One document matched: draft-ietf-cdni-control-triggers-04.txt
Differences from draft-ietf-cdni-control-triggers-03.txt
Network Working Group R. Murray
Internet-Draft B. Niven-Jenkins
Intended status: Standards Track Velocix (Alcatel-Lucent)
Expires: March 7, 2015 September 3, 2014
CDNI Control Interface / Triggers
draft-ietf-cdni-control-triggers-04
Abstract
This document describes the part of the CDN 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 invalidates or
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 March 7, 2015.
Copyright Notice
Copyright (c) 2014 IETF Trust and the persons identified as the
document authors. All rights reserved.
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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
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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 . . . . . . . . . . . . . . . . . . . 4
2.1. Timing of Triggered Activity . . . . . . . . . . . . . . 6
2.2. Trigger Results . . . . . . . . . . . . . . . . . . . . . 6
3. Collections of Trigger Status Resources . . . . . . . . . . . 6
4. CDNI Trigger Interface . . . . . . . . . . . . . . . . . . . 7
4.1. Creating Triggers . . . . . . . . . . . . . . . . . . . . 8
4.2. Checking Status . . . . . . . . . . . . . . . . . . . . . 10
4.2.1. Polling Trigger Status Resource collections . . . . . 10
4.2.2. Polling Trigger Status Resources . . . . . . . . . . 10
4.3. Cancelling Triggers . . . . . . . . . . . . . . . . . . . 10
4.4. Deleting Triggers . . . . . . . . . . . . . . . . . . . . 11
4.5. Expiry of Trigger Status Resources . . . . . . . . . . . 12
4.6. Loop Detection and Prevention . . . . . . . . . . . . . . 12
4.7. Error Handling . . . . . . . . . . . . . . . . . . . . . 13
4.8. Content URLs . . . . . . . . . . . . . . . . . . . . . . 13
5. CI/T Object Properties and Encoding . . . . . . . . . . . . . 14
5.1. CI/T Objects . . . . . . . . . . . . . . . . . . . . . . 14
5.1.1. CI/T Commands . . . . . . . . . . . . . . . . . . . . 14
5.1.2. Trigger Status Resource . . . . . . . . . . . . . . . 15
5.1.3. Trigger Collection . . . . . . . . . . . . . . . . . 16
5.2. Properties of CI/T Objects . . . . . . . . . . . . . . . 17
5.2.1. Trigger Specification . . . . . . . . . . . . . . . . 18
5.2.2. Trigger Type . . . . . . . . . . . . . . . . . . . . 19
5.2.3. Trigger Status . . . . . . . . . . . . . . . . . . . 19
5.2.4. PatternMatch . . . . . . . . . . . . . . . . . . . . 20
5.2.5. Absolute Time . . . . . . . . . . . . . . . . . . . . 21
5.2.6. Error Description . . . . . . . . . . . . . . . . . . 21
5.2.7. Error Code . . . . . . . . . . . . . . . . . . . . . 22
6. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . 22
6.1. Creating Triggers . . . . . . . . . . . . . . . . . . . . 23
6.1.1. Preposition . . . . . . . . . . . . . . . . . . . . . 23
6.1.2. Invalidate . . . . . . . . . . . . . . . . . . . . . 24
6.2. Examining Trigger Status . . . . . . . . . . . . . . . . 25
6.2.1. Collection of All Triggers . . . . . . . . . . . . . 25
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6.2.2. Filtered Collections of Triggers . . . . . . . . . . 26
6.2.3. Trigger Status Resources . . . . . . . . . . . . . . 28
6.2.4. Polling for Change . . . . . . . . . . . . . . . . . 30
6.2.5. Removing a Trigger . . . . . . . . . . . . . . . . . 33
6.2.6. Error Reporting . . . . . . . . . . . . . . . . . . . 35
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 36
7.1. Media type registrations . . . . . . . . . . . . . . . . 36
7.1.1. CI/T Commands . . . . . . . . . . . . . . . . . . . . 36
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 . . 39
8.2. Denial of Service . . . . . . . . . . . . . . . . . . . . 39
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 40
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 40
10.1. Normative References . . . . . . . . . . . . . . . . . . 40
10.2. Informative References . . . . . . . . . . . . . . . . . 40
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 41
1. Introduction
[RFC6707] introduces the 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).
[RFC7336] expands on the information provided in [RFC6707] and
describes each of the interfaces and the relationships between them
in more detail.
This document describes the "CI/T" interface, "CDNI Control interface
/ Triggers". It does not consider those parts of the control
interface that relate to configuration, bootstrapping or
authentication of CDN Interconnect interfaces. Section 4 of
[RFC7337] identifies the requirements specific to the CI interface,
requirements applicable to the CI/T interface are CI-1 to CI-6.
o Section 2 outlines the model for the CI/T Interface at a high
level.
o Section 3 describes collections of Trigger Status Resources.
o Section 4 defines the web service provided by the dCDN.
o Section 5 lists properties of CI/T Commands and Status Resources.
o Section 6 contains example messages.
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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 the dCDN
to do some work relating to data originating from the uCDN.
The trigger can 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.
Multiple representations of an HTTP resource may share the same URL.
Requests to invalidate and purge metadata or content apply to all
resource representations with matching URLs.
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 can poll Trigger Status Resources to monitor
progress.
The dCDN maintains a collection of Trigger Status 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 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 can GET the
Trigger Status Resource. To request cancellation of a trigger the
uCDN can POST to the collection of Trigger Status Resources, or
simply DELETE the Trigger Status Resource.
In addition to the collection of all Trigger Status Resources for the
uCDN, the dCDN can maintain filtered views of that collection. These
filtered views are defined in Section 3 and include collections of
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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 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". 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 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.
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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 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 pre-
positions the new content, then immediately invalidates or purges it
(as a result of the two uCDN requests running in parallel).
2.2. Trigger Results
Each trigger can operate on multiple metadata and content URLs. The
trigger MUST NOT be reported as "complete" until all actions have
been completed successfully. The reasons for failure, and URLs or
Patterns affected, SHOULD be enumerated in the Trigger Status
Resource. For more detail, see section Section 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' in a CDN
until it is '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' 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.
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The dCDN MUST make a collection of a uCDN's Trigger Status Resources
available to that uCDN. This collection includes 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 4.4). 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, or by filtering the response based on the client uCDN.
To trigger activity in a dCDN, or to cancel triggered activity, the
uCDN POSTs a CI/T Command to the dCDN's collection of the uCDN's
Trigger Status Resources.
In order to allow the uCDN to check the status of multiple jobs in a
single request, the dCDN 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 and 'processed' triggers for which no
further status updates will be made by the dCDN.
o Failed - Trigger Status Resources representing activity that
failed or was cancelled by the uCDN.
4. CDNI Trigger Interface
This section describes an interface to enable an upstream CDN to
trigger activity in a downstream CDN.
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 dCDNs
implementing CI/T that contain a response body SHOULD include an ETag
to enable validation of cached versions of returned resources.
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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 collection of all Trigger Status Resources
needs to be either discovered by, or configured in, the uCDN. The
mechanism for discovery of that URL is outside the scope of this
document.
CI/T Commands are POSTed to the dCDN's collection of all Trigger
Status Resources. If a 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 dCDNs are free to assign whatever structure they
desire to the URIs for CI/T resources. Therefore uCDNs MUST NOT make
any assumptions regarding the structure of CI/T URIs or the mapping
between CI/T objects and their associated URIs. URIs present in the
examples in this document are purely illustrative and are not
intended to impose a definitive structure on CI/T interface
implementations.
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.
The dCDN MUST ensure that activity triggered by the uCDN only affects
metadata or content originating from that uCDN.
4.1. Creating Triggers
To create a new trigger, 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 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 MUST either
respond with an appropriate 4xx HTTP error code and a resource MUST
NOT be created on the dCDN, or create a 'failed' Trigger Status
Resource containing an appropriate error description.
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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 "trigger" property of the Trigger Status Resource contains the
Trigger Specification posted in the body of the CI/T Command. Note
that this need not be a byte-for-byte copy. For example, in the JSON
representation the dCDN may re-serialise the information differently.
If the dCDN is not able to track the execution of triggered activity,
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 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 can be cancelled 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.
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4.2. Checking Status
The uCDN has two ways to check progress of activity it has triggered
in the dCDN, described in 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 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 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 URI provided by the dCDN for each Trigger Status
Resource it has created, it may fetch that resource at any time.
This can be used to retrieve progress information, and to fetch the
result of triggered activity.
When polling in this way, the uCDN SHOULD use HTTP Entity Tags to
monitor for change, rather than repeatedly fetching the Trigger
Status Resource.
4.3. Cancelling Triggers
The uCDN can request cancellation of a trigger by POSTing a 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
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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 accepted by
the dCDN, the dCDN SHOULD NOT start processing of that activity.
Cancelling a "pending" trigger does not however guarantee that not
activity is 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
triggered activity. However, as with cancellation of a "pending"
trigger, the dCDN does not guarantee this.
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" 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 resource SHOULD fail.
If a "pending" Trigger Status Resource is deleted, the dCDN SHOULD
NOT start processing of that 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.
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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", "failed" or "cancelled".
To ensure it is able to get the status of its completed and failed
triggers, it is recommended that the uCDN's polling interval is less
than the time after which records for completed activity will be
deleted.
4.6. Loop Detection and Prevention
Given three CDNs, A, B and C. If CDNs B and C delegate delivery of
CDN A's content to each other, CDN A's 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 loops, each CDN uses a CDN
Provider ID to uniquely identify itself. Each CDN MUST insert its
CDN Provider ID into the 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.
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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 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 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 is still "pending" or
"active", if the trigger is still running for some URLs or Patterns
in the Trigger Specification.
Once a request has been accepted, processing errors are reported in
the Trigger Status Resource using a list of Error Descriptions. Each
Error Description is used to report errors against one or more of the
URLs or Patterns in the Trigger Specification.
If a surrogate affected by a trigger is offline in the dCDN, or the
dCDN is unable to pass a CI/T Command on to any of its cascaded
dCDNs:
o If the request is abandoned by the dCDN, the dCDN SHOULD 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.
o "preposition" and "purge" triggers 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 in state "pending" or
"active" until the trigger is acted upon, or the 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 as in the metadata it supplied to the dCDN. By definition,
it is always possible for the dCDN to locate content based on URLs in
this form.
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Therefore, if content URLs are transformed by an intermediate CDN in
a cascade, that intermediate CDN MUST transform URLs in CI/T commands
it passes to its dCDN.
When processing Trigger Specifications, CDNs MUST ignore the URL
scheme (http or https) in comparing URLs. For example, for an
invalidate or purge trigger, content MUST be invalidated or purged
regardless of the protocol clients use to request it.
5. CI/T Object Properties and Encoding
CI/T Commands, Trigger Status Resources and Trigger Collections and
their properties 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 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.
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
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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.
Value: Absolute Time, as defined in Section 5.2.5.
Mandatory: Yes
Name: mtime
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Description: Time at which the Trigger Status Resource was last
modified. Time is determined by the dCDN, there is no
requirement to synchronise clocks between interconnected CDNs.
Value: Absolute Time, as defined in Section 5.2.5.
Mandatory: Yes
Name: etime
Description: Estimate of the time at which the dCDN expects to
complete the activity. Time is determined by the dCDN, there
is no requirement to synchronise clocks between interconnected
CDNs.
Value: Absolute Time, as defined in Section 5.2.5.
Mandatory: No
Name: status
Description: Current status of the triggered activity.
Value: Trigger Status, as defined in Section 5.2.3.
Mandatory: Yes
Name: errors
Description: Descriptions of errors that have occurred while
processing a Trigger Command.
Value: A list of Error Descriptions, as defined in
Section 5.2.6.
Mandatory: No.
5.1.3. Trigger Collection
Trigger Collections SHOULD use a MIME Media Type of application/
cdni.ci.TriggerCollection+json.
A Trigger Collection is encoded as a JSON object containing the
following name/value pairs.
Name: triggers
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Description: Links to Trigger Status Resources in the
collection.
Value: A JSON array of URLs represented as JSON strings.
Mandatory: Yes
Name: staleresourcetime
Description: The length of time for which the dCDN guarantees
to keep a completed Trigger Status Resource. After this time,
the dCDN SHOULD delete the resource and all references to it
from collections.
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.
Names: coll-all, coll-pending, coll-active, coll-complete, coll-
failed
Description: Link to a Trigger Collection.
Value: A URL represented as a JSON string.
Mandatory: Links to 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 of the dCDN.
Value: A JSON string, the dCDN's CDN Provider Identifier, 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.
5.2. Properties of CI/T Objects
This section defines the values that can appear in the top level
objects described in Section 5.1, and their encodings.
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5.2.1. Trigger Specification
A Trigger Collection is encoded as a JSON object containing the
following name/value pairs.
An unrecognised 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 the type of the trigger.
Value: Trigger Type, as defined in Section 5.2.2.
Mandatory: Yes
Name: metadata.urls
Description: The uCDN URLs of the metadata the 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 the trigger applies to, see
Section 4.8.
Value: A JSON array of URLs represented as JSON strings.
Mandatory: No, but at least one of 'metadata.*' or 'content.*'
MUST be present and non-empty.
Name: content.ccid
Description: The Content Collection Identifier of content the
trigger applies to. The 'ccid' is a grouping of content, as
defined by [I-D.ietf-cdni-metadata].
Value: A JSON array of strings, where each string is a Content
Collection Identifier.
Mandatory: No, but at least one of 'metadata.*' or 'content.*'
MUST be present and non-empty.
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Name: metadata.patterns
Description: The metadata the trigger applies to.
Value: A JSON 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 TriggerType is Preposition.
Name: content.patterns
Description: The content data the trigger applies to.
Value: A JSON 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 content.patterns MUST NOT be
present if the TriggerType is Preposition.
5.2.2. Trigger Type
Trigger Type is used in a Trigger Specification to describe trigger
action. It MUST be one of the JSON strings in the following table:
+-------------+-----------------------------------------------------+
| JSON String | Description |
+-------------+-----------------------------------------------------+
| preposition | A request for the dCDN to acquire metadata or |
| | content. |
| invalidate | A request for the dCDN to invalidate metadata or |
| | content. After servicing this request the dCDN will |
| | not use the specified data without first re- |
| | validating it using, for example, an "If-None- |
| | Match" HTTP request. The dCDN need not erase the |
| | associated data. |
| purge | A request for the dCDN to erase metadata or |
| | content. After servicing the request, the specified |
| | data MUST NOT be held on the dCDN. |
+-------------+-----------------------------------------------------+
5.2.3. Trigger Status
This describes the current status of a Trigger. It MUST be one of
the JSON strings in the following table:
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+------------+------------------------------------------------------+
| JSON | Description |
| String | |
+------------+------------------------------------------------------+
| pending | The trigger has not yet been acted upon. |
| active | The trigger is currently being acted upon. |
| complete | The triggered activity completed successfully. |
| processed | The trigger has been accepted and no further status |
| | update will be made (can be used in cases where |
| | completion cannot be confirmed). |
| failed | The triggered activity could not be completed. |
| cancelling | The triggered activity is still in progress, but the |
| | trigger has been cancelled by the uCDN. |
| cancelled | The triggered activity was cancelled by the uCDN. |
+------------+------------------------------------------------------+
5.2.4. PatternMatch
A Pattern Match consists of a string pattern to match, 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 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 "\?".
Mandatory: Yes.
Name: case-sensitive
Description: Flag indicating whether or not case-sensitive
matching should be used.
Value: One of the JSON values 'true' or 'false'.
Mandatory: No, default is case-insensitive match.
Name: match-query-string
Description: Flag indicating whether or not the query string
should be included in the pattern match.
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Value: One of the JSON values 'true' or 'false'.
Mandatory: No, default is not to include 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
}
5.2.5. Absolute Time
A JSON number, seconds since the UNIX epoch.
5.2.6. Error Description
An Error Description is used to report failure of a Trigger Command,
or in the activity it triggered.
Name: error
Value: Error Code, as defined in Section 5.2.7.
Mandatory: Yes.
Names: metadata.urls, content.urls, metadata.patterns,
content.patterns
Description: Metadata and content references copied from the
Trigger Specification. Only those URLs and patterns to which
the error applies are included in each property, but those URLs
and patterns MUST be exactly as they appear in the request, the
dCDN MUST NOT generalise the URLs. (For example, if the uCDN
requests prepositioning of 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 these name/value pairs is mandatory
in each Error Description object.
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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.
+------------+------------------------------------------------------+
| Error Code | Description |
+------------+------------------------------------------------------+
| emeta | The dCDN was unable to acquire metadata required to |
| | fulfil the request. |
| econtent | The dCDN was unable to acquire content (preposition |
| | triggers only). |
| eperm | The uCDN does not have permission to trigger the |
| | requested activity (for example, the data is owned |
| | by another CDN). |
| ereject | The dCDN is not willing to fulfil the request (for |
| | example, a preposition request for content at a time |
| | when the dCDN would not accept Request Routing |
| | requests from the uCDN). |
| ecdn | An internal error in the dCDN or one of its |
| | downstream CDNs. |
| ecancelled | The uCDN cancelled the request. |
+------------+------------------------------------------------------+
6. Examples
The following sections provide examples of different CI/T objects
encoded as JSON.
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 URL 'http://dcdn.example.com/
triggers' is used as the location of the collection of all triggers,
and the CDN Provider Id of uCDN is "AS64496:1".
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6.1. Creating Triggers
Examples of the uCDN triggering activity in the dCDN:
6.1.1. Preposition
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 Specification.
REQUEST:
POST /triggers HTTP/1.1
User-Agent: example-user-agent/0.1
Host: dcdn.example.com
Accept: */*
Content-Type: application/cdni.ci.TriggerCommand+json
Content-Length: 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: Sun, 31 Aug 2014 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": 1409478798,
"etime": 1409478806,
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"mtime": 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"
}
}
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:
POST /triggers HTTP/1.1
User-Agent: example-user-agent/0.1
Host: dcdn.example.com
Accept: */*
Content-Type: application/cdni.ci.TriggerCommand+json
Content-Length: 384
{
"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
}
]
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},
"cdn-path" : [ "AS64496:1" ]
}
RESPONSE:
HTTP/1.1 201 Created
Date: Sun, 31 Aug 2014 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": 1409478799,
"etime": 1409478807,
"mtime": 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"
}
}
6.2. Examining Trigger Status
Once triggers have been created, the uCDN can check their status as
shown in these examples.
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:
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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: 347
Expires: Sun, 31 Aug 2014 09:54:19 GMT
Server: example-server/0.1
Etag: "-6516741166528256414"
Cache-Control: max-age=60
Date: Sun, 31 Aug 2014 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"
]
}
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:
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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: Sun, 31 Aug 2014 09:54:19 GMT
Server: example-server/0.1
Etag: "5012053611544832286"
Cache-Control: max-age=60
Date: Sun, 31 Aug 2014 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:
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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: Sun, 31 Aug 2014 09:54:19 GMT
Server: example-server/0.1
Etag: "2986340333785000363"
Cache-Control: max-age=60
Date: Sun, 31 Aug 2014 09:53:19 GMT
Content-Type: application/cdni.ci.TriggerCollection+json
{
"staleresourcetime": 86400,
"triggers": []
}
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:
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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: Sun, 31 Aug 2014 09:54:19 GMT
Server: example-server/0.1
Etag: "-4765587034697674779"
Cache-Control: max-age=60
Date: Sun, 31 Aug 2014 09:53:19 GMT
Content-Type: application/cdni.ci.TriggerStatus+json
{
"ctime": 1409478798,
"etime": 1409478806,
"mtime": 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"
}
}
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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: Sun, 31 Aug 2014 09:54:19 GMT
Server: example-server/0.1
Etag: "-7657333837290433420"
Cache-Control: max-age=60
Date: Sun, 31 Aug 2014 09:53:19 GMT
Content-Type: application/cdni.ci.TriggerStatus+json
{
"ctime": 1409478799,
"etime": 1409478807,
"mtime": 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"
}
}
6.2.4. Polling for Change
The uCDN SHOULD use the Entity Tags of collections or resources when
polling for change in status, as shown in the following examples:
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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: Sun, 31 Aug 2014 09:54:19 GMT
Server: example-server/0.1
Etag: "5012053611544832286"
Cache-Control: max-age=60
Date: Sun, 31 Aug 2014 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: "-4765587034697674779"
RESPONSE:
HTTP/1.1 304 Not Modified
Content-Length: 0
Expires: Sun, 31 Aug 2014 09:54:19 GMT
Server: example-server/0.1
Etag: "-4765587034697674779"
Cache-Control: max-age=60
Date: Sun, 31 Aug 2014 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 might look like:
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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: Sun, 31 Aug 2014 09:54:29 GMT
Server: example-server/0.1
Etag: "-4471185573414616962"
Cache-Control: max-age=60
Date: Sun, 31 Aug 2014 09:53:29 GMT
Content-Type: application/cdni.ci.TriggerCollection+json
{
"staleresourcetime": 86400,
"triggers": []
}
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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: Sun, 31 Aug 2014 09:54:30 GMT
Server: example-server/0.1
Etag: "-1508172875796647067"
Cache-Control: max-age=60
Date: Sun, 31 Aug 2014 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"
]
}
6.2.5. Removing a Trigger
To request the dCDN to cancel a Trigger, the uCDN can delete the
Trigger Resource. It can also delete completed and failed triggers
to reduce the size of the collections. For example, to remove the
"preposition" request from earlier examples:
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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: Sun, 31 Aug 2014 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: Sun, 31 Aug 2014 09:54:30 GMT
Server: example-server/0.1
Etag: "-1842390246836476263"
Cache-Control: max-age=60
Date: Sun, 31 Aug 2014 09:53:30 GMT
Content-Type: application/cdni.ci.TriggerCollection+json
{
"staleresourcetime": 86400,
"triggers": [
"http://dcdn.example.com/triggers/1"
]
}
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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: Sun, 31 Aug 2014 09:54:38 GMT
Server: example-server/0.1
Etag: "-3893590191073700822"
Cache-Control: max-age=60
Date: Sun, 31 Aug 2014 09:53:38 GMT
Content-Type: application/cdni.ci.TriggerStatus+json
{
"ctime": 1409478810,
"errors": [
{
"content.urls": [
"http://newsite.example.com/index.html"
],
"description":
"No HostIndex entry found for newsite.example.com",
"error": "emeta"
}
],
"etime": 1409478818,
"mtime": 1409478814,
"status": "active",
"trigger": {
"content.urls": [
"http://newsite.example.com/index.html"
],
"type": "preposition"
}
}
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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>
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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 Trigger Status Resource
The MIME media type for CI/T Trigger Status Resources is 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 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>
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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 type for CI/T Trigger Collections is 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 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>
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Note: No "charset" parameter is defined for this registration because
a charset parameter is not defined for application/json [RFC7159].
8. Security Considerations
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 CI/T Commands from, or reporting status to,
an 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 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.
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).
Depending on the implementation, triggered activity may consume
significant processing and bandwidth in the dCDN. A malicious or
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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 input.
10. References
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.
10.2. Informative References
[I-D.ietf-cdni-metadata]
Niven-Jenkins, B., Murray, R., Caulfield, M., Leung, K.,
and K. Ma, "CDN Interconnection Metadata", draft-ietf-
cdni-metadata-07 (work in progress), July 2014.
[I-D.ietf-cdni-redirection]
Niven-Jenkins, B. and R. Brandenburg, "Request Routing
Redirection Interface for CDN Interconnection", draft-
ietf-cdni-redirection-03 (work in progress), August 2014.
[RFC2818] Rescorla, E., "HTTP Over TLS", RFC 2818, May 2000.
[RFC5288] Salowey, J., Choudhury, A., and D. McGrew, "AES Galois
Counter Mode (GCM) Cipher Suites for TLS", RFC 5288,
August 2008.
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[RFC6707] Niven-Jenkins, B., Le Faucheur, F., and N. Bitar, "Content
Distribution Network Interconnection (CDNI) Problem
Statement", RFC 6707, September 2012.
[RFC7336] Peterson, L., Davie, B., and R. 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
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