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. Murray & Niven-Jenkins Expires March 7, 2015 [Page 1] Internet-Draft CDN Interconnect Triggers September 2014 This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must 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 . . . . . . . . . . . . . . . . . . . . . . . . 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 Murray & Niven-Jenkins Expires March 7, 2015 [Page 2] Internet-Draft CDN Interconnect Triggers September 2014 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. Murray & Niven-Jenkins Expires March 7, 2015 [Page 3] Internet-Draft CDN Interconnect Triggers September 2014 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 Murray & Niven-Jenkins Expires March 7, 2015 [Page 4] Internet-Draft CDN Interconnect Triggers September 2014 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. Murray & Niven-Jenkins Expires March 7, 2015 [Page 5] Internet-Draft CDN Interconnect Triggers September 2014 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. Murray & Niven-Jenkins Expires March 7, 2015 [Page 6] Internet-Draft CDN Interconnect Triggers September 2014 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. Murray & Niven-Jenkins Expires March 7, 2015 [Page 7] Internet-Draft CDN Interconnect Triggers September 2014 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. Murray & Niven-Jenkins Expires March 7, 2015 [Page 8] Internet-Draft CDN Interconnect Triggers September 2014 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. Murray & Niven-Jenkins Expires March 7, 2015 [Page 9] Internet-Draft CDN Interconnect Triggers September 2014 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 Murray & Niven-Jenkins Expires March 7, 2015 [Page 10] Internet-Draft CDN Interconnect Triggers September 2014 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. Murray & Niven-Jenkins Expires March 7, 2015 [Page 11] Internet-Draft CDN Interconnect Triggers September 2014 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. Murray & Niven-Jenkins Expires March 7, 2015 [Page 12] Internet-Draft CDN Interconnect Triggers September 2014 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. Murray & Niven-Jenkins Expires March 7, 2015 [Page 13] Internet-Draft CDN Interconnect Triggers September 2014 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 Murray & Niven-Jenkins Expires March 7, 2015 [Page 14] Internet-Draft CDN Interconnect Triggers September 2014 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 Murray & Niven-Jenkins Expires March 7, 2015 [Page 15] Internet-Draft CDN Interconnect Triggers September 2014 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 Murray & Niven-Jenkins Expires March 7, 2015 [Page 16] Internet-Draft CDN Interconnect Triggers September 2014 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. Murray & Niven-Jenkins Expires March 7, 2015 [Page 17] Internet-Draft CDN Interconnect Triggers September 2014 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. Murray & Niven-Jenkins Expires March 7, 2015 [Page 18] Internet-Draft CDN Interconnect Triggers September 2014 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: Murray & Niven-Jenkins Expires March 7, 2015 [Page 19] Internet-Draft CDN Interconnect Triggers September 2014 +------------+------------------------------------------------------+ | 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. Murray & Niven-Jenkins Expires March 7, 2015 [Page 20] Internet-Draft CDN Interconnect Triggers September 2014 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. Murray & Niven-Jenkins Expires March 7, 2015 [Page 21] Internet-Draft CDN Interconnect Triggers September 2014 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". Murray & Niven-Jenkins Expires March 7, 2015 [Page 22] Internet-Draft CDN Interconnect Triggers September 2014 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, Murray & Niven-Jenkins Expires March 7, 2015 [Page 23] Internet-Draft CDN Interconnect Triggers September 2014 "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 } ] Murray & Niven-Jenkins Expires March 7, 2015 [Page 24] Internet-Draft CDN Interconnect Triggers September 2014 }, "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: Murray & Niven-Jenkins Expires March 7, 2015 [Page 25] Internet-Draft CDN Interconnect Triggers September 2014 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: Murray & Niven-Jenkins Expires March 7, 2015 [Page 26] Internet-Draft CDN Interconnect Triggers September 2014 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: Murray & Niven-Jenkins Expires March 7, 2015 [Page 27] Internet-Draft CDN Interconnect Triggers September 2014 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: Murray & Niven-Jenkins Expires March 7, 2015 [Page 28] Internet-Draft CDN Interconnect Triggers September 2014 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" } } Murray & Niven-Jenkins Expires March 7, 2015 [Page 29] Internet-Draft CDN Interconnect Triggers September 2014 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: Murray & Niven-Jenkins Expires March 7, 2015 [Page 30] Internet-Draft CDN Interconnect Triggers September 2014 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: Murray & Niven-Jenkins Expires March 7, 2015 [Page 31] Internet-Draft CDN Interconnect Triggers September 2014 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": [] } Murray & Niven-Jenkins Expires March 7, 2015 [Page 32] Internet-Draft CDN Interconnect Triggers September 2014 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: Murray & Niven-Jenkins Expires March 7, 2015 [Page 33] Internet-Draft CDN Interconnect Triggers September 2014 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" ] } Murray & Niven-Jenkins Expires March 7, 2015 [Page 34] Internet-Draft CDN Interconnect Triggers September 2014 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" } } Murray & Niven-Jenkins Expires March 7, 2015 [Page 35] Internet-Draft CDN Interconnect Triggers September 2014 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 Intended Usage: COMMON Restrictions on usage: None Author: Rob Murray Change controller: IESG Murray & Niven-Jenkins Expires March 7, 2015 [Page 36] Internet-Draft CDN Interconnect Triggers September 2014 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 Intended Usage: COMMON Restrictions on usage: None Author: Rob Murray Change controller: IESG Murray & Niven-Jenkins Expires March 7, 2015 [Page 37] Internet-Draft CDN Interconnect Triggers September 2014 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 Intended Usage: COMMON Restrictions on usage: None Author: Rob Murray Change controller: IESG Murray & Niven-Jenkins Expires March 7, 2015 [Page 38] Internet-Draft CDN Interconnect Triggers September 2014 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 Murray & Niven-Jenkins Expires March 7, 2015 [Page 39] Internet-Draft CDN Interconnect Triggers September 2014 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. Murray & Niven-Jenkins Expires March 7, 2015 [Page 40] Internet-Draft CDN Interconnect Triggers September 2014 [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 Murray & Niven-Jenkins Expires March 7, 2015 [Page 41]