wdiff rfc8007.original rfc8007.txt

Network Working Group
Internet Engineering Task Force (IETF) R. Murray
Internet-Draft
Request for Comments: 8007 B. Niven-Jenkins
Intended status:
Category: Standards Track Nokia
Expires: November 20, 2016 May 19,
ISSN: 2070-1721 December 2016

CDNI

Content Delivery Network Interconnection (CDNI)
Control Interface / Triggers
draft-ietf-cdni-control-triggers-15

Abstract

This document describes the part of the CDN Content Delivery Network
Interconnection (CDNI) Control
Interface 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-positions pre-position metadata or content, content or
to request that it invalidates invalidate or
purges purge metadata or content. The
upstream CDN can monitor the status of activity that it has triggered
in the downstream CDN.

Requirements Language

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

Status of This Memo

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provisions of BCP 78 and BCP 79.

Internet-Drafts are working documents an Internet Standards Track document.

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(IETF). Note that other groups may also distribute
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Internet Engineering Steering Group (IESG). Further information on
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This Internet-Draft will expire on November 20, 2016.
http://www.rfc-editor.org/info/rfc8007.

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Table of Contents

1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 ....................................................3
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4 ................................................4
2. Model for CDNI Triggers . . . . . . . . . . . . . . . . . . . 4 .........................................4
2.1. Timing of Triggered Activity . . . . . . . . . . . . . . 6 ...............................6
2.2. Scope of Triggered Activity . . . . . . . . . . . . . . . 6 ................................7
2.2.1. Multiple Interconnected CDNs . . . . . . . . . . . . 7 ........................7
2.3. Trigger Results . . . . . . . . . . . . . . . . . . . . . 8 ............................................8
3. Collections of Trigger Status Resources . . . . . . . . . . . 8 .........................9
4. CDNI Trigger Interface . . . . . . . . . . . . . . . . . . . 9 .........................................10
4.1. Creating Triggers . . . . . . . . . . . . . . . . . . . . 10 .........................................11
4.2. Checking Status . . . . . . . . . . . . . . . . . . . . . 11 ...........................................12
4.2.1. Polling Trigger Status Resource collections . . . . . 12 Collections ........12
4.2.2. Polling Trigger Status Resources . . . . . . . . . . 12 ...................13
4.3. Cancelling Canceling Triggers . . . . . . . . . . . . . . . . . . . 12 ........................................13
4.4. Deleting Triggers . . . . . . . . . . . . . . . . . . . . 13 .........................................14
4.5. Expiry of Trigger Status Resources . . . . . . . . . . . 14 ........................14
4.6. Loop Detection and Prevention . . . . . . . . . . . . . . 14 .............................15
4.7. Error Handling . . . . . . . . . . . . . . . . . . . . . 15 ............................................15
4.8. Content URLs . . . . . . . . . . . . . . . . . . . . . . 16 ..............................................16
5. CI/T Object Properties and Encoding . . . . . . . . . . . . . 16 ............................17
5.1. CI/T Objects . . . . . . . . . . . . . . . . . . . . . . 16 ..............................................17
5.1.1. CI/T Commands . . . . . . . . . . . . . . . . . . . . 16 ......................................17
5.1.2. Trigger Status Resource . . . . . . . . . . . . . . . 17 Resources ...........................18
5.1.3. Trigger Collection . . . . . . . . . . . . . . . . . 19 Collections ................................20
5.2. Properties of CI/T Objects . . . . . . . . . . . . . . . 20 ................................21
5.2.1. Trigger Specification . . . . . . . . . . . . . . . . 20 ..............................21
5.2.2. Trigger Type . . . . . . . . . . . . . . . . . . . . 21 .......................................23
5.2.3. Trigger Status . . . . . . . . . . . . . . . . . . . 22 .....................................24
5.2.4. PatternMatch . . . . . . . . . . . . . . . . . . . . 23 .......................................24
5.2.5. Absolute Time . . . . . . . . . . . . . . . . . . . . 24 ......................................25
5.2.6. Error Description . . . . . . . . . . . . . . . . . . 24 ..................................26
5.2.7. Error Code . . . . . . . . . . . . . . . . . . . . . 25 .........................................26
6. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . 26 .......................................................27
6.1. Creating Triggers . . . . . . . . . . . . . . . . . . . . 26 .........................................28
6.1.1. Preposition . . . . . . . . . . . . . . . . . . . . . 26 ........................................28
6.1.2. Invalidate . . . . . . . . . . . . . . . . . . . . . 28 Invalidate .........................................30
6.2. Examining Trigger Status . . . . . . . . . . . . . . . . 29 ..................................32
6.2.1. Collection of All Triggers . . . . . . . . . . . . . 29 .........................32
6.2.2. Filtered Collections of Trigger Status Resources . . 30 ...33
6.2.3. Individual Trigger Status Resources . . . . . . . . . 32 ................34
6.2.4. Polling for Change . . . . . . . . . . . . . . . . . 34 Changes in Status ......................36
6.2.5. Deleting Trigger Status Resources . . . . . . . . . . 37 ..................38
6.2.6. Error Reporting . . . . . . . . . . . . . . . . . . . 38 ....................................39
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 39 ............................................40
7.1. CDNI Payload Type Parameter Registrations . . . . . . . . 40 .................40
7.2. CDNI CI/T Trigger Types Registry . . . . . . . . . . . . 40
7.3. CDNI "CDNI CI/T Error Codes Registry . . . . . . . . . . . . . 40
8. Security Considerations . . . . . . . . . . . . . . . . . . . 41
8.1. Authentication, Authorization, Confidentiality, Integrity
Protection . . . . . . . . . . . . . . . . . . . . . . . 41
8.2. Denial of Service . . . . . . . . . . . . . . . . . . . . 42
8.3. Privacy . . . . . . . . . . . . . . . . . . . . . . . . . 43 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. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 43
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 43
10.1. .....................................................44
9.1. Normative References . . . . . . . . . . . . . . . . . . 43
10.2. ......................................44
9.2. Informative References . . . . . . . . . . . . . . . . . 44 ....................................45
Appendix A. Formalization of the JSON Data . . . . . . . . . . . 45 ........................47
Acknowledgments ...................................................49
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 46 ................................................49

1. Introduction

[RFC6707] introduces the problem scope for CDN 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, interface -- "CDNI Control
interface / Triggers". It does not consider those parts of the control
Control interface that relate to configuration, bootstrapping bootstrapping, or
authentication of CDN Interconnect interfaces. Section 4 of
[RFC7337] identifies the requirements specific to the CI interface, 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 interface at a high
level.

o Section 3 describes collections of Trigger Status Resources.

o Section 4 defines the web service provided by the dCDN. downstream CDN.

o Section 5 lists properties of CI/T Commands and Status Resources.

o Section 6 contains example messages.

1.1. Terminology

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

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 Command: Commands: CI/T Trigger Commands, 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 re-using 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 Commands to be issued, 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 HTTP/HTTPS URIs, as
defined in
[RFC7230] section 2.7. Section 2.7 of [RFC7230].

When the dCDN accepts a CI/T Command Command, it creates a resource
describing the status of the triggered activity, 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 CDN
interconnection CDNI is
established.

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
Command, the uCDN can POST to the collection of Trigger Status
Resources,
Resources or simply DELETE 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, 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
The steps in Figure 1 are: are as follows:

1. The uCDN triggers action in the dCDN by posting POSTing a CI/T Command to
a collection of Trigger Status Resources, Resources --
"https://dcdn.example.com/triggers/uCDN". The This URL of this was given to
the uCDN when the CI/T interface was established.

2. The dCDN authenticates the request, validates the CI/T Command 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, 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 start time and pacing of the activity in the network.

CI/T invalidate "invalidate" and purge "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 "invalidate" and purge "purge" commands to data
acquired after the CI/T Command was accepted, but this may not always
be
achievable 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
prepositioning. pre-positioning. Otherwise, there is a risk that the
dCDN pre-
positions 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 "invalidate" and purge
"purge" commands to content acquisition that has already started when
the command is received.

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 CDNs, a single uCDN will originate a
given item of metadata and associated content, it content. It may distribute
that metadata and content to more than one dCDN, which may in-turn in turn
distribute that metadata and content to further-downstream CDNs. CDNs located further
downstream.

An intermediate CDN is a dCDN that passes on CDNI metadata Metadata and
content to further-downstream dCDNs. dCDNs located further downstream.

A diamond "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 Commands originating in the single source uCDN affect metadata
and content in all dCDNs but, 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 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 data content by using, for example,
HTTP "403 Forbidden". 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 "invalidate" CI/T command, Command, a dCDN will
receive that command from multiple directly connected uCDNs. The
dCDN may schedule multiple those such commands separately, and the last
scheduled command may affect content already revalidated following
execution of the
invalidate "invalidate" command that was scheduled first.

o If one of a dCDN's directly-connected directly connected uCDNs loses its rights to
distribute content, it may issue a CI/T purge "purge" command. That
purge may affect content the dCDN could retain because it's
distributed by another directly-connected directly connected uCDN. But, that content
can be re-
acquired 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 preposition - pre-position, two directly connected uCDNs will pass
those commands to a dCDN. That dCDN implementation need not merge
those operations, operations or notice the repetition. In 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 "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 re-acquire 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
"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
Section 5.2.3.

The CI/T Trigger Command MUST NOT be reported as 'complete' "complete" until all
actions have been completed successfully. The reasons for failure,
and URLs or Patterns patterns affected, SHOULD be enumerated in the Trigger
Status Resource. For more detail, details, see section Section 4.7.

If a dCDN is also acting as a uCDN in a cascade, it MUST forward CI/T
Commands to any downstream CDNs dCDNs that may be affected. The CI/T Trigger Command
MUST NOT be reported as 'complete' "complete" in a CDN until it is 'complete' "complete" in
all of its downstream CDNs. dCDNs. If a CI/T Trigger Command is reported as 'processed'
"processed" in any dCDN, intermediate CDNs MUST NOT report 'complete', instead
"complete"; instead, they MUST also report
'processed'. "processed". A CI/T
Command MAY be reported as 'failed' "failed" as soon as it fails in a CDN or
in any of its downstream CDNs. dCDNs. A cancelled canceled CI/T Trigger Command MUST be
reported as 'cancelling' "cancelling" until it has been reported as 'cancelled', 'complete', "cancelled",
"complete", or 'failed' "failed" by all dCDNs in a cascade.

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 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, uCDN and by filtering the response
based on the uCDN with which the HTTP client is associated.

To trigger activity in a dCDN, 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, "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, 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' "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 cancelled canceled by the uCDN.

4. CDNI Trigger Interface

This section describes an interface to enable an upstream CDN a uCDN to trigger
activity in a downstream CDN. 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 POST,
and DELETE methods as defined in [RFC7231].

The only representation specified in this document is JSON, 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, by or configured in, 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
CI/T resources. Therefore 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.

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, Resource or create a 'failed' "failed" Trigger Status Resource
containing an appropriate error description. Error Description.

When a CI/T Trigger Command is accepted, the uCDN MUST create a new
Trigger Status Resource which 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. 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 created, the dCDN MUST NOT re-
use
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. 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 complete Trigger Status Resources. The dCDN
SHOULD also provide an estimated completion time for the request, request by
using the "etime" property of the Trigger Status Resource. This will
allow the uCDN to schedule prepositioning 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
CI/T Command is queued by the dCDN for later action, the status "status"
property of the Trigger Status Resource MUST be "pending". Once
processing has started started, the "status" status MUST be "active". Finally, once
the CI/T Command is complete, the status MUST be set to "complete" or
"failed".

A CI/T Trigger Command may result in no activity in the dCDN if, for
example, it is an invalidate "invalidate" or purge "purge" request for data the dCDN
has not yet acquired, or a pre-position "preposition" request for data that it has
already acquired and which that is still valid. In this case, the "status" 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
complete Trigger Status Resources.

Once created, Trigger Status Resources can be cancelled 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, code -- for example example, 405 "Method ("Method Not
Allowed".
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 Section Sections 4.2.1 and
Section 4.2.2.

To allow the uCDN to check for change changes in the status of a Trigger
Status Resource or collection of Trigger Status Resources without re-
fetching
refetching the whole Resource resource or Collection, collection, the dCDN SHOULD include
Entity Tags
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 Collections

The uCDN can fetch the collection of its Trigger Status Resources, 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 active to the Completed completed collection, the uCDN can
fetch the result of that activity.

When polling in this way, the uCDN SHOULD use HTTP Entity Tags ETags to monitor
for change, rather than repeatedly fetching the whole collection. An
example of this is given in section Section 6.2.4.

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 created. It may fetch that Trigger Status Resource
at any time.

This can be used to retrieve progress information, information and to fetch the
result of the CI/T Command.

When polling in this way, the uCDN SHOULD use HTTP Entity Tags ETags to monitor
for change, rather than repeatedly fetching the Trigger Status
Resource.

4.3. Cancelling 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, appropriately -- for
example
example, with HTTP status code 200 "OK" ("OK") if the cancellation has
been processed and the CI/T Command is inactive, 202 "Accepted" ("Accepted") if
the command has been accepted but the CI/T Command remains active, or
501
"Not Implemented" ("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 CT/T CI/T Cancel Command for a "pending" Trigger Status Resource
does not however 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
Status Resource MUST be set to "cancelled", and the Trigger Status
Resource MUST be included in the collection of failed CT/T 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 not, however, guarantee that
it has not started 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" "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
RECOMMENDED that Trigger Status Resources are not automatically
deleted by the dCDN for at least 24 hours after they become
"complete", "processed", "failed" "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 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 Provider ID PID to a JSON array under an entry named
"cdn-path". When receiving CI/T Commands Commands, a dCDN MUST check the cdn-
path
cdn-path and reject any CI/T Command which that already contains its own
CDN
Provider ID 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 Provider Id PID consists of the two characters "AS" followed by the CDN Provider's
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 deployed -- for
example, "AS64496:0".

If the CDN provider has multiple Autonomous Systems, ASes, the same AS number SHOULD be
used in all messages from that CDN provider, unless there are
multiple distinct CDNs.

If the RI CDNI Request Routing Redirection interface (RI) described in [I-D.ietf-cdni-redirection]
[RFC7975] is implemented by the dCDN, the CI/T interface and the RI interfaces
SHOULD use the same CDN Provider Id. PID.

4.7. Error Handling

A dCDN can signal rejection of a CI/T Command using HTTP status
codes. For 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.

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 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 patterns in the Trigger Specification.

If a surrogate Surrogate affected by a CI/T Trigger Command is offline in the
dCDN,
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
Surrogates that may have the data are offline. In this case,
surrogates
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,
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 (HTTP or https) HTTPS) in comparing URLs. For example, for a CI/T
invalidate
"invalidate" or purge "purge" command, content MUST be invalidated or
purged regardless of the protocol clients use used to request it.

5. CI/T Object Properties and Encoding

The CI/T Commands, Trigger Status Resources Resources, and Trigger Collections
and Collections,
as well as their properties properties, are encoded using JSON, as defined in sections
Section
Sections 5.1.1, Section 5.2.1, 5.1.2, and Section 5.1.2. 5.1.3. They MUST use the MIME Media Type 'application/cdni', media type
"application/cdni", with parameter 'ptype' "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 lower-case. lowercase.

JSON types, including 'object', 'array', 'number' "object", "array", "number", and 'string' "string", are
defined in [RFC7159].

Unrecognised

Unrecognized name/value pairs in JSON objects SHOULD NOT be treated
as an error by either the uCDN or dCDN. They SHOULD be ignored in
the processing,
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 media type of 'application/cdni;
ptype=ci-trigger-command'. "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, 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.

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 Provider Identifiers 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 Provider Identifier PID as defined in Section 4.6.

Mandatory: Yes.

5.1.2. Trigger Status Resource Resources

Trigger Status Resources MUST use a MIME Media Type media type of 'application/
cdni; ptype=ci-trigger-status'.
"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 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-
serialise
re-serialize the information differently.

Value: A Trigger Specification, as defined in Section 5.2.1.

Mandatory: Yes Yes.

Name: ctime

Description: Time at which the CI/T Command was received by the
dCDN. Time is determined by the dCDN, dCDN; there is no requirement
to synchronise synchronize clocks between interconnected CDNs.

Value: Absolute Time, as defined in Section 5.2.5.

Mandatory: Yes Yes.

Name: mtime

Description: Time at which the Trigger Status Resource was last
modified. Time is determined by the dCDN, dCDN; there is no
requirement to synchronise synchronize clocks between interconnected CDNs.

Value: Absolute Time, as defined in Section 5.2.5.

Mandatory: Yes Yes.

Name: etime

Description: Estimate of the time at which the dCDN expects to
complete the activity. Time is determined by the dCDN, dCDN; there
is no requirement to synchronise synchronize clocks between interconnected
CDNs.

Value: Absolute Time, as defined in Section 5.2.5.

Mandatory: No No.

Name: status

Description: Current status of the triggered activity.

Value: Trigger Status, as defined in Section 5.2.3.

Mandatory: Yes Yes.

Name: errors

Description: Descriptions of errors that have occurred while
processing a Trigger Command.

Value: An array of Error Description, Descriptions, as defined in
Section 5.2.6. An empty array is allowed, allowed and is equivalent to
omitting "errors" from the object.

Mandatory: No.

5.1.3. Trigger Collection Collections

Trigger Collections MUST use a MIME Media Type media type of 'application/cdni;
ptype=ci-trigger-collection'. "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 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.

Names: coll-all, coll-pending, coll-active, coll-complete, coll-
failed
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 Provider Identifier PID of the dCDN.

Value: A JSON string, the dCDN's CDN Provider Identifier, 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 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 unrecognised 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: This property defines Defines the type of the CI/T Trigger Command.

Value: Trigger Type, as defined in Section 5.2.2.

Mandatory: Yes Yes.

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.*' "metadata.*" or 'content.*' "content.*"
MUST be present and non-empty.

Name: content.urls

Description: URLs of content the CI/T Trigger Command applies
to, see
to. See Section 4.8.

Value: A JSON array of URLs represented as JSON strings.

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

Name: content.ccid

Description: The Content Collection Identifier IDentifier of content the
trigger applies to. The 'ccid' "ccid" is a grouping of content, as
defined by [I-D.ietf-cdni-metadata]. [RFC8006].

Value: A JSON array of strings, where each string is a Content
Collection Identifier. IDentifier.

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

Name: metadata.patterns

Description: The metadata the trigger applies to.

Value: A JSON array of Pattern Match, PatternMatch objects, as defined in
Section 5.2.4.

Mandatory: No, but at least one of 'metadata.*' "metadata.*" or 'content.*' "content.*"
MUST be present and non-empty, and metadata.patterns MUST NOT
be present if the TriggerType Trigger Type is Preposition. "preposition".

Name: content.patterns

Description: The content data the trigger applies to.

Value: A JSON array of Pattern Match, PatternMatch objects, as defined in
Section 5.2.4.

Mandatory: No, but at least one of 'metadata.*' "metadata.*" or 'content.*' "content.*"
MUST be present and non-empty, and content.patterns MUST NOT be
present if the TriggerType Trigger Type is Preposition. "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
Types" registry (see Section 7.2).

A dCDN receiving a request containing a trigger type it does not
recognise
recognize or does not support MUST reject the request by creating a
Trigger Status Resource with a status to 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 request, the dCDN will |
| | will not use the specified data without first re- |
| | validating revalidating it using, for example, an "If-None- |
| | Match" "If-None-Match" HTTP request. The dCDN need not erase the |
| | erase the associated data. |
| purge | A request for the dCDN to erase metadata or |
| | content. After servicing the request, the specified |
| | specified data MUST NOT be held on the dCDN (the dCDN should |
| | re-acquire dCDN should reacquire the metadata or content from uCDN if it |
| | the uCDN if it needs it). |
+-------------+-----------------------------------------------------+

5.2.3. Trigger Status

This

Trigger Status describes the current status of a Trigger. the triggered
activity. It MUST be one of the JSON strings in the following table:

+------------+------------------------------------------------------+

5.2.4. PatternMatch

A Pattern Match 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 may 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.

Name: case-sensitive

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

Value: One of the JSON values 'true' "true" (the matching is case- case
sensitive) or 'false' "false" (the matching is case-insensitive). case insensitive).

Mandatory: No, No; default is case-insensitive match.

Name: match-query-string

Description: Flag indicating whether or not to include the query part
of the URI should be included in when comparing against the pattern match. pattern.

Value: One of the JSON values 'true' "true" (the full URI URI, including
the query part part, should be compared against the given pattern), pattern)
or 'false' "false" (the query part of the URI should be dropped before
comparison with the given pattern).

Mandatory: No, No; default is 'false', the "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 epoch (00:00:00 UTC on
1 January 1970. 1970).

5.2.6. Error Description

An Error Description is used to report the failure of a CI/T Command, 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, request; the
dCDN MUST NOT generalise generalize the URLs. (For example, if the uCDN
requests prepositioning pre-positioning of URLs
"https://content.example.com/a" and
"https://content.example.com/b", the dCDN must not
generalise generalize
its error report to Pattern the pattern
"https://content.example.com/*".)

Value: A JSON array of JSON strings, where each string is
copied from a 'content.*' "content.*" or 'metadata.*' "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 Error Codes MUST be registered in the IANA "CDNI
CI/T Error Codes Codes" registry (see Section 7.3). Unknown error codes Error Codes
MUST be treated as fatal errors, and the request MUST NOT be
automatically retried without modification.

The following error codes Error Codes are defined by this document, document and MUST be
supported by an implementation of the CI/T interface.

6. Examples

The following sections subsections provide examples of different CI/T objects
encoded as JSON.

Discovery of the triggers CI/T interface is out of scope of 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' "https://dcdn.example.com/
triggers" is used as the location of the collection of all Trigger
Status Resources, and the CDN Provider Id PID of the uCDN is "AS64496:1".

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, "preposition" command -- a POST to the
collection of all Trigger Status Resources.

Note that "metadata.patterns" and "content.patterns" are not allowed
in a preposition 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" :
"trigger": {
"type": "preposition",

"metadata.urls" :

"metadata.urls": [ "https://metadata.example.com/a/b/c" ],
"content.urls" :
"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" :
"cdn-path": [ "AS64496:1" ]
}
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"
}
}

6.1.2. Invalidate

Below is an example of a CI/T invalidate command, "invalidate" command -- another POST to
the collection of all Trigger Status Resources. This instructs the
dCDN to re-validate revalidate the content at "https://www.example.com/a/index.html", "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/" respectively, using
case-sensitive
matching. 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" :
"trigger": {
"type": "invalidate",

"metadata.patterns" :

"metadata.patterns": [
{ "pattern" : "pattern": "https://metadata.example.com/a/b/*" }
],

"content.urls" :

"content.urls": [ "https://www.example.com/a/index.html" ],
"content.patterns" :
"content.patterns": [
{ "pattern" : "pattern": "https://www.example.com/a/b/*",
"case-sensitive" :
"case-sensitive": true
}
]
},
"cdn-path" :
"cdn-path": [ "AS64496:1" ]
}
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"
}
}

6.2. Examining Trigger Status

Once Trigger Status Resources have been created, the uCDN can check
their status as shown in these 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"
]
}

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 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: */*
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 detail 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: */*
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

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
{
"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 Change Changes in Status

The uCDN SHOULD use the Entity Tags ETags of collections or Trigger Status
Resources when polling for change 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
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 Entity Tags. 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": []
}
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
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 example, the uCDN has requested prepositioning 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: */*
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

[RFC Editor Note: Please replace references to [RFCthis] in this
section with this document's RFC number before publication.]

7.1. CDNI Payload Type Parameter Registrations

The IANA is requested to register the following new Payload Types in
the CDNI "CDNI Payload Type Parameter Types" registry defined by [RFC7736], for use with
the 'application/cdni' "application/cdni" MIME media type.

7.2. CDNI "CDNI CI/T Trigger Types Types" Registry

The IANA is requested to create a new "CDNI CI/T Trigger Types"
subregistry under the "Content Delivery Networks Network Interconnection
(CDNI) Parameters" registry.

Additions to the CDNI "CDNI CI/T Error Code Registry Trigger Types" registry will be made via "RFC
Required"
the RFC Required policy as defined in [RFC5226].

The initial contents of the CDNI "CDNI CI/T Trigger Types Registry Types" registry
comprise the names and descriptions listed in section Section 5.2.2 of this
document, with this document acting as the specification.

7.3. CDNI "CDNI CI/T Error Codes Codes" Registry

The IANA is requested to create a new "CDNI CI/T Error Codes"
subregistry under the "Content Delivery Networks Network Interconnection
(CDNI) Parameters" registry.

Additions to the CDNI "CDNI CI/T Error Codes Registry Codes" registry will be made via
"Specification Required"
the Specification Required policy as defined in [RFC5226]. The
Designated Expert will verify that new error code Error Code registrations do
not duplicate existing error code 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 "CDNI CI/T Error Codes Registry 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 state. states. The CI/T interface does not allow access to to, or
modification of of, the uCDN or dCDN metadata relating to content
delivery,
delivery or to the content itself. It can only control the presence
of that metadata in the dCDN, and the processing work and network
utilisation
utilization involved in ensuring that presence.

By examining pre-positioning "preposition" requests to a dCDN, and correctly
interpreting content and metadata URLs, an attacker could learn the
uCDN
uCDN's or content owner's predictions for future content popularity.
By examining invalidate "invalidate" or purge "purge" requests, an attacker could
learn about changes in the content owner's catalogue. catalog.

By injecting CI/T commands Commands, an attacker, attacker or a misbehaving uCDN, uCDN would
generate work in the dCDN and uCDN as they process those requests.
And so
So would a man in the middle man-in-the-middle attacker modifying valid CI/T
commands Commands
generated by the uCDN. In both cases, that would decrease the dCDN dCDN's
caching efficiency by causing it to unnecessarily acquire or
re-acquire
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 re-acquisition reacquisition load.

An origin that chooses to delegate its delivery to a CDN is trusting
that CDN to deliver content on its behalf, CDN-interconnection behalf; the interconnection of
CDNs is an extension of that trust to downstream CDNs. dCDNs. That trust relationship
is a commercial arrangement, outside the scope of the CDNi CDNI protocols.
So, while a malicious CDN could deliberately generate load on a dCDN
using the CI/T, CI/T interface, the protocol does not otherwise attempt to
address malicious behaviour behavior between interconnected CDNs.

8.1. Authentication, Authorization, Confidentiality, Integrity
Protection

A CI/T implementation MUST support TLS Transport Layer Security (TLS)
transport for HTTP (https) (HTTPS) as per [RFC2818] and [RFC7230].

TLS MUST be used by the server-side server side (dCDN) and the client-side 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:

o The allows the dCDN
and the uCDN to authenticate each other using TLS client
auth
authentication and TLS server auth.

And, once they authentication.

Once the dCDN and the uCDN have mutually authenticated each other, it
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, dCDN-specific and are not standardised
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" 403 ("Forbidden") or "404 Not Found". 404 ("Not Found"). This is intended to
prevent
unauthorised unauthorized users from generating unnecessary load in dCDN dCDNs
or uCDN uCDNs due to revalidation, reacquisition, or unnecessary
acquisition.

When deploying a network of interconnected CDNs, the possible
inefficiencies related to the "diamond" 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
Denial-of-Service (DoS) attacks on the CI/T. 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, overload -- for example example,
by rate-limiting acceptance or processing of CI/T Commands, or batching
up its by
performing batch processing.

8.3. Privacy

The CI/T protocol does not carry any information about individual End
Users end
users of a CDN, CDN; there are no privacy concerns for End Users. end users.

The CI/T protocol does carry information which 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, transit and prevents
parties other than the authorised 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. Acknowledgements

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

10. References

10.1.

9.1. Normative References

[I-D.ietf-cdni-metadata]
Niven-Jenkins, B., Murray, R., Caulfield, M., and K. Ma,
"CDN Interconnection Metadata", draft-ietf-cdni-
metadata-16 (work in progress), April 2016.

[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. 1997,
<http://www.rfc-editor.org/info/rfc2119>.

[RFC2818] Rescorla, E., "HTTP Over TLS", RFC 2818,
DOI 10.17487/RFC2818, May 2000. 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. 2012, <http://www.rfc-editor.org/info/rfc6707>.

[RFC7159] Bray, T., Ed., "The JavaScript Object Notation (JSON) Data
Interchange Format", RFC 7159, DOI 10.17487/RFC7159,
March 2014. 2014, <http://www.rfc-editor.org/info/rfc7159>.

[RFC7230] Fielding, R. R., Ed., and J. Reschke, Ed., "Hypertext
Transfer Protocol (HTTP/1.1): Message Syntax and Routing",
RFC 7230, DOI 10.17487/RFC7230, June
2014. 2014,
<http://www.rfc-editor.org/info/rfc7230>.

[RFC7231] Fielding, R. R., Ed., and J. Reschke, Ed., "Hypertext
Transfer Protocol (HTTP/1.1): Semantics and Content",
RFC 7231, DOI 10.17487/RFC7231, June 2014. 2014,
<http://www.rfc-editor.org/info/rfc7231>.

[RFC7232] Fielding, R. R., Ed., and J. Reschke, Ed., "Hypertext
Transfer Protocol (HTTP/1.1): Conditional Requests",
RFC 7232, DOI 10.17487/RFC7232, June 2014. 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.

10.2. 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

[I-D.greevenbosch-appsawg-cbor-cddl]

[CBOR-CDDL]
Vigano, C. and H. Birkholz, "CBOR data definition language
(CDDL): a notational convention to express CBOR data
structures", draft-greevenbosch-appsawg-cbor-cddl-08 (work
in progress), March 2016.

[I-D.ietf-cdni-redirection]
Niven-Jenkins, B. and R. Brandenburg, "Request Routing
Redirection interface for CDN Interconnection", draft-
ietf-cdni-redirection-18 (work Work in progress), April 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. 2014, <http://www.rfc-editor.org/info/rfc7336>.

[RFC7337] Leung, K. K., Ed., and Y. Lee, Ed., "Content Distribution
Network Interconnection (CDNI) Requirements", RFC 7337,
DOI 10.17487/RFC7337, August
2014. 2014,
<http://www.rfc-editor.org/info/rfc7337>.

[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>.

Appendix A. Formalization of the JSON Data

This appendix is non-normative.

The JSON data described in this document has been formalised formalized using
CDDL [I-D.greevenbosch-appsawg-cbor-cddl]
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]
}
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, 5.2.5 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" / "ecancelled" "ecanceled" ; see Section 5.2.7

Ccid = tstr ; see I-D.ietf-cdni-metadata RFC 8006

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

URI = tstr

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
UK
United Kingdom

Email: rob.murray@nokia.com

Ben Niven-Jenkins
Nokia
3 Ely Road
Milton, Cambridge CB24 6DD
UK
United Kingdom

Email: ben.niven-jenkins@nokia.com