Network Working Group R. Murray Internet-Draft B. Niven-Jenkins Intended status: Standards Track Velocix (Alcatel-Lucent) Expires: March 3, 2013 August 30, 2012 CDN Interconnect Triggers draft-murray-cdni-triggers-01 Abstract This document proposes a mechanism for 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 or purge metadata or content. The upstream CDN can monitor the status of activity that it has triggered in the downstream CDN. Requirements Language The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119 [RFC2119]. Status of this Memo 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 3, 2013. Copyright Notice Copyright (c) 2012 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents Murray & Niven-Jenkins Expires March 3, 2013 [Page 1] Internet-Draft CDN Interconnect Triggers August 2012 (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 5 2. Model for CDNI Triggers . . . . . . . . . . . . . . . . . . . 5 2.1. Timing of Triggered Activity . . . . . . . . . . . . . . . 7 2.2. Trigger Results . . . . . . . . . . . . . . . . . . . . . 7 3. Collections of Trigger Status Resources . . . . . . . . . . . 8 4. CDNI Trigger interface . . . . . . . . . . . . . . . . . . . . 8 4.1. Creating Triggers . . . . . . . . . . . . . . . . . . . . 10 4.2. Checking Status . . . . . . . . . . . . . . . . . . . . . 11 4.2.1. Polling Trigger Status Resource collections . . . . . 11 4.2.2. Polling Trigger Status Resources . . . . . . . . . . . 11 4.3. Deleting Triggers . . . . . . . . . . . . . . . . . . . . 11 4.4. Expiry of Trigger Status Resources . . . . . . . . . . . . 12 5. Properties of Triggers . . . . . . . . . . . . . . . . . . . . 12 5.1. Properties of Trigger Requests . . . . . . . . . . . . . . 12 5.1.1. Content URLs . . . . . . . . . . . . . . . . . . . . . 13 5.2. Properties of Trigger Status Resources . . . . . . . . . . 13 5.3. Properties of Trigger Collections . . . . . . . . . . . . 14 5.4. Trigger Resource Simple Data Type Descriptions . . . . . . 15 5.4.1. TriggerType . . . . . . . . . . . . . . . . . . . . . 15 5.4.2. TriggerStatus . . . . . . . . . . . . . . . . . . . . 15 5.4.3. URLs . . . . . . . . . . . . . . . . . . . . . . . . . 15 5.4.4. UrlPatterns . . . . . . . . . . . . . . . . . . . . . 15 5.4.5. AbsoluteTime . . . . . . . . . . . . . . . . . . . . . 16 6. JSON Encoding of Objects . . . . . . . . . . . . . . . . . . . 16 6.1. JSON Encoding of Embedded Types . . . . . . . . . . . . . 17 6.1.1. TriggerType . . . . . . . . . . . . . . . . . . . . . 17 6.1.2. TriggerStatus . . . . . . . . . . . . . . . . . . . . 17 6.1.3. Metadata and Content References . . . . . . . . . . . 17 6.1.4. Pattern . . . . . . . . . . . . . . . . . . . . . . . 18 6.1.5. Relationship . . . . . . . . . . . . . . . . . . . . . 18 6.2. MIME Media Types . . . . . . . . . . . . . . . . . . . . . 19 7. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 7.1. Creating Triggers . . . . . . . . . . . . . . . . . . . . 20 7.1.1. Preposition . . . . . . . . . . . . . . . . . . . . . 20 7.1.2. Invalidate . . . . . . . . . . . . . . . . . . . . . . 21 7.2. Examining Trigger Status . . . . . . . . . . . . . . . . . 23 Murray & Niven-Jenkins Expires March 3, 2013 [Page 2] Internet-Draft CDN Interconnect Triggers August 2012 7.2.1. Collection of All Triggers . . . . . . . . . . . . . . 23 7.2.2. Filtered Collections of Triggers . . . . . . . . . . . 24 7.2.3. Trigger Status Resources . . . . . . . . . . . . . . . 25 7.2.4. Polling for Change . . . . . . . . . . . . . . . . . . 28 7.2.5. Cancelling or Removing a Trigger . . . . . . . . . . . 30 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 32 9. Security Considerations . . . . . . . . . . . . . . . . . . . 32 10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 32 11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 32 11.1. Normative References . . . . . . . . . . . . . . . . . . . 32 11.2. Informative References . . . . . . . . . . . . . . . . . . 32 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 33 Murray & Niven-Jenkins Expires March 3, 2013 [Page 3] Internet-Draft CDN Interconnect Triggers August 2012 1. Introduction [I-D.ietf-cdni-problem-statement] 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). [I-D.ietf-cdni-framework] expands on the information provided in [I-D.ietf-cdni-problem-statement] and describes each of the interfaces and the relationships between them in more detail. This draft concentrates on the "High" and "Medium" priority requirements for the CDNI Control Interface identified in section 4 of [I-D.ietf-cdni-requirements], reproduced here for convenience: CNTL-1 [HIGH] The CDNI Control interface shall allow the Upstream CDN to request that the Downstream CDN (and, if cascaded CDNs are supported by the solution, that the potential cascaded Downstream CDNs) perform the following actions on an object or object set: * Mark an object(s) and/or its CDNI metadata as "stale" and revalidate them before they are delivered again. * Delete an object(s) and/or its CDNI metadata from the CDN surrogates and any storage. Only the object(s) and CDNI metadata that pertain to the requesting Upstream CDN are allowed to be purged. CNTL-2 [HIGH] The CDNI Control interface shall allow the downstream CDN to report on the completion of these actions (by itself, and if cascaded CDNs are supported by the solution, by potential cascaded Downstream CDNs), in a manner appropriate for the action (e.g. synchronously or asynchronously). CNTL-3 [HIGH] The CDNI Control interface shall support initiation and control by the Upstream CDN of pre-positioned CDNI metadata acquisition by the Downstream CDN. CNTL-4 [MED] The CDNI Control interface should support initiation and control by the Upstream CDN of pre-positioned content acquisition by the Downstream CDN. This document does not consider those parts of the control interface that relate to configuration, bootstrapping or authentication of CDN Interconnect interfaces. o Section 2 outlines the model for the Trigger Interface at a high level. o Section 3 describes collections of Trigger Resources. o Section 4 defines the RESTful web service provided by dCDN. Murray & Niven-Jenkins Expires March 3, 2013 [Page 4] Internet-Draft CDN Interconnect Triggers August 2012 o Section 5 lists properties of Trigger Requests and Status Resources. o Section 6 defines a JSON encoding for Trigger Requests and Status Resources. o Section 7 contains example messages. 1.1. Terminology This document reuses the terminology defined in [I-D.ietf-cdni-problem-statement]. 2. Model for CDNI Triggers A trigger, sent from uCDN to dCDN, is a request for dCDN to do some work relating to data originating from uCDN. The trigger may request action on either metadata or content, the following actions can be requested: o preposition - used to instruct dCDN to fetch metadata from uCDN, or content from any origin including uCDN. o invalidate - used to instruct dCDN to revalidate specific metadata or content before re-using it. o purge - used to instruct dCDN to delete specific metadata or content. The CDNI trigger interface is a RESTful web service offered by dCDN. It allows creation and deletion of triggers, and tracking of the triggered activity. When 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 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 dCDN, uCDN will POST to the collection of Trigger Status Resources. If dCDN accepts the trigger, it creates a new Trigger Status Resource and returns its location to uCDN. To monitor progress, uCDN may GET the Trigger Status Resource. To cancel a trigger, or remove a trigger from the collection once its activity has been completed, uCDN may DELETE the Trigger Status Murray & Niven-Jenkins Expires March 3, 2013 [Page 5] Internet-Draft CDN Interconnect Triggers August 2012 Resource. In addition to the collection of all Trigger Status Resources for uCDN, uCDN shall have access to 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 dCDN, and for uCDN to discover the status of that activity. Only successful triggering is shown. Examples of the messages are given in Section 7. 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. uCDN triggers action in dCDN by posting to a collection of Trigger Status Resources, "http://dcdn.example.com/triggers/uCDN". The URL of this was given to uCDN when the trigger interface was established. 2. dCDN authenticates the request, validates the trigger and if it accepts the request, creates a new Trigger Status Resource. 3. dCDN responds to uCDN with an HTTP 201 response status, and the location of the Trigger Status Resource. 4. uCDN may repeatedly poll the Trigger Status Resource in dCDN. 5. dCDN responds with the Trigger Status Resource, describing progress or results of the triggered activity. Murray & Niven-Jenkins Expires March 3, 2013 [Page 6] Internet-Draft CDN Interconnect Triggers August 2012 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 triggered activity is under dCDN 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 dCDN. The dCDN MAY apply the triggers to data acquired after trigger creation. If uCDN triggers preposition as well as invalidate or purge of data in a single request, dCDN MUST ensure that data is not immediately invalidated or purged as it is prepositioned as a result of that same trigger. It MUST therefore also pass those triggers on to any downstream CDNs that have the data in a single Trigger Request to ensure that the further downstream CDN behaves in the same way. Note that each CDN may perform preposition and invalidate/purge activity in parallel even if triggered by the same request, but only if it is able to ensure that newly prepositioned data is not affected. It may achieve this by, for example, only invalidating/ purging data acquired before the trigger was created. 2.2. Trigger Results Each Trigger Request may operate on multiple data items, and may request different actions. The trigger shall be reported as successful only if all actions can be completed successfully. If any part of the trigger request fails, the trigger shall be reported as failed, and the error property in the Trigger Status Resource will be used to enumerate which actions failed and the reasons for failure. If a dCDN is also acting as 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. A trigger MAY be reported as failed as soon as it fails in a CDN or in any of its downstream CDNs. [Editor's Note: behaviour in case of partial failure is an open issue to be addressed in a later version of this draft - should the CDN report failure immediately or attempt to complete all actions first, and exactly how are partial failures reported?] Murray & Niven-Jenkins Expires March 3, 2013 [Page 7] Internet-Draft CDN Interconnect Triggers August 2012 3. Collections of Trigger Status Resources As described in Section 2, Trigger Status Resources exist in 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 dCDN, uCDN creates a new Trigger Status Resource by posting to dCDN's collection of uCDN's Trigger Status Resources. The URL of each Trigger Status Resource is generated by the dCDN when it accepts the trigger, and returned to uCDN. This immediately enables uCDN to check the status of that trigger. The dCDN must present a different set of Trigger Status Resources to each interconnected uCDN, only Trigger Status Resources belonging to a uCDN shall be visible to it. The dCDN may, for example, achieve this by offering different collection URLs to uCDNs, or by filtering the response based on the client uCDN. The dCDN resource representing the collection of all uCDN's Trigger Status Resources is accessible to uCDN. This collection lists all uCDN triggers that have been accepted by dCDN, and have not yet been deleted by uCDN or expired and removed by dCDN. In order to allow uCDN to check status of multiple jobs in a single request, dCDN shall also maintain collections representing filtered views of the collection of all Trigger Status Resources. 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 dCDN. o Complete - Trigger Status Resources representing activity that completed successfully. o Failed - Trigger Status Resources representing activity that failed. 4. CDNI Trigger interface This section describes an interface to enable an upstream CDN to trigger defined activities 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. The CDNI Trigger interface is built on the principles of RESTful web services. Requests are made over HTTP, and the HTTP Method defines Murray & Niven-Jenkins Expires March 3, 2013 [Page 8] Internet-Draft CDN Interconnect Triggers August 2012 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 implementing the CDNI Triggers interface that contain a response body SHOULD include an ETag to enable validation of cached versions of returned resources. Servers implementing the CDNI Trigger interface MUST support the HTTP GET, HEAD, POST and DELETE methods. The only representation specified in this document is JSON. Trigger Requests are POSTed to a URI in dCDN. If the trigger is accepted by dCDN, it creates a Trigger Status Resource and returns its URI to dCDN in an HTTP 201 response. The triggered activity can then be monitored by uCDN using that resource and the collections described in Section 3. The URI that Trigger Requests should be POSTed to needs to be either discovered by or configured in the upstream CDN. Performing a GET on that URI retrieves a collection of the URIs of all Trigger Status Resources. The URI of each Trigger Status Resource is also returned to uCDN when it is created. This means all Trigger Status Resources can be discovered, so CDNI Trigger servers are free to assign whatever structure they desire to the URIs for CDNI Trigger resources. CDNI Trigger clients MUST NOT make any assumptions regarding the structure of CDNI Trigger URIs or the mapping between CDNI Trigger objects and their associated URIs. Therefore any URIs present in the examples below are purely illustrative and are not intended to impose a definitive structure on CDNI Trigger interface implementations. The CDNI Trigger interface builds on top of HTTP, so CDNI Trigger servers may make use of any HTTP feature when implementing the CDNI Trigger interface. For example, a CDNI Trigger server may make use of HTTP's caching mechanisms to indicate that the returned response/ representation has not been modified since it was last returned, reducing the 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. For example, it is anticipated that decisions on use of HTTPS for other CDNI interfaces will be adopted for Triggers. Discovery of the CDNI Triggers Interface is outside the scope of this document. It is anticipated that a common mechanism for discovery of all CDNI interfaces will be defined. Murray & Niven-Jenkins Expires March 3, 2013 [Page 9] Internet-Draft CDN Interconnect Triggers August 2012 The dCDN must ensure that activity triggered by 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, uCDN makes an HTTP POST to the unfiltered collection of its triggers. The request body of that POST is a Trigger Request. dCDN validates and authenticates that request, if it is malformed or uCDN does not have sufficient access rights it MAY reject the request immediately. In this case, it SHALL respond with an appropriate 4xx HTTP error code and no resource shall be created on dCDN. If the request is accepted, uCDN SHALL create a new Trigger Status Resource. The HTTP response to dCDN SHALL have status code 201 and the URI of the Trigger Status Resource in the Location header field. The HTTP response MAY 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 dCDN MUST NOT re-use its location, even after that resource has been removed through deletion or expiry. The "request" property of the Trigger Status Resource SHALL contain the information posted in the body of the Trigger Request. 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 trigger is queued by dCDN for later action, the "status" property of the Trigger Status Resource SHALL be "pending". Once trigger processing has started the "status" SHALL be "active". A trigger may result in no activity in dCDN if, for example, it is an invalidate or purge request for data the dCDN has not acquired, or a prepopulate request for data it has already acquired. In this case, the "status" of the Trigger Status Resource shall be "complete" and the Trigger Status Resource shall be added to the dCDN collection of Complete Triggers. Once created, Trigger Status Resources may be deleted by uCDN but not modified. The dCDN MUST reject PUT and POST requests from uCDN to Trigger Status Resources using HTTP status code 403. Murray & Niven-Jenkins Expires March 3, 2013 [Page 10] Internet-Draft CDN Interconnect Triggers August 2012 4.2. Checking Status The uCDN has two ways to check progress of activity it has triggered in dCDN, described in the following sections. Because the triggers protocol is based on HTTP, Entity Tags may be used by the uCDN as cache validators, as defined in section 3.11 of [RFC2616], to check for change in status of a resource or collection of resources without re-fetching the whole resource or collection. 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 uCDN should poll for change. 4.2.1. Polling Trigger Status Resource collections 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 dCDN moves a Trigger Status Resource from the Active to the Completed collection, uCDN may chose to fetch the result of that activity. When polling in this way, uCDN may choose to use HTTP Entity Tags to monitor for change, rather than repeatedly fetching the whole collection. 4.2.2. Polling Trigger Status Resources uCDN has a reference (URI provided by the dCDN) for each Trigger Status Resource it has created, it may fetch that resource at any time. This may 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 the HTTP DELETE method. Once deleted, the references to a Trigger Status Resource MUST be removed from all Trigger Status Resource collections. Subsequent requests for the resource shall be handled as required by HTTP, and so will receive responses with status 404 or 410. If a "pending" Trigger Status Resource is deleted, dCDN SHOULD NOT Murray & Niven-Jenkins Expires March 3, 2013 [Page 11] Internet-Draft CDN Interconnect Triggers August 2012 start processing of that activity. Deleting a "pending" trigger does not however guarantee that it is not started because, once it has triggered activity, uCDN cannot control the timing of that activity. Processing may, for example, start after the DELETE is sent by uCDN and before the DELETE is processed by dCDN. If an "active" Trigger Status Resource is deleted, dCDN MAY stop processing the triggered activity. However, as with deletion of a "pending" trigger, dCDN does not guarantee this. Deletion of a "complete" or "failed" Trigger Status Resource requires no processing in dCDN other than deletion of the resource. 4.4. Expiry of Trigger Status Resources The dCDN MAY choose to automatically delete Trigger Status Resources some time after they become completed or failed. In this case, dCDN will remove the resource and respond to subsequent requests for it with HTTP status 404 or 410. If dCDN performs this housekeeping, it MUST have reported the length of time after which completed Trigger Status Resources become stale via a property of the collection of all Trigger Status Resources. It is recommended that Trigger Status Resources are automatically deleted 24 hours after they become completed or failed. To ensure it has access to the status of its completed and failed triggers, it is recommended that uCDN's polling interval is half the time after which records for completed activity will be considered stale. 5. Properties of Triggers 5.1. Properties of Trigger Requests Properties of Trigger Requests are defined in the following subsections. Property: type Description: This property defines the type of the trigger: Type: TriggerType Mandatory: Yes Property: metadata.urls Description: The uCDN URL for the metadata the trigger applies to. Murray & Niven-Jenkins Expires March 3, 2013 [Page 12] Internet-Draft CDN Interconnect Triggers August 2012 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: metadata.patterns Description: The metadata the trigger applies to. Type: UrlPatterns 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: UrlPatterns 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. 5.1.1. Content URLs Once interfaces for metadata and request routing interfaces have been agreed, it will be possible to define a way to make reference to content. That form of reference will be used in Trigger Requests. Some possible options for content references are: o Canonical URL - a reference to the content that is shared by all Interconnected CDNs. A potential problem is that the URL visible to dCDN may have been modified by uCDN during request redirection. o Origin URL - the URL from which dCDN acquired the content. May be different in each CDN as each dCDN may use its uCDN as the origin. o Metadata URL - some portion of the metadata served to uCDN by dCDN will describe content, it would be possible to refer to content fetched as a result of that metadata description. If the Content URL is modifed by uCDN, it is uCDN's responsibility to translate and pass-on Trigger Requests relating to that content using appropriately modified Content URLs. 5.2. Properties of Trigger Status Resources Property: trigger Description: The properties of trigger request that created this record. Murray & Niven-Jenkins Expires March 3, 2013 [Page 13] Internet-Draft CDN Interconnect Triggers August 2012 Type: TriggerRequest Mandatory: Yes Property: ctime Description: Time at which the request was received by dCDN. Time is local to dCDN, there is no requirement to synchronise clocks between interconnected CDNs. Type: AbsoluteTime Mandatory: Yes Property: mtime Description: Time at which the resource was last modified. Time is local to dCDN, there is no requirement to synchronise clocks between interconnected CDNs. Type: AbsoluteTime Mandatory: Yes Property: etime Description: Estimate of the time at which dCDN expects to complete the activity. Time is local to dCDN, there is no requirement to synchronise clocks between interconnected CDNs. Type: AbsoluteTime Mandatory: No Property: status Description: Current status of the triggered activity. Type: TriggerStatus Mandatory: Yes Property: error Description: Error indication. Type: (To be decided - a set of standard error conditions needs to be defined. The namespace for these errors codes should allow vendor-defined error codes for extension of the protocol. This may allow, for example, for the definition of more specific error codes when two CDNs supplied by the same vendor are interconnected.) Mandatory: No, and only allowed when "status" is "Failed". 5.3. Properties of Trigger Collections Property: links Description: References to Trigger Status Resources in the collection. Type: List of Relationships. Mandatory: Yes Property: staleresourcetime Murray & Niven-Jenkins Expires March 3, 2013 [Page 14] Internet-Draft CDN Interconnect Triggers August 2012 Description: The length of time for which dCDN guarantees to keep a completed Trigger Status Resource. After this time, dCDN MAY delete the resource and all references to it from collections. Type: Integer, time in seconds. Mandatory: Yes, in the collection of all Trigger Status Resources if 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. 5.4. Trigger Resource Simple Data Type Descriptions This section describes the simpler data types that are used for properties of Trigger Status resources. 5.4.1. TriggerType This type defines the type of action being triggered, permitted actions are: o Preposition - a request for dCDN to acquire metadata or content. o Invalidate - a request for 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. o Purge - a request for dCDN to erase metadata or content. After servicing the request, the specified data must not be held on dCDN. 5.4.2. TriggerStatus This type describes the current status of a Trigger, possible values are: o Pending - the trigger has not yet been acted upon. o Active - the trigger is currently being acted upon. o Complete - the triggered activity completed successfully. o Failed - the triggered activity could not be completed. 5.4.3. URLs This type describes a set of references to metadata or content, it is simply a list of absolute URLs. 5.4.4. UrlPatterns This type describes a reference to a set of metadata or content. It is a set of 'pattern.string' properties each of which has an optional Murray & Niven-Jenkins Expires March 3, 2013 [Page 15] Internet-Draft CDN Interconnect Triggers August 2012 'pattern.flags'. The intention is to align this with the pattern matching capabilities of the CDNI metadata interface, once defined. This current definition is based on that in [I-D.cjlmw-cdni-metadata]. Property: pattern.string Description: String to match against the URL of metadata or content, i.e. a [RFC3986] path-absolute. Type: Pattern Mandatory: Yes Property: pattern.flags Description: Flags to control the pattern match. Type: PatternFlags Mandatory: No (default Case-sensitive infix matching) 5.4.5. AbsoluteTime Times are expressed in seconds since the UNIX epoch. 6. JSON Encoding of Objects This encoding is based on that described in [I-D.cjlmw-cdni-metadata], but has been reproduced here while metadata work is in progress. Once that work is complete, the authors would look to align with the structure of the metadata draft and make reference to common definitions as appropriate. The encoding for a CDNI Trigger object is a JSON object containing a dictionary of (key,value) pairs where the keys are the property names, and the values are the associated property values. The keys of the dictionary are the names 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 of the returned resource). Likewise, the values associated with each key are dependent on the specific object being encoded (i.e. dependent on the MIME Media Type of the returned resource). The "triggers" property of the top level JSON object lists the requested actions. Key: triggers Description: List of triggers. Type: List of JSON objects, each specifying a trigger type and a set of data to act upon. Murray & Niven-Jenkins Expires March 3, 2013 [Page 16] Internet-Draft CDN Interconnect Triggers August 2012 Mandatory: Yes. Object keys in JSON are case sensitive and therefore any dictionary key defined by this document (for example the names of CDNI Triggers object properties) MUST always be represented in lowercase. In addition to the properties of the object, the following additional keys may be present. Key: base Description: Provides a prefix for any relative URLs in the object. This is similar to the XML base tag [XML-BASE]. If absent, all URLs in the remainder of the document must be absolute URLs. Type: URI Mandatory: No Key: links Description: The relationships of this object to other addressable objects. Type: List of Relationships. Mandatory: Yes 6.1. JSON Encoding of Embedded Types 6.1.1. TriggerType Key: type Description: One of "preposition", "invalidate" or "purge". Type: string Mandatory: Yes 6.1.2. TriggerStatus Key: status Description: One of "pending", "active", "failed", "complete" Type: string Mandatory: Yes 6.1.3. Metadata and Content References Keys: metadata.urls, content.urls Description: A list of URLs of the addressable objects being referenced. Type: URLs Mandatory: No Murray & Niven-Jenkins Expires March 3, 2013 [Page 17] Internet-Draft CDN Interconnect Triggers August 2012 Keys: metadata.patterns, content.patterns Description: A list of patterns to match against URLs of objects being referenced. Type: list of Patterns Mandatory: No 6.1.4. Pattern JSON: A dictionary with two keys, "pattern.string" and "pattern.flags": Key: pattern.string Description: The string to match URLs against. Type: string Mandatory: Yes Key: pattern.flags Description: A number calculated by adding together the values associated with each flag that is set. + 1 - Case-insensitive + 2 - Prefix + 4 - Suffix Type: integer Mandatory: Yes Example of case-insensitive prefix match against "http://www.example.com/trailers/": { "pattern.string": "http://www.example.com/trailers", "pattern.flags": 3 } 6.1.5. Relationship JSON: A dictionary with the following keys: o href - The URI of the of the addressable object being referenced. o rel - The Relationship between the referring object and the object it is referencing. o type - The MIME Media Type of the referenced object. See Section 6.2 for the MIME Media Types of objects specified in this document. o title - An optional title for the Relationship/link. Note: The above structure follows the pattern of atom:link in [RFC4287]. Example Relationship to a CDNI Trigger Resource within a CDNI Trigger Collection: Murray & Niven-Jenkins Expires March 3, 2013 [Page 18] Internet-Draft CDN Interconnect Triggers August 2012 { "href": "http://triggers.cdni.example.com/trigger/12345", "rel": "Trigger", "type": "application/vnd.cdni.control.trigger.status+json" } The format of relationship values is expected to align with other CDNI interfaces. For example, rather than use simple names (like "Trigger" in this case), there may be a namespace that allows well- known and proprietary values to co-exist. 6.2. MIME Media Types Table 1 lists the MIME Media Type for each trigger object (resource) that is retrievable through the CDNI Trigger interface. Note: A prefix of "vnd.cdni" is used, however it is expected that a more appropriate prefix will be used if the CDNI WG accepts this document. +-------------------+-----------------------------------------------+ | Data Object | MIME Media Type | +-------------------+-----------------------------------------------+ | TriggerStatus | application/ | | | vnd.cdni.control.trigger.status+json | | TriggerCollection | application/ | | | vnd.cdni.control.trigger.collection+json | +-------------------+-----------------------------------------------+ Table 1: MIME Media Types for CDNI Trigger resources 7. Examples The following sections provide examples of different CDNI Trigger 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 URLs are under control of dCDN and the uCDN must not attempt to ascribe any meaning to individual elements of the path. In examples in this section, the following URLs are used as the location of the collections of triggers: Murray & Niven-Jenkins Expires March 3, 2013 [Page 19] Internet-Draft CDN Interconnect Triggers August 2012 o 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. Creating Triggers Examples of uCDN triggering activity in dCDN: 7.1.1. Preposition An example of a preposition request, a POST to the "AllTriggers" collection. Note that a preposition request must not include any "metadata.patterns" or "content.patterns": REQUEST: POST /triggers HTTP/1.1 User-Agent: example-user-agent/0.1 Host: dcdn.example.com Accept: */* Content-Type: application/vnd.cdni.control.trigger.request+json Content-Length: 318 { "triggers" : [{ "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" ] }] } RESPONSE: HTTP/1.1 201 Created Date: Sun, 15 Apr 2012 19:33:48 GMT Content-Length: 533 Content-Type: application/vnd.cdni.control.trigger.status+json Murray & Niven-Jenkins Expires March 3, 2013 [Page 20] Internet-Draft CDN Interconnect Triggers August 2012 Location: http://dcdn.example.com/triggers/0 Server: example-server/0.1 { "ctime": 1334518428, "etime": 1334518436, "mtime": 1334518428, "status": "pending", "triggers": [ { "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. Invalidate An example of an invalidate request, another POST to the "AllTriggers" collection. This instructs 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/vnd.cdni.control.trigger.request+json Content-Length: 386 { "triggers" : [{ "type": "invalidate", "metadata.patterns" : [ { "pattern.string" : "http://metadata.example.com/a/b/", "pattern.flags" : 3 } Murray & Niven-Jenkins Expires March 3, 2013 [Page 21] Internet-Draft CDN Interconnect Triggers August 2012 ], "content.urls" : [ "http://www.example.com/a/index.html" ], "content.patterns" : [ { "pattern.string" : "http://www.example.com/a/b/", "pattern.flags" : 3 } ] }] } RESPONSE: HTTP/1.1 201 Created Date: Sun, 15 Apr 2012 19:33:48 GMT Content-Length: 681 Content-Type: application/vnd.cdni.control.trigger.status+json Location: http://dcdn.example.com/triggers/1 Server: example-server/0.1 { "ctime": 1334518428, "etime": 1334518436, "mtime": 1334518428, "status": "pending", "triggers": [ { "content.patterns": [ { "pattern.flags": 3, "pattern.string": "http://www.example.com/a/b/" } ], "content.urls": [ "http://www.example.com/a/index.html" ], "metadata.patterns": [ { "pattern.flags": 3, "pattern.string": "http://metadata.example.com/a/b/" } ], "type": "invalidate" } ] } Murray & Niven-Jenkins Expires March 3, 2013 [Page 22] Internet-Draft CDN Interconnect Triggers August 2012 7.2. Examining Trigger Status Once triggers have been created, uCDN can check their status as shown in these examples. 7.2.1. 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: 418 Expires: Sun, 15 Apr 2012 19:34:48 GMT Server: example-server/0.1 ETag: "-1621644187315998047" Cache-Control: max-age=60 Date: Sun, 15 Apr 2012 19:33:48 GMT Content-Type: application/vnd.cdni.control.trigger.collection+json { "links": [ { "href": "http://dcdn.example.com/triggers/0", "rel": "Trigger", "type": "application/vnd.cdni.control.trigger.status+json" }, { "href": "http://dcdn.example.com/triggers/1", "rel": "Trigger", "type": "application/vnd.cdni.control.trigger.status+json" } ], "staleresourcetime": 86400 } Murray & Niven-Jenkins Expires March 3, 2013 [Page 23] Internet-Draft CDN Interconnect Triggers August 2012 7.2.2. Filtered Collections of Triggers The filtered collections are also available to uCDN. Before dCDN starts processing the two triggers shown above, both will appear in the collection of Pending Triggers, for example: REQUEST: GET /triggers/pending HTTP/1.1 User-Agent: example-user-agent/0.1 Host: dcdn.example.com Accept: */* RESPONSE: HTTP/1.1 200 OK Content-Length: 418 Expires: Sun, 15 Apr 2012 19:34:48 GMT Server: example-server/0.1 ETag: "8328231265607503653" Cache-Control: max-age=60 Date: Sun, 15 Apr 2012 19:33:48 GMT Content-Type: application/vnd.cdni.control.trigger.collection+json { "links": [ { "href": "http://dcdn.example.com/triggers/0", "rel": "Trigger", "type": "application/vnd.cdni.control.trigger.status+json" }, { "href": "http://dcdn.example.com/triggers/1", "rel": "Trigger", "type": "application/vnd.cdni.control.trigger.status+json" } ], "staleresourcetime": 86400 } At this point, if no other triggers had been created, the other filtered views of the triggers would be empty. For example: Murray & Niven-Jenkins Expires March 3, 2013 [Page 24] Internet-Draft CDN Interconnect Triggers August 2012 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: 53 Expires: Sun, 15 Apr 2012 19:34:49 GMT Server: example-server/0.1 ETag: "-654105208640281650" Cache-Control: max-age=60 Date: Sun, 15 Apr 2012 19:33:49 GMT Content-Type: application/vnd.cdni.control.trigger.collection+json { "links": [], "staleresourcetime": 86400 } 7.2.3. 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: Murray & Niven-Jenkins Expires March 3, 2013 [Page 25] Internet-Draft CDN Interconnect Triggers August 2012 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: 533 Expires: Sun, 15 Apr 2012 19:34:48 GMT Server: example-server/0.1 ETag: "-6152251159861441046" Cache-Control: max-age=60 Date: Sun, 15 Apr 2012 19:33:48 GMT Content-Type: application/vnd.cdni.control.trigger.status+json { "ctime": 1334518428, "etime": 1334518436, "mtime": 1334518428, "status": "pending", "triggers": [ { "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" } ] } Murray & Niven-Jenkins Expires March 3, 2013 [Page 26] Internet-Draft CDN Interconnect Triggers August 2012 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: 681 Expires: Sun, 15 Apr 2012 19:34:49 GMT Server: example-server/0.1 ETag: "3718394748848505642" Cache-Control: max-age=60 Date: Sun, 15 Apr 2012 19:33:49 GMT Content-Type: application/vnd.cdni.control.trigger.status+json { "ctime": 1334518428, "etime": 1334518436, "mtime": 1334518428, "status": "pending", "triggers": [ { "content.patterns": [ { "pattern.flags": 3, "pattern.string": "http://www.example.com/a/b/" } ], "content.urls": [ "http://www.example.com/a/index.html" ], "metadata.patterns": [ { "pattern.flags": 3, "pattern.string": "http://metadata.example.com/a/b/" } ], "type": "invalidate" } ] } Murray & Niven-Jenkins Expires March 3, 2013 [Page 27] Internet-Draft CDN Interconnect Triggers August 2012 7.2.4. Polling for Change The uCDN may 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: "8328231265607503653" RESPONSE: HTTP/1.1 304 Not Modified Content-Length: 0 Expires: Sun, 15 Apr 2012 19:34:48 GMT Server: example-server/0.1 ETag: "8328231265607503653" Cache-Control: max-age=60 Date: Sun, 15 Apr 2012 19:33:48 GMT Content-Type: application/vnd.cdni.control.trigger.collection+json REQUEST: GET /triggers/0 HTTP/1.1 User-Agent: example-user-agent/0.1 Host: dcdn.example.com Accept: */* If-None-Match: "-6152251159861441046" RESPONSE: HTTP/1.1 304 Not Modified Content-Length: 0 Expires: Sun, 15 Apr 2012 19:34:48 GMT Server: example-server/0.1 ETag: "-6152251159861441046" Cache-Control: max-age=60 Date: Sun, 15 Apr 2012 19:33:48 GMT Content-Type: application/vnd.cdni.control.trigger.status+json When the triggered activity is complete, the contents of the filtered collections will be updated, along with their Entity Tags. For Murray & Niven-Jenkins Expires March 3, 2013 [Page 28] Internet-Draft CDN Interconnect Triggers August 2012 example, when the two example triggers are complete, the collections of pending and complete triggers may 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: 53 Expires: Sun, 15 Apr 2012 19:34:53 GMT Server: example-server/0.1 ETag: "-7056231826368088123" Cache-Control: max-age=60 Date: Sun, 15 Apr 2012 19:33:53 GMT Content-Type: application/vnd.cdni.control.trigger.collection+json { "links": [], "staleresourcetime": 86400 } Murray & Niven-Jenkins Expires March 3, 2013 [Page 29] Internet-Draft CDN Interconnect Triggers August 2012 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: 418 Expires: Sun, 15 Apr 2012 19:34:59 GMT Server: example-server/0.1 ETag: "1388228818267892536" Cache-Control: max-age=60 Date: Sun, 15 Apr 2012 19:33:59 GMT Content-Type: application/vnd.cdni.control.trigger.collection+json { "links": [ { "href": "http://dcdn.example.com/triggers/0", "rel": "Trigger", "type": "application/vnd.cdni.control.trigger.status+json" }, { "href": "http://dcdn.example.com/triggers/1", "rel": "Trigger", "type": "application/vnd.cdni.control.trigger.status+json" } ], "staleresourcetime": 86400 } 7.2.5. Cancelling or Removing a Trigger To request dCDN to cancel a Trigger, uCDN may delete the Trigger Resource. It may also delete completed and failed triggers to reduce the size of the collections. For example, to remove the "preposition" request from earlier examples: Murray & Niven-Jenkins Expires March 3, 2013 [Page 30] Internet-Draft CDN Interconnect Triggers August 2012 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, 15 Apr 2012 19:33:59 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: 237 Expires: Sun, 15 Apr 2012 19:35:00 GMT Server: example-server/0.1 ETag: "-8850203857096517156" Cache-Control: max-age=60 Date: Sun, 15 Apr 2012 19:34:00 GMT Content-Type: application/vnd.cdni.control.trigger.collection+json { "links": [ { "href": "http://dcdn.example.com/triggers/1", "rel": "Trigger", "type": "application/vnd.cdni.control.trigger.status+json" } ], "staleresourcetime": 86400 } Murray & Niven-Jenkins Expires March 3, 2013 [Page 31] Internet-Draft CDN Interconnect Triggers August 2012 8. IANA Considerations TBD. 9. Security Considerations The dCDN must ensure that each uCDN only has access to its own Trigger Status Resources. It is anticipated that a common authentication mechanism will be used by this and other CDNI Interconnect interfaces, the mechanism must exist but is not identified in this document. The dCDN must ensure that activity triggered by uCDN only affects metadata or content originating from that uCDN. 10. Acknowledgements TBD. 11. References 11.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC2616] Fielding, R., Gettys, J., Mogul, J., Frystyk, H., Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999. [RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform Resource Identifier (URI): Generic Syntax", STD 66, RFC 3986, January 2005. 11.2. Informative References [I-D.cjlmw-cdni-metadata] Niven-Jenkins, B., Murray, R., Watson, G., Caulfield, M., and K. Leung, "CDN Interconnect Metadata", draft-cjlmw-cdni-metadata-00 (work in progress), July 2012. [I-D.ietf-cdni-framework] Peterson, L. and B. Davie, "Framework for CDN Murray & Niven-Jenkins Expires March 3, 2013 [Page 32] Internet-Draft CDN Interconnect Triggers August 2012 Interconnection", draft-ietf-cdni-framework-01 (work in progress), July 2012. [I-D.ietf-cdni-problem-statement] Niven-Jenkins, B., Faucheur, F., and N. Bitar, "Content Distribution Network Interconnection (CDNI) Problem Statement", draft-ietf-cdni-problem-statement-08 (work in progress), June 2012. [I-D.ietf-cdni-requirements] Leung, K. and Y. Lee, "Content Distribution Network Interconnection (CDNI) Requirements", draft-ietf-cdni-requirements-03 (work in progress), June 2012. [RFC4287] Nottingham, M., Ed. and R. Sayre, Ed., "The Atom Syndication Format", RFC 4287, December 2005. [XML-BASE] Marsh, J., Ed. and R. Tobin, Ed., "XML Base (Second Edition) - http://www.w3.org/TR/xmlbase/", January 2009. 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 Murray & Niven-Jenkins Expires March 3, 2013 [Page 33]