value: A non-empty JSON array of JSON strings, where each
       string is a CDN PID as defined in Section 4.6.
       Mandatory: Yes.

5.1.2. Trigger Status Resources

 Trigger Status Resources MUST use a MIME media type of
 "application/cdni; ptype=ci-trigger-status".
 A Trigger Status Resource is encoded as a JSON object containing the
 following name/value pairs.
    Name: trigger
       Description: The Trigger Specification POSTed in the body of
       the CI/T Command.  Note that this need not be a byte-for-byte
       copy.  For example, in the JSON representation the dCDN may
       re-serialize the information differently.
       Value: A Trigger Specification, as defined in Section 5.2.1.
       Mandatory: Yes.

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    Name: ctime
       Description: Time at which the CI/T Command was received by the
       dCDN.  Time is determined by the dCDN; there is no requirement
       to synchronize clocks between interconnected CDNs.
       Value: Absolute Time, as defined in Section 5.2.5.
       Mandatory: Yes.
    Name: mtime
       Description: Time at which the Trigger Status Resource was last
       modified.  Time is determined by the dCDN; there is no
       requirement to synchronize clocks between interconnected CDNs.
       Value: Absolute Time, as defined in Section 5.2.5.
       Mandatory: Yes.
    Name: etime
       Description: Estimate of the time at which the dCDN expects to
       complete the activity.  Time is determined by the dCDN; there
       is no requirement to synchronize clocks between interconnected
       CDNs.
       Value: Absolute Time, as defined in Section 5.2.5.
       Mandatory: No.
    Name: status
       Description: Current status of the triggered activity.
       Value: Trigger Status, as defined in Section 5.2.3.
       Mandatory: Yes.

Murray & Niven-Jenkins Standards Track [Page 19] RFC 8007 CDN Interconnect Triggers December 2016

    Name: errors
       Description: Descriptions of errors that have occurred while
       processing a Trigger Command.
       Value: An array of Error Descriptions, as defined in
       Section 5.2.6.  An empty array is allowed and is equivalent to
       omitting "errors" from the object.
       Mandatory: No.

5.1.3. Trigger Collections

 Trigger Collections MUST use a MIME media type of "application/cdni;
 ptype=ci-trigger-collection".
 A Trigger Collection is encoded as a JSON object containing the
 following name/value pairs.
    Name: triggers
       Description: Links to Trigger Status Resources in the
       collection.
       Value: A JSON array of zero or more URLs, represented as JSON
       strings.
       Mandatory: Yes.
    Name: staleresourcetime
       Description: The length of time for which the dCDN guarantees
       to keep a completed Trigger Status Resource.  After this time,
       the dCDN SHOULD delete the Trigger Status Resource and all
       references to it from collections.
       Value: A JSON number, which must be a positive integer,
       representing time in seconds.
       Mandatory: Yes, in the collection of all Trigger Status
       Resources if the dCDN deletes stale entries.  If the property
       is present in the filtered collections, it MUST have the same
       value as in the collection of all Trigger Status Resources.

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    Names: coll-all, coll-pending, coll-active, coll-complete,
    coll-failed
       Description: Link to a Trigger Collection.
       Value: A URL represented as a JSON string.
       Mandatory: Links to all of the filtered collections are
       mandatory in the collection of all Trigger Status Resources, if
       the dCDN implements the filtered collections.  Otherwise,
       optional.
    Name: cdn-id
       Description: The CDN PID of the dCDN.
       Value: A JSON string, the dCDN's CDN PID, as defined in
       Section 4.6.
       Mandatory: Only in the collection of all Trigger Status
       Resources, if the dCDN implements the filtered collections.
       Optional in the filtered collections (the uCDN can always find
       the dCDN's cdn-id in the collection of all Trigger Status
       Resources, but the dCDN can choose to repeat that information
       in its implementation of filtered collections).

5.2. Properties of CI/T Objects

 This section defines the values that can appear in the top-level
 objects described in Section 5.1, and their encodings.

5.2.1. Trigger Specification

 A Trigger Collection is encoded as a JSON object containing the
 following name/value pairs.
 An unrecognized name/value pair in the Trigger Specification object
 contained in a CI/T Command SHOULD be preserved in the Trigger
 Specification of any Trigger Status Resource it creates.
    Name: type
       Description: Defines the type of the CI/T Trigger Command.
       Value: Trigger Type, as defined in Section 5.2.2.
       Mandatory: Yes.

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    Name: metadata.urls
       Description: The uCDN URLs of the metadata the CI/T Trigger
       Command applies to.
       Value: A JSON array of URLs represented as JSON strings.
       Mandatory: No, but at least one of "metadata.*" or "content.*"
       MUST be present and non-empty.
    Name: content.urls
       Description: URLs of content the CI/T Trigger Command applies
       to.  See Section 4.8.
       Value: A JSON array of URLs represented as JSON strings.
       Mandatory: No, but at least one of "metadata.*" or "content.*"
       MUST be present and non-empty.
    Name: content.ccid
       Description: The Content Collection IDentifier of content the
       trigger applies to.  The "ccid" is a grouping of content, as
       defined by [RFC8006].
       Value: A JSON array of strings, where each string is a Content
       Collection IDentifier.
       Mandatory: No, but at least one of "metadata.*" or "content.*"
       MUST be present and non-empty.
    Name: metadata.patterns
       Description: The metadata the trigger applies to.
       Value: A JSON array of PatternMatch objects, as defined in
       Section 5.2.4.
       Mandatory: No, but at least one of "metadata.*" or "content.*"
       MUST be present and non-empty, and metadata.patterns MUST NOT
       be present if the Trigger Type is "preposition".

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    Name: content.patterns
       Description: The content data the trigger applies to.
       Value: A JSON array of PatternMatch objects, as defined in
       Section 5.2.4.
       Mandatory: No, but at least one of "metadata.*" or "content.*"
       MUST be present and non-empty, and content.patterns MUST NOT be
       present if the Trigger Type is "preposition".

5.2.2. Trigger Type

 Trigger Type is used in a Trigger Specification to describe trigger
 action.
 All trigger types MUST be registered in the IANA "CDNI CI/T Trigger
 Types" registry (see Section 7.2).
 A dCDN receiving a request containing a trigger type it does not
 recognize or does not support MUST reject the request by creating a
 Trigger Status Resource with a status of "failed" and the "errors"
 array containing an Error Description with error "eunsupported".
 The following trigger types are defined by this document:
 +-------------+-----------------------------------------------------+
 | JSON String | Description                                         |
 +-------------+-----------------------------------------------------+
 | preposition | A request for the dCDN to acquire metadata or       |
 |             | content.                                            |
 | invalidate  | A request for the dCDN to invalidate metadata or    |
 |             | content.  After servicing this request, the dCDN    |
 |             | will not use the specified data without first       |
 |             | revalidating it using, for example, an              |
 |             | "If-None-Match" HTTP request.  The dCDN need not    |
 |             | erase the associated data.                          |
 | purge       | A request for the dCDN to erase metadata or         |
 |             | content.  After servicing the request, the          |
 |             | specified data MUST NOT be held on the dCDN (the    |
 |             | dCDN should reacquire the metadata or content from  |
 |             | the uCDN if it needs it).                           |
 +-------------+-----------------------------------------------------+

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5.2.3. Trigger Status

 Trigger Status describes the current status of the triggered
 activity.  It MUST be one of the JSON strings in the following table:
 +-----------+-------------------------------------------------------+
 | JSON      | Description                                           |
 | String    |                                                       |
 +-----------+-------------------------------------------------------+
 | pending   | The CI/T Trigger Command has not yet been acted upon. |
 | active    | The CI/T Trigger Command is currently being acted     |
 |           | upon.                                                 |
 | complete  | The CI/T Trigger Command completed successfully.      |
 | processed | The CI/T Trigger Command has been accepted, and no    |
 |           | further status update will be made (can be used in    |
 |           | cases where completion cannot be confirmed).          |
 | failed    | The CI/T Trigger Command could not be completed.      |
 | canceling | Processing of the CI/T Trigger Command is still in    |
 |           | progress, but the CI/T Trigger Command has been       |
 |           | canceled by the uCDN.                                 |
 | canceled  | The CI/T Trigger Command was canceled by the uCDN.    |
 +-----------+-------------------------------------------------------+

5.2.4. PatternMatch

 A PatternMatch consists of a string pattern to match against a URI,
 and flags describing the type of match.
 It is encoded as a JSON object with the following name/value pairs:
    Name: pattern
       Description: A pattern for URI matching.
       Value: A JSON string representing the pattern.  The pattern can
       contain the wildcards * and ?, where * matches any sequence of
       [RFC3986] pchar or "/" characters (including the empty string)
       and ? matches exactly one [RFC3986] pchar character.  The three
       literals $, * and ? MUST be escaped as $$, $* and $? (where $
       is the designated escape character).  All other characters are
       treated as literals.
       Mandatory: Yes.

Murray & Niven-Jenkins Standards Track [Page 24] RFC 8007 CDN Interconnect Triggers December 2016

    Name: case-sensitive
       Description: Flag indicating whether or not case-sensitive
       matching should be used.
       Value: One of the JSON values "true" (the matching is case
       sensitive) or "false" (the matching is case insensitive).
       Mandatory: No; default is case-insensitive match.
    Name: match-query-string
       Description: Flag indicating whether to include the query part
       of the URI when comparing against the pattern.
       Value: One of the JSON values "true" (the full URI, including
       the query part, should be compared against the given pattern)
       or "false" (the query part of the URI should be dropped before
       comparison with the given pattern).
       Mandatory: No; default is "false".  The query part of the URI
       should be dropped before comparison with the given pattern.
 Example of case-sensitive prefix match against
 "https://www.example.com/trailers/":
 {
     "pattern": "https://www.example.com/trailers/*",
     "case-sensitive": true
 }

5.2.5. Absolute Time

 A JSON number, seconds since the UNIX epoch (00:00:00 UTC on
 1 January 1970).

Murray & Niven-Jenkins Standards Track [Page 25] RFC 8007 CDN Interconnect Triggers December 2016

5.2.6. Error Description

 An Error Description is used to report the failure of a CI/T Command
 or failure in the activity it triggered.  It is encoded as a JSON
 object with the following name/value pairs:
    Name: error
       Value: Error Code, as defined in Section 5.2.7.
       Mandatory: Yes.
    Names: metadata.urls, content.urls, metadata.patterns,
    content.patterns
       Description: Metadata and content references copied from the
       Trigger Specification.  Only those URLs and patterns to which
       the error applies are included in each property, but those URLs
       and patterns MUST be exactly as they appear in the request; the
       dCDN MUST NOT generalize the URLs.  (For example, if the uCDN
       requests pre-positioning of URLs
       "https://content.example.com/a" and
       "https://content.example.com/b", the dCDN must not generalize
       its error report to the pattern
       "https://content.example.com/*".)
       Value: A JSON array of JSON strings, where each string is
       copied from a "content.*" or "metadata.*" value in the
       corresponding Trigger Specification.
       Mandatory: At least one of these name/value pairs is mandatory
       in each Error Description object.
    Name: description
       Description: A human-readable description of the error.
       Value: A JSON string, the human-readable description.
       Mandatory: No.

5.2.7. Error Code

 This type is used by the dCDN to report failures in trigger
 processing.  All Error Codes MUST be registered in the IANA "CDNI
 CI/T Error Codes" registry (see Section 7.3).  Unknown Error Codes
 MUST be treated as fatal errors, and the request MUST NOT be
 automatically retried without modification.

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 The following Error Codes are defined by this document and MUST be
 supported by an implementation of the CI/T interface.
 +--------------+----------------------------------------------------+
 | Error Code   | Description                                        |
 +--------------+----------------------------------------------------+
 | emeta        | The dCDN was unable to acquire metadata required   |
 |              | to fulfill the request.                            |
 | econtent     | The dCDN was unable to acquire content (CI/T       |
 |              | "preposition" commands only).                      |
 | eperm        | The uCDN does not have permission to issue the     |
 |              | CI/T Command (for example, the data is owned by    |
 |              | another CDN).                                      |
 | ereject      | The dCDN is not willing to fulfill the CI/T        |
 |              | Command (for example, a "preposition" request for  |
 |              | content at a time when the dCDN would not accept   |
 |              | Request Routing requests from the uCDN).           |
 | ecdn         | An internal error in the dCDN or one of its dCDNs. |
 | ecanceled    | The uCDN canceled the request.                     |
 | eunsupported | The Trigger Specification contained a "type" that  |
 |              | is not supported by the dCDN.  No action was taken |
 |              | by the dCDN other than to create a Trigger Status  |
 |              | Resource in state "failed".                        |
 +--------------+----------------------------------------------------+

6. Examples

 The following subsections provide examples of different CI/T objects
 encoded as JSON.
 Discovery of the CI/T interface is out of scope for this document.
 In an implementation, all CI/T URLs are under the control of the
 dCDN.  The uCDN MUST NOT attempt to ascribe any meaning to individual
 elements of the path.
 In examples in this section, the URL "https://dcdn.example.com/
 triggers" is used as the location of the collection of all Trigger
 Status Resources, and the CDN PID of the uCDN is "AS64496:1".

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6.1. Creating Triggers

 Examples of the uCDN triggering activity in the dCDN:

6.1.1. Preposition

 Below is an example of a CI/T "preposition" command -- a POST to the
 collection of all Trigger Status Resources.
 Note that "metadata.patterns" and "content.patterns" are not allowed
 in a pre-position Trigger Specification.
 REQUEST:
   POST /triggers HTTP/1.1
   User-Agent: example-user-agent/0.1
   Host: dcdn.example.com
   Accept: */*
   Content-Type: application/cdni; ptype=ci-trigger-command
   Content-Length: 352
   {
     "trigger": {
       "type": "preposition",
       "metadata.urls": [ "https://metadata.example.com/a/b/c" ],
       "content.urls": [
           "https://www.example.com/a/b/c/1",
           "https://www.example.com/a/b/c/2",
           "https://www.example.com/a/b/c/3",
           "https://www.example.com/a/b/c/4"
         ]
     },
     "cdn-path": [ "AS64496:1" ]
   }

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 RESPONSE:
   HTTP/1.1 201 Created
   Date: Wed, 04 May 2016 08:48:10 GMT
   Content-Length: 467
   Content-Type: application/cdni; ptype=ci-trigger-status
   Location: https://dcdn.example.com/triggers/0
   Server: example-server/0.1
   {
       "ctime": 1462351690,
       "etime": 1462351698,
       "mtime": 1462351690,
       "status": "pending",
       "trigger": {
           "content.urls": [
               "https://www.example.com/a/b/c/1",
               "https://www.example.com/a/b/c/2",
               "https://www.example.com/a/b/c/3",
               "https://www.example.com/a/b/c/4"
           ],
           "metadata.urls": [
               "https://metadata.example.com/a/b/c"
           ],
           "type": "preposition"
       }
   }

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6.1.2. Invalidate

 Below is an example of a CI/T "invalidate" command -- another POST to
 the collection of all Trigger Status Resources.  This instructs the
 dCDN to revalidate the content at "https://www.example.com/a/
 index.html", as well as any metadata and content whose URLs are
 prefixed by "https://metadata.example.com/a/b/" using
 case-insensitive matching, and "https://www.example.com/a/b/" using
 case-sensitive matching, respectively.
 REQUEST:
   POST /triggers HTTP/1.1
   User-Agent: example-user-agent/0.1
   Host: dcdn.example.com
   Accept: */*
   Content-Type: application/cdni; ptype=ci-trigger-command
   Content-Length: 387
   {
     "trigger": {
       "type": "invalidate",
       "metadata.patterns": [
           { "pattern": "https://metadata.example.com/a/b/*" }
         ],
       "content.urls": [ "https://www.example.com/a/index.html" ],
       "content.patterns": [
           { "pattern": "https://www.example.com/a/b/*",
             "case-sensitive": true
           }
         ]
     },
     "cdn-path": [ "AS64496:1" ]
   }

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 RESPONSE:
   HTTP/1.1 201 Created
   Date: Wed, 04 May 2016 08:48:11 GMT
   Content-Length: 545
   Content-Type: application/cdni; ptype=ci-trigger-status
   Location: https://dcdn.example.com/triggers/1
   Server: example-server/0.1
   {
       "ctime": 1462351691,
       "etime": 1462351699,
       "mtime": 1462351691,
       "status": "pending",
       "trigger": {
           "content.patterns": [
               {
                   "case-sensitive": true,
                   "pattern": "https://www.example.com/a/b/*"
               }
           ],
           "content.urls": [
               "https://www.example.com/a/index.html"
           ],
           "metadata.patterns": [
               {
                   "pattern": "https://metadata.example.com/a/b/*"
               }
           ],
           "type": "invalidate"
       }
   }

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6.2. Examining Trigger Status

 Once Trigger Status Resources have been created, the uCDN can check
 their status as shown in the following examples.

6.2.1. Collection of All Triggers

 The uCDN can fetch the collection of all Trigger Status Resources it
 has created that have not yet been deleted or removed as expired.
 After creation of the "preposition" and "invalidate" triggers shown
 above, this collection might look as follows:
 REQUEST:
   GET /triggers HTTP/1.1
   User-Agent: example-user-agent/0.1
   Host: dcdn.example.com
   Accept: */*
 RESPONSE:
   HTTP/1.1 200 OK
   Content-Length: 341
   Expires: Wed, 04 May 2016 08:49:11 GMT
   Server: example-server/0.1
   ETag: "-936094426920308378"
   Cache-Control: max-age=60
   Date: Wed, 04 May 2016 08:48:11 GMT
   Content-Type: application/cdni; ptype=ci-trigger-collection
   {
       "cdn-id": "AS64496:0",
       "coll-active": "/triggers/active",
       "coll-complete": "/triggers/complete",
       "coll-failed": "/triggers/failed",
       "coll-pending": "/triggers/pending",
       "staleresourcetime": 86400,
       "triggers": [
           "https://dcdn.example.com/triggers/0",
           "https://dcdn.example.com/triggers/1"
       ]
   }

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6.2.2. Filtered Collections of Trigger Status Resources

 The filtered collections are also available to the uCDN.  Before the
 dCDN starts processing the two CI/T Trigger Commands shown above,
 both will appear in the collection of pending triggers.  For example:
 REQUEST:
   GET /triggers/pending HTTP/1.1
   User-Agent: example-user-agent/0.1
   Host: dcdn.example.com
   Accept: */*
 RESPONSE:
   HTTP/1.1 200 OK
   Content-Length: 152
   Expires: Wed, 04 May 2016 08:49:11 GMT
   Server: example-server/0.1
   ETag: "4331492443626270781"
   Cache-Control: max-age=60
   Date: Wed, 04 May 2016 08:48:11 GMT
   Content-Type: application/cdni; ptype=ci-trigger-collection
   {
       "staleresourcetime": 86400,
       "triggers": [
           "https://dcdn.example.com/triggers/0",
           "https://dcdn.example.com/triggers/1"
       ]
   }
 At this point, if no other Trigger Status Resources had been created,
 the other filtered views would be empty.  For example:
 REQUEST:
   GET /triggers/complete HTTP/1.1
   User-Agent: example-user-agent/0.1
   Host: dcdn.example.com
   Accept: */*

Murray & Niven-Jenkins Standards Track [Page 33] RFC 8007 CDN Interconnect Triggers December 2016

 RESPONSE:
   HTTP/1.1 200 OK
   Content-Length: 54
   Expires: Wed, 04 May 2016 08:49:11 GMT
   Server: example-server/0.1
   ETag: "7958041393922269003"
   Cache-Control: max-age=60
   Date: Wed, 04 May 2016 08:48:11 GMT
   Content-Type: application/cdni; ptype=ci-trigger-collection
   {
       "staleresourcetime": 86400,
       "triggers": []
   }

6.2.3. Individual Trigger Status Resources

 The Trigger Status Resources can also be examined for details about
 individual CI/T Trigger Commands.  For example, for the CI/T
 "preposition" and "invalidate" commands from previous examples:
 REQUEST:
   GET /triggers/0 HTTP/1.1
   User-Agent: example-user-agent/0.1
   Host: dcdn.example.com
   Accept: */*

Murray & Niven-Jenkins Standards Track [Page 34] RFC 8007 CDN Interconnect Triggers December 2016

 RESPONSE:
   HTTP/1.1 200 OK
   Content-Length: 467
   Expires: Wed, 04 May 2016 08:49:10 GMT
   Server: example-server/0.1
   ETag: "6990548174277557683"
   Cache-Control: max-age=60
   Date: Wed, 04 May 2016 08:48:10 GMT
   Content-Type: application/cdni; ptype=ci-trigger-status
   {
       "ctime": 1462351690,
       "etime": 1462351698,
       "mtime": 1462351690,
       "status": "pending",
       "trigger": {
           "content.urls": [
               "https://www.example.com/a/b/c/1",
               "https://www.example.com/a/b/c/2",
               "https://www.example.com/a/b/c/3",
               "https://www.example.com/a/b/c/4"
           ],
           "metadata.urls": [
               "https://metadata.example.com/a/b/c"
           ],
           "type": "preposition"
       }
   }
 REQUEST:
   GET /triggers/1 HTTP/1.1
   User-Agent: example-user-agent/0.1
   Host: dcdn.example.com
   Accept: */*
 RESPONSE:
   HTTP/1.1 200 OK
   Content-Length: 545
   Expires: Wed, 04 May 2016 08:49:11 GMT
   Server: example-server/0.1
   ETag: "-554385204989405469"
   Cache-Control: max-age=60
   Date: Wed, 04 May 2016 08:48:11 GMT
   Content-Type: application/cdni; ptype=ci-trigger-status

Murray & Niven-Jenkins Standards Track [Page 35] RFC 8007 CDN Interconnect Triggers December 2016

   {
       "ctime": 1462351691,
       "etime": 1462351699,
       "mtime": 1462351691,
       "status": "pending",
       "trigger": {
           "content.patterns": [
               {
                   "case-sensitive": true,
                   "pattern": "https://www.example.com/a/b/*"
               }
           ],
           "content.urls": [
               "https://www.example.com/a/index.html"
           ],
           "metadata.patterns": [
               {
                   "pattern": "https://metadata.example.com/a/b/*"
               }
           ],
           "type": "invalidate"
       }
   }

6.2.4. Polling for Changes in Status

 The uCDN SHOULD use the ETags of collections or Trigger Status
 Resources when polling for changes in status, as shown in the
 following examples:
 REQUEST:
   GET /triggers/pending HTTP/1.1
   User-Agent: example-user-agent/0.1
   Host: dcdn.example.com
   Accept: */*
   If-None-Match: "4331492443626270781"
 RESPONSE:
   HTTP/1.1 304 Not Modified
   Content-Length: 0
   Expires: Wed, 04 May 2016 08:49:11 GMT
   Server: example-server/0.1
   ETag: "4331492443626270781"
   Cache-Control: max-age=60
   Date: Wed, 04 May 2016 08:48:11 GMT
   Content-Type: application/cdni; ptype=ci-trigger-collection

Murray & Niven-Jenkins Standards Track [Page 36] RFC 8007 CDN Interconnect Triggers December 2016

 REQUEST:
   GET /triggers/0 HTTP/1.1
   User-Agent: example-user-agent/0.1
   Host: dcdn.example.com
   Accept: */*
   If-None-Match: "6990548174277557683"
 RESPONSE:
   HTTP/1.1 304 Not Modified
   Content-Length: 0
   Expires: Wed, 04 May 2016 08:49:10 GMT
   Server: example-server/0.1
   ETag: "6990548174277557683"
   Cache-Control: max-age=60
   Date: Wed, 04 May 2016 08:48:10 GMT
   Content-Type: application/cdni; ptype=ci-trigger-status
 When the CI/T Trigger Command is complete, the contents of the
 filtered collections will be updated along with their ETags.  For
 example, when the two example CI/T Trigger Commands are complete, the
 collections of pending and complete Trigger Status Resources might
 look like:
 REQUEST:
   GET /triggers/pending HTTP/1.1
   User-Agent: example-user-agent/0.1
   Host: dcdn.example.com
   Accept: */*
 RESPONSE:
   HTTP/1.1 200 OK
   Content-Length: 54
   Expires: Wed, 04 May 2016 08:49:15 GMT
   Server: example-server/0.1
   ETag: "1337503181677633762"
   Cache-Control: max-age=60
   Date: Wed, 04 May 2016 08:48:15 GMT
   Content-Type: application/cdni; ptype=ci-trigger-collection
   {
       "staleresourcetime": 86400,
       "triggers": []
   }

Murray & Niven-Jenkins Standards Track [Page 37] RFC 8007 CDN Interconnect Triggers December 2016

 REQUEST:
   GET /triggers/complete HTTP/1.1
   User-Agent: example-user-agent/0.1
   Host: dcdn.example.com
   Accept: */*
 RESPONSE:
   HTTP/1.1 200 OK
   Content-Length: 152
   Expires: Wed, 04 May 2016 08:49:22 GMT
   Server: example-server/0.1
   ETag: "4481489539378529796"
   Cache-Control: max-age=60
   Date: Wed, 04 May 2016 08:48:22 GMT
   Content-Type: application/cdni; ptype=ci-trigger-collection
   {
       "staleresourcetime": 86400,
       "triggers": [
           "https://dcdn.example.com/triggers/0",
           "https://dcdn.example.com/triggers/1"
       ]
   }

6.2.5. Deleting Trigger Status Resources

 The uCDN can delete completed and failed Trigger Status Resources to
 reduce the size of the collections, as described in Section 4.4.  For
 example, to delete the "preposition" request from earlier examples:
 REQUEST:
   DELETE /triggers/0 HTTP/1.1
   User-Agent: example-user-agent/0.1
   Host: dcdn.example.com
   Accept: */*
 RESPONSE:
   HTTP/1.1 204 No Content
   Date: Wed, 04 May 2016 08:48:22 GMT
   Content-Length: 0
   Content-Type: text/html; charset=UTF-8
   Server: example-server/0.1

Murray & Niven-Jenkins Standards Track [Page 38] RFC 8007 CDN Interconnect Triggers December 2016

 This would, for example, cause the collection of completed Trigger
 Status Resources shown in the example above to be updated to:
 REQUEST:
   GET /triggers/complete HTTP/1.1
   User-Agent: example-user-agent/0.1
   Host: dcdn.example.com
   Accept: */*
 RESPONSE:
   HTTP/1.1 200 OK
   Content-Length: 105
   Expires: Wed, 04 May 2016 08:49:22 GMT
   Server: example-server/0.1
   ETag: "-6938620031669085677"
   Cache-Control: max-age=60
   Date: Wed, 04 May 2016 08:48:22 GMT
   Content-Type: application/cdni; ptype=ci-trigger-collection
   {
       "staleresourcetime": 86400,
       "triggers": [
           "https://dcdn.example.com/triggers/1"
       ]
   }

6.2.6. Error Reporting

 In this example, the uCDN has requested pre-positioning of
 "https://newsite.example.com/index.html", but the dCDN was unable to
 locate metadata for that site:
 REQUEST:
   GET /triggers/2 HTTP/1.1
   User-Agent: example-user-agent/0.1
   Host: dcdn.example.com
   Accept: */*

Murray & Niven-Jenkins Standards Track [Page 39] RFC 8007 CDN Interconnect Triggers December 2016

 RESPONSE:
   HTTP/1.1 200 OK
   Content-Length: 486
   Expires: Wed, 04 May 2016 08:49:26 GMT
   Server: example-server/0.1
   ETag: "5182824839919043757"
   Cache-Control: max-age=60
   Date: Wed, 04 May 2016 08:48:26 GMT
   Content-Type: application/cdni; ptype=ci-trigger-status
   {
       "ctime": 1462351702,
       "errors": [
           {
               "content.urls": [
                   "https://newsite.example.com/index.html"
               ],
               "description": "newsite.example.com not in HostIndex",
               "error": "emeta"
           }
       ],
       "etime": 1462351710,
       "mtime": 1462351706,
       "status": "active",
       "trigger": {
           "content.urls": [
               "https://newsite.example.com/index.html"
           ],
           "type": "preposition"
       }
   }

7. IANA Considerations

7.1. CDNI Payload Type Parameter Registrations

 The IANA is requested to register the following new Payload Types in
 the "CDNI Payload Types" registry defined by [RFC7736], for use with
 the "application/cdni" MIME media type.
               +-----------------------+---------------+
               | Payload Type          | Specification |
               +-----------------------+---------------+
               | ci-trigger-command    | RFC 8007      |
               | ci-trigger-status     | RFC 8007      |
               | ci-trigger-collection | RFC 8007      |
               +-----------------------+---------------+

Murray & Niven-Jenkins Standards Track [Page 40] RFC 8007 CDN Interconnect Triggers December 2016

7.2. "CDNI CI/T Trigger Types" Registry

 The IANA is requested to create a new "CDNI CI/T Trigger Types"
 subregistry under the "Content Delivery Network Interconnection
 (CDNI) Parameters" registry.
 Additions to the "CDNI CI/T Trigger Types" registry will be made via
 the RFC Required policy as defined in [RFC5226].
 The initial contents of the "CDNI CI/T Trigger Types" registry
 comprise the names and descriptions listed in Section 5.2.2 of this
 document, with this document acting as the specification.

7.3. "CDNI CI/T Error Codes" Registry

 The IANA is requested to create a new "CDNI CI/T Error Codes"
 subregistry under the "Content Delivery Network Interconnection
 (CDNI) Parameters" registry.
 Additions to the "CDNI CI/T Error Codes" registry will be made via
 the Specification Required policy as defined in [RFC5226].  The
 Designated Expert will verify that new Error Code registrations do
 not duplicate existing Error Code definitions (in name or
 functionality), prevent gratuitous additions to the namespace, and
 prevent any additions to the namespace that would impair the
 interoperability of CDNI implementations.
 The initial contents of the "CDNI CI/T Error Codes" registry comprise
 the names and descriptions of the Error Codes listed in Section 5.2.7
 of this document, with this document acting as the specification.

8. Security Considerations

 The CI/T interface provides a mechanism to allow a uCDN to generate
 requests into the dCDN and to inspect its own CI/T requests and their
 current states.  The CI/T interface does not allow access to, or
 modification of, the uCDN or dCDN metadata relating to content
 delivery or to the content itself.  It can only control the presence
 of that metadata in the dCDN, and the processing work and network
 utilization involved in ensuring that presence.
 By examining "preposition" requests to a dCDN, and correctly
 interpreting content and metadata URLs, an attacker could learn the
 uCDN's or content owner's predictions for future content popularity.
 By examining "invalidate" or "purge" requests, an attacker could
 learn about changes in the content owner's catalog.

Murray & Niven-Jenkins Standards Track [Page 41] RFC 8007 CDN Interconnect Triggers December 2016

 By injecting CI/T Commands, an attacker or a misbehaving uCDN would
 generate work in the dCDN and uCDN as they process those requests.
 So would a man-in-the-middle attacker modifying valid CI/T Commands
 generated by the uCDN.  In both cases, that would decrease the dCDN's
 caching efficiency by causing it to unnecessarily acquire or
 reacquire content metadata and/or content.
 A dCDN implementation of CI/T MUST restrict the actions of a uCDN to
 the data corresponding to that uCDN.  Failure to do so would allow
 uCDNs to detrimentally affect each other's efficiency by generating
 unnecessary acquisition or reacquisition load.
 An origin that chooses to delegate its delivery to a CDN is trusting
 that CDN to deliver content on its behalf; the interconnection of
 CDNs is an extension of that trust to dCDNs.  That trust relationship
 is a commercial arrangement, outside the scope of the CDNI protocols.
 So, while a malicious CDN could deliberately generate load on a dCDN
 using the CI/T interface, the protocol does not otherwise attempt to
 address malicious behavior between interconnected CDNs.

8.1. Authentication, Authorization, Confidentiality, Integrity

    Protection
 A CI/T implementation MUST support Transport Layer Security (TLS)
 transport for HTTP (HTTPS) as per [RFC2818] and [RFC7230].
 TLS MUST be used by the server side (dCDN) and the client side (uCDN)
 of the CI/T interface, including authentication of the remote end,
 unless alternate methods are used for ensuring the security of the
 information in the CI/T interface requests and responses (such as
 setting up an IPsec tunnel between the two CDNs or using a physically
 secured internal network between two CDNs that are owned by the same
 corporate entity).
 The use of TLS for transport of the CI/T interface allows the dCDN
 and the uCDN to authenticate each other using TLS client
 authentication and TLS server authentication.

Murray & Niven-Jenkins Standards Track [Page 42] RFC 8007 CDN Interconnect Triggers December 2016

 Once the dCDN and the uCDN have mutually authenticated each other,
 TLS allows:
 o  The dCDN and the uCDN to authorize each other (to ensure that they
    are receiving CI/T Commands from, or reporting status to, an
    authorized CDN).
 o  CDNI commands and responses to be transmitted with
    confidentiality.
 o  Protection of the integrity of CDNI commands and responses.
 When TLS is used, the general TLS usage guidance in [RFC7525] MUST be
 followed.
 The mechanisms for access control are dCDN-specific and are not
 standardized as part of this CI/T specification.
 HTTP requests that attempt to access or operate on CI/T data
 belonging to another CDN MUST be rejected using, for example,
 HTTP 403 ("Forbidden") or 404 ("Not Found").  This is intended to
 prevent unauthorized users from generating unnecessary load in dCDNs
 or uCDNs due to revalidation, reacquisition, or unnecessary
 acquisition.
 When deploying a network of interconnected CDNs, the possible
 inefficiencies related to the diamond configuration discussed in
 Section 2.2.1 should be considered.

8.2. Denial of Service

 This document does not define a specific mechanism to protect against
 Denial-of-Service (DoS) attacks on the CI/T interface.  However, CI/T
 endpoints can be protected against DoS attacks through the use of TLS
 transport and/or via mechanisms outside the scope of the CI/T
 interface, such as firewalling or the use of Virtual Private Networks
 (VPNs).
 Depending on the implementation, triggered activity may consume
 significant processing and bandwidth in the dCDN.  A malicious or
 faulty uCDN could use this to generate unnecessary load in the dCDN.
 The dCDN should consider mechanisms to avoid overload -- for example,
 by rate-limiting acceptance or processing of CI/T Commands, or by
 performing batch processing.

Murray & Niven-Jenkins Standards Track [Page 43] RFC 8007 CDN Interconnect Triggers December 2016

8.3. Privacy

 The CI/T protocol does not carry any information about individual end
 users of a CDN; there are no privacy concerns for end users.
 The CI/T protocol does carry information that could be considered
 commercially sensitive by CDN operators and content owners.  The use
 of mutually authenticated TLS to establish a secure session for the
 transport of CI/T data, as discussed in Section 8.1, provides
 confidentiality while the CI/T data is in transit and prevents
 parties other than the authorized dCDN from gaining access to that
 data.  The dCDN MUST ensure that it only exposes CI/T data related to
 a uCDN to clients it has authenticated as belonging to that uCDN.

9. References

9.1. Normative References

 [RFC1930]  Hawkinson, J. and T. Bates, "Guidelines for creation,
            selection, and registration of an Autonomous System (AS)",
            BCP 6, RFC 1930, DOI 10.17487/RFC1930, March 1996,
            <http://www.rfc-editor.org/info/rfc1930>.
 [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
            Requirement Levels", BCP 14, RFC 2119,
            DOI 10.17487/RFC2119, March 1997,
            <http://www.rfc-editor.org/info/rfc2119>.
 [RFC2818]  Rescorla, E., "HTTP Over TLS", RFC 2818,
            DOI 10.17487/RFC2818, May 2000,
            <http://www.rfc-editor.org/info/rfc2818>.
 [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>.
 [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>.
 [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>.

Murray & Niven-Jenkins Standards Track [Page 44] RFC 8007 CDN Interconnect Triggers December 2016

 [RFC7159]  Bray, T., Ed., "The JavaScript Object Notation (JSON) Data
            Interchange Format", RFC 7159, DOI 10.17487/RFC7159,
            March 2014, <http://www.rfc-editor.org/info/rfc7159>.
 [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>.
 [RFC7231]  Fielding, R., Ed., and J. Reschke, Ed., "Hypertext
            Transfer Protocol (HTTP/1.1): Semantics and Content",
            RFC 7231, DOI 10.17487/RFC7231, June 2014,
            <http://www.rfc-editor.org/info/rfc7231>.
 [RFC7232]  Fielding, R., Ed., and J. Reschke, Ed., "Hypertext
            Transfer Protocol (HTTP/1.1): Conditional Requests",
            RFC 7232, DOI 10.17487/RFC7232, June 2014,
            <http://www.rfc-editor.org/info/rfc7232>.
 [RFC7525]  Sheffer, Y., Holz, R., and P. Saint-Andre,
            "Recommendations for Secure Use of Transport Layer
            Security (TLS) and Datagram Transport Layer Security
            (DTLS)", BCP 195, RFC 7525, DOI 10.17487/RFC7525,
            May 2015, <http://www.rfc-editor.org/info/rfc7525>.
 [RFC8006]  Niven-Jenkins, B., Murray, R., Caulfield, M., and K. Ma,
            "Content Delivery Network Interconnection (CDNI)
            Metadata", RFC 8006, DOI 10.17487/RFC8006, December 2016,
            <http://www.rfc-editor.org/info/rfc8006>.

9.2. Informative References

 [CBOR-CDDL]
            Vigano, C. and H. Birkholz, "CBOR data definition language
            (CDDL): a notational convention to express CBOR data
            structures", Work in Progress,
            draft-greevenbosch-appsawg-cbor-cddl-09, September 2016.
 [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>.
 [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>.

Murray & Niven-Jenkins Standards Track [Page 45] RFC 8007 CDN Interconnect Triggers December 2016

 [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>.
 [RFC7975]  Niven-Jenkins, B., Ed., and R. van Brandenburg, Ed.,
            "Request Routing Redirection Interface for Content
            Delivery Network (CDN) Interconnection", RFC 7975,
            DOI 10.17487/RFC7975, October 2016,
            <http://www.rfc-editor.org/info/rfc7975>.

Murray & Niven-Jenkins Standards Track [Page 46] RFC 8007 CDN Interconnect Triggers December 2016

Appendix A. Formalization of the JSON Data

 This appendix is non-normative.
 The JSON data described in this document has been formalized using
 the CBOR Data Definition Language (CDDL) [CBOR-CDDL] (where "CBOR"
 means "Concise Binary Object Representation"), as follows:

CIT-object = CIT-command / Trigger-Status-Resource / Trigger-Collection

CIT-command ; use media type application/cdni; ptype=ci-trigger-command = {

 ? trigger: Triggerspec
 ? cancel: [* URI]
 cdn-path: [* Cdn-PID]

}

Trigger-Status-Resource ; application/cdni; ptype=ci-trigger-status = {

 trigger: Triggerspec
 ctime: Absolute-Time
 mtime: Absolute-Time
 ? etime: Absolute-Time
 status: Trigger-Status
 ? errors: [* Error-Description]

}

Trigger-Collection ; application/cdni; ptype=ci-trigger-collection = {

 triggers: [* URI]
 ? staleresourcetime: int ; time in seconds
 ? coll-all: URI
 ? coll-pending: URI
 ? coll-active: URI
 ? coll-complete: URI
 ? coll-failed: URI
 ? cdn-id: Cdn-PID

}

Triggerspec = { ; see Section 5.2.1

 type: Trigger-Type
 ? metadata.urls: [* URI]
 ? content.urls: [* URI]
 ? content.ccid: [* Ccid]
 ? metadata.patterns: [* Pattern-Match]
 ? content.patterns: [* Pattern-Match]

}

Murray & Niven-Jenkins Standards Track [Page 47] RFC 8007 CDN Interconnect Triggers December 2016

Trigger-Type = "preposition" / "invalidate"

  / "purge" ; see Section 5.2.2

Trigger-Status = "pending" / "active" / "complete" / "processed"

  / "failed" / "cancelling" / "cancelled" ; see Section 5.2.3

Pattern-Match = { ; see Section 5.2.4

 pattern: tstr
 ? case-sensitive: bool
 ? match-query-string: bool

}

Absolute-Time = number ; seconds since UNIX epoch (Section 5.2.5)

Error-Description = { ; see Section 5.2.6

 error: Error-Code
 ? metadata.urls: [* URI]
 ? content.urls: [* URI]
 ? metadata.patterns: [* Pattern-Match]
 ? content.patterns: [* Pattern-Match]
 ? description: tstr

}

Error-Code = "emeta" / "econtent" / "eperm" / "ereject"

  / "ecdn" / "ecanceled"  ; see Section 5.2.7

Ccid = tstr ; see RFC 8006

Cdn-PID = tstr .regexp "AS[0-9]+:[0-9]+"

URI = tstr

Murray & Niven-Jenkins Standards Track [Page 48] RFC 8007 CDN Interconnect Triggers December 2016

Acknowledgments

 The authors thank Kevin Ma for his input, and Carsten Bormann for his
 review and formalization of the JSON data.

Authors' Addresses

 Rob Murray
 Nokia
 3 Ely Road
 Milton, Cambridge  CB24 6DD
 United Kingdom
 Email: rob.murray@nokia.com
 Ben Niven-Jenkins
 Nokia
 3 Ely Road
 Milton, Cambridge  CB24 6DD
 United Kingdom
 Email: ben.niven-jenkins@nokia.com

Murray & Niven-Jenkins Standards Track [Page 49]

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