wdiff draft-ietf-cdni-control-triggers-03.txt draft-ietf-cdni-control-triggers-04.txt

Network Working Group R. Murray
Internet-Draft B. Niven-Jenkins
Intended status: Standards Track Velocix (Alcatel-Lucent)
Expires: January 3, March 7, 2015 July 2, September 3, 2014

CDNI Control Interface / Triggers
draft-ietf-cdni-control-triggers-03
draft-ietf-cdni-control-triggers-04

Abstract

This document describes the part of the CDN Interconnect Interconnection Control
Interface that allows a CDN to trigger activity in an interconnected
CDN that is configured to deliver content on its behalf. The
upstream CDN can use this mechanism to request that the downstream
CDN pre-positions metadata or content, or that it re-validate invalidates or
purge
purges 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

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

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

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

This Internet-Draft will expire on January 3, March 7, 2015.

This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
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described in the Simplified BSD License.

Table of Contents

1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4
2. Model for CDNI Triggers . . . . . . . . . . . . . . . . . . . 5 4
2.1. Timing of Triggered Activity . . . . . . . . . . . . . . 7 6
2.2. Trigger Results . . . . . . . . . . . . . . . . . . . . . 7 6
3. Collections of Trigger Status Resources . . . . . . . . . . . 7 6
4. CDNI Trigger interface Interface . . . . . . . . . . . . . . . . . . . 8 7
4.1. Creating Triggers . . . . . . . . . . . . . . . . . . . . 9 8
4.2. Checking Status . . . . . . . . . . . . . . . . . . . . . 11 10
4.2.1. Polling Trigger Status Resource collections . . . . . 11 10
4.2.2. Polling Trigger Status Resources . . . . . . . . . . 11 10
4.3. Deleting Cancelling Triggers . . . . . . . . . . . . . . . . . . . . 11 10
4.4. Expiry of Trigger Status Resources . . . . . . . . . . . 12
4.5. Error Handling . . . . . . . . . . . . . . . . . . . . . 12
5. Properties of Deleting Triggers . . . . . . . . . . . . . . . . . . . 13
5.1. Properties . 11
4.5. Expiry of Trigger Requests . . . . . . . . . . . . . 13
5.1.1. Content URLs . . . . . . . . . . . . . . . Status Resources . . . . . 14
5.2. Properties of Trigger Status Resources . . . . . . 12
4.6. Loop Detection and Prevention . . . 15
5.3. Properties of ErrorDesc . . . . . . . . . . . 12
4.7. Error Handling . . . . . . 16
5.4. Properties of Trigger Collections . . . . . . . . . . . . 17
5.5. Trigger Resource Simple Data Type Descriptions . . . 13
4.8. Content URLs . . 17
5.5.1. TriggerType . . . . . . . . . . . . . . . . . . . . 13
5. CI/T Object Properties and Encoding . 17
5.5.2. TriggerStatus . . . . . . . . . . . . 14
5.1. CI/T Objects . . . . . . . . 18
5.5.3. URLs . . . . . . . . . . . . . . 14
5.1.1. CI/T Commands . . . . . . . . . . 18
5.5.4. AbsoluteTime . . . . . . . . . . 14
5.1.2. Trigger Status Resource . . . . . . . . . . 18
5.5.5. ErrorCode . . . . . 15
5.1.3. Trigger Collection . . . . . . . . . . . . . . . . . 18
6. JSON Encoding 16
5.2. Properties of CI/T Objects . . . . . . . . . . . . . . . 17
5.2.1. Trigger Specification . . . 19
6.1. JSON Encoding of Embedded Types . . . . . . . . . . . . . 20
6.1.1. TriggerType . . 18
5.2.2. Trigger Type . . . . . . . . . . . . . . . . . . . 20
6.1.2. TriggerStatus . 19
5.2.3. Trigger Status . . . . . . . . . . . . . . . . . . . 20
6.1.3. 19
5.2.4. PatternMatch . . . . . . . . . . . . . . . . . . . . 20
6.1.4. ErrorDesc . .
5.2.5. Absolute Time . . . . . . . . . . . . . . . . . . . . 21
6.1.5. ErrorCode . . .
5.2.6. Error Description . . . . . . . . . . . . . . . . . . 21
5.2.7. Error Code . 22
6.2. MIME Media Types . . . . . . . . . . . . . . . . . . . . 22
7.
6. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . 22
7.1.
6.1. Creating Triggers . . . . . . . . . . . . . . . . . . . . 23
7.1.1.
6.1.1. Preposition . . . . . . . . . . . . . . . . . . . . . 23
7.1.2.
6.1.2. Invalidate . . . . . . . . . . . . . . . . . . . . . 24
7.2.
6.2. Examining Trigger Status . . . . . . . . . . . . . . . . 25
7.2.1.
6.2.1. Collection of All Triggers . . . . . . . . . . . . . 25
7.2.2.
6.2.2. Filtered Collections of Triggers . . . . . . . . . . 26
7.2.3.
6.2.3. Trigger Status Resources . . . . . . . . . . . . . . 28
7.2.4.
6.2.4. Polling for Change . . . . . . . . . . . . . . . . . 30
7.2.5. Cancelling or
6.2.5. Removing a Trigger . . . . . . . . . . . . . . . . . 33
7.2.6.
6.2.6. Error Reporting . . . . . . . . . . . . . . . . . . . 35
8.
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 36
8.1. CI/T MIME
7.1. Media Types . . type registrations . . . . . . . . . . . . . . . . 36
9. Security Considerations
7.1.1. CI/T Commands . . . . . . . . . . . . . . . . . . . . 36
9.1.
7.1.2. CI/T Trigger Status Resource . . . . . . . . . . . . 37
7.1.3. CI/T Trigger Collection . . . . . . . . . . . . . . . 38
8. Security Considerations . . . . . . . . . . . . . . . . . . . 39
8.1. Authentication, Confidentiality, Integrity Protection . . 36
9.2. 39
8.2. Denial of Service . . . . . . . . . . . . . . . . . . . . 37
10. 39
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 37
11. 40
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 37
11.1. 40
10.1. Normative References . . . . . . . . . . . . . . . . . . 37
11.2. 40
10.2. Informative References . . . . . . . . . . . . . . . . . 37 40
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 38 41

1. Introduction

[RFC6707] introduces the Problem problem scope for CDN Interconnection (CDNI)
and lists the four categories of interfaces that may be used to
compose a CDNI solution (Control, Metadata, Request Routing,
Logging).

[I-D.ietf-cdni-framework]

[RFC7336] expands on the information provided in [RFC6707] and
describes each of the interfaces and the relationships between them
in more detail.

This document describes the "CI/T" interface, "CDNI Control interface
/ Triggers". It does not consider those parts of the control
interface that relate to configuration, bootstrapping or
authentication of CDN Interconnect interfaces. Requirements for Section 4 of
[RFC7337] identifies the requirements specific to the CI interface,
requirements applicable to the CI/T interface are CI-1 to CI-6.

o Section 2 outlines the "High" and "Medium" priority requirements model for the CI
identified in section CI/T Interface at a high
level.

o Section 3 describes collections of Trigger Status Resources.

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

o Section 5 lists properties of [I-D.ietf-cdni-requirements], reproduced
here CI/T Commands and Status Resources.

o Section 6 contains example messages.

1.1. Terminology

This document reuses the terminology defined in [RFC6707].

2. Model for convenience:

CI-1 [HIGH] The CDNI Control interface shall allow Triggers

A trigger, sent from the Upstream
CDN uCDN to the dCDN, is a request that for the Downstream CDN, including downstream
cascaded CDNs, delete an object dCDN
to do some work relating to data originating from the uCDN.

The trigger can request action on either metadata or set of objects and/or its CDNI content, the
following actions can be requested:

o preposition - used to instruct the dCDN to fetch metadata from the CDN surrogates and
uCDN, or content from any storage. Only origin including the
object(s) and CDNI metadata that pertain uCDN.

o invalidate - used to instruct the requesting
Upstream CDN are allowed dCDN to be purged.

CI-2 [MED] The CDNI Control interface should allow for multiple
content items identified by a Content Collection ID revalidate specific
metadata or content before re-using it.

o purge - used to be purged
using a single Content Purge action.

CI-3 [MED] The CDNI Control interface should allow instruct the Upstream
CDN dCDN to request that the Downstream CDN, including downstream
cascaded CDNs, mark an object delete specific metadata or set
content.

Multiple representations of objects and/or its CDNI
metadata as "stale" and revalidate them before they are delivered
again.

CI-4 [HIGH] The CDNI Control interface shall allow an HTTP resource may share the Downstream
CDN same URL.
Requests to report on the completion of these actions (by itself, invalidate and
including downstream cascaded CDNs, in a manner appropriate for
the action (e.g. synchronously or asynchronously). The
confirmation receipt should include a success purge metadata or failure
indication. The failure indication along with the reason are used
if the Downstream CDN cannot delete the content in its storage.

CI-5 [MED] apply to all
resource representations with matching URLs.

The CDNI Control CI/T interface should support initiation
and control is a web service offered by the Upstream CDN dCDN. It allows
creation and deletion of pre-positioned CDNI metadata
acquisition by the Downstream CDN.

CI-6 [MED] The CDNI Control interface should support initiation triggers, and control by the Upstream CDN tracking of pre-positioned content
acquisition by the Downstream CDN.

o Section 2 outlines the model for triggered
activity. When the CI/T Interface at dCDN accepts a high
level.

o Section 3 describes collections trigger it creates a resource
describing status of Trigger Resources.

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

o Section 5 lists properties of triggered activity, a Trigger Requests and Status
Resources.

o Section 6 defines
Resource. The uCDN can poll Trigger Status Resources to monitor
progress.

The dCDN maintains a JSON encoding for collection of Trigger Requests and Status
Resources.

o Section 7 contains example messages.

1.1. Terminology

This document reuses the terminology defined in [RFC6707].

2. Model for CDNI Triggers

A trigger, sent from the uCDN to the dCDN, is a request for dCDN to
do some work relating to data originating from the uCDN.

The trigger may request action on either metadata or content, the
following actions can be requested:

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 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
creation and deletion of triggers, and tracking of the triggered
activity. When the dCDN accepts a trigger it creates a resource
describing status of the triggered activity, a Trigger Status
Resource. The uCDN MAY poll Trigger Status Resources to monitor
progress.

Requests to invalidate and purge metadata or content apply to all
variants of that data with a given URI.

The dCDN maintains a collection of Trigger Status Resources Resources for each
uCDN, each uCDN only has access to its own collection and the
location of that collection is shared when CDN interconnection is
established.

To trigger activity in the dCDN, the uCDN will POST POSTs a CI/T Command to the
collection of Trigger Status Resources. If the dCDN accepts the
trigger, it creates a new Trigger Status Resource and returns its
location to the uCDN. To monitor progress, the uCDN MAY can GET the
Trigger Status Resource. To cancel a trigger, or remove request cancellation of a trigger from the
collection once its activity has been completed, the
uCDN MAY can POST to the collection of Trigger Status Resources, or
simply DELETE the Trigger Status Resource.

In addition to the collection of all Trigger Status Resources for the
uCDN, uCDN has access to the dCDN can maintain filtered views of that collection. These
filtered views are defined in Section 3 and include collections of
active and completed triggers. These collections provide a mechanism
for polling the status of multiple jobs.

Figure 1 is an example showing the basic message flow used by the
uCDN to trigger activity in the dCDN, and for the uCDN to discover
the status of that activity. Only successful triggering is shown.
Examples of the messages are given in Section 7. 6.

uCDN dCDN
| (1) POST http://dcdn.example.com/triggers/uCDN |
[ ] --------------------------------------------------> [ ]--+
| [ ] | (2)
| (3) HTTP 201 Response [ ]<-+
[ ] <-------------------------------------------------- [ ]
| Loc: http://dcdn.example.com/triggers/uCDN/123 |
| |
. . .
. . .
. . .
| |
| (4) GET http://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:

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

2. The dCDN authenticates the request, validates the trigger and if
it accepts the request, creates a new Trigger Status Resource.

3. The dCDN responds to the uCDN with an HTTP 201 response status,
and the location of the Trigger Status Resource.

4. The uCDN may can repeatedly poll the Trigger Status Resource in the
dCDN.

5. The dCDN responds with the Trigger Status Resource, describing
progress or results of the triggered activity.

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 triggered activity is under the dCDN's
control, including its start-time and pacing of the activity in the
network.

Invalidate and purge triggers MUST be applied to all data acquired
before the trigger was created in the dCDN. The dCDN may MAY apply the
triggers to data acquired after trigger creation.

If the uCDN wishes to invalidate or purge content, then immediately
pre-position replacement content at the same URLs, it SHOULD ensure
the dCDN has completed the invalidate/purge before initiating the
prepositioning. Otherwise, there is a risk that the dCDN may pre-position pre-
positions the new content content, then immediately invalidate invalidates or purge purges it
(as a result of the two uCDN requests running in parallel).

2.2. Trigger Results

Each Trigger Request may trigger can operate on multiple data items. metadata and content URLs. The
trigger MUST NOT be reported as "complete" unless until all actions can be have
been completed successfully, otherwise it MUST be reported as "failed" or
"processed". successfully. The reasons for failure failure, and URLs or
Patterns affected affected, SHOULD be enumerated in the Trigger Status
Resource. For more detail, see section Section 4.5. 4.7.

If a dCDN is also acting as a uCDN in a cascade, it MUST forward
triggers to any downstream CDNs that may have data affected by the
trigger. The trigger MUST NOT be reported as complete 'complete' in a CDN
until it is complete 'complete' in all of its downstream CDNs. If a trigger
is reported as 'processed' in any dCDN, intermediate CDNs MUST NOT
report 'complete', instead they must also report 'processed'. A
trigger MAY be reported as failed 'failed' as soon as it fails in a CDN or
in any of its downstream CDNs. A cancelled trigger MUST be reported
as 'cancelling' until it has been reported as 'cancelled',
'complete', or '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.

To trigger activity in the dCDN, the uCDN creates

The dCDN MUST make a new Trigger
Status Resource by posting to the dCDN's collection of a uCDN's Trigger Status Resources. The URL of each Trigger Status Resource is
generated by the dCDN when it accepts the trigger, and returned Resources
available to
the that uCDN. This immediately enables collection includes all of the uCDN to check the status of
triggers that trigger.

The have been accepted by the dCDN, and have not yet been
deleted by the uCDN, or expired and removed by the dCDN MUST present a different set of Trigger Status Resources to
each interconnected uCDN. (as described
in section Section 4.4). Trigger Status Resources belonging to a
uCDN MUST NOT be visible to any other client. CDN. The dCDN may, could, for
example, achieve this by offering different collection URLs to uCDNs, each
uCDN, or by filtering the response based on the client uCDN.

The dCDN resource representing

To trigger activity in a dCDN, or to cancel triggered activity, the
uCDN POSTs a CI/T Command to the dCDN's collection of all the uCDN's
Trigger Status Resources is accessible to the uCDN. This collection
lists all of the uCDN triggers 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 4.3). Resources.

In order to allow the uCDN to check the status of multiple jobs in a
single request, the dCDN SHOULD also maintain collections
representing filtered views of the collection of all Trigger Status
Resources. If it implements these filtered collections, the dCDN
MUST include links to them in the collection of all triggers. The
filtered collections are:

o Pending - Trigger Status Resources for triggers that have been
accepted, but not yet acted upon.

o Active - Trigger Status Resources for triggered activity that is
currently being processed in the dCDN.

o Complete - Trigger Status Resources representing activity that
completed successfully, or successfully and 'processed' triggers for which no
further status updates will be made by the dCDN.

o Failed - Trigger Status Resources representing activity that
failed.
failed or was cancelled by the uCDN.

4. CDNI Trigger interface Interface

This section describes an interface to enable an upstream CDN to
trigger defined activities activity in a downstream CDN. The interface is
intended to be independent of the set of activities defined now, or
that may be defined in future.

CI/T is built on the principles of RESTful web services.

Requests are made over HTTP, and the HTTP Method defines the
operation the request would like to perform. The corresponding HTTP
Response returns the status of the operation in the HTTP Status Code
and returns the current representation of the resource (if
appropriate) in the Response Body. HTTP Responses from servers dCDNs
implementing CI/T that contain a response body SHOULD include an ETag
to enable validation of cached versions of returned resources.

Servers

All dCDNs implementing CI/T MUST support the HTTP GET, HEAD, POST and
DELETE methods as defined in [RFC7231]. The only representation
specified in this document is JSON, [RFC7159].

The URL of the dCDN's collections collection of all Trigger Status Resources need
needs to be either discovered by, or configured in, the uCDN. The
mechanism for discovery of those URLs that URL is outside the scope of this
document.

Trigger Requests

CI/T Commands are POSTed to the dCDN's collection of all Trigger
Status Resources. If the a command to create a new trigger is accepted
by the dCDN, it creates a new Trigger Status Resource and returns its
URI to the dCDN 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. This means all Trigger Status Resources can be
discovered, so CI/T servers dCDNs are free to assign whatever structure they
desire to the URIs for CI/T resources. CI/T clients 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. Therefore
any URIs present in the
examples below in this document are purely illustrative and are not
intended to impose a definitive structure on CI/T interface
implementations.

The CI/T interface builds on top of HTTP, so CI/T servers dCDNs may make use of
any HTTP feature when implementing the CI/T interface. For example,
a CI/T server may 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.

This specification is neutral with regard to the transport below the
HTTP layer.

The dCDN MUST ensure that activity triggered by the uCDN only affects
metadata or content originating from that uCDN. Since only one CDN
can be authoritative for a given item of metadata or content, this
requirement means there cannot be any "loops" in trigger requests
between CDNs.

4.1. Creating Triggers

To create a new trigger, the uCDN makes an HTTP POST to the
unfiltered dCDN's
collection of its triggers. all of the uCDN's Trigger Status Resources. The
request body of that POST is a Trigger Request. CI/T Command with a "trigger", as
described in Section 5.1.1.

The dCDN validates and authenticates that request, if it is malformed
or the uCDN does not have sufficient access rights it MAY reject the
request immediately. In this case, it MUST either
respond with an appropriate 4xx HTTP error code and a resource MUST
NOT be created on
dCDN. the dCDN, or create a 'failed' Trigger Status
Resource containing an appropriate error description.

If the request is accepted, the uCDN MUST create a new Trigger Status
Resource. The HTTP response to the dCDN MUST have status code 201
and the URI of the Trigger Status Resource in the Location header
field. The HTTP response SHOULD include the content of the newly
created Trigger Status Resource, this is recommended particularly in
cases where the trigger has completed immediately.

Once a Trigger Status Resource has been created the dCDN MUST NOT re-
use its location, even after that resource has been removed.

The "request" "trigger" property of the Trigger Status Resource contains the
information
Trigger Specification posted in the body of the Trigger Request. 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 the information differently.

If the dCDN is not able to track the execution of triggered activity,
it MUST indicate that 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 Triggers. The dCDN SHOULD also provide an estimated
completion time for the request, by using the "etime" property of the
Trigger Status Resource. This will allow the uCDN to schedule
prepositioning after an earlier delete of the same URLs is expected
to have finished.

If the dCDN is able to track the execution of triggered activity, the
trigger is queued by the dCDN for later action, the "status" property
of the Trigger Status Resource MUST be "pending". Once trigger
processing has started the "status" MUST be "active". Finally, once
the triggered activity is complete, the trigger status MUST be set to
"complete" or "failed".

A trigger may result in no activity in the dCDN if, for example, it
is an invalidate or purge request for data the dCDN has not yet
acquired, or a prepopulate request for data it has already acquired
and which is still valid. In this case, the "status" of the Trigger
Status Resource MUST be "processed" or "complete", and the Trigger
Status Resource MUST be added to the dCDN's collection of Complete
Triggers.

Once created, Trigger Status Resources may can be cancelled or deleted by
the uCDN uCDN, but not modified. The dCDN MUST reject PUT and POST
requests from the uCDN to Trigger Status Resources using by responding with
an appropriate HTTP status code 403. code.

4.2. Checking Status

The uCDN has two ways to check progress of activity it has triggered
in the dCDN, described in the following sections. sections Section 4.2.1 and Section 4.2.2.

To check for change in status of a resource or collection of
resources without re-fetching the whole resource or collection,
Entity Tags SHOULD be used included by the dCDN 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 the uCDN should poll for change.

4.2.1. Polling Trigger Status Resource collections

The uCDN can fetch the collection of its Trigger Status Resources, or
filtered views of that collection.

This makes it possible to poll status of all triggered activity in a
single request. If the dCDN moves a Trigger Status Resource from the
Active to the Completed collection, the uCDN may chose to can fetch the result of
that activity.

When polling in this way, the uCDN SHOULD use HTTP Entity Tags to
monitor for change, rather than repeatedly fetching the whole
collection.

4.2.2. Polling Trigger Status Resources

The uCDN has a reference (URI URI provided by the dCDN) dCDN for each Trigger Status
Resource it has created, it may fetch that resource at any time.

This MAY can be used to retrieve progress information, and to fetch the
result of triggered activity.

4.3. Deleting Triggers

The uCDN MAY delete Trigger Status Resources at any time, using

When polling in this way, the uCDN SHOULD use HTTP DELETE method.

Once deleted, the references Entity Tags to a Trigger Status Resource MUST be
removed from all Trigger Status Resource collections. Subsequent
requests
monitor for change, rather than repeatedly fetching the resource MUST be handled as required Trigger
Status Resource.

4.3. Cancelling Triggers

The uCDN can request cancellation of a trigger by HTTP, and so
will receive responses with status 404 or 410.

If POSTing a "pending" Trigger
"cancel" Command to the collection of all triggers.

The uCDN should respond to that command appropriately, for example
with HTTP status code 200 "OK" if the cancellation has been processed
and the trigger is inactive, 202 "Accepted" if the command has been
accepted but the trigger remains active, or 403 "Forbidden" if
cancellation is not supported by the dCDN.

If cancellation of a "pending" Trigger Status Resource is deleted, accepted by
the dCDN, the dCDN SHOULD NOT start processing of that activity. Deleting
Cancelling a "pending" trigger does not however guarantee that it is not started
activity is started, because the uCDN cannot control the timing of
that activity. Processing may, could, for example, start after the DELETE POST
is sent by the uCDN but before the
DELETE that request is processed by the dCDN.

If cancellation of an "active" or "processed" Trigger Status Resource
is deleted, accepted by the dCDN, the dCDN MAY SHOULD stop processing the
triggered activity. However, as with deletion cancellation of a "pending"
trigger, the dCDN does not guarantee this.

Deletion

If the triggered activity cannot be stopped immediately, the
trigger's status MUST be set to "cancelling" and the Trigger Status
Resource remains in the collection of active triggers. If processing
is stopped before normal completion, the trigger's status MUST be set
to "cancelled" and included in the collection of failed triggers.

Cancellation of a "complete", "processed" "complete" or "failed" Trigger Status Resource
requires no processing in the dCDN other than deletion of
the resource. dCDN, its status MUST NOT be changed to
"cancelled".

4.4. Expiry of Deleting Triggers

The uCDN can delete Trigger Status Resources at any time, using the
HTTP DELETE method. The dCDN MAY choose effect is similar to automatically delete cancellation, but no
Trigger Status Resources
some time after they become "complete", "processed" or "failed". In
this case, the dCDN will remove Resource remains afterwards.

Once deleted, the resource and respond references to
subsequent requests for it with HTTP status 404 or 410.

If the dCDN performs this housekeeping, it a Trigger Status Resource MUST have reported the
length of time after which completed be
removed from all Trigger Status Resources become
stale via a property of Resource collections. Subsequent
requests to GET the collection of all deleted resource SHOULD fail.

If a "pending" Trigger Status
Resources. It Resource is recommended deleted, the dCDN SHOULD
NOT start processing of that Trigger Status Resources activity. Deleting a "pending" trigger
does not however guarantee that it has not started because the uCDN
cannot control the timing of that activity. Processing may, for
example, start after the DELETE is sent by the uCDN but before that
request is processed by the dCDN.

If an "active" or "processed" Trigger Status Resource is deleted, the
dCDN MAY stop processing the triggered activity. However, as with
deletion of a "pending" trigger, 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 resource.

4.5. Expiry of Trigger Status Resources

The dCDN can choose to automatically delete Trigger Status Resources
some time after they become "complete", "processed", "failed" or
"cancelled". In this case, the dCDN will remove the resource and
respond to subsequent requests for it with an HTTP error.

If the dCDN performs this housekeeping, it MUST have reported the
length of time after which completed Trigger Status Resources will be
deleted via a property of the collection of all Trigger Status
Resources. It is recommended that Trigger Status Resources are not
automatically deleted for at least 24 hours after they become
"complete", "processed" "processed", "failed" or "failed". "cancelled".

To ensure it has access is able to get the status of its completed and failed
triggers, it is recommended that the uCDN's polling interval is half less
than the time after which records for completed activity will be
considered stale.

4.5. Error Handling

A
deleted.

4.6. Loop Detection and Prevention

Given three CDNs, A, B and C. If CDNs B and C delegate delivery of
CDN A's content to each other, CDN A's triggers 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 server may reject loops, each CDN uses a trigger request using HTTP status codes.
For example, 400 if CDN
Provider ID to uniquely identify itself. Each CDN MUST insert its
CDN Provider ID into the request is cdn-path key of every CI/T Command it
originates or cascades. When receiving CI/T commands a dCDN MUST
check the cdn-path and reject any CI/T Command which already contains
its own CDN Provider ID 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 cdn-path.

The CDN Provider Id consists of the characters AS followed by the CDN
Provider's AS number, then a colon (':') and an additional qualifier
that is used to guarantee uniqueness in case a particular AS has
multiple independent CDNs deployed. For example "AS64496:0".

If the RI interface described in [I-D.ietf-cdni-redirection] is
implemented by the dCDN, the CI/T and RI interfaces SHOULD use the
same CDN Provider Id.

4.7. Error Handling

A dCDN can reject a CI/T Command using HTTP status codes. For
example, 400 if the request is malformed, or 401 if the client uCDN does not
have permission to create triggers or it is trying to act on another
CDN's data.

If any part of the trigger request 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 may can be present while the trigger is still "pending" or
"active", if the trigger is still running for some URLs or Patterns
in the trigger request. Trigger Specification.

Once a request has been accepted, processing errors are reported in
the Trigger Status Resource using a list of "ErrorDesc". Error Descriptions. Each
ErrorDesc
Error Description is used to report errors against one or more of the
URLs or Patterns in the trigger request. Trigger Specification.

If a surrogate affected by a trigger is offline in the dCDN, or the
dCDN is unable to pass a trigger request CI/T Command on to any of its cascaded
dCDNs; the dCDN SHOULD report an error if the request is abandoned.
Otherwise, it SHOULD keep the trigger in state "pending" or "active"
until it's acted upon or the uCDN chooses to cancel it. Or, if
dCDNs:

o If the request is queued and abandoned by the dCDN will not report further status, dCDN, the dCDN MAY report the trigger as "processed", in which case it SHOULD
also provide an estimated completion time.

Note that report an
error.

o An "invalidate" trigger may be reported as "complete" when
surrogates that may have the data are offline. In this case,
surrogates MUST NOT use the affected data without first
revalidating it when they are back online. This does not apply to

o "preposition"
or and "purge" triggers.

5. Properties of Triggers

5.1. Properties of Trigger Requests

Properties of Trigger Requests triggers can be reported as "processed"
if affected caches are defined in the following
subsections.

Property: type

Description: This property defines the type of offline and the trigger.

Type: TriggerType

Mandatory: Yes

Property: metadata.urls

Description: The uCDN URL for activity will complete when
they return to service.

o Otherwise, the metadata dCDN SHOULD keep the trigger applies
to.

Type: URLs

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

Property: content.urls

Description: URLs of content data the trigger applies to, see
Section 5.1.1.

Type: URLs

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

Property: content.ccid

Description: The Content Collection IDentifier of data the
trigger applies to.

Type: List of strings

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

Property: metadata.patterns

Description: The metadata
"active" until the trigger applies to.

Type: List of PatternMatch

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

Property: content.patterns

Description: The content data the trigger applies to.

Type: List of PatternMatch

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

5.1.1. uCDN chooses to
cancel it.

4.8. Content URLs

To refer to content in the dCDN, the uCDN MUST present URLs in the
same form clients will use to access content as in that dCDN, after
transformation the metadata it supplied to remove any surrogate-specific parts of a
302-redirect URL form. the dCDN. By definition,
it is always possible for the dCDN to locate content based on URLs in
this form.

Therefore, if content URLs are transformed by an intermediate CDN in
a cascade, that intermediate CDN MUST transform URLs in trigger requests CI/T commands
it passes to its dCDN.

When processing trigger requests, Trigger Specifications, CDNs MUST ignore the URL
scheme (http or https) in comparing URLs. For example, for an
invalidate or purge trigger, content MUST be invalidated or purged
regardless of the protocol clients use to request it.

5.2.

5. CI/T Object Properties of and Encoding

CI/T Commands, Trigger Status Resources

Property: trigger

Description: The and Trigger Collections and
their properties of trigger request that created
this record.

Type: TriggerRequest

Mandatory: Yes

Property: ctime

Description: Time at which are encoded using JSON, as defined in sections
Section 5.1.1, Section 5.2.1, and Section 5.1.2.

Names in JSON are case sensitive and therefore the request was received names and literal
values specified here MUST always use lower-case.

Unrecognised name/value pairs in JSON objects SHOULD NOT be treated
as an error by either the uCDN or dCDN. Time is

5.1. CI/T Objects

The top-level objects defined by the CI/T interface are described in
this section. Each has an associated MIME Media Type. The encoding
of values used by these objects is described in Section 5.2.

5.1.1. CI/T Commands

CI/T Commands SHOULD use a MIME Media Type of application/
cdni.ci.TriggerCommand+json.

A CI/T Command is encoded as a JSON object containing the following
name/value pairs.

Name: trigger

Description: A specification of the trigger type, and a set of
data to act upon.

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

Mandatory: No, but exactly one of "trigger" or "cancel" MUST be
present in a CI/T Command.

Name: cancel
Description: The URLs of Trigger Status Resources for triggers
that the uCDN wants to cancel.

Value: A 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 of CDNs that have
already accepted the CI/T Command.

Value: A JSON array of JSON strings, where each string is a CDN
Provider Identifier as defined in Section 4.6.

Mandatory: Yes.

5.1.2. Trigger Status Resource

Trigger Status Resources SHOULD use a MIME Media Type of application/
cdni.ci.TriggerStatus+json.

A Trigger Status Resource is encoded as a JSON object containing the
following name/value pairs.

Name: trigger

Description: The Trigger Specification that was used to create
this Trigger Status Resource.

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

Mandatory: Yes

Name: ctime

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

Type: AbsoluteTime

Value: Absolute Time, as defined in Section 5.2.5.

Mandatory: Yes

Property:

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

Type: AbsoluteTime

Value: Absolute Time, as defined in Section 5.2.5.

Mandatory: Yes

Property:

Name: etime

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

Type: AbsoluteTime

Value: Absolute Time, as defined in Section 5.2.5.

Mandatory: No

Property:

Name: status

Description: Current status of the triggered activity.

Type: TriggerStatus

Value: Trigger Status, as defined in Section 5.2.3.

Mandatory: Yes

Property:

Name: errors

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

Value: A list of ErrorDesc. Error Descriptions, as defined in
Section 5.2.6.

Mandatory: No.

5.3. Properties of ErrorDesc

An ErrorDesc object is used to report failure for URLs and patterns
in

5.1.3. Trigger Collection

Trigger Collections SHOULD use a trigger request.

Property: error

Type: ErrorCode.

Mandatory: Yes.

Property: metadata.urls, content.urls, metadata.patterns,
content.patterns

Description: Metadata and content references copied from the
trigger request. Only those URLs and patterns to which the
error applies shall be included in each property, but those
URLs and patterns MUST be exactly as they appear in the
request, the dCDN must not generalise the URLs. (For example,
if the uCDN requests prepositioning of URLs
"http://ucdn.example.com/a" and "http://ucdn.example.com/b",
the dCDN must not generalise its error report to Pattern
"http://ucdn.example.com/*").

Mandatory: At least one MIME Media Type of these properties is mandatory in
each ErrorDesc.

Property: description

Description: application/
cdni.ci.TriggerCollection+json.

A String containing Trigger Collection is encoded as a human-readable description
of JSON object containing the error.

Mandatory: No.

5.4. Properties of Trigger Collections

Property:
following name/value pairs.

Name: triggers
Description: Links to Trigger Status Resources in the
collection.

Type: URLs.

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

Mandatory: Yes

Property:

Name: staleresourcetime

Description: The length of time for which the dCDN guarantees
to keep a completed Trigger Status Resource. After this time,
the dCDN MAY SHOULD delete the resource and all references to it
from collections.

Type: Integer,

Value: A JSON number, integer 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.

5.5.

Names: coll-all, coll-pending, coll-active, coll-complete, coll-
failed

Description: Link to a Trigger Resource Simple Data Type Descriptions

This section describes the simpler data types that Collection.

Value: A URL represented as a JSON string.

Mandatory: Links to filtered collections are used for
properties mandatory in the
collection of all Trigger Status resources.

5.5.1. TriggerType

This type defines Resources, if the type dCDN
implements the filtered collections. Otherwise, optional.

Name: cdn-id

Description: The CDN Provider Identifier of action being triggered, permitted
actions are:

o Preposition - a request for the dCDN to acquire metadata or
content.

o Invalidate - a request for dCDN.

Value: A JSON string, the dCDN to invalidate metadata or
content. After servicing this request dCDN's CDN Provider Identifier, as
defined in Section 4.6.

Mandatory: Only in the dCDN will not use collection of all Trigger Status
Resources, if the
specified data without first re-validating it using, for example,
an "If-None-Match" HTTP request. The dCDN need not erase the
associated data.

o Purge - a request for the dCDN to erase metadata or content.
After servicing implements the request, filtered collections.
Optional in the specified data MUST NOT be held
on dCDN.

5.5.2. TriggerStatus filtered collections.

5.2. Properties of CI/T Objects

This type describes section defines the current status of a Trigger, possible values
are:

o Pending - the trigger has not yet been acted upon.

o Active - that can appear in the trigger top level
objects described in Section 5.1, and their encodings.

5.2.1. Trigger Specification

A Trigger Collection is currently being acted upon.

o Complete - encoded as a JSON object containing the triggered activity completed successfully.

o Processed -
following name/value pairs.

An unrecognised name/value pair in the trigger has been accepted and no further status
update will be made (may be used Trigger Specification object
contained in cases where completion cannot a CI/T Command SHOULD be confirmed).

o Failed - preserved in the triggered activity could not be completed.

5.5.3. URLs

This type describes a set Trigger
Specification of references to metadata or content, any Trigger Status Resource it is
simply a list of absolute URLs.

5.5.4. AbsoluteTime

Times are expressed in seconds since the UNIX epoch.

5.5.5. ErrorCode creates.

Name: type

Description: This property defines the type is used by dCDN to report failures of the trigger.

Value: Trigger Type, as defined in trigger processing.

o EMETA - Section 5.2.2.

Mandatory: Yes

Name: metadata.urls

Description: The uCDN URLs of the dCDN was unable to acquire metadata required to fulfil
the request.

o ECONTENT - the dCDN was unable to acquire trigger applies
to.

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

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

Name: content.urls

Description: URLs of content (preposition
triggers only).

o EPERM - the uCDN does not have permission to trigger the requested
activity (for example, the data is owned by another CDN).

o EREJECT - the dCDN is not willing to fulfil the request (for
example, a preposition request for content at a time when dCDN
would not accept Request Routing requests from uCDN).

o ECDN - An internal error in the dCDN or one of its downstream
CDNs.

6. applies to, see
Section 4.8.

Value: A JSON Encoding array of Objects

The encoding for a CI/T object is a URLs represented as JSON object containing a
dictionary strings.

Mandatory: No, but at least one of (key,value) pairs where the keys are the property
names, 'metadata.*' or 'content.*'
MUST be present and the values are the associated property values. non-empty.

Name: content.ccid

Description: The keys Content Collection Identifier of content the dictionary are the names
trigger applies to. The 'ccid' is a grouping of the properties associated
with the object and are therefore dependent on the specific object
being encoded (i.e. dependent on the MIME Media Type content, as
defined by [I-D.ietf-cdni-metadata].

Value: A JSON array of the returned
resource). Likewise, the values associated with strings, where each key are
dependent on the specific object being encoded (i.e. dependent on the
MIME Media Type string is a Content
Collection Identifier.

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

Name: metadata.patterns

Description: The "trigger" property of metadata the top level trigger applies to.

Value: A JSON object lists array of Pattern Match, as defined in
Section 5.2.4.

Mandatory: No, but at least one of 'metadata.*' or 'content.*'
MUST be present and non-empty, and metadata.patterns MUST NOT
be present if the
requested action.

Key: trigger TriggerType is Preposition.

Name: content.patterns

Description: An object specifying The content data the trigger type and a set of
data to act upon.

Type: applies to.

Value: A JSON object.

Mandatory: Yes.

Object keys array of Pattern Match, as defined in JSON are case sensitive and therefore any dictionary
key defined by this document (for example the names
Section 5.2.4.

Mandatory: No, but at least one of CI/T object
properties) 'metadata.*' or 'content.*'
MUST always be represented present and non-empty, and content.patterns MUST NOT be
present if the TriggerType is Preposition.

5.2.2. Trigger Type

Trigger Type is used in lowercase.

In addition a Trigger Specification to the properties describe trigger
action. It MUST be one of an object, the JSON strings in the following additional
keys MAY be present.

Key: base

Description: Provides a prefix table:

+-------------+-----------------------------------------------------+
| JSON String | Description |
+-------------+-----------------------------------------------------+
| preposition | A request for any relative URLs in the
object. This is similar dCDN to acquire metadata or |
| | content. |
| invalidate | A request for the XML base tag [XML-BASE]. If
absent, all URLs in dCDN to invalidate metadata or |
| | content. After servicing this request the remainder of dCDN will |
| | not use the document MUST be
absolute URLs.

Type: URI

Mandatory: No

Key: _links
Description: specified data without first re- |
| | validating it using, for example, an "If-None- |
| | Match" HTTP request. The relationships of this object dCDN need not erase the |
| | associated data. |
| purge | A request for the dCDN to other
addressable objects.

Type: Array of Relationships.

Mandatory: Yes

6.1. JSON Encoding of Embedded Types

6.1.1. TriggerType

Key: type

Description: One of "preposition", "invalidate" erase metadata or "purge".

Type: string

6.1.2. TriggerStatus

Key: |
| | content. After servicing the request, the specified |
| | data MUST NOT be held on the dCDN. |
+-------------+-----------------------------------------------------+

5.2.3. Trigger Status

This describes the current status

Description: One of "pending", "active", "failed", "complete"

Type: string

6.1.3. PatternMatch

A PatternMatch is encoded as a Trigger. It MUST be one of
the JSON Object containing strings in the following table:

5.2.4. PatternMatch

A Pattern Match consists of a string pattern to
match match, and flags
describing the type of match.

Key:

It is encoded as a JSON object with the following name/value pairs:

Name: pattern

Description: A pattern for string matching.

Value: A JSON string representing the pattern. The pattern may
contain the wildcards * and ?, where * matches any sequence of
characters (including the empty string) and ? matches exactly
one character. The three literals \ "\" , * "*" and ? "?" MUST be
escaped as \\, \* "\\", "\*" and \?

Type: String "\?".

Mandatory: Yes

Key: Yes.

Name: case-sensitive

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

Type: Boolean

Value: One of the JSON values 'true' or 'false'.

Mandatory: No, default is case-insensitive match.

Key:

Name: match-query-string

Description: Flag indicating whether or not the query string
should be included in the pattern match.

Type: Boolean

Value: One of the JSON values 'true' or 'false'.

Mandatory: No, default is not to include query. the query string in
the pattern match.

Example of case-sensitive prefix match against
"http://www.example.com/trailers/":

{
"pattern": "http://www.example.com/trailers/*",
"case-sensitive": true
}

6.1.4. ErrorDesc

ErrorDesc

5.2.5. Absolute Time

A JSON number, seconds since the UNIX epoch.

5.2.6. Error Description

An Error Description is encoded as used to report failure of a JSON object with Trigger Command,
or in the following keys:

Key: activity it triggered.

Name: error

Type: ErrorCode

Value: Error Code, as defined in Section 5.2.7.

Mandatory: Yes

Keys: Yes.

Names: metadata.urls, content.urls

Type: Array of strings

Mandatory: At least one of metadata.* or content.* MUST be
present.

Keys: content.urls, metadata.patterns,
content.patterns

Type: Array

Description: Metadata and content references copied from the
Trigger Specification. Only those URLs and patterns to which
the error applies are included in each property, but those URLs
and patterns MUST be exactly as they appear in the request, the
dCDN MUST NOT generalise the URLs. (For example, if the uCDN
requests prepositioning of PatternMatch URLs "http://content.example.com/a"
and "http://content.example.com/b", the dCDN must not
generalise its error report to Pattern
"http://content.example.com/*".)

Value: A JSON array of JSON strings, where each string is
copied from a 'content.*' or 'metadata.*' value in the
corresponding Trigger Specification.

Mandatory: At least one of metadata.* or content.* MUST be
present.

Key: these name/value pairs is mandatory
in each Error Description object.

Name: description

Type: String

Description: A human-readable description of the error.

Value: A JSON string, the human-readable description.

Mandatory: No.

6.1.5. ErrorCode

One of

5.2.7. Error Code

This type is used by the strings "EMETA", "ECONTENT", "EPERM", "EREJECT" or "ECDN".

6.2. MIME Media Types

Table 1 lists dCDN to report failures in trigger
processing.

+-------------------+--------------------------------------------+ request (for | Data Object
| MIME Media Type |
+-------------------+--------------------------------------------+ example, a preposition request for content at a time |
| TriggerRequest | application/cdni.ci.TriggerRequest+json when the dCDN would not accept Request Routing |
| TriggerStatus | application/cdni.ci.TriggerStatus+json requests from the uCDN). |
| TriggerCollection ecdn | application/cdni.ci.TriggerCollection+json An internal error in the dCDN or one of its |
+-------------------+--------------------------------------------+

Table 1: MIME Media Types for CDNI Trigger resources

6. Examples

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

No authentication is shown in the following illustrative examples, it
is anticipated that authentication mechanisms will be aligned with
other CDNI Interfaces as and when those mechanisms are defined.

Discovery of the triggers interface is out of scope of 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 following
URLs are URL 'http://dcdn.example.com/
triggers' is used as the location of the collections of triggers:

o Collection collection of all Triggers belonging to one uCDN:

http://dcdn.example.com/triggers

o Filtered collections:

Pending: http://dcdn.example.com/triggers/pending

Active: http://dcdn.example.com/triggers/active

Complete: http://dcdn.example.com/triggers/complete

Failed: http://dcdn.example.com/triggers/failed

7.1. triggers,
and the CDN Provider Id of uCDN is "AS64496:1".

6.1. Creating Triggers

Examples of the uCDN triggering activity in the dCDN:

7.1.1.

6.1.1. Preposition

An example of a preposition request, a POST to the "AllTriggers"
collection.

Note that "metadata.patterns" and "content.patterns" are not allowed
in a preposition trigger request. Trigger Specification.

REQUEST:

POST /triggers HTTP/1.1
User-Agent: example-user-agent/0.1
Host: dcdn.example.com
Accept: */*
Content-Type: application/cdni.ci.TriggerRequest+json application/cdni.ci.TriggerCommand+json
Content-Length: 315 347

{
"trigger" : {
"type": "preposition",

"metadata.urls" : [ "http://metadata.example.com/a/b/c" ],
"content.urls" : [
"http://www.example.com/a/b/c/1",
"http://www.example.com/a/b/c/2",
"http://www.example.com/a/b/c/3",
"http://www.example.com/a/b/c/4"
]
}
},
"cdn-path" : [ "AS64496:1" ]
}

RESPONSE:

HTTP/1.1 201 Created
Date: Wed, 02 Jul Sun, 31 Aug 2014 18:57:19 09:53:18 GMT
Content-Length: 472
Content-Type: application/cdni.ci.TriggerStatus+json
Location: http://dcdn.example.com/triggers/0
Server: example-server/0.1

{
"ctime": 1404327439, 1409478798,
"etime": 1404327447, 1409478806,
"mtime": 1404327439, 1409478798,
"status": "pending",
"trigger": {
"content.urls": [
"http://www.example.com/a/b/c/1",
"http://www.example.com/a/b/c/2",
"http://www.example.com/a/b/c/3",
"http://www.example.com/a/b/c/4"
],
"metadata.urls": [
"http://metadata.example.com/a/b/c"
],
"type": "preposition"
}
}

7.1.2.

6.1.2. Invalidate

An example of an invalidate request, another POST to the
"AllTriggers" collection. This instructs the dCDN to re-validate the
content at "http://www.example.com/a/index.html", as well as any
metadata and content whose URLs are prefixed by
"http://metadata.example.com/a/b/" and "http://www.example.com/a/b/"
respectively, using case-insensitive matching.

REQUEST:

{
"trigger" : {
"type": "invalidate",

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

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

},
"cdn-path" : [ "AS64496:1" ]
}

RESPONSE:

HTTP/1.1 201 Created
Date: Wed, 02 Jul Sun, 31 Aug 2014 18:57:20 09:53:19 GMT
Content-Length: 551
Content-Type: application/cdni.ci.TriggerStatus+json
Location: http://dcdn.example.com/triggers/1
Server: example-server/0.1

{
"ctime": 1404327440, 1409478799,
"etime": 1404327448, 1409478807,
"mtime": 1404327440, 1409478799,
"status": "pending",
"trigger": {
"content.patterns": [
{
"case-sensitive": true,
"pattern": "http://www.example.com/a/b/*"
}
],
"content.urls": [
"http://www.example.com/a/index.html"
],
"metadata.patterns": [
{
"pattern": "http://metadata.example.com/a/b/*"
}
],
"type": "invalidate"
}
}

7.2.

6.2. Examining Trigger Status

Once triggers have been created, the uCDN can check their status as
shown in these examples.

7.2.1.

6.2.1. Collection of All Triggers

The uCDN can fetch the set of all the triggers it has created and
which 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: 153 347
Expires: Wed, 02 Jul Sun, 31 Aug 2014 18:58:20 09:54:19 GMT
Server: example-server/0.1
Etag: "9179988753593038498" "-6516741166528256414"
Cache-Control: max-age=60
Date: Wed, 02 Jul Sun, 31 Aug 2014 18:57:20 09:53:19 GMT
Content-Type: application/cdni.ci.TriggerCollection+json

{
"cdn-id": "AS64496:0",
"coll-active": "/triggers/active",
"coll-complete": "/triggers/complete",
"coll-failed": "/triggers/failed",
"coll-pending": "/triggers/pending",
"staleresourcetime": 86400,
"triggers": [
"http://dcdn.example.com/triggers/0",
"http://dcdn.example.com/triggers/1"
]
}

7.2.2.

6.2.2. Filtered Collections of Triggers

The filtered collections are also available to the uCDN. Before the
dCDN starts processing the two triggers shown above, both will appear
in the collection of Pending Triggers, for example:

RREQUEST:

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: 153
Expires: Wed, 02 Jul Sun, 31 Aug 2014 18:58:20 09:54:19 GMT
Server: example-server/0.1
Etag: "5012053611544832286"
Cache-Control: max-age=60
Date: Wed, 02 Jul Sun, 31 Aug 2014 18:57:20 09:53:19 GMT
Content-Type: application/cdni.ci.TriggerCollection+json

{
"staleresourcetime": 86400,
"triggers": [
"http://dcdn.example.com/triggers/0",
"http://dcdn.example.com/triggers/1"
]
}

At this point, if no other triggers had been created, the other
filtered views of the triggers 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: 56
Expires: Wed, 02 Jul Sun, 31 Aug 2014 18:58:20 09:54:19 GMT
Server: example-server/0.1
Etag: "2986340333785000363"
Cache-Control: max-age=60
Date: Wed, 02 Jul Sun, 31 Aug 2014 18:57:20 09:53:19 GMT
Content-Type: application/cdni.ci.TriggerCollection+json

{
"staleresourcetime": 86400,
"triggers": []
}

7.2.3.

6.2.3. Trigger Status Resources

The Trigger Status Resources can also be examined for detail about
individual triggers. For example, for the "preposition" and
"invalidate" triggers 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: 472
Expires: Wed, 02 Jul Sun, 31 Aug 2014 18:58:20 09:54:19 GMT
Server: example-server/0.1
Etag: "-3651695664007658154" "-4765587034697674779"
Cache-Control: max-age=60
Date: Wed, 02 Jul Sun, 31 Aug 2014 18:57:20 09:53:19 GMT
Content-Type: application/cdni.ci.TriggerStatus+json

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: 551
Expires: Wed, 02 Jul Sun, 31 Aug 2014 18:58:20 09:54:19 GMT
Server: example-server/0.1
Etag: "-7664987687828084413" "-7657333837290433420"
Cache-Control: max-age=60
Date: Wed, 02 Jul Sun, 31 Aug 2014 18:57:20 09:53:19 GMT
Content-Type: application/cdni.ci.TriggerStatus+json

7.2.4.

6.2.4. Polling for Change

The uCDN may SHOULD use the Entity Tags of collections or resources when
polling for change 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: "5012053611544832286"

RESPONSE:

HTTP/1.1 304 Not Modified
Content-Length: 0
Expires: Wed, 02 Jul Sun, 31 Aug 2014 18:58:20 09:54:19 GMT
Server: example-server/0.1
Etag: "5012053611544832286"
Cache-Control: max-age=60
Date: Wed, 02 Jul Sun, 31 Aug 2014 18:57:20 09:53:19 GMT
Content-Type: application/cdni.ci.TriggerCollection+json

REQUEST:

GET /triggers/0 HTTP/1.1
User-Agent: example-user-agent/0.1
Host: dcdn.example.com
Accept: */*
If-None-Match: "-3651695664007658154" "-4765587034697674779"

RESPONSE:

HTTP/1.1 304 Not Modified
Content-Length: 0
Expires: Wed, 02 Jul Sun, 31 Aug 2014 18:58:20 09:54:19 GMT
Server: example-server/0.1
Etag: "-3651695664007658154" "-4765587034697674779"
Cache-Control: max-age=60
Date: Wed, 02 Jul Sun, 31 Aug 2014 18:57:20 09:53:19 GMT
Content-Type: application/cdni.ci.TriggerStatus+json

When the triggered activity is complete, the contents of the filtered
collections will be updated, along with their Entity Tags. For
example, when the two example triggers are complete, the collections
of pending and complete triggers may 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: 56
Expires: Wed, 02 Jul Sun, 31 Aug 2014 18:58:24 09:54:29 GMT
Server: example-server/0.1
Etag: "-4471185573414616962"
Cache-Control: max-age=60
Date: Wed, 02 Jul Sun, 31 Aug 2014 18:57:24 09:53:29 GMT
Content-Type: application/cdni.ci.TriggerCollection+json

{
"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: 153
Expires: Wed, 02 Jul Sun, 31 Aug 2014 18:58:31 09:54:30 GMT
Server: example-server/0.1
Etag: "-1508172875796647067"
Cache-Control: max-age=60
Date: Wed, 02 Jul Sun, 31 Aug 2014 18:57:31 09:53:30 GMT
Content-Type: application/cdni.ci.TriggerCollection+json

{
"staleresourcetime": 86400,
"triggers": [
"http://dcdn.example.com/triggers/0",
"http://dcdn.example.com/triggers/1"
]
}

7.2.5. Cancelling or

6.2.5. Removing a Trigger

To request the dCDN to cancel a Trigger, the uCDN may can delete the
Trigger Resource. It may can also delete completed and failed triggers
to reduce the size of the collections. For example, to remove 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, 02 Jul Sun, 31 Aug 2014 18:57:31 09:53:30 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 triggers
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: 106
Expires: Wed, 02 Jul Sun, 31 Aug 2014 18:58:31 09:54:30 GMT
Server: example-server/0.1
Etag: "-1842390246836476263"
Cache-Control: max-age=60
Date: Wed, 02 Jul Sun, 31 Aug 2014 18:57:31 09:53:30 GMT
Content-Type: application/cdni.ci.TriggerCollection+json

{
"staleresourcetime": 86400,
"triggers": [
"http://dcdn.example.com/triggers/1"
]
}

7.2.6.

6.2.6. Error Reporting

In this example the uCDN has requested prepositioning of
"http://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: 505
Expires: Wed, 02 Jul Sun, 31 Aug 2014 19:16:48 09:54:38 GMT
Server: example-server/0.1
Etag: "-6310233270471598826" "-3893590191073700822"
Cache-Control: max-age=60
Date: Wed, 02 Jul Sun, 31 Aug 2014 19:15:48 09:53:38 GMT
Content-Type: application/cdni.ci.TriggerStatus+json

{
"ctime": 1404328544, 1409478810,
"errors": [
{
"content.urls": [
"http://newsite.example.com/index.html"
],
"description":
"No HostIndex entry found for newsite.example.com",
"error": "EMETA"
}
],
"etime": 1404328552,
"mtime": 1404328548,
"status": "active",
"trigger": {
"content.urls": [
"http://newsite.example.com/index.html"
],
"type": "preposition"
}
}

8. IANA Considerations

8.1. newsite.example.com",
"error": "emeta"
}
],
"etime": 1409478818,
"mtime": 1409478814,
"status": "active",
"trigger": {
"content.urls": [
"http://newsite.example.com/index.html"
],
"type": "preposition"
}
}

7. IANA Considerations

7.1. Media type registrations

7.1.1. CI/T Commands

The MIME media type for CI/T Commands is application/
cdni.ci.TriggerCommand+json.

Type Name: application

Subtype name: cdni.ci.TriggerCommand+json

Required parameters: N/A

Optional parameters: N/A

Encoding considerations: binary

Security Considerations: See [RFCthis], Section 8

Interoperability Considerations: Described in [RFCthis]

Published Specification: [RFCthis]

Applications that use this media type: No known applications
currently use this media type.

Additional Information:

Deprecated alias names for this type: N/A

Magic number(s): N/A

File Extensions: N/A

Macintosh file type code(s): TEXT

Person & email address to contact for further information: IESG
<iesg@ietf.org>

Intended Usage: COMMON

Restrictions on usage: None

Author: Rob Murray <rob.murray@alcatel-lucent.com>

Change controller: IESG <iesg@ietf.org>
Note: No "charset" parameter is defined for this registration because
a charset parameter is not defined for application/json [RFC7159].

7.1.2. CI/T MIME Media Types Trigger Status Resource

The IANA MIME media type for CI/T Trigger Status Resources is requested application/
cdni.ci.TriggerStatus+json.

Type Name: application

Subtype name: cdni.ci.TriggerStatus+json

Required parameters: N/A

Optional parameters: N/A

Encoding considerations: binary

Security Considerations: See [RFCthis], Section 8

Interoperability Considerations: Described in [RFCthis]

Published Specification: [RFCthis]

Applications that use this media type: No known applications
currently use this media type.

Additional Information:

Deprecated alias names for this type: N/A

Magic number(s): N/A

File Extensions: N/A

Macintosh file type code(s): TEXT

Person & email address to allocate the following MIME Media Types in
the contact for further information: IESG
<iesg@ietf.org>

Intended Usage: COMMON

Restrictions on usage: None

Author: Rob Murray <rob.murray@alcatel-lucent.com>

Change controller: IESG <iesg@ietf.org>
Note: No "charset" parameter is defined for this registration because
a charset parameter is not defined for application/json [RFC7159].

7.1.3. CI/T Trigger Collection

The MIME Media Types registry:

o application/cdni.ci.TriggerRequest

o application/cdni.ci.TriggerStatus

o application/cdni.ci.TriggerCollection

Use of these types media type for CI/T Trigger Collections is specified in application/
cdni.ci.TriggerCollection+json.

Type Name: application

Subtype name: cdni.ci.TriggerCollection+json

Required parameters: N/A

Optional parameters: N/A

Encoding considerations: binary

Security Considerations: See [RFCthis], Section 6.2 of the present
document.

9. 8

Interoperability Considerations: Described in [RFCthis]

Published Specification: [RFCthis]

Applications that use this media type: No known applications
currently use this media type.

Additional Information:

Deprecated alias names for this type: N/A

Magic number(s): N/A

File Extensions: N/A

Macintosh file type code(s): TEXT

Person & email address to contact for further information: IESG
<iesg@ietf.org>

Intended Usage: COMMON

Restrictions on usage: None

Author: Rob Murray <rob.murray@alcatel-lucent.com>

Change controller: IESG <iesg@ietf.org>
Note: No "charset" parameter is defined for this registration because
a charset parameter is not defined for application/json [RFC7159].

8. Security Considerations

9.1.

8.1. Authentication, Confidentiality, Integrity Protection

A CI/T dCDN server implementation MUST support TLS transport for HTTP
(https) as per [RFC2818]. The use of TLS for transport of the CI/T
interface allows the dCDN and the uCDN to authenticate each other (to
ensure they are receiving trigger requests from, or reporting status
to, an authenticated CDN).

HTTP requests that attempt to access or operate on CI/T data
belonging to another CDN MUST be rejected using either HTTP "403
Forbidden" or "404 Not Found". (Note that in a "diamond"
configuration, where one uCDN's content can be acquired via more than
one directly-connected uCDN, it may not be possible for the dCDN to
determine from which uCDN it acquired content. In this case, it MUST
allow each upstream that may have been responsible for acquisition of
that content to act upon it using trigger requests.)

Trigger creation requests that attempt to operate on metadata or
content not acquired from the uCDN making the request MUST be
rejected. The rejection can either be signalled to dCDN using HTTP
"403 Forbidden" or "404 Not Found", authenticate each other (to
ensure they are receiving CI/T Commands from, or a Trigger Status Resource can
be created with reporting status to,
an ErrorDesc value of EPERM for any affected URLs. authenticated CDN).

In an environment where any such protection is required, TLS SHOULD
be used for transport of the CI/T requests and responses, unless
alternate methods are used for ensuring that only authorised clients
are able to access their own data (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). Both
parties of the transaction (the uCDN and the dCDN) SHOULD use mutual
authentication.

A CI/T TLS implementation of CI/T MUST support the
TLS_DHE_RSA_WITH_AES_128_GCM_SHA256 cipher suite ([RFC5288]). An
implementation of the CI/T Interface SHOULD prefer cipher suites
which support perfect forward secrecy over cipher suites that don't.

9.2.

HTTP requests that attempt to access or operate on CI/T data
belonging to another CDN MUST be rejected using, for example, HTTP
"403 Forbidden" or "404 Not Found".

Note that in a "diamond" configuration, where one uCDN's content can
be acquired via more than one directly-connected uCDN, it may not be
possible for the dCDN to determine from which uCDN it acquired
content. In this case, the dCDN MUST allow each uCDN from which the
content could have been acquired to act upon that content using CI/T
Commands.

8.2. Denial of Service

This document does not define a specific mechanism to protect against
Denial of Service (DoS) attacks on the CI/T. 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 use of Virtual Private Networks (VPNs).

10.

Depending on the implementation, triggered activity may consume
significant processing and bandwidth in the dCDN. A malicious or
faulty uCDN could use this to generate unnecessary load in the dCDN.
The dCDN should consider mechanisms to avoid overload, for example by
rate-limiting acceptance or processing of CI/T Commands, or batching
up its processing.

9. Acknowledgements

The authors thank Kevin Ma for his ongoing input.

11.

10. References

11.1.

10.1. Normative References

[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.

[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
Resource Identifier (URI): Generic Syntax", STD 66, RFC
3986, January 2005.

[RFC7159] Bray, T., "The JavaScript Object Notation (JSON) Data
Interchange Format", RFC 7159, March 2014.

[RFC7231] Fielding, R. and J. Reschke, "Hypertext Transfer Protocol
(HTTP/1.1): Semantics and Content", RFC 7231, June 2014.

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

11.2.

10.2. Informative References

[I-D.ietf-cdni-framework]
Peterson, L., Davie, B., and R. Brandenburg, "Framework
for CDN Interconnection", draft-ietf-cdni-framework-14
(work in progress), June 2014.

[I-D.ietf-cdni-metadata]
Niven-Jenkins, B., Murray, R., Watson, G., Caulfield, M., Leung, K.,
and K. Ma, "CDN Interconnect Interconnection Metadata", draft-
ietf-cdni-metadata-06 draft-ietf-
cdni-metadata-07 (work in progress), February July 2014.

[I-D.ietf-cdni-requirements]
Leung, K.

[I-D.ietf-cdni-redirection]
Niven-Jenkins, B. and Y. Lee, "Content Distribution Network
Interconnection (CDNI) Requirements", draft-ietf-cdni-
requirements-17 R. Brandenburg, "Request Routing
Redirection Interface for CDN Interconnection", draft-
ietf-cdni-redirection-03 (work in progress), January August 2014.

[RFC2818] Rescorla, E., "HTTP Over TLS", RFC 2818, May 2000.

[RFC4287] Nottingham, M., Ed. and R. Sayre, Ed., "The Atom
Syndication Format", RFC 4287, December 2005.

[RFC5288] Salowey, J., Choudhury, A., and D. McGrew, "AES Galois
Counter Mode (GCM) Cipher Suites for TLS", RFC 5288,
August 2008.

[RFC6707] Niven-Jenkins, B., Le Faucheur, F., and N. Bitar, "Content
Distribution Network Interconnection (CDNI) Problem
Statement", RFC 6707, September 2012.

[XML-BASE]
Marsh, J., Ed.

[RFC7336] Peterson, L., Davie, B., and R. Tobin, Ed., "XML Base (Second
Edition) - http://www.w3.org/TR/xmlbase/", January 2009. van Brandenburg,
"Framework for Content Distribution Network
Interconnection (CDNI)", RFC 7336, August 2014.

[RFC7337] Leung, K. and Y. Lee, "Content Distribution Network
Interconnection (CDNI) Requirements", RFC 7337, August
2014.

Authors' Addresses

Rob Murray
Velocix (Alcatel-Lucent)
3 Ely Road
Milton, Cambridge CB24 6DD
UK

Email: rmurray@velocix.com

Ben Niven-Jenkins
Velocix (Alcatel-Lucent)
3 Ely Road
Milton, Cambridge CB24 6DD
UK

Email: ben@velocix.com