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2	Network Working Group                                       O. Finkelman
3	Internet-Draft                                                     Qwilt
4	Updates: 8007 (if approved)                                    S. Mishra
5	Intended status: Standards Track                                 Verizon
6	Expires: December 22, 2021                                     N. Sopher
7	                                                                   Qwilt
8	                                                           June 20, 2021

10	               CDNI Control Triggers Interface Extensions
11	                 draft-ietf-cdni-triggers-extensions-09

13	Abstract

15	   Open Caching architecture is a use case of Content Delivery Network
16	   Interconnection (CDNI) in which the commercial Content Delivery
17	   Network (CDN) is the upstream CDN (uCDN) and the ISP caching layer
18	   serves as the downstream CDN (dCDN).  This document defines
19	   extensions to the Content Delivery Network Interconnection (CDNI)
20	   Control Interface/Triggers defined in RFC 8007.  These extensions are
21	   derived from requirements raised by Open Caching architecture but are
22	   also applicable to CDNI use cases in general.

24	Requirements Language

26	   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
27	   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
28	   document are to be interpreted as described in RFC 2119 [RFC2119].

30	Status of This Memo

32	   This Internet-Draft is submitted in full conformance with the
33	   provisions of BCP 78 and BCP 79.

35	   Internet-Drafts are working documents of the Internet Engineering
36	   Task Force (IETF).  Note that other groups may also distribute
37	   working documents as Internet-Drafts.  The list of current Internet-
38	   Drafts is at https://datatracker.ietf.org/drafts/current/.

40	   Internet-Drafts are draft documents valid for a maximum of six months
41	   and may be updated, replaced, or obsoleted by other documents at any
42	   time.  It is inappropriate to use Internet-Drafts as reference
43	   material or to cite them other than as "work in progress."

45	   This Internet-Draft will expire on December 22, 2021.

47	Copyright Notice

49	   Copyright (c) 2021 IETF Trust and the persons identified as the
50	   document authors.  All rights reserved.

52	   This document is subject to BCP 78 and the IETF Trust's Legal
53	   Provisions Relating to IETF Documents
54	   (https://trustee.ietf.org/license-info) in effect on the date of
55	   publication of this document.  Please review these documents
56	   carefully, as they describe your rights and restrictions with respect
57	   to this document.  Code Components extracted from this document must
58	   include Simplified BSD License text as described in Section 4.e of
59	   the Trust Legal Provisions and are provided without warranty as
60	   described in the Simplified BSD License.

62	Table of Contents

64	   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
65	     1.1.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   4
66	     1.2.  Structure of this document  . . . . . . . . . . . . . . .   4
67	   2.  Interfaces Extensions Overview  . . . . . . . . . . . . . . .   5
68	     2.1.  CDNI Control Interface / Triggers Extensions  . . . . . .   5
69	       2.1.1.  CI/T Objects  . . . . . . . . . . . . . . . . . . . .   5
70	       2.1.2.  Trigger Specification . . . . . . . . . . . . . . . .   5
71	       2.1.3.  Content Selection . . . . . . . . . . . . . . . . . .   5
72	       2.1.4.  Trigger Extensibility . . . . . . . . . . . . . . . .   6
73	       2.1.5.  Error Handling  . . . . . . . . . . . . . . . . . . .   6
74	     2.2.  CDNI Footprint and Capabilities Interface Extensions  . .   7
75	   3.  CI/T Version 2  . . . . . . . . . . . . . . . . . . . . . . .   7
76	     3.1.  CI/T Objects V2 . . . . . . . . . . . . . . . . . . . . .   7
77	     3.2.  Error Handling V2 . . . . . . . . . . . . . . . . . . . .  10
78	       3.2.1.  Extension Errors  . . . . . . . . . . . . . . . . . .  10
79	       3.2.2.  Error propagation . . . . . . . . . . . . . . . . . .  11
80	     3.3.  Properties of CI/T Version 2 objects  . . . . . . . . . .  13
81	       3.3.1.  Trigger Specification Version 2 . . . . . . . . . . .  14
82	       3.3.2.  RegexMatch  . . . . . . . . . . . . . . . . . . . . .  15
83	       3.3.3.  Playlist  . . . . . . . . . . . . . . . . . . . . . .  16
84	       3.3.4.  MediaProtocol . . . . . . . . . . . . . . . . . . . .  17
85	       3.3.5.  CI/T Trigger Extensions . . . . . . . . . . . . . . .  17
86	         3.3.5.1.  Enforcement Options . . . . . . . . . . . . . . .  17
87	         3.3.5.2.  GenericExtensionObject  . . . . . . . . . . . . .  20
88	       3.3.6.  Error Description Version 2 . . . . . . . . . . . . .  22
89	       3.3.7.  Error codes . . . . . . . . . . . . . . . . . . . . .  24
90	     3.4.  Examples  . . . . . . . . . . . . . . . . . . . . . . . .  24
91	       3.4.1.  Invalidation with Regex . . . . . . . . . . . . . . .  24
92	       3.4.2.  Preposition with Playlists  . . . . . . . . . . . . .  26
93	       3.4.3.  Extensions with Error Propagation . . . . . . . . . .  27
94	   4.  Trigger Extension Objects . . . . . . . . . . . . . . . . . .  29
95	     4.1.  LocationPolicy extension  . . . . . . . . . . . . . . . .  29
96	     4.2.  TimePolicy Extension  . . . . . . . . . . . . . . . . . .  31
97	       4.2.1.  UTCWindow . . . . . . . . . . . . . . . . . . . . . .  33
98	       4.2.2.  LocalTimeWindow . . . . . . . . . . . . . . . . . . .  34
99	       4.2.3.  DateLocalTime . . . . . . . . . . . . . . . . . . . .  35
100	         4.2.3.1.  Date and Local Time Format  . . . . . . . . . . .  35
101	         4.2.3.2.  Restrictions  . . . . . . . . . . . . . . . . . .  36
102	   5.  Footprint and Capabilities  . . . . . . . . . . . . . . . . .  36
103	     5.1.  CI/T Versions Capability Object . . . . . . . . . . . . .  36
104	       5.1.1.  CI/T Versions Capability Object Serialization . . . .  37
105	     5.2.  CI/T Playlist Protocol Capability Object  . . . . . . . .  37
106	       5.2.1.  CI/T Playlist Protocol Capability Object
107	               Serialization . . . . . . . . . . . . . . . . . . . .  37
108	     5.3.  CI/T Trigger Extension Capability Object  . . . . . . . .  38
109	       5.3.1.  CI/T Trigger Extension Capability Object
110	               Serialization . . . . . . . . . . . . . . . . . . . .  38
111	   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  39
112	     6.1.  CDNI Payload Types  . . . . . . . . . . . . . . . . . . .  39
113	       6.1.1.  CDNI ci-trigger-command.v2 Payload Type . . . . . . .  39
114	       6.1.2.  CDNI ci-trigger-status.v2 Payload Type  . . . . . . .  40
115	       6.1.3.  CDNI CI/T LocationPolicy Trigger Extension Type . . .  40
116	       6.1.4.  CDNI CI/T TimePolicy Trigger Extension Type . . . . .  40
117	       6.1.5.  CDNI FCI CI/T Versions Payload Type . . . . . . . . .  40
118	       6.1.6.  CDNI FCI CI/T Playlist Protocol Payload Type  . . . .  40
119	       6.1.7.  CDNI FCI CI/T Extension Objects Payload Type  . . . .  41
120	     6.2.  CDNI CI/T Trigger Error Codes types . . . . . . . . . . .  41
121	     6.3.  CDNI Media protocol types . . . . . . . . . . . . . . . .  41
122	   7.  Security Considerations . . . . . . . . . . . . . . . . . . .  42
123	   8.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .  42
124	   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  42
125	     9.1.  Normative References  . . . . . . . . . . . . . . . . . .  42
126	     9.2.  Informative References  . . . . . . . . . . . . . . . . .  44
127	   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  44

129	1.  Introduction

131	   The Streaming Video Alliance [SVA] is a global association that works
132	   to solve streaming video challenges in an effort to improve end-user
133	   experience and adoption.  The Open Caching Working Group [OCWG] of
134	   the Streaming Video Alliance [SVA] is focused on the delegation of
135	   video delivery requests from commerical CDNs to a caching layer at
136	   the ISP's network.  Open Caching architecture is a specific use case
137	   of CDNI where the commercial CDN is the upstream CDN (uCDN) and the
138	   ISP caching layer is the downstream CDN (dCDN).  The Open Caching
139	   Content Management Operations Specification [OC-CM] defines objects
140	   and extensions required by Open Caching architecture for granular
141	   content management operations.  This document adds those extensions
142	   to the CDNI Control Interface / Triggers [RFC8007] as required for
143	   Open Caching content management options.  This document also
144	   specifies a generic extension mechanism to enable adding future
145	   functions for controlling the trigger execution>.

147	   The CDNI Metadata Interface is described in [RFC8006].

149	   The CDNI Footprint and Capability Interface is described in
150	   [RFC8008].

152	   The CDNI Control Interface / Triggers is described in [RFC8007].

154	   For consistency with other CDNI documents, this document follows the
155	   CDNI convention of uCDN (upstream CDN) and dCDN (downstream CDN) as
156	   described in [RFC6707] to represent the commercial CDN and ISP
157	   caching layer, respectively.

159	1.1.  Terminology

161	   This document reuses the terminology defined in [RFC6707], [RFC7736]
162	   [RFC8006], [RFC8007], and [RFC8008].

164	   Additionally, the following terms are used throughout this document
165	   and are defined as follows:

167	   o  HLS - HTTP Live Streaming

169	   o  DASH - Dynamic Adaptive Streaming Over HTTP

171	   o  MSS - Microsoft Smooth Streaming

173	1.2.  Structure of this document

175	   The remainder of this document is organized as follows:

177	   o  Section 2 gives an overview of the extensions specified in this
178	      document.

180	   o  Section 3 specifies version 2 of the CDNI Control Interface /
181	      Triggers.

183	   o  Section 4 specifies an initial set of trigger extension objects.

185	   o  Section 5 specifies Footprint and Capability objects for CI/T
186	      version and extensions.

188	   o  Section 6 list the IANA considerations of this document.

190	   o  Section 7 describes the security considerations for the specified
191	      properties and extensions.

193	2.  Interfaces Extensions Overview

195	   This document defines extensions for the CDNI Control Interface /
196	   Triggers (CI/T) [RFC8007] and defines FCI objects as per the CDNI
197	   Footprint and Capabilities Interface [RFC8008].

199	2.1.  CDNI Control Interface / Triggers Extensions

201	2.1.1.  CI/T Objects

203	   This document specifies version 2 of the CI/T commands and objects.
204	   In this context the CI/T commands and objects as were specified in
205	   [RFC8007] are considered to be version 1.

207	2.1.2.  Trigger Specification

209	   This document specifies version 2 of the Trigger Specification which
210	   is an enhancement of the Trigger Specification that includes all
211	   properties as defined in Section 5.2.1 of [RFC8007] as well as the
212	   additional properties required by the use cases listed below in
213	   Section 2.1.3 and Section 2.1.4.

215	2.1.3.  Content Selection

217	   The trigger specification as defined in Section 5.2.1 of [RFC8007]
218	   provides means to select content objects by matching a full content
219	   URL or patterns with wildcards.  This document specifies two
220	   additional selection options:

222	   o  Regular Expression - Using regex, a uCDN can create more complex
223	      rules to select the content objects for the cases of
224	      "invalidation" and "purge".  For example, purging specific content
225	      within a specific directory path.

227	   o  Content Playlist - Using video playlist files, a uCDN can trigger
228	      an operation that will be applied to a collection of distinct
229	      media files in a format that is natural for a streaming video
230	      content provider.  A playlist may have several formats,
231	      specifically HTTP Live Streaming (HLS) *.m3u8 manifest [RFC8216],
232	      Microsoft Smooth Streaming (MSS) *.ismc client manifest [MSS], and
233	      Dynamic Adaptive Streaming over HTTP (DASH) *.mpd file [ISO/IEC
234	      23009-1:2014] [MPEG-DASH].

236	2.1.4.  Trigger Extensibility

238	   The CDNI Control Interface / Triggers [RFC8007] defines a set of
239	   properties and objects used by the trigger commands.  In this
240	   document we define an extension mechanism to the triggers interface
241	   that enables the application to add various functions that allow
242	   finer control over the trigger execution.  This document specifies a
243	   generic trigger extension object wrapper for managing individual CDNI
244	   trigger extensions in an opaque manner.

246	   This document also registers CDNI Payload Types [RFC7736] under the
247	   namespace CIT for the initial set of trigger extension types:

249	   o  CIT.LocationPolicy (for controlling the locations in which the
250	      trigger is executed)

252	   o  CIT.TimePolicy (for scheduling a trigger to run in a specific time
253	      window)

255	   Example use cases

257	   o  Pre-position with cache location policy

259	   o  Purge content with cache location policy

261	   o  Pre-position at a specific time

263	   o  Purge by content acquisition time (e.g. purge all content acquired
264	      in the past X hours)

266	2.1.5.  Error Handling

268	   This document extends the CI/T Error Handling (see Section 4.7 of
269	   [RFC8007]) to support the following:

271	   o  Playlists and Regexs - report errors that happened due to specific
272	      playlists and/or regexs.

274	   o  Extension errors - report an error that happened due to an
275	      extension object.

277	   o  Error propagation - enable the uCDN to traceback an error to the
278	      dCDN in which it occurred.

280	2.2.  CDNI Footprint and Capabilities Interface Extensions

282	   Extending the trigger mechanism with optional properties requires the
283	   ability for the dCDN to advertise which optional properties it
284	   supports.

286	   The CDNI Footprint and Capabilities Interface [RFC8008] enables the
287	   dCDN to advertise the capabilities it supports across different
288	   footprints.  This document introduces FCI objects to support the
289	   advertisement of these optional properties.

291	   Example use cases

293	   o  Trigger types: Advertise which trigger types are supported by the
294	      dCDN.  CDNI defines three trigger types (purge, invalidate, pre-
295	      position), but it does not necessarily mean that all dCDNs support
296	      all of them.  The uCDN may prefer to work only with dCDN that
297	      support what the uCDN needs.

299	   o  Content selection rule types: Advertise which selection types are
300	      supported.  For example, if adding content regex as a means to
301	      match on content URLs, not all dCDN would support it.  For
302	      playlist mapping, advertise which types and versions of protocols
303	      are supported, e.g.  HLS.vX/DASH.vY/MSS.vX, DASH templates.  Note
304	      that the version string or schema are protocol specific.

306	   o  Trigger extensions: Advertise which trigger extensions object
307	      types are supported by the dCDN.

309	3.  CI/T Version 2

311	   [RFC8007] does not define a version number and versioning scheme.
312	   We, therefore, designate the interface and objects as defined in
313	   Section 5 of [RFC8007] as version 1.  The following sections define
314	   version 2 of the CI/T objects and their properties as extensions of
315	   version 1.

317	3.1.  CI/T Objects V2

319	   Version 2 of the CI/T interface requires the support of the following
320	   objects:

322	   o  CI/T Commands v2: A trigger command request using the payload type
323	      ci-trigger-command.v2.  Version 2 MUST only use "trigger.v2"
324	      objects as defined in Section 3.3.1, instead of "trigger" objects.
325	      All other properties of the trigger command v2 are as defined in
326	      Section 5.1.1 of [RFC8007].

328	   o  Trigger Status Resource v2: A trigger status resource response
329	      using the payload type ci-trigger-status.v2.  Version 2 MUST only
330	      use "trigger.v2" objects as defined in Section 3.3.1, instead of a
331	      "trigger" object, as well as "errors.v2" array as defined in
332	      Section 3.3.6, instead of a "errors" array.  All other properties
333	      of the trigger status v2 are as defined in Section 5.1.2 of
334	      [RFC8007].  The errors array "errors.v2" is a list of all errors
335	      that occurred in any of the downstream CDNs along the execution
336	      path.  When a downstream CDN, dCDN-A, propagates a trigger to
337	      another downstream CDN, dCDN-B, it MUST also propagate back all
338	      errors reported by dCDN-B in the trigger status resource and add
339	      them to its own trigger status resource.

341	   o  Trigger Collections: The payload type ci-trigger-collection is
342	      used with no changes and as defined in 5.1.3 of [RFC8007].

344	   Usage example of version 2 of trigger command
345	   REQUEST:

347	     POST /triggers HTTP/1.1
348	     User-Agent: example-user-agent/0.1
349	     Host: triggers.dcdn.example.com
350	     Accept: */*
351	     Content-Type: application/cdni; ptype=ci-trigger-command.v2
352	     {
353	       "trigger.v2": { <properties of a trigger.v2 object> },
354	       "cdn-path": [ "AS64496:0" ]
355	     }

357	   RESPONSE:

359	     HTTP/1.1 201 Created
360	     Date: Wed, 04 May 2016 08:48:10 GMT
361	     Content-Length: 467
362	     Content-Type: application/cdni; ptype=ci-trigger-status.v2
363	     Location: https://triggers.dcdn.example.com/triggers/0
364	     Server: example-server/0.1

366	     {
367	        "errors.v2": [ { <properties of 1st error.v2 object> },
368	                         ...,
369	                       { <properties of Nth error.v2 object> }
370	        ],
371	        "ctime": 1462351690,
372	        "etime": 1462351698,
373	        "mtime": 1462351690,
374	        "status": "pending",
375	        "trigger.v2": { <properties of a trigger.v2 object> }
376	     }

378	   Usage example of version 2 of trigger status for the trigger created
379	   in the above trigger command example:

381	   REQUEST:

383	     GET /triggers/0 HTTP/1.1
384	     User-Agent: example-user-agent/0.1
385	     Host: triggers.dcdn.example.com
386	     Accept: */*

388	   RESPONSE:

390	     HTTP/1.1 200 OK
391	     Content-Length: 467
392	     Expires: Wed, 04 May 2016 08:49:10 GMT
393	     Server: example-server/0.1
394	     ETag: "6990548174277557683"
395	     Cache-Control: max-age=60
396	     Date: Wed, 04 May 2016 08:48:10 GMT
397	     Content-Type: application/cdni; ptype=ci-trigger-status.v2

399	     {
400	        "errors.v2": [ { <properties of 1st error.v2 object> },
401	                         ...,
402	                       { <properties of Nth error.v2 object> }
403	        ],
404	        "ctime": 1462351690,
405	        "etime": 1462351698,
406	        "mtime": 1462351690,
407	        "status": "pending",
408	        "trigger.v2": { <properties of a trigger.v2 object> }
409	     }

411	3.2.  Error Handling V2

413	   The CDNI CI/T interface defines a mechanism for error reporting (see
414	   Section 4.7 of [RFC8007]) and an Error Description object for
415	   reporting errors (see Section 5.2.6 of [RFC8007]).  This document
416	   specifies version 2 of CI/T error handling in order to support the
417	   following:

419	3.2.1.  Extension Errors

421	   Report an error that occures due to an extension object.  As
422	   extension objects are expected to be added to the interface whenever
423	   new requirement comes along, it is expected that in some cases a dCDN
424	   may receive a trigger that it cannot process or it does not
425	   understand.  It is therefore essential for the trigger caller to be
426	   able to know when such errors occur so they can take actions to fix
427	   them.  This document adds a mechanism to report extension errors.

429	3.2.2.  Error propagation

431	   This subsection explains the mechanism for enabling the uCDN to
432	   traceback an error to the dCDN in which it occurred.  CDNI triggers
433	   may be propagated over a chain of downstream CDNs.  For example, an
434	   upstream CDN A (uCDN-A) that is delegating to a downstream CDN B
435	   (dCDN-B) and dCDN-B is delegating to a downstream CDN C (dCDN-C).
436	   Triggers sent from uCDN-A to dCDN-B may be redistributed from dCDN-B
437	   to dCDN-C and errors can occur anywhere along the path.  Therefore,
438	   it might be essential for uCDN-A that sets the trigger, to be able to
439	   trace back an error to the downstream CDN where it occurred.  This
440	   document adds a mechanism to propagate the CDN Provider ID (PID) of
441	   the dCDN where the fault occured, back to the uCDN by adding the PID
442	   to the error description.  When dCDN-B propagates a trigger to the
443	   further downstream dCDN-C, it MUST also propagate back the errors
444	   received in the trigger status resource from dCDN-C by adding them to
445	   the errors array in its own status resource to be sent back to the
446	   originating uCDN-A.  While propagating back the errors, and depending
447	   on the implementation, dCDN-B MAY also specify the dCDN-C PID,
448	   indicating to which CDN the error relates spefically.  The trigger
449	   originating upstream CDN will receive an array of errors that
450	   occurred in all the CDNs along the execution path, where each error
451	   MAY be carrying its own CDN identifier.

453	   Figure 1 below is an example showing the message flow used by uCDN-A
454	   to trigger activity in the dCDN-B, followed by dCDN-C, as well as the
455	   discovery of the status of that activity, including the Error
456	   Propagation.

458	   uCDN-A                         dCDN-B                         dCDN-C
459	    |                              |                              |
460	    | (1) POST                     |                              |
461	    | https://dcdn-b.example.com   |                              |
462	    | /triggers/uCDN-A             |                              |
463	   [ ]--------------------------->[ ]--+                          |
464	    |                             [ ]  | (2)                      |
465	    |                             [ ]<-+                          |
466	    | (3) HTTP 201 Response.      [ ]                             |
467	    |<----------------------------[ ]                             |
468	    | Loc:                        [ ]                             |
469	    | https://dcdn-b.example.com  [ ] (4) POST                    |
470	    | /triggers/uCDN-A/123        [ ] https://dcdn-c.example.com  |
471	    |                             [ ] /triggers/uCDN-A            | (5)
472	    |                             [ ]--------------------------->[ ]--+
473	    |                              |                             [ ]  |
474	    |                              |                             [ ]<-+
475	    |                              | (6) HTTP 201 Response.      [ ]
476	    |                             [ ]<---------------------------[ ]
477	    |                              |  Loc:                        |
478	    |                              |  https://dcdn-c.example.com  |
479	    |                              |  /triggers/dCDN-B/456        |
480	    |                              |                              |
481	    |                             [ ]--+                          |
482	    |                             [ ]  | (7.1)                    |
483	    |                             [ ]<-+                         [ ]--+
484	    |                              |                       (7.2) [ ]  |
485	    |                              |                             [ ]<-+
486	    |                              |                              |
487	    .                              .                              .
488	    .                              .                              .
489	    .                              .                              .
490	    |                              | (8) GET                      |
491	    |                              | https://dcdn-c.example.com   |
492	    |                              | /triggers/dCDN-B/456         |
493	    |                             [ ]--------------------------->[ ]
494	    |                              |                             [ ]
495	    |                              | (9) HTTP 200                [ ]
496	    |                              | Trigger Status Resource     [ ]
497	    |                             [ ]<---------------------------[ ]
498	    |                              |                              |
499	    .                              .                              .
500	    .                              .                              .
501	    .                              .                              .
502	    | (10) GET                     |                              |
503	    | https://dcdn-b.example.com   |                              |
504	    | /triggers/uCDN-A/123         |                              |
505	   [ ]--------------------------->[ ]                             |
506	    |                             [ ]                             |
507	    | (11) HTTP 200               [ ]                             |
508	    | Trigger Status Resource     [ ]                             |
509	   [ ]<---------------------------[ ]                             |

511	   Figure 1: CDNI Message Flow for Triggers, Including Error Propagation

513	   The steps in Figure 1 are as follows:

515	   1.   The uCDN-A triggers action in the dCDN-B by POSTing a CI/T
516	        Command to a collection of Trigger Status Resources
517	        "https://dcdn-b.example.com/triggers/uCDN-A".  This URL was
518	        given to the uCDN-A when the CI/T interface was established.

520	   2.   The dCDN-B authenticates the request, validates the CI/T
521	        Command, and, if it accepts the request, creates a new Trigger
522	        Status Resource.

524	   3.   The dCDN-B responds to the uCDN-A with an HTTP 201 response
525	        status and the location of the Trigger Status Resource.

527	   4.   The dCDN-B triggers the action in the dCDN-C by POSTing a CI/T
528	        Command to a collection of Trigger Status Resources
529	        "https://dcdn-c.example.com/triggers/dCDN-B".  This URL was
530	        given to the uCDN-A when the CI/T interface was established.

532	   5.   The dCDN-C authenticates the request, validates the CI/T
533	        Command, and, if it accepts the request, creates a new Trigger
534	        Status Resource.

536	   6.   The dCDN-C responds to the dCDN-B with an HTTP 201 response
537	        status and the location of the Trigger Status Resource.

539	   7.   The dCDN-C acts upon the CI/T Command.  However, the command
540	        fails at dCDN-C as, for example, the Tigger Specification
541	        contains a "type" that is not supported by dCDN-C.

543	   8.   The dCDN-B can poll, possibly repeatedly, the Trigger Status
544	        Resource in dCDN-C.

546	   9.   The dCDN-C responds with the Trigger Status Resource, describing
547	        the progress or results of the CI/T Trigger Command.  In the
548	        described flow, the returned Status is "failed", with an Error
549	        Description Object holding an "eunsupported" Error Code
550	        reflecting the status response.

552	   10.  The uCDN-A can poll, possibly repeatedly, the Trigger Status
553	        Resource in dCDN-B.

555	   11.  The dCDN-B responds with the Trigger Status Resource, describing
556	        the progress or results of the CI/T Trigger Command.  In the
557	        flow described above, the returned Status is "failed", and the
558	        "eunsupported" error received in the trigger status resource
559	        from dCDN-C is propagated along with dCDN-C PID by adding it to
560	        the errors array in dCDN-B's own status resource to be sent back
561	        to the originating uCDN-A.

563	3.3.  Properties of CI/T Version 2 objects

565	   This section defines the values that can appear in the top-level
566	   objects described in Section 3.1, and their encodings.

568	3.3.1.  Trigger Specification Version 2

570	   Version 2 of the Trigger Specification adds the following properties
571	   on top of the existing properties of the trigger specification
572	   defined in Section 5.2.1 of [RFC8007].

574	      Property: content.regexs

576	         Description: Regexs of content URLs to which the CI/T trigger
577	         command applies.

579	         Type: A JSON array of RegexMatch objects (see Section 3.3.2).

581	         Mandatory: No, but at least one of "metadata.*" or "content.*"
582	         MUST be present and non-empty.

584	      Property: content.playlists

586	         Description: Playlists of content the CI/T trigger command
587	         applies to.

589	         Type: A JSON array of Playlist objects (see Section 3.3.3).

591	         Mandatory: No, but at least one of "metadata.*" or "content.*"
592	         MUST be present and non-empty.

594	      Property: extensions

596	         Description: Array of trigger extension data.

598	         Type: Array of GenericTriggerExtension objects (see
599	         Section 3.3.5.2).

601	         Mandatory: No.  The default is no extensions.

603	   Example of a JSON serialized invalidation trigger.v2 object with a
604	   list of regex objects, a list of playlist objects, and extensions:

606	   {
607	     "trigger.v2": {
608	       "type": "invalidate",
609	       "content.regexs": [ <list of RegexMatch objects> ],
610	       "content.playlists": [ <list of Playlist objects> ],
611	       "extensions": [ <list of GenericTriggerExtension objects ]
612	     },
613	     "cdn-path": [ "AS64496:0" ]
614	   }

616	3.3.2.  RegexMatch

618	   A RegexMatch consists of a regular expression string a URI is matched
619	   against, and flags describing the type of match.  It is encoded as a
620	   JSON object with following properties:

622	      Property: regex

624	         Description: A regular expression for URI matching.

626	         Type: A regular expression to match against the URI, i.e
627	         against the path-absolute and the query string parameters
628	         [RFC3986].  The regular expression string MUST be compatible
629	         with PCRE [PCRE841].

631	         Note: Because '\' has a special meaning in JSON [RFC8259] as
632	         the escape character within JSON strings, the regular
633	         expression character '\' MUST be escaped as '\\'.

635	         Mandatory: Yes.

637	      Property: case-sensitive

639	         Description: Flag indicating whether or not case-sensitive
640	         matching should be used.

642	         Type: JSON boolean.  Either "true" (the matching is case
643	         sensitive) or "false" (the matching is case insensitive).

645	         Mandatory: No; default is case-insensitive match (i.e., a value
646	         of "false").

648	      Property: match-query-string

650	         Description: Flag indicating whether to include the query part
651	         of the URI when comparing against the regex.

653	         Type: JSON boolean.  Either "true" (the full URI, including the
654	         query part, should be compared against the regex) or "false"
655	         (the query part of the URI should be dropped before comparison
656	         with the given regex).

658	         Mandatory: No; default is "false".  The query part of the URI
659	         MUST be dropped before comparison with the given regex.  This
660	         makes the regular expression simpler and safer for cases in
661	         which the query parameters are not relevant for the match.

663	   Example of a case sensitive, no query parameters, regex match
664	   against:

666	   "^(https:\/\/video\.example\.com)\/([a-z])\/
667	    movie1\/([1-7])\/*(index.m3u8|\d{3}.ts)$"

669	   {
670	     "regex": "^(https:\\/\\/video\\.example\\.com)\\/([a-z])\\/movie1\
671	              \/([1-7])\\/*(index.m3u8|\\d{3}.ts)$",
672	     "case-sensitive": true,
673	     "match-query-string": false
674	   }

676	   This regex matches URLs of domain video.example.com where the path
677	   structure is /(single lower case letter)/(name-of-title)/(single
678	   digit between 1 to 7)/(index.m3u8 or a 3 digit number with ts
679	   extension).  For example:

681	   https://video.example.com/d/movie1/5/index.m3u8
682	   or
683	   https://video.example.com/k/movie1/4/013.ts

685	3.3.3.  Playlist

687	   A Playlist consists of a full URL and a media protocol identifier.
688	   An implementation that supports a specific playlist media protocol
689	   MUST be able to parse playlist files of that protocol type and
690	   extract, possibly recursively, the URLs to all media objects and/or
691	   sub playlist files, and apply the trigger to each one of them
692	   separately.

694	   Playlist is encoded as a JSON object with following properties:

696	      Property: playlist

698	         Description: A URL to the playlist file.

700	         Type: A URL represented as a JSON string.

702	         Mandatory: Yes.

704	      Property: media-protocol

706	         Description: Media protocol to be when parsing and interpreting
707	         this playlist.

709	         Type: MediaProtocol (see Section 3.3.4).

711	         Mandatory: Yes.

713	   Example of a JSON serialized HLS playlist object:

715	   {
716	     "playlist": "https://www.example.com/hls/title/index.m3u8",
717	     "media-protocol": "hls"
718	   }

720	3.3.4.  MediaProtocol

722	   Media Protocol objects are used to specify registered type of media
723	   protocol (see Section 6.3) used for protocol related operations like
724	   pre-position according to playlist.

726	   Type: JSON string

728	   Example:

730	   "dash"

732	3.3.5.  CI/T Trigger Extensions

734	   A "trigger.v2" object, as defined in Section 3.3.1 includes an
735	   optional array of trigger extension objects.  A trigger extension
736	   contain properties that are used as directives for dCDN when
737	   executing the trigger command -- for example, location policies, time
738	   policies and so on.  Each such CDNI Trigger extension is a
739	   specialization of a CDNI GenericTriggerExtension object.  The
740	   GenericTriggerExtension object abstracts the basic information
741	   required for trigger distribution from the specifics of any given
742	   property (i.e., property semantics, enforcement options, etc.).  All
743	   trigger extensions are optional, and it is thus the responsibility of
744	   the extension specification to define a consistent default behavior
745	   for the case the extension is not present.

747	3.3.5.1.  Enforcement Options

749	   The trigger enforcement options concept is in accordance with the
750	   metadata enforcement options as defined in Section 3.2 of [RFC8006].

752	   The GenericTriggerExtension object defines the properties contained
753	   within it as well as whether or not the properties are "mandatory-to-
754	   enforce".  If the dCDN does not understand or support a mandatory-to-
755	   enforce property, the dCDN MUST NOT execute the trigger command.  If
756	   the extension is not mandatory-to-enforce, then that
757	   GenericTriggerExtension object can be safely ignored and the trigger
758	   command can be processed in accordance with the rest of the CDNI
759	   Trigger spec.

761	   Although, a CDN MUST NOT execute a trigger command if a mandatory-to-
762	   enforce extension cannot be enforced, it could still be safe to
763	   redistribute that trigger (the "safe-to-redistribute" property) to
764	   another CDN without modification.  For example, in the cascaded CDN
765	   case, a transit CDN (tCDN) could convey mandatory-to-enforce trigger
766	   extension to a dCDN.  For a trigger extension that does not require
767	   customization or translation (i.e., trigger extension that is safe-
768	   to-redistribute), the data representation received off the wire MAY
769	   be stored and redistributed without being understood or supported by
770	   the tCDN.  However, for trigger extension that requires translation,
771	   transparent redistribution of the uCDN trigger values might not be
772	   appropriate.  Certain triggers extensions can be safely, though
773	   perhaps not optimally, redistributed unmodified.  For example, pre-
774	   position command might be executed in suboptimal times for some
775	   geographies if transparently redistributed, but it might still work.

777	   Redistribution safety MUST be specified for each
778	   GenericTriggerExtension property.  If a CDN does not understand or
779	   support a given GenericTriggerExtension property that is not safe-to-
780	   redistribute, the CDN MUST set the "incomprehensible" flag to true
781	   for that GenericTriggerExtension object before redistributing it.
782	   The "incomprehensible" flag signals to a dCDN that trigger metadata
783	   was not properly transformed by the tCDN.  A CDN MUST NOT attempt to
784	   execute a trigger with an extension that has been marked as
785	   "incomprehensible" by a uCDN.

787	   tCDNs MUST NOT change the value of mandatory-to-enforce or safe-to-
788	   redistribute when propagating a trigger to a dCDN.  Although a tCDN
789	   can set the value of "incomprehensible" to true, a tCDN MUST NOT
790	   change the value of "incomprehensible" from true to false.

792	   Table 1 describes the action to be taken by a tCDN for the different
793	   combinations of mandatory-to-enforce ("MtE") and safe-to-redistribute
794	   ("StR") properties when the tCDN either does or does not understand
795	   the trigger extension object in question:

797	   +-------+-------+------------+--------------------------------------+
798	   | MtE   | StR   | Extension  | Trigger action                       |
799	   |       |       | object     |                                      |
800	   |       |       | understood |                                      |
801	   |       |       | by tCDN    |                                      |
802	   +-------+-------+------------+--------------------------------------+
803	   | False | True  | True       | Can execute and redistribute.        |
804	   | False | True  | False      | Can execute and redistribute.        |
805	   | False | False | False      | Can execute. MUST set                |
806	   |       |       |            | "incomprehensible" to true when      |
807	   |       |       |            | redistributing.                      |
808	   | False | False | True       | Can execute. Can redistribute after  |
809	   |       |       |            | transforming the trigger extension   |
810	   |       |       |            | (if the CDN knows how to do so       |
811	   |       |       |            | safely); otherwise, MUST set         |
812	   |       |       |            | "incomprehensible" to true when      |
813	   |       |       |            | redistributing.                      |
814	   | True  | True  | True       | Can execute and redistribute.        |
815	   | True  | True  | False      | MUST NOT execute but can             |
816	   |       |       |            | redistribute..                       |
817	   | True  | False | True       | Can execute. Can redistribute after  |
818	   |       |       |            | transforming the trigger extension   |
819	   |       |       |            | (if the CDN knows how to do so       |
820	   |       |       |            | safely); otherwise, MUST set         |
821	   |       |       |            | "incomprehensible" to true when      |
822	   |       |       |            | redistributing.                      |
823	   | True  | False | False      | MUST NOT serve.  MUST set            |
824	   |       |       |            | "incomprehensible" to true when      |
825	   |       |       |            | redistributing.                      |
826	   +-------+-------+------------+--------------------------------------+

828	   Table 1: Action to be taken by a tCDN for the different combinations
829	                         of MtE and StR properties

831	   Table 2 describes the action to be taken by a dCDN for the different
832	   combinations of mandatory-to-enforce and "incomprehensible"
833	   ("Incomp") properties, when the dCDN either does or does not
834	   understand the trigger extension object in question:

836	   +-------+--------+---------------+----------------------------------+
837	   | MtE   | Incomp | Extension     | Trigger action                   |
838	   |       |        | object        |                                  |
839	   |       |        | understood by |                                  |
840	   |       |        | dCDN          |                                  |
841	   +-------+--------+---------------+----------------------------------+
842	   | False | False  | True          | Can execute.                     |
843	   | False | True   | True          | Can execute but MUST NOT         |
844	   |       |        |               | interpret/apply any trigger      |
845	   |       |        |               | extension marked as              |
846	   |       |        |               | "incomprehensible".              |
847	   | False | False  | False         | Can execute.                     |
848	   | False | True   | False         | Can execute but MUST NOT         |
849	   |       |        |               | interpret/apply any trigger      |
850	   |       |        |               | extension marked as              |
851	   |       |        |               | "incomprehensible".              |
852	   | True  | False  | True          | Can execute.                     |
853	   | True  | True   | True          | MUST NOT execute.                |
854	   | True  | False  | False         | MUST NOT execute.                |
855	   | True  | True   | False         | MUST NOT execute.                |
856	   +-------+--------+---------------+----------------------------------+

858	   Table 2: Action to be taken by a dCDN for the different combinations
859	                       of MtE and Incomp properties

861	3.3.5.2.  GenericExtensionObject

863	   A GenericTriggerExtension object is a wrapper for managing individual
864	   CDNI Trigger extensions in an opaque manner.

866	      Property: generic-trigger-extension-type

868	         Description: Case-insensitive CDNI Trigger extension object
869	         type.

871	         Type: String containing the CDNI Payload Type [RFC7736] of the
872	         object contained in the generic-trigger-extension-value
873	         property (see table in Section 6.1).

875	         Mandatory: Yes.

877	      Property: generic-trigger-extension-value

879	         Description: CDNI Trigger extension object.

881	         Type: Format/Type is defined by the value of the generic-
882	         trigger-extension-type property above.

884	         Mandatory: Yes.

886	      Property: mandatory-to-enforce

888	         Description: Flag identifying whether or not the enforcement of
889	         this trigger extension is mandatory.

891	         Type: Boolean

893	         Mandatory: No.  Default is to treat the trigger extension as
894	         mandatory-to-enforce (i.e., a value of True).

896	      Property: safe-to-redistribute

898	         Description: Flag identifying whether or not this trigger
899	         extension can be safely redistributed without modification,
900	         even if the CDN fails to understand the extension.

902	         Type: Boolean

904	         Mandatory: No.  Default is to allow transparent redistribution
905	         (i.e., a value of True).

907	      Property: incomprehensible

909	         Description: Flag identifying whether or not any CDN in the
910	         chain of delegation has failed to understand and/or failed to
911	         properly transform this trigger extension object.  Note: This
912	         flag only applies to trigger extension objects whose safe-to-
913	         redistribute property has a value of False.

915	         Type: Boolean

917	         Mandatory: No.  Default is comprehensible (i.e., a value of
918	         False).

920	   Example of a JSON serialized GenericTriggerExtension object
921	   containing a specific trigger extension object:

923	   {
924	     "generic-trigger-extension-type":
925	        <Type of this trigger extension object>,
926	     "generic-trigger-extension-value":
927	         {
928	           <properties of this trigger extension object>
929	         },
930	     "mandatory-to-enforce": true,
931	     "safe-to-redistribute": true,
932	     "incomprehensible": false
933	   }

935	3.3.6.  Error Description Version 2

937	   Version 2 of the Error Description adds the "content.playlists",
938	   "content.regexs", "extensions" and "cdn" properties on top of the
939	   existing properties of version 1 of the trigger Error Description as
940	   defined in Section 5.2.6 of [RFC8007].

942	      Properties: content.regexs, content.playlists

944	         Description: Content Regex and Playlist references copied from
945	         the Trigger Specification.  Only those regexs and playlists to
946	         which the error applies are included in each property, but
947	         those references MUST be exactly as they appear in the request;
948	         the dCDN MUST NOT change or generalize the URLs or Regexs.
949	         Note that these properties are added on top of the already
950	         existing properties: "metadata.urls", "content.urls",
951	         "metadata.patterns" and "content.patterns".

953	         Type: A JSON array of JSON strings, where each string is copied
954	         from a "content.regexs" or "content.playlists" value in the
955	         corresponding Trigger Specification.

957	         Mandatory: At least one of "content.regexs",
958	         "content.playlists", "metadata.urls", "content.urls",
959	         "metadata.patterns" or "content.patterns" is mandatory in each
960	         Error Description object.

962	      Property: extensions

964	         Description: Array of trigger extension objects copied from the
965	         corresponding "extensions" array from the Trigger
966	         Specification.  Only those extensions to which the error
967	         applies are included, but those extensions MUST be exactly as
968	         they appear in the request.

970	         Type: Array of GenericTriggerExtension objects, where each
971	         extension object is copied from the "extensions" array values
972	         in the Trigger Specification.

974	         Mandatory: No.  The "extensions" array SHOULD be used only if
975	         the error relates to extension objects.

977	      Property: cdn

979	         Description: The CDN PID of the CDN where the error occurred.
980	         The "cdn" property is used by the originating uCDN or by
981	         propagating dCDN in order to distinguish in which CDN the error
982	         occured.

984	         Type: A non-empty JSON string, where the string is a CDN PID as
985	         defined in Section 4.6 of [RFC8007].

987	         Mandatory: Yes. In the case the dCDN does not like to expose
988	         this information, it should provide its own CDN PID.

990	   Example of a JSON serialized Error Description object reporting a
991	   malformed Playlist:

993	   {
994	      "content.playlists": [
995	         {
996	           "playlist": "https://www.example.com/hls/title/index.m3u8",
997	           "media-protocol": "hls"
998	         }
999	       ],
1000	      "description": "Failed to parse HLS playlist",
1001	      "error": "econtent",
1002	      "cdn": "AS64500:0"
1003	   },

1005	   Example of a JSON serialized Error Description object reporting an
1006	   unsupported extension object:

1008	   {
1009	     "errors.v2": [
1010	      {
1011	        "extensions": [
1012	          {
1013	           "generic-trigger-extension-type":
1014	             <Type of this erroneous trigger extension object>,
1015	           "generic-trigger-extension-value":
1016	             {
1017	              <properties of this erroneous trigger extension object>
1018	             },
1019	          }
1020	        ],
1021	        "description": "unrecognized extension <type>",
1022	        "error": "eextension",
1023	        "cdn": "AS64500:0"
1024	      },
1025	     ]
1026	   }

1028	3.3.7.  Error codes

1030	   This document adds the error code "eextension" to the error codes
1031	   table defined in Section 5.2.6 of [RFC8007].  This error code
1032	   designates that an error occurred while parsing a generic trigger
1033	   extension, or that the specific extension is not supported by the
1034	   CDN.  A CDN that fails to execute a trigger due a generic extension
1035	   object which is "mandatory-to-enforce" MUST report it using the
1036	   "errors.v2" array within the trigger status resource, while setting
1037	   the error code to "eextension" and providing an appropriate
1038	   description.  The "eextension" error code is a registered type of
1039	   "CDNI CI/T Trigger Error Codes" (see Section 6.2).

1041	3.4.  Examples

1043	   The following subsections provides usage examples of the specified
1044	   interface extensions being used by the trigger command and status
1045	   resource.

1047	3.4.1.  Invalidation with Regex

1049	   In the following example a CI/T "invalidate" command uses the Regex
1050	   property to specify the range of content objects for invalidation,
1051	   the command is rejected by the dCDN due to regex complexity, and an
1052	   appropriate error is reflected in the status response.

1054	   REQUEST:

1056	     POST /triggers HTTP/1.1
1057	     User-Agent: example-user-agent/0.1
1058	     Host: triggers.dcdn.example.com
1059	     Accept: */*
1060	     Content-Type: application/cdni; ptype=ci-trigger-command.v2
1061	     {
1062	       "trigger.v2": {
1063	         "type": "invalidate",
1064	         "content.regexs": [
1065	           {
1066	             "regex": "^(https:\\/\\/video\\.example\\.com)\\/
1067	             ([a-z])\\/movie1\\/([1-7])\\/*(index.m3u8|\\d{3}.ts)$",
1068	             "case-sensitive": true,
1069	             "match-query-string": false
1070	           },
1071	           { <RegexMatch #2> },
1072	           ...
1073	           { <RegexMatch #N> },
1074	         ],
1075	       },
1076	       "cdn-path": [ "AS64496:0" ]
1077	     }

1079	   RESPONSE:

1081	     HTTP/1.1 201 Created
1082	     Date: Wed, 04 May 2016 08:48:10 GMT
1083	     Content-Length: 467
1084	     Content-Type: application/cdni; ptype=ci-trigger-status.v2
1085	     Location: https://triggers.dcdn.example.com/triggers/0
1086	     Server: example-server/0.1

1088	     {
1089	       "errors.v2": [
1090	         {
1091	           "content.regexs": [
1092	             {
1093	               "regex": "^(https:\\/\\/video\\.example\\.com)\\/
1094	               ([a-z])\\/movie1\\/([1-7])\\/*(index.m3u8|\\d{3}.ts)$",
1095	               "case-sensitive": true,
1096	               "match-query-string": false
1097	             },
1098	           ],
1099	           "description": "The dCDN rejected a regex due to complexity",
1100	           "error": "ereject",
1101	           "cdn": "AS64500:0"
1102	         },
1103	       ],
1104	       "ctime": 1462351690,
1105	       "etime": 1462351698,
1106	       "mtime": 1462351690,
1107	       "status": "failed",
1108	       "trigger.v2": { <content of trigger object from the command> }
1109	     }

1111	3.4.2.  Preposition with Playlists

1113	   In the following example a CI/T "preposition" command uses the
1114	   Playlist property to specify the full media library of a specific
1115	   content.  The command fails due to playlist parse error and an
1116	   appropriate error is reflected in the status response.

1118	   REQUEST:

1120	     POST /triggers HTTP/1.1
1121	     User-Agent: example-user-agent/0.1
1122	     Host: triggers.dcdn.example.com
1123	     Accept: */*
1124	     Content-Type: application/cdni; ptype=ci-trigger-command.v2
1125	     {
1126	       "trigger.v2": {
1127	         "type": "preposition",
1128	         "content.playlists": [
1129	          {
1130	           "playlist": "https://www.example.com/hls/title/index.m3u8",
1131	           "media-protocol": "hls"
1132	          },
1133	          { <Playlist #2> },
1134	          ...
1135	          { <Playlist #N> },
1136	         ],
1137	       },
1138	       "cdn-path": [ "AS64496:0" ]
1139	     }

1141	   RESPONSE:

1143	     HTTP/1.1 201 Created
1144	     Date: Wed, 04 May 2016 08:48:10 GMT
1145	     Content-Length: 467
1146	     Content-Type: application/cdni; ptype=ci-trigger-status.v2
1147	     Location: https://triggers.dcdn.example.com/triggers/0
1148	     Server: example-server/0.1

1150	     {
1151	       "errors.v2": [
1152	         {
1153	          "content.playlists": [
1154	            {
1155	             "playlist": "https://www.example.com/hls/title/index.m3u8",
1156	             "media-protocol": "hls"
1157	            },
1158	           ],
1159	          "description": "The dCDN was not able to parse the playlist",
1160	          "error": "econtent",
1161	          "cdn": "AS64500:0"
1162	         },
1163	       ],
1164	       "ctime": 1462351690,
1165	       "etime": 1462351698,
1166	       "mtime": 1462351690,
1167	       "status": "failed",
1168	       "trigger.v2": { <content of trigger object from the command> }
1169	     }

1171	3.4.3.  Extensions with Error Propagation

1173	   In the following example a CI/T "preposition" command is using two
1174	   extensions to control the way the trigger is executed.  In this
1175	   example the receiving dCDN identified as "AS64500:0" does not support
1176	   the first extension in the extensions array. dCDN "AS64500:0" further
1177	   distributes this trigger to another downstream CDN that is identified
1178	   as "AS64501:0", which does not support the second extension in the
1179	   extensions array.  The error is propagated from "AS64501:0" to
1180	   "AS64500:0" and the errors.v2 array reflects both errors.

1182	   REQUEST:

1184	     POST /triggers HTTP/1.1
1185	     User-Agent: example-user-agent/0.1
1186	     Host: triggers.dcdn.example.com
1187	     Accept: */*
1188	     Content-Type: application/cdni; ptype=ci-trigger-command.v2
1189	     {
1190	       "trigger.v2": {
1191	         "type": "preposition",
1192	         "content.playlists": [
1193	          {
1194	            "playlist": "https://www.example.com/hls/title/index.m3u8",
1195	            "media-protocol": "hls"
1196	          },
1197	         ],
1198	         "extensions": [
1199	             {
1200	               "generic-trigger-extension-type":
1201	                  <Type of trigger extension object #1>,
1202	               "generic-trigger-extension-value":
1203	                   {
1204	                     <properties of trigger extension object #1>
1205	                   },
1206	               "mandatory-to-enforce": true,
1207	               "safe-to-redistribute": true,
1208	             },
1209	             {
1210	               "generic-trigger-extension-type":
1211	                  <Type of trigger extension object #2>,
1212	               "generic-trigger-extension-value":
1213	                   {
1214	                     <properties of trigger extension object #2>
1215	                   },
1216	               "mandatory-to-enforce": true,
1217	               "safe-to-redistribute": true,
1218	             },
1219	         ],
1220	       },
1221	       "cdn-path": [ "AS64496:0" ]
1222	     }

1224	   RESPONSE:

1226	     HTTP/1.1 201 Created
1227	     Date: Wed, 04 May 2016 08:48:10 GMT
1228	     Content-Length: 467
1229	     Content-Type: application/cdni; ptype=ci-trigger-status.v2
1230	     Location: https://triggers.dcdn.example.com/triggers/0
1231	     Server: example-server/0.1

1233	     {
1234	        "errors.v2": [
1235	          {
1236	            "extensions": [
1237	               {
1238	                 "generic-trigger-extension-type":
1239	                    <Type of trigger extension object #1>,
1240	                 "generic-trigger-extension-value":
1241	                     {
1242	                       <properties of trigger extension object #1>
1243	                     },
1244	                 "mandatory-to-enforce": true,
1245	                 "safe-to-redistribute": true,
1246	               },
1247	             ],

1249	            "description": "unrecognized extension <type>",
1250	            "error": "eextension",
1251	            "cdn": "AS64500:0"
1252	          },
1253	          {
1254	            "extensions": [
1255	               {
1256	                 "generic-trigger-extension-type":
1257	                    <Type of trigger extension object #2>,
1258	                 "generic-trigger-extension-value":
1259	                     {
1260	                       <properties of trigger extension object #2>
1261	                     },
1262	                 "mandatory-to-enforce": true,
1263	                 "safe-to-redistribute": true,
1264	               },
1265	             ],
1266	            "description": "unrecognized extension <type>",
1267	            "error": "eextension",
1268	            "cdn": "AS64501:0"
1269	          },
1270	        ],
1271	        "ctime": 1462351690,
1272	        "etime": 1462351698,
1273	        "mtime": 1462351690,
1274	        "status": "failed",
1275	        "trigger.v2": { <content of trigger object from the command> }
1276	     }

1278	4.  Trigger Extension Objects

1280	   The objects defined below are intended to be used in the
1281	   GenericTriggerExtension object's generic-trigger-extension-value
1282	   field as defined in Section Section 3.3.5.2, and their generic-
1283	   trigger-extension-type property MUST be set to the appropriate CDNI
1284	   Payload Type as defined in Section 6.1 .

1286	4.1.  LocationPolicy extension

1288	   A content operation may be relevant for a specific geographical
1289	   region, or need to be excluded from a specific region.  In this case,
1290	   the trigger should be applied only to parts of the network that are
1291	   either "included" or "not excluded" by the location policy.  Note
1292	   that the restrictions here are on the cache location rather than the
1293	   client location.

1295	   The LocationPolicy object defines which CDN or cache locations for
1296	   which the trigger command is relevant.

1298	   Example use cases:

1300	   o  Pre-position: Certain contracts allow for pre-positioning or
1301	      availability of contract in all regions except for certain
1302	      excluded regions in the world, including caches.  For example,
1303	      some content cannot ever knowingly touch servers in a specific
1304	      country, including cached content.  Therefore, these regions MUST
1305	      be excluded from a pre-positioning operation.

1307	   o  Purge: In certain cases, content may have been located on servers
1308	      in regions where the content must not reside.  In such cases, a
1309	      purge operation to remove content specifically from that region,
1310	      is required.

1312	   Object specification

1314	      Property: locations

1316	         Description: An Access List that allows or denies (blocks) the
1317	         trigger execution per cache location.

1319	         Type: Array of LocationRule objects (see Section 4.2.2.1 of
1320	         [RFC8006])

1322	         Mandatory: Yes.

1324	   If a location policy object is not listed within the trigger command,
1325	   the default behavior is to execute the trigger in all available
1326	   caches and locations of the dCDN.

1328	   The trigger command is allowed, or denied, for a specific cache
1329	   location according to the action of the first location whose
1330	   footprint matches against that cache's location.  If two or more
1331	   footprints overlap, the first footprint that matches against the
1332	   cache's location determines the action a CDN MUST take.  If the
1333	   "locations" property is an empty list or if none of the listed
1334	   footprints match the location of a specific cache location, then the
1335	   result is equivalent to a "deny" action.

1337	   The following is an example of a JSON serialized generic trigger
1338	   extension object containing a location policy object that allows the
1339	   trigger execution in the US but blocks its execution in Canada:

1341	   {
1342	      "generic-trigger-extension-type": "CIT.LocationPolicy",
1343	      "generic-trigger-extension-value":
1344	       {
1345	          "locations": [
1346	            {
1347	              "action": "allow",
1348	              "footprints": [
1349	                {
1350	                  "footprint-type": "countrycode",
1351	                  "footprint-value": ["us"]
1352	                }
1353	              ]
1354	            },
1355	            {
1356	              "action": "deny",
1357	              "footprints": [
1358	                {
1359	                  "footprint-type": "countrycode",
1360	                  "footprint-value": ["ca"]
1361	                }
1362	              ]
1363	            }
1364	          ]
1365	       },
1366	      "mandatory-to-enforce": true,
1367	      "safe-to-redistribute": true,
1368	      "incomprehensible": false
1369	   }

1371	4.2.  TimePolicy Extension

1373	   A uCDN may wish to perform content management operations on the dCDN
1374	   in a specific schedule.  The TimePolicy extensions allows the uCDN to
1375	   instruct the dCDN to execute the trigger command in a desired time
1376	   window.  For example, a content provider that wishes to pre-populate
1377	   a new episode at off-peak time so that it would be ready on caches at
1378	   prime time when the episode is released for viewing.  A scheduled
1379	   operation enables the uCDN to direct the dCDN in what time frame to
1380	   execute the trigger.

1382	   A uCDN may wish to to schedule a trigger such that the dCDN will
1383	   execute it in local time, as it is measured in each region.  For
1384	   example, a uCDN may wish the dCDN to pull the content at off-peak
1385	   hours, between 2AM-4AM, however, as a CDN is distributed across
1386	   multiple time zones, the UTC definition of 2AM depends on the actual
1387	   location.

1389	   We define two alternatives for localized scheduling:

1391	   o  Regional schedule: When used in conjunction with the Location
1392	      Policy defined in Section 4.1, the uCDN can trigger separate
1393	      commands for different geographical regions, for each region using
1394	      a different schedule.  This allows the uCDN to control the
1395	      execution time per region.

1397	   o  Local Time schedule: We introduce a "local time" version for
1398	      Internet timestamps that follows the notation for local time as
1399	      defined in Section 4.2.2 of [ISO8601].  When local time is used,
1400	      that dCDN SHOULD execute the triggers at different absolute times,
1401	      according the local time of each execution location.

1403	   Object specification

1405	      Property: unix-time-window

1407	         Description: A UNIX epoch time window in which the trigger
1408	         SHOULD be executed.

1410	         Type: TimeWindow object using UNIX epoch timestamps (see
1411	         Section 4.2.3.2 of [RFC8006])

1413	         Mandatory: No, but exactly one of "unixEpochWindow",
1414	         "utcWindow" or "localTimeWindow" MUST be present.

1416	      Property: utc-window

1418	         Description: A UTC time window in which the trigger SHOULD be
1419	         executed.

1421	         Type: UTCWindow object as defined in Section 4.2.1.

1423	         Mandatory: No, but exactly one of "unixEpochWindow",
1424	         "utcWindow" or "localTimeWindow" MUST be present.

1426	      Property: local-time-window

1428	         Description: A local time window.  The dCDN SHOULD execute the
1429	         trigger at the defined time frame, interpreted as the the local
1430	         time per location.

1432	         Type: LocalTimeWindow object as defined in Section 4.2.2.

1434	         Mandatory: No, but exactly one of "unixEpochWindow",
1435	         "utcWindow" or "localTimeWindow" MUST be present.

1437	   If a time policy object is not listed within the trigger command, the
1438	   default behavior is to execute the trigger in a time frame most
1439	   suitable to the dCDN taking under consideration other constrains and
1440	   / or obligations.

1442	   Example of a JSON serialized generic trigger extension object
1443	   containing a time policy object that schedules the trigger execution
1444	   to a window between 09:00 01/01/2000 UTC and 17:00 01/01/2000 UTC,
1445	   using the "unix-time-window" property:

1447	   {
1448	      "generic-trigger-extension-type": "CIT.TimePolicy",
1449	      "generic-trigger-extension-value":
1450	       {
1451	         "unix-time-window": {
1452	            "start": 946717200,
1453	            "end": 946746000
1454	         }
1455	       }
1456	      "mandatory-to-enforce": true,
1457	      "safe-to-redistribute": true,
1458	      "incomprehensible": false
1459	   }

1461	4.2.1.  UTCWindow

1463	   A UTCWindow object describes a time range in UTC or UTC and a zone
1464	   offset that can be applied by a TimePolicy.

1466	      Property: start

1468	         Description: The start time of the window.

1470	         Type: Internet date and time as defined in [RFC3339].

1472	         Mandatory: No, but at least one of "start" or "end" MUST be
1473	         present and non-empty.

1475	      Property: end

1477	         Description: The end time of the window.

1479	         Type: Internet date and time as defined in [RFC3339].

1481	         Mandatory: No, but at least one of "start" or "end" MUST be
1482	         present and non-empty.

1484	   Example JSON serialized UTCWindow object that describes a time window
1485	   from 02:30 01/01/2000 UTC to 04:30 01/01/2000 UTC:

1487	   {
1488	     "start": 2000-01-01T02:30:00.00Z,
1489	     "end": 2000-01-01T04:30:00.00Z,
1490	   }

1492	   Example JSON serialized UTCWindow object that describes a time window
1493	   in New York time zone offset UTC-05:00 from 02:30 01/01/2000 to 04:30
1494	   01/01/2000:

1496	   {
1497	     "start": 2000-01-01T02:30:00.00-05:00,
1498	     "end": 2000-01-01T04:30:00.00-05:00,
1499	   }

1501	4.2.2.  LocalTimeWindow

1503	   A LocalTimeWindow object describes a time range in local time.  The
1504	   reader of this object MUST interpret it as "the local time at the
1505	   location of execution".  For example, if the time window states 2AM
1506	   to 4AM local time then a dCDN that has presence in both London (UTC)
1507	   and New York (UTC-05:00) will execute the trigger at 2AM-4AM UTC in
1508	   London and at 2AM-4AM UTC-05:00 in New York.

1510	      Property: start

1512	         Description: The start time of the window.

1514	         Type: JSON string formatted as DateLocalTime as defined in
1515	         Section 4.2.3.

1517	         Mandatory: No, but at least one of "start" or "end" MUST be
1518	         present and non-empty.

1520	      Property: end

1522	         Description: The end time of the window.

1524	         Type: JSON string formatted as DateLocalTime as defined in
1525	         Section 4.2.3.

1527	         Mandatory: No, but at least one of "start" or "end" MUST be
1528	         present and non-empty.

1530	   Example JSON serialized LocalTimeWindow object that describes a local
1531	   time window from 02:30 01/01/2000 to 04:30 01/01/2000.

1533	   {
1534	     "start": 2000-01-01T02:30:00.00,
1535	     "end": 2000-01-01T04:30:00.00,
1536	   }

1538	4.2.3.  DateLocalTime

1540	   DateLocalTime is a timestamp that follows the date and local time
1541	   notation in Section 4.3.2 of [ISO8601] as a complete date and time
1542	   extended representation, where the time zone designator is omitted.
1543	   In addition, for simplicity and as exact accuracy is not an objective
1544	   in this case, this specification does not support the decimal
1545	   fractions of seconds, and does not take leap second into
1546	   consideration.

1548	   Type: JSON string using the format "date-local-time" as defined in
1549	   Section 4.2.3.1.

1551	4.2.3.1.  Date and Local Time Format

1553	   The Date and Local Time format is specified here using the syntax
1554	   description notation defined in [ABNF].

1556	   date-fullyear   = 4DIGIT
1557	   date-month      = 2DIGIT  ; 01-12
1558	   date-mday       = 2DIGIT  ; 01-28, 01-29, 01-30, 01-31 based on
1559	                             ; month/year
1560	   time-hour       = 2DIGIT  ; 00-23
1561	   time-minute     = 2DIGIT  ; 00-59
1562	   time-second     = 2DIGIT  ; 00-59 leap seconds are not supported

1564	   local-time      = time-hour ":" time-minute ":" time-second
1565	   full-date       = date-fullyear "-" date-month "-" date-mday
1566	   date-local-time = full-date "T" local-time

1568	   Example time representing 09:00AM on 01/01/2000 local time:

1570	   2000-01-01T09:00:00.00

1572	      NOTE: Per [ABNF] and [ISO8601], the "T" character in this syntax
1573	      may alternatively be lower case "t".  For simplicity, Applications
1574	      that generate the "date-local-time" format defined here, SHOULD
1575	      only use the upper case letter "T".

1577	4.2.3.2.  Restrictions

1579	   The grammar element date-mday represents the day number within the
1580	   current month.  The maximum value varies based on the month and year
1581	   as follows:

1583	   Month Number  Month/Year           Maximum value of date-mday
1584	   ------------  ----------           --------------------------
1585	   01            January              31
1586	   02            February, normal     28
1587	   02            February, leap year  29
1588	   03            March                31
1589	   04            April                30
1590	   05            May                  31
1591	   06            June                 30
1592	   07            July                 31
1593	   08            August               31
1594	   09            September            30
1595	   10            October              31
1596	   11            November             30
1597	   12            December             31

1599	   See Appendix C of [RFC3339] for a sample C code that determines if a
1600	   year is a leap year.

1602	   The grammar element time-second may have the values 0-59.  The value
1603	   of 60 that is used in [ISO8601] to represent a leap second MUST NOT
1604	   be used.

1606	   Although [ISO8601] permits the hour to be "24", this profile of
1607	   [ISO8601] only allows values between "00" and "23" for the hour in
1608	   order to reduce confusion.

1610	5.  Footprint and Capabilities

1612	   This section covers the FCI objects required for advertisement of the
1613	   extensions and properties introduced in this document.

1615	5.1.  CI/T Versions Capability Object

1617	   The CI/T versions capability object is used to indicate support for
1618	   one or more CI/T objects versions.  Note that the default version as
1619	   originally defined in [RFC8007] MUST be implicitly supported
1620	   regardless of the versions listed in this capability object.

1622	      Property: versions

1624	         Description: A list of version numbers.

1626	         Type: An array of JSON strings

1628	         Mandatory: No.  The default is version 1.  A missing or an
1629	         empty versions list means that only version 1 of the interface
1630	         and objects is supported.

1632	5.1.1.  CI/T Versions Capability Object Serialization

1634	   The following shows an example of a JSON serialized CI/T Versions
1635	   Capability object serialization for a dCDN that supports versions 2
1636	   and 2.1 of the CI/T interface.

1638	   {
1639	    "capabilities": [
1640	      {
1641	        "capability-type": "FCI.TriggerVersion",
1642	        "capability-value": {
1643	          "versions": [ "1", "2", "2.1" ]
1644	        },
1645	        "footprints": [
1646	          <Footprint objects>
1647	        ]
1648	      }
1649	    ]
1650	   }

1652	5.2.  CI/T Playlist Protocol Capability Object

1654	   The CI/T Playlist Protocol capability object is used to indicate
1655	   support for one or more MediaProtocol types listed in Section 6.3 by
1656	   the playlists property of the "trigger.v2" object.

1658	      Property: media-protocols

1660	         Description: A list of media protocols.

1662	         Type: A list of MediaProtocol (from the CDNI Triggers media
1663	         protocol types Section 6.3)

1665	         Mandatory: No.  The default, in case of a missing or an empty
1666	         list, is none supported.

1668	5.2.1.  CI/T Playlist Protocol Capability Object Serialization

1670	   The following shows an example of a JSON serialized CI/T Playlist
1671	   Protocol Capability object serialization for a dCDN that supports
1672	   "hls" and "dash".

1674	   {
1675	    "capabilities": [
1676	      {
1677	        "capability-type": "FCI.TriggerPlaylistProtocol",
1678	        "capability-value": {
1679	          "media-protocols": ["hls", "dash"]
1680	        },
1681	        "footprints": [
1682	          <Footprint objects>
1683	        ]
1684	      }
1685	    ]
1686	   }

1688	5.3.  CI/T Trigger Extension Capability Object

1690	   The CI/T Generic Extension capability object is used to indicate
1691	   support for one or more GenericExtensionObject types.

1693	      Property: trigger-extension

1695	         Description: A list of supported CDNI CI/T
1696	         GenericExtensionObject types.

1698	         Type: List of strings corresponding to entries from the "CDNI
1699	         Payload Types" registry [RFC7736] that are under the CIT
1700	         namespace, and that correspond to CDNI CI/T
1701	         GenericExtensionObject objects.

1703	         Mandatory: No.  The default, in case of a missing or an empty
1704	         list, MUST be interpreted as "no GenericExtensionObject types
1705	         are supported".  A non-empty list MUST be interpreted as
1706	         containing "the only GenericExtensionObject types that are
1707	         supported".

1709	5.3.1.  CI/T Trigger Extension Capability Object Serialization

1711	   The following shows an example of a JSON serialized CI/T Trigger
1712	   Extension Capability object serialization for a dCDN that supports
1713	   the "CIT.LocationPolicy" and the "CIT.TimePolicy" objects.

1715	   {
1716	    "capabilities": [
1717	      {
1718	        "capability-type": "FCI.TriggerGenericExtension",
1719	        "capability-value": {
1720	          "trigger-extension": ["CIT.LocationPolicy", "CIT.TimePolicy"]
1721	        },
1722	        "footprints": [
1723	          <Footprint objects>
1724	        ]
1725	      }
1726	    ]
1727	   }

1729	6.  IANA Considerations

1731	6.1.  CDNI Payload Types

1733	   This document requests the registration of the following CDNI Payload
1734	   Types under the IANA "CDNI Payload Types" registry defined in
1735	   [RFC7736]:

1737	              +-----------------------------+---------------+
1738	              | Payload Type                | Specification |
1739	              +-----------------------------+---------------+
1740	              | ci-trigger-command.v2       | RFCthis       |
1741	              | ci-trigger-status.v2        | RFCthis       |
1742	              | CIT.LocationPolicy          | RFCthis       |
1743	              | CIT.TimePolicy              | RFCthis       |
1744	              | FCI.TriggerVersion          | RFCthis       |
1745	              | FCI.TriggerPlaylistProtocol | RFCthis       |
1746	              | FCI.TriggerGenericExtension | RFCthis       |
1747	              +-----------------------------+---------------+

1749	   [RFC Editor: Please replace RFCthis with the published RFC number for
1750	   this document.]

1752	6.1.1.  CDNI ci-trigger-command.v2 Payload Type

1754	   Purpose: The purpose of this payload type is to distinguish version 2
1755	   of the CI/T command (and any associated capability advertisement)

1757	   Interface: CI/T

1759	   Encoding: see Section 3.1

1761	6.1.2.  CDNI ci-trigger-status.v2 Payload Type

1763	   Purpose: The purpose of this payload type is to distinguish version 2
1764	   of the CI/T status resource response (and any associated capability
1765	   advertisement)

1767	   Interface: CI/T

1769	   Encoding: see Section 3.1

1771	6.1.3.  CDNI CI/T LocationPolicy Trigger Extension Type

1773	   Purpose: The purpose of this Trigger Extension type is to distinguish
1774	   LocationPolicy CIT Trigger Extension objects.

1776	   Interface: CI/T

1778	   Encoding: see Section 4.1

1780	6.1.4.  CDNI CI/T TimePolicy Trigger Extension Type

1782	   Purpose: The purpose of this Trigger Extension type is to distinguish
1783	   TimePolicy CI/T Trigger Extension objects.

1785	   Interface: CI/T

1787	   Encoding: see Section 4.2

1789	6.1.5.  CDNI FCI CI/T Versions Payload Type

1791	   Purpose: The purpose of this payload type is to distinguish FCI
1792	   advertisement objects for CI/T Triggers Versions objects

1794	   Interface: FCI

1796	   Encoding: see Section 5.1.1

1798	6.1.6.  CDNI FCI CI/T Playlist Protocol Payload Type

1800	   Purpose: The purpose of this payload type is to distinguish FCI
1801	   advertisement objects for CI/T Playlist Protocol objects

1803	   Interface: FCI

1805	   Encoding: see Section 5.2.1

1807	6.1.7.  CDNI FCI CI/T Extension Objects Payload Type

1809	   Purpose: The purpose of this payload type is to distinguish FCI
1810	   advertisement objects for CI/T Extension objects

1812	   Interface: FCI

1814	   Encoding: see Section 5.3.1

1816	6.2.  CDNI CI/T Trigger Error Codes types

1818	   The IANA is requested to update the "CDNI CI/T Error Codes"
1819	   subregistry (defined in Section 7.3 of [RFC8007] and located at
1820	   <https://www.iana.org/assignments/cdni-parameters>) with the
1821	   following registration:

1823	   +------------+--------------------------------------+---------------+
1824	   | Error Code | Description                          | Specification |
1825	   +------------+--------------------------------------+---------------+
1826	   | eextension | The dCDN failed to parse a generic   | Section       |
1827	   |            | "mandatory-to-enforce" extension     | Section 3.3.7 |
1828	   |            | object, or does not support this     | of this       |
1829	   |            | extension.                           | document.     |
1830	   +------------+--------------------------------------+---------------+

1832	6.3.  CDNI Media protocol types

1834	   The IANA is requested to create a new "CDNI MediaProtocol Types"
1835	   subregistry in the "Content Delivery Networks Interconnection (CDNI)
1836	   Parameters" registry.  The "CDNI MediaProtocol Types" namespace
1837	   defines the valid MediaProtocol object values in
1838	   Section Section 3.3.4, used by the Playlist object.  Additions to the
1839	   MediaProtocol namespace conform to the "Specification Required"
1840	   policy as defined in Section 4.6 of [RFC8126], where the
1841	   specification defines the MediaProtocol Type and the protocol to
1842	   which it is associated.  The designated expert will verify that new
1843	   protocol definitions do not duplicate existing protocol definitions
1844	   and prevent gratuitous additions to the namespace.

1846	   The following table defines the initial MediaProtocol values
1847	   corresponding to the HLS, MSS, and DASH protocols:

1849	   +---------------+-------------------+---------------+---------------+
1850	   | MediaProtocol | Description       | Specification | Protocol      |
1851	   | Type          |                   |               | Specification |
1852	   +---------------+-------------------+---------------+---------------+
1853	   | hls           | HTTP Live         | RFCthis       | RFC 8216      |
1854	   |               | Streaming         |               | [RFC8216]     |
1855	   | mss           | Microsoft Smooth  | RFCthis       | MSS [MSS]     |
1856	   |               | Streaming         |               |               |
1857	   | dash          | Dynamic Adaptive  | RFCthis       | MPEG-DASH     |
1858	   |               | Streaming over    |               | [MPEG-DASH]   |
1859	   |               | HTTP (MPEG-DASH)  |               |               |
1860	   +---------------+-------------------+---------------+---------------+

1862	   [RFC Editor: Please replace RFCthis with the published RFC number for
1863	   this document.]

1865	7.  Security Considerations

1867	   All security considerations listed in Section 8 of [RFC8007] and
1868	   Section 7 of [RFC8008] apply to this document as well.

1870	   This document defines the capability to use regular expression within
1871	   the trigger specification for more granular content selection.  The
1872	   usage of regex introduced the risk of regex complexity attacks, a.k.a
1873	   ReDos attacks.  An attacker may be able to craft a regular expression
1874	   that can exhaust server resources and may take exponential time in
1875	   the worst case.  An implementation MUST protect itself at a minimum
1876	   by accepting triggers only from an authenticated party over a secured
1877	   connection.  An implementation SHOULD also protect itself by using
1878	   secure programing techniques and decline trigger commands that use
1879	   potentially risky regex, such techniques are readily available in
1880	   secure programming literature and are beyond the scope of this
1881	   document.

1883	8.  Acknowledgments

1885	   The authors thank Kevin J.  Ma for his guidance as well as careful
1886	   and methodical reviews and feedback.

1888	9.  References

1890	9.1.  Normative References

1892	   [ABNF]     Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
1893	              Specifications: ABNF", STD 68, RFC 5234,
1894	              DOI 10.17487/RFC5234, January 2008,
1895	              <https://www.rfc-editor.org/info/rfc5234>.

1897	   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
1898	              Requirement Levels", BCP 14, RFC 2119,
1899	              DOI 10.17487/RFC2119, March 1997,
1900	              <https://www.rfc-editor.org/info/rfc2119>.

1902	   [RFC3339]  Klyne, G. and C. Newman, "Date and Time on the Internet:
1903	              Timestamps", RFC 3339, DOI 10.17487/RFC3339, July 2002,
1904	              <https://www.rfc-editor.org/info/rfc3339>.

1906	   [RFC3986]  Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
1907	              Resource Identifier (URI): Generic Syntax", STD 66,
1908	              RFC 3986, DOI 10.17487/RFC3986, January 2005,
1909	              <https://www.rfc-editor.org/info/rfc3986>.

1911	   [RFC6707]  Niven-Jenkins, B., Le Faucheur, F., and N. Bitar, "Content
1912	              Distribution Network Interconnection (CDNI) Problem
1913	              Statement", RFC 6707, DOI 10.17487/RFC6707, September
1914	              2012, <https://www.rfc-editor.org/info/rfc6707>.

1916	   [RFC7736]  Ma, K., "Content Delivery Network Interconnection (CDNI)
1917	              Media Type Registration", RFC 7736, DOI 10.17487/RFC7736,
1918	              December 2015, <https://www.rfc-editor.org/info/rfc7736>.

1920	   [RFC8006]  Niven-Jenkins, B., Murray, R., Caulfield, M., and K. Ma,
1921	              "Content Delivery Network Interconnection (CDNI)
1922	              Metadata", RFC 8006, DOI 10.17487/RFC8006, December 2016,
1923	              <https://www.rfc-editor.org/info/rfc8006>.

1925	   [RFC8007]  Murray, R. and B. Niven-Jenkins, "Content Delivery Network
1926	              Interconnection (CDNI) Control Interface / Triggers",
1927	              RFC 8007, DOI 10.17487/RFC8007, December 2016,
1928	              <https://www.rfc-editor.org/info/rfc8007>.

1930	   [RFC8008]  Seedorf, J., Peterson, J., Previdi, S., van Brandenburg,
1931	              R., and K. Ma, "Content Delivery Network Interconnection
1932	              (CDNI) Request Routing: Footprint and Capabilities
1933	              Semantics", RFC 8008, DOI 10.17487/RFC8008, December 2016,
1934	              <https://www.rfc-editor.org/info/rfc8008>.

1936	   [RFC8126]  Cotton, M., Leiba, B., and T. Narten, "Guidelines for
1937	              Writing an IANA Considerations Section in RFCs", BCP 26,
1938	              RFC 8126, DOI 10.17487/RFC8126, June 2017,
1939	              <https://www.rfc-editor.org/info/rfc8126>.

1941	   [RFC8259]  Bray, T., Ed., "The JavaScript Object Notation (JSON) Data
1942	              Interchange Format", STD 90, RFC 8259,
1943	              DOI 10.17487/RFC8259, December 2017,
1944	              <https://www.rfc-editor.org/info/rfc8259>.

1946	9.2.  Informative References

1948	   [ISO8601]  ISO, "Data elements and interchange formats -- Information
1949	              interchange -- Representation of dates and times",
1950	              ISO 8601:2004, Edition 3, 12 2004,
1951	              <https://www.iso.org/standard/40874.html>.

1953	   [MPEG-DASH]
1954	              ISO, "Information technology -- Dynamic adaptive streaming
1955	              over HTTP (DASH) -- Part 1: Media presentation description
1956	              and segment format", ISO/IEC 23009-1:2014, Edition 2, 05
1957	              2014, <https://www.iso.org/standard/65274.html>.

1959	   [MSS]      Microsoft, "[MS-SSTR]: Smooth Streaming Protocol",
1960	              Protocol Revision 8.0, September 2017,
1961	              <https://msdn.microsoft.com/en-us/library/ff469518.aspx>.

1963	   [OC-CM]    Finkelman, O., Ed., Devabhaktuni, J., and M. Stock, "Open
1964	              Caching Content Management Operations Specification",
1965	              November 2017,
1966	              <https://www.streamingvideoalliance.org/document/open-
1967	              caching-content-management-operations-specification/>.

1969	   [OCWG]     Streaming Video Alliance, "Open Caching",
1970	              <https://www.streamingvideoalliance.org/technical-groups/
1971	              open-caching/>.

1973	   [PCRE841]  Hazel, P., "Perl Compatible Regular Expressions",
1974	              Version 8.41, July 2017, <http://www.pcre.org/>.

1976	   [RFC8216]  Pantos, R., Ed. and W. May, "HTTP Live Streaming",
1977	              RFC 8216, DOI 10.17487/RFC8216, August 2017,
1978	              <https://www.rfc-editor.org/info/rfc8216>.

1980	   [SVA]      "Streaming Video Alliance",
1981	              <https://www.streamingvideoalliance.org>.

1983	Authors' Addresses

1985	   Ori Finkelman
1986	   Qwilt
1987	   6, Ha'harash
1988	   Hod HaSharon  4524079
1989	   Israel

1991	   Email: ori.finkelman.ietf@gmail.com
1992	   Sanjay Mishra
1993	   Verizon
1994	   13100 Columbia Pike
1995	   Silver Spring, MD  20904
1996	   USA

1998	   Email: sanjay.mishra@verizon.com

2000	   Nir B. Sopher
2001	   Qwilt
2002	   6, Ha'harash
2003	   Hod HaSharon  4524079
2004	   Israel

2006	   Email: nir@apache.org