Network Working Group R. Murray Internet-Draft B. Niven-Jenkins Intended status: Standards Track Velocix (Alcatel-Lucent) Expires: April 18, 2016 October 16, 2015 CDNI Control Interface / Triggers draft-ietf-cdni-control-triggers-09 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 April 18, 2016. Copyright Notice Copyright (c) 2015 IETF Trust and the persons identified as the document authors. All rights reserved. Murray & Niven-Jenkins Expires April 18, 2016 [Page 1] Internet-Draft CDN Interconnect Triggers October 2015 This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must 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. Scope of Triggered Activity . . . . . . . . . . . . . . . 6 2.3. Trigger Results . . . . . . . . . . . . . . . . . . . . . 6 3. Collections of Trigger Status Resources . . . . . . . . . . . 7 4. CDNI Trigger Interface . . . . . . . . . . . . . . . . . . . 8 4.1. Creating Triggers . . . . . . . . . . . . . . . . . . . . 9 4.2. Checking Status . . . . . . . . . . . . . . . . . . . . . 10 4.2.1. Polling Trigger Status Resource collections . . . . . 10 4.2.2. Polling Trigger Status Resources . . . . . . . . . . 11 4.3. Cancelling Triggers . . . . . . . . . . . . . . . . . . . 11 4.4. Deleting Triggers . . . . . . . . . . . . . . . . . . . . 12 4.5. Expiry of Trigger Status Resources . . . . . . . . . . . 12 4.6. Loop Detection and Prevention . . . . . . . . . . . . . . 13 4.7. Error Handling . . . . . . . . . . . . . . . . . . . . . 13 4.8. Content URLs . . . . . . . . . . . . . . . . . . . . . . 14 5. CI/T Object Properties and Encoding . . . . . . . . . . . . . 14 5.1. CI/T Objects . . . . . . . . . . . . . . . . . . . . . . 15 5.1.1. CI/T Commands . . . . . . . . . . . . . . . . . . . . 15 5.1.2. Trigger Status Resource . . . . . . . . . . . . . . . 16 5.1.3. Trigger Collection . . . . . . . . . . . . . . . . . 17 5.2. Properties of CI/T Objects . . . . . . . . . . . . . . . 18 5.2.1. Trigger Specification . . . . . . . . . . . . . . . . 19 5.2.2. Trigger Type . . . . . . . . . . . . . . . . . . . . 20 5.2.3. Trigger Status . . . . . . . . . . . . . . . . . . . 21 5.2.4. PatternMatch . . . . . . . . . . . . . . . . . . . . 21 5.2.5. Absolute Time . . . . . . . . . . . . . . . . . . . . 22 5.2.6. Error Description . . . . . . . . . . . . . . . . . . 22 5.2.7. Error Code . . . . . . . . . . . . . . . . . . . . . 23 5.3. Formalization of the JSON Data . . . . . . . . . . . . . 23 6. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . 25 6.1. Creating Triggers . . . . . . . . . . . . . . . . . . . . 25 6.1.1. Preposition . . . . . . . . . . . . . . . . . . . . . 25 6.1.2. Invalidate . . . . . . . . . . . . . . . . . . . . . 27 Murray & Niven-Jenkins Expires April 18, 2016 [Page 2] Internet-Draft CDN Interconnect Triggers October 2015 6.2. Examining Trigger Status . . . . . . . . . . . . . . . . 28 6.2.1. Collection of All Triggers . . . . . . . . . . . . . 28 6.2.2. Filtered Collections of Trigger Status Resources . . 29 6.2.3. Individual Trigger Status Resources . . . . . . . . . 31 6.2.4. Polling for Change . . . . . . . . . . . . . . . . . 33 6.2.5. Deleting Trigger Status Resources . . . . . . . . . . 36 6.2.6. Error Reporting . . . . . . . . . . . . . . . . . . . 38 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 39 7.1. CDNI Payload Type Parameter Registrations . . . . . . . . 39 8. Security Considerations . . . . . . . . . . . . . . . . . . . 39 8.1. Authentication, Authorization, Confidentiality, Integrity Protection . . . . . . . . . . . . . . . . . . . . . . . 40 8.2. Denial of Service . . . . . . . . . . . . . . . . . . . . 40 8.3. Privacy . . . . . . . . . . . . . . . . . . . . . . . . . 41 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 41 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 41 10.1. Normative References . . . . . . . . . . . . . . . . . . 41 10.2. Informative References . . . . . . . . . . . . . . . . . 42 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 43 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 April 18, 2016 [Page 3] Internet-Draft CDN Interconnect Triggers October 2015 1.1. Terminology This document reuses the terminology defined in [RFC6707]. 2. Model for CDNI Triggers A CI/T Command, sent from the uCDN to the dCDN, is a request for the dCDN to do some work relating to data associated with content requests originating from the uCDN. There are two types of CI/T Command, CI/T Trigger Commands and CI/T Cancel Commands. The CI/T Cancel Command can be used to request cancellation of an earlier CI/T Trigger Command. A CI/T Trigger Command is of one of the following types: o preposition - used to instruct the dCDN to fetch metadata from the uCDN, or content from any origin including the uCDN. o invalidate - used to instruct the dCDN to revalidate specific metadata or content before re-using it. o purge - used to instruct the dCDN to delete specific metadata or content. The CI/T interface is a web service offered by the dCDN. It allows CI/T commands to be issued, and triggered activity to be tracked. When the dCDN accepts a CI/T Command 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 at least one collection of Trigger Status Resources for each uCDN. Each uCDN only has access to its own collections, the locations of which are shared when CDN interconnection is established. To trigger activity in the dCDN, the uCDN POSTs a CI/T Command to the collection of Trigger Status Resources. If the dCDN accepts the CI/T Command, it creates a new Trigger Status Resource and returns its location to the uCDN. To monitor progress, the uCDN can GET the Trigger Status Resource. To request cancellation of a CI/T Trigger Command 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 Trigger Status Resources corresponding to active and completed CI/T Murray & Niven-Jenkins Expires April 18, 2016 [Page 4] Internet-Draft CDN Interconnect Triggers October 2015 Trigger Commands. These collections provide a mechanism for polling the status of multiple jobs. Figure 1 is an example showing the basic message flow used by the uCDN to trigger activity in the dCDN, 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 CI/T interface was established. 2. The dCDN authenticates the request, validates the CI/T Command and, if it accepts the request, creates a new Trigger Status Resource. 3. The dCDN responds to the uCDN with an HTTP 201 response status, and the location of the Trigger Status Resource. 4. The uCDN can poll, possibly repeatedly, the Trigger Status Resource in the dCDN. Murray & Niven-Jenkins Expires April 18, 2016 [Page 5] Internet-Draft CDN Interconnect Triggers October 2015 5. The dCDN responds with the Trigger Status Resource, describing progress or results of the CI/T Trigger Command. The remainder of this document describes the messages, Trigger Status Resources, and collections of Trigger Status Resources in more detail. 2.1. Timing of Triggered Activity Timing of the execution of CI/T Commands is under the dCDN's control, including its start-time and pacing of the activity in the network. CI/T invalidate and purge commands MUST be applied to all data acquired before the command was accepted by the dCDN. The dCDN SHOULD NOT apply CI/T invalidate and purge commands to data acquired after the CI/T Command was accepted, but this may not always be achievable so the uCDN cannot count on that. 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). Because the CI/T Command timing is under the dCDN's control, the dCDN implementation can choose whether to apply CI/T invalidate and purge commands to content acquisition that has already started when the command is received. 2.2. Scope of Triggered Activity Each CI/T Command can operate on multiple metadata and content URLs. Multiple representations of an HTTP resource may share the same URL. CI/T Trigger Commands that invalidate or purge metadata or content apply to all resource representations with matching URLs. The dCDN MUST reject CI/T Commands from a uCDN that act on another uCDN's data. Security considerations are discussed further in section Section 8. 2.3. Trigger Results Possible states for a Trigger Status Resource are defined in section Section 5.2.3. Murray & Niven-Jenkins Expires April 18, 2016 [Page 6] Internet-Draft CDN Interconnect Triggers October 2015 The CI/T Trigger Command 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 CI/T Commands to any downstream CDNs that may be affected. The CI/T Trigger Command MUST NOT be reported as 'complete' in a CDN until it is 'complete' in all of its downstream CDNs. If a CI/T Trigger Command is reported as 'processed' in any dCDN, intermediate CDNs MUST NOT report 'complete', instead they must also report 'processed'. A CI/T Command MAY be reported as 'failed' as soon as it fails in a CDN or in any of its downstream CDNs. A cancelled CI/T Trigger Command 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. The dCDN MUST make a collection of a uCDN's Trigger Status Resources available to that uCDN. This collection includes all of the Trigger Status Resources created for CI/T Commands from the uCDN that have been accepted by the dCDN, and have not yet been deleted by the uCDN, or expired and removed by the dCDN (as described in section Section 4.4). Trigger Status Resources belonging to a uCDN MUST NOT be visible to any other CDN. The dCDN could, for example, achieve this by offering different collection URLs to each uCDN, and/or by filtering the response based on the uCDN with which the HTTP client is associated. 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. These filtered collections are optional-to-implement but, if implemented, the dCDN MUST include links to them in the collection of all Trigger Status Resources. The filtered collections are: Murray & Niven-Jenkins Expires April 18, 2016 [Page 7] Internet-Draft CDN Interconnect Triggers October 2015 o Pending - Trigger Status Resources for CI/T Trigger Commands that have been accepted, but not yet acted upon. o Active - Trigger Status Resources for CI/T Trigger Commands that are currently being processed in the dCDN. o Complete - Trigger Status Resources representing activity that completed successfully, and 'processed' CI/T Trigger Commands for which no further status updates will be made by the dCDN. o Failed - Trigger Status Resources representing CI/T Commands that failes or were 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. The CI/T interface builds on top of HTTP, so dCDNs may make use of any HTTP feature when implementing the CI/T interface. For example, a dCDN SHOULD make use of HTTP's caching mechanisms to indicate that a requested response/representation has not been modified, reducing the uCDN's processing needed to determine whether the status of triggered activity has changed. All dCDNs implementing CI/T MUST support the HTTP GET, HEAD, POST and DELETE methods as defined in [RFC7231]. The only representation specified in this document is JSON, [RFC7159]. It MUST be supported by the uCDN and by the dCDN. The URL of the dCDN's collection of all Trigger Status Resources needs to be either discovered by, 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 CI/T Trigger Command is accepted by the dCDN, the dCDN creates a new Trigger Status Resource and returns its URI to the uCDN in an HTTP 201 response. The triggered activity can then be monitored by the uCDN using that resource and the collections described in Section 3. The URI of each Trigger Status Resource is returned to the uCDN when it is created, and URIs of all Trigger Status Resources are listed in the dCDN's collection of all Trigger Status Resources. This means all Trigger Status Resources can be discovered by the uCDN, so dCDNs are free to assign whatever structure they desire to the URIs for CI/ Murray & Niven-Jenkins Expires April 18, 2016 [Page 8] Internet-Draft CDN Interconnect Triggers October 2015 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. 4.1. Creating Triggers To issue a CI/T Command, the uCDN makes an HTTP POST to the dCDN's collection of all of the uCDN's Trigger Status Resources. The request body of that POST is a CI/T Command, as described in Section 5.1.1. The dCDN validates the CI/T Command, if 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 Trigger Status Resource MUST NOT be created on the dCDN, or create a 'failed' Trigger Status Resource containing an appropriate error description. When a CI/T Trigger Command is accepted, the uCDN MUST create a new Trigger Status Resource which will convey a specification of the CI/T Command and its current status. The HTTP response to the dCDN MUST have status code 201 and MUST convey the URI of the Trigger Status Resource in the Location header field. The HTTP response SHOULD include the content of the newly created Trigger Status Resource, this is recommended particularly in cases where the CI/T Trigger Command has completed immediately. Once a Trigger Status Resource has been created the dCDN MUST NOT re- use its URI, even after that Trigger Status Resource has been removed. The dCDN SHOULD track and report on progress of CI/T Trigger Commands. If the dCDN is not able to do that, it MUST indicate that it has accepted the request but will not be providing further status updates. To do this, it sets the "status" of the Trigger Status Resource to "processed". In this case, CI/T processing should continue as for a "complete" request, so the Trigger Status Resource MUST be added to the dCDN's collection of Complete Trigger Status Resources. 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 CI/T Commands and a CI/ T Command is queued by the dCDN for later action, the "status" property of the Trigger Status Resource MUST be "pending". Once processing has started the "status" MUST be "active". Finally, once Murray & Niven-Jenkins Expires April 18, 2016 [Page 9] Internet-Draft CDN Interconnect Triggers October 2015 the CI/T Command is complete, the status MUST be set to "complete" or "failed". A CI/T Trigger Command may result in no activity in the dCDN if, for example, it is an invalidate 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 Trigger Status Resources. 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, for example 405 "Method Not Allowed". 4.2. Checking Status The uCDN has two ways to check progress of CI/T Commands it has issued to the dCDN, described in sections Section 4.2.1 and Section 4.2.2. To check for change in status of a Trigger Status Resource or collection of Trigger Status 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 CI/T Trigger Commands 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. An example of this is given in section Section 6.2.4. Murray & Niven-Jenkins Expires April 18, 2016 [Page 10] Internet-Draft CDN Interconnect Triggers October 2015 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 Trigger Status Resource at any time. This can be used to retrieve progress information, and to fetch the result of the CI/T Command. 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 CI/T Trigger Command by POSTing a CI/T Cancel Command to the collection of all Trigger Status Resources. Cancellation of a CI/T Trigger Command is optional-to-implement in the dCDN. The dCDN MUST respond to the CI/T Cancel Command appropriately, for example with HTTP status code 200 "OK" if the cancellation has been processed and the CI/T Command is inactive, 202 "Accepted" if the command has been accepted but the CI/T Command remains active, or 501 "Not Implemented" if cancellation is not supported by the dCDN. If cancellation of a "pending" Trigger Status Resource is accepted by the dCDN, the dCDN SHOULD NOT start processing of that activity. Issuing a CT/T cancel command for a "pending" Trigger Status Resource does not however guarantee that the corresponding activity will not be started, because the uCDN cannot control the timing of that activity. Processing could, for example, start after the POST is sent by the uCDN but before that request is processed by the dCDN. If cancellation of an "active" or "processed" Trigger Status Resource is accepted by the dCDN, the dCDN SHOULD stop processing the CI/T Command. However, as with cancellation of a "pending" CI/T Command, the dCDN does not guarantee this. If the CI/T Command cannot be stopped immediately, the status in the corresponding Trigger Status Resource MUST be set to "cancelling", and the Trigger Status Resource MUST remain in the collection of Trigger Status Resources for active CI/T Commands. If processing is stopped before normal completion, the status value in the Trigger Status Resource MUST be set to "cancelled", and the Trigger Status Murray & Niven-Jenkins Expires April 18, 2016 [Page 11] Internet-Draft CDN Interconnect Triggers October 2015 Resource MUST be included in the collection of failed CT/T Trigger Commands. Cancellation of a "complete" or "failed" Trigger Status Resource requires no processing in the dCDN, its status MUST NOT be changed to "cancelled". 4.4. Deleting Triggers The uCDN can delete Trigger Status Resources at any time, using the HTTP DELETE method. The effect is similar to cancellation, but no Trigger Status Resource remains afterwards. Once deleted, the references to a Trigger Status Resource MUST be removed from all Trigger Status Resource collections. Subsequent requests to GET the deleted Trigger Status Resource SHOULD be rejected by the dCDN with an HTTP error. If a "pending" Trigger Status Resource is deleted, the dCDN SHOULD NOT start processing of that activity. Deleting a "pending" Trigger Status Resource 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 SHOULD stop processing the CI/T Command. However, as with deletion of a "pending" Trigger Status Resource, the dCDN does not guarantee this. Deletion of a "complete" or "failed" Trigger Status Resource requires no processing in the dCDN other than deletion of the Trigger Status Resource. 4.5. Expiry of Trigger Status Resources The dCDN can choose to automatically delete Trigger Status Resources some time after they become "complete", "processed", "failed" or "cancelled". In this case, the dCDN will remove the Trigger Status Resource and respond to subsequent requests for it with an HTTP error. If the dCDN 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 by the dCDN for at least 24 hours after they become "complete", "processed", "failed" or "cancelled". Murray & Niven-Jenkins Expires April 18, 2016 [Page 12] Internet-Draft CDN Interconnect Triggers October 2015 To ensure it is able to get the status of its Trigger Status Resources for completed and failed CI/T Commands, it is RECOMMENDED that the uCDN polling interval is less than the time after which records for completed activity will be deleted. 4.6. Loop Detection and Prevention Given three CDNs, A, B and C. If CDNs B and C delegate delivery of CDN A's content to each other, CDN A's CI/T Commands could be passed between CDNs B and C in a loop. More complex networks of CDNs could contain similar loops involving more hops. In order to prevent and detect such CI/T loops, each CDN uses a CDN Provider ID to uniquely identify itself. In every CI/T Command it originates or cascades, each CDN MUST append an array element containing its CDN Provider ID to a JSON array under an entry named "cdn-path". 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 two characters "AS" followed by the CDN Provider's Autonomous System 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 CDN provider has multiple Autonomous Systems, the same AS number SHOULD be used in all messages from that CDN provider, unless there are multiple distinct CDNs. If the RI interface described in [I-D.ietf-cdni-redirection] is implemented by the dCDN, the CI/T and RI interfaces SHOULD use the same CDN Provider Id. 4.7. Error Handling A dCDN can signal rejection of a CI/T Command using HTTP status codes. For example, 400 if the request is malformed, or 403 or 404 if the uCDN does not have permission to issue CI/T Commands or it is trying to act on another CDN's data. If any part of the CI/T Trigger Command fails, the trigger SHOULD be reported as "failed" once its activity is complete or if no further errors will be reported. The "errors" property in the Trigger Status Resource will be used to enumerate which actions failed and the reasons for failure, and can be present while the Trigger Status Murray & Niven-Jenkins Expires April 18, 2016 [Page 13] Internet-Draft CDN Interconnect Triggers October 2015 Resource is still "pending" or "active", if the CI/T Trigger Command 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 CI/T Trigger Command 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 CI/T Command is abandoned by the dCDN, the dCDN SHOULD report an error. o A CI/T "invalidate" command may be reported as "complete" when surrogates 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 CI/T "preposition" and "purge" commands can be reported as "processed" if affected caches are offline and the activity will complete when they return to service. o Otherwise, the dCDN SHOULD keep the Trigger Status Resource in state "pending" or "active" until the CI/T Command is acted upon, or the uCDN chooses to cancel it. 4.8. Content URLs 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 a CI/T invalidate or purge command, 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. They MUST use the MIME Media Type 'application/cdni', with parameter 'ptype' values as defined below and in Section 7.1. Murray & Niven-Jenkins Expires April 18, 2016 [Page 14] Internet-Draft CDN Interconnect Triggers October 2015 Names in JSON are case sensitive. The names and literal values specified in the present document MUST always use lower-case. JSON types, including 'object', 'array', 'number' and 'string' are defined in [RFC7159]. Unrecognised name/value pairs in JSON objects SHOULD NOT be treated as an error by either the uCDN or dCDN. They SHOULD be ignored in the processing, and passed on by dCDN to any further dCDNs in a cascade. 5.1. CI/T Objects The top-level objects defined by the CI/T interface are described in this section. The encoding of values used by these objects is described in Section 5.2. 5.1.1. CI/T Commands CI/T Commands MUST use a MIME Media Type of 'application/cdni; ptype=ci-trigger-command'. A CI/T Command is encoded as a JSON object containing the following name/value pairs. Name: trigger Description: A specification of the trigger type, and a set of data to act upon. Value: A Trigger Specification, as defined in Section 5.2.1. Mandatory: No, but exactly one of "trigger" or "cancel" MUST be present in a CI/T Command. Name: cancel Description: The URLs of Trigger Status Resources for CI/T Trigger Commands that the uCDN wants to cancel. Value: A non-empty JSON array of URLs represented as JSON strings. Mandatory: No, but exactly one of "trigger" or "cancel" MUST be present in a CI/T Command. Murray & Niven-Jenkins Expires April 18, 2016 [Page 15] Internet-Draft CDN Interconnect Triggers October 2015 Name: cdn-path Description: The CDN Provider Identifiers of CDNs that have already accepted the CI/T Command. Value: A non-empty 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 MUST use a MIME Media Type of 'application/ cdni; ptype=ci-trigger-status'. A Trigger Status Resource is encoded as a JSON object containing the following name/value pairs. Name: trigger Description: The Trigger Specification posted 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. 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 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 Murray & Niven-Jenkins Expires April 18, 2016 [Page 16] Internet-Draft CDN Interconnect Triggers October 2015 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: An array of Error Description, as defined in Section 5.2.6. An empty array is allowed, and equivalent to omitting "errors" from the object. Mandatory: No. 5.1.3. Trigger Collection Trigger Collections MUST use a MIME Media Type of 'application/cdni; ptype=ci-trigger-collection'. A Trigger Collection is encoded as a JSON object containing the following name/value pairs. Name: triggers Description: Links to Trigger Status Resources in the collection. Value: A JSON array of zero or more URLs, represented as JSON strings. Mandatory: Yes Murray & Niven-Jenkins Expires April 18, 2016 [Page 17] Internet-Draft CDN Interconnect Triggers October 2015 Name: staleresourcetime Description: The length of time for which the dCDN guarantees to keep a completed Trigger Status Resource. After this time, the dCDN SHOULD delete the Trigger Status Resource and all references to it from collections. Value: A JSON number, which must be a positive integer, representing time in seconds. Mandatory: Yes, in the collection of all Trigger Status Resources if the dCDN deletes stale entries. If the property is present in the filtered collections, it MUST have the same value as in the collection of all Trigger Status Resources. Names: coll-all, coll-pending, coll-active, coll-complete, coll- failed Description: Link to a Trigger Collection. Value: A URL represented as a JSON string. Mandatory: Links to all of the filtered collections are mandatory in the collection of all Trigger Status Resources, if the dCDN implements the filtered collections. Otherwise, optional. Name: cdn-id Description: The CDN Provider Identifier 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 (the uCDN can always find the dCDN's cdn-id in the collection of all Trigger Status Resources, but the dCDN can choose to repeat that information in its implementation of filtered collections). 5.2. Properties of CI/T Objects This section defines the values that can appear in the top level objects described in Section 5.1, and their encodings. Murray & Niven-Jenkins Expires April 18, 2016 [Page 18] Internet-Draft CDN Interconnect Triggers October 2015 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 CI/T Trigger Command. Value: Trigger Type, as defined in Section 5.2.2. Mandatory: Yes Name: metadata.urls Description: The uCDN URLs of the metadata the CI/T Trigger Command applies to. Value: A JSON array of URLs represented as JSON strings. Mandatory: No, but at least one of 'metadata.*' or 'content.*' MUST be present and non-empty. Name: content.urls Description: URLs of content the CI/T Trigger Command 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. Murray & Niven-Jenkins Expires April 18, 2016 [Page 19] Internet-Draft CDN Interconnect Triggers October 2015 Mandatory: No, but at least one of 'metadata.*' or 'content.*' MUST be present and non-empty. 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 (the dCDN should | | | re-acquire the metadata or content from uCDN if it | | | needs it). | +-------------+-----------------------------------------------------+ Murray & Niven-Jenkins Expires April 18, 2016 [Page 20] Internet-Draft CDN Interconnect Triggers October 2015 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: +------------+------------------------------------------------------+ | JSON | Description | | String | | +------------+------------------------------------------------------+ | pending | The CI/T Trigger Command has not yet been acted | | | upon. | | active | The CI/T Trigger Command is currently being acted | | | upon. | | complete | The CI/T Trigger Command completed successfully. | | processed | The CI/T Trigger Command has been accepted and no | | | further status update will be made (can be used in | | | cases where completion cannot be confirmed). | | failed | The CI/T Trigger Command could not be completed. | | cancelling | Processing of the CI/T Trigger Command is still in | | | progress, but the CI/T Trigger Command has been | | | cancelled by the uCDN. | | cancelled | The CI/T Trigger Command 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. Murray & Niven-Jenkins Expires April 18, 2016 [Page 21] Internet-Draft CDN Interconnect Triggers October 2015 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. 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 CI/T Command, or in the activity it triggered. It is encoded as a JSON object with the following name/value pairs: Name: error Value: Error Code, as defined in Section 5.2.7. Mandatory: Yes. Names: metadata.urls, content.urls, metadata.patterns, content.patterns Description: Metadata and content references copied from the Trigger Specification. Only those URLs and patterns to which the error applies are included in each property, but those URLs and patterns MUST be exactly as they appear in the request, 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 Murray & Niven-Jenkins Expires April 18, 2016 [Page 22] Internet-Draft CDN Interconnect Triggers October 2015 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. 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 (CT/T | | | preposition commands only). | | eperm | The uCDN does not have permission to issue the CI/T | | | Command (for example, the data is owned by another | | | CDN). | | ereject | The dCDN is not willing to fulfil the CI/T Command | | | (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. | +------------+------------------------------------------------------+ 5.3. Formalization of the JSON Data The JSON data described in this document has been formalised using CDDL [I-D.greevenbosch-appsawg-cbor-cddl] as follows: CIT-object = CIT-command / Trigger-Status-Resource / Trigger-Collection Murray & Niven-Jenkins Expires April 18, 2016 [Page 23] Internet-Draft CDN Interconnect Triggers October 2015 CIT-command ; use media type application/cdni; ptype=ci-trigger-command = { ? trigger: Triggerspec ? cancel: [* URI] cdn-path: [* Cdn-PID] } Trigger-Status-Resource ; application/cdni; ptype=ci-trigger-status = { trigger: Triggerspec ctime: Absolute-Time mtime: Absolute-Time ? etime: Absolute-Time status: Trigger-Status ? errors: [* Error-Description] } Trigger-Collection ; application/cdni; ptype=ci-trigger-collection = { triggers: [* URI] ? staleresourcetime: int ; time in seconds ? coll-all: URI ? coll-pending: URI ? coll-active: URI ? coll-complete: URI ? coll-failed: URI ? cdn-id: Cdn-PID } Triggerspec = { ; 5.2.1 type: Trigger-Type ? metadata.urls: [* URI] ? content.urls: [* URI] ? content.ccid: [* Ccid] ? metadata.patterns: [* Pattern-Match] ? content.patterns: [* Pattern-Match] } Trigger-Type = "preposition" / "invalidate" / "purge" ; 5.2.2 Trigger-Status = "pending" / "active" / "complete" / "processed" / "failed" / "cancelling" / "cancelled" ; 5.2.3 Pattern-Match = { ; 5.2.4 pattern: tstr ? case-sensitive: bool ? match-query-string: bool } Murray & Niven-Jenkins Expires April 18, 2016 [Page 24] Internet-Draft CDN Interconnect Triggers October 2015 Absolute-Time = number ; seconds since UNIX epoch, 5.2.5 Error-Description = { ; 5.2.6 error: Error-Code ? metadata.urls: [* URI] ? content.urls: [* URI] ? metadata.patterns: [* Pattern-Match] ? content.patterns: [* Pattern-Match] ? description: tstr } Error-Code = "emeta" / "econtent" / "eperm" / "ereject" / "ecdn" / "ecancelled" ; 5.2.7 Ccid = tstr ; see I-D.ietf-cdni-metadata Cdn-PID = tstr .regexp "AS[0-9]+:[0-9]+" URI = tstr 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 Trigger Status Resources, and the CDN Provider Id of uCDN is "AS64496:1". 6.1. Creating Triggers Examples of the uCDN triggering activity in the dCDN: 6.1.1. Preposition An example of a CI/T preposition command, a POST to the collection of all Trigger Status Resources. Note that "metadata.patterns" and "content.patterns" are not allowed in a preposition Trigger Specification. REQUEST: Murray & Niven-Jenkins Expires April 18, 2016 [Page 25] Internet-Draft CDN Interconnect Triggers October 2015 POST /triggers HTTP/1.1 User-Agent: example-user-agent/0.1 Host: dcdn.example.com Accept: */* Content-Type: application/cdni; ptype=ci-trigger-command Content-Length: 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; ptype=ci-trigger-status Location: http://dcdn.example.com/triggers/0 Server: example-server/0.1 { "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 April 18, 2016 [Page 26] Internet-Draft CDN Interconnect Triggers October 2015 } 6.1.2. Invalidate An example of a CI/T invalidate command, another POST to the collection of all Trigger Status Resources. 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/" using case-insensitive matching, and "http://www.example.com/a/b/" respectively, using case-sensitive matching. REQUEST: POST /triggers HTTP/1.1 User-Agent: example-user-agent/0.1 Host: dcdn.example.com Accept: */* Content-Type: application/cdni; ptype=ci-trigger-command Content-Length: 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 } ] }, "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; ptype=ci-trigger-status Location: http://dcdn.example.com/triggers/1 Server: example-server/0.1 Murray & Niven-Jenkins Expires April 18, 2016 [Page 27] Internet-Draft CDN Interconnect Triggers October 2015 { "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 Trigger Status Resources 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 collection of all Trigger Status Resources it has created that have not yet been deleted or removed as expired. After creation of the "preposition" and "invalidate" triggers shown above, this collection might look as follows: Murray & Niven-Jenkins Expires April 18, 2016 [Page 28] Internet-Draft CDN Interconnect Triggers October 2015 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; ptype=ci-trigger-collection { "cdn-id": "AS64496:0", "coll-active": "/triggers/active", "coll-complete": "/triggers/complete", "coll-failed": "/triggers/failed", "coll-pending": "/triggers/pending", "staleresourcetime": 86400, "triggers": [ "http://dcdn.example.com/triggers/0", "http://dcdn.example.com/triggers/1" ] } 6.2.2. Filtered Collections of Trigger Status Resources The filtered collections are also available to the uCDN. Before the dCDN starts processing the two CI/T Trigger Commands shown above, both will appear in the collection of Pending Triggers, for example: Murray & Niven-Jenkins Expires April 18, 2016 [Page 29] Internet-Draft CDN Interconnect Triggers October 2015 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; ptype=ci-trigger-collection { "staleresourcetime": 86400, "triggers": [ "http://dcdn.example.com/triggers/0", "http://dcdn.example.com/triggers/1" ] } At this point, if no other Trigger Status Resources had been created, the other filtered views would be empty. For example: Murray & Niven-Jenkins Expires April 18, 2016 [Page 30] Internet-Draft CDN Interconnect Triggers October 2015 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; ptype=ci-trigger-collection { "staleresourcetime": 86400, "triggers": [] } 6.2.3. Individual Trigger Status Resources The Trigger Status Resources can also be examined for detail about individual CI/T Trigger Commands. For example, for the CI/T "preposition" and "invalidate" commands from previous examples: Murray & Niven-Jenkins Expires April 18, 2016 [Page 31] Internet-Draft CDN Interconnect Triggers October 2015 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; ptype=ci-trigger-status { "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 April 18, 2016 [Page 32] Internet-Draft CDN Interconnect Triggers October 2015 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; ptype=ci-trigger-status { "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 Trigger Status Resources when polling for change in status, as shown in the following examples: Murray & Niven-Jenkins Expires April 18, 2016 [Page 33] Internet-Draft CDN Interconnect Triggers October 2015 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; ptype=ci-trigger-collection REQUEST: GET /triggers/0 HTTP/1.1 User-Agent: example-user-agent/0.1 Host: dcdn.example.com Accept: */* If-None-Match: "-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; ptype=ci-trigger-status When the CI/T Trigger Command is complete, the contents of the filtered collections will be updated along with their Entity Tags. For example, when the two example CI/T Trigger Commands are complete, the collections of pending and complete Trigger Status Resources might look like: Murray & Niven-Jenkins Expires April 18, 2016 [Page 34] Internet-Draft CDN Interconnect Triggers October 2015 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/1.1 200 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; ptype=ci-trigger-collection { "staleresourcetime": 86400, "triggers": [] } Murray & Niven-Jenkins Expires April 18, 2016 [Page 35] Internet-Draft CDN Interconnect Triggers October 2015 REQUEST: GET /triggers/complete HTTP/1.1 User-Agent: example-user-agent/0.1 Host: dcdn.example.com Accept: */* If-None-Match: "2986340333785000363" 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; ptype=ci-trigger-collection { "staleresourcetime": 86400, "triggers": [ "http://dcdn.example.com/triggers/0", "http://dcdn.example.com/triggers/1" ] } 6.2.5. Deleting Trigger Status Resources The dCDN can delete completed and failed Trigger Status Resources to reduce the size of the collections. For example, to delete the "preposition" request from earlier examples: Murray & Niven-Jenkins Expires April 18, 2016 [Page 36] Internet-Draft CDN Interconnect Triggers October 2015 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 Trigger Status Resources shown in the example above to be updated to: REQUEST: GET /triggers/complete HTTP/1.1 User-Agent: example-user-agent/0.1 Host: dcdn.example.com Accept: */* RESPONSE: HTTP/1.1 200 OK Content-Length: 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; ptype=ci-trigger-collection { "staleresourcetime": 86400, "triggers": [ "http://dcdn.example.com/triggers/1" ] } Murray & Niven-Jenkins Expires April 18, 2016 [Page 37] Internet-Draft CDN Interconnect Triggers October 2015 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; ptype=ci-trigger-status { "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 April 18, 2016 [Page 38] Internet-Draft CDN Interconnect Triggers October 2015 7. IANA Considerations 7.1. CDNI Payload Type Parameter Registrations The IANA is requested to register the following new Payload Types in the CDNI Payload Type Parameter registry defined by [I-D.ietf-cdni-media-type], for use with the 'application/cdni' MIME media type. RFC Editor Note: Please replace references to [RFCthis] below with this document's RFC number before publication. +-----------------------+---------------+ | Payload Type | Specification | +-----------------------+---------------+ | ci-trigger-command | [RFCthis] | | ci-trigger-status | [RFCthis] | | ci-trigger-collection | [RFCthis] | +-----------------------+---------------+ 8. Security Considerations The CI/T interface provides a mechanism to allow a uCDN to generate requests into the dCDN and to inspect its own CI/T requests and their current state. The CI/T interface does not allow access to or modification of the uCDN or dCDN metadata relating to content delivery, or to the content itself. It can only control the presence of that metadata in the dCDN, and the processing work and network utilisation involved in ensuring that presence. By examining pre-positioning requests to a dCDN, and correctly interpreting content and metadata URLs, an attacker could learn the uCDN or content owner's predictions for future content popularity. By examining invalidate or purge requests, an attacker could learn about changes in the content owner's catalogue. By injecting CI/T commands an attacker, or a misbehaving uCDN, would generate work in the dCDN and uCDN as they process those requests. And so would a man in the middle attacker modifying valid CI/T commands generated by the uCDN. In both cases, that would decrease the dCDN caching efficiency by causing it to unnecessarily acquire or re-acquire content metadata and/or content. A dCDN implementation of CI/T MUST restrict the actions of a uCDN to the data corresponding to that uCDN. Failure to do so would allow uCDNs to detrimentally affect each other's efficiency by generating unnecessary acquisition or re-acquisition load. Murray & Niven-Jenkins Expires April 18, 2016 [Page 39] Internet-Draft CDN Interconnect Triggers October 2015 8.1. Authentication, Authorization, Confidentiality, Integrity Protection A CI/T implementation MUST support TLS transport for HTTP (https) as per [RFC2818] and [RFC7230]. The use of TLS for transport of the CI/T interface allows: o The dCDN and the uCDN to authenticate each other. And, once they have mutually authenticated each other, it allows: o The dCDN and the uCDN to authorize each other (to ensure they are receiving CI/T Commands from, or reporting status to, an authorized CDN). o CDNI commands and responses to be transmitted with confidentiality. o Protection of the integrity of CDNI commands and responses. In an environment where any such protection is required, mutually authenticated encrypted transport MUST be used to ensure confidentiality of the CI/T information. To that end, TLS MUST be used by CI/T, including authentication of the remote end. When TLS is used, the general TLS usage guidance in [RFC7525] MUST be followed. 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". This is intended to prevent unauthorised users from generating unnecessary load in dCDN or uCDN due to revalidation, reacquisition, or unnecessary acquisition. 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 Murray & Niven-Jenkins Expires April 18, 2016 [Page 40] Internet-Draft CDN Interconnect Triggers October 2015 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 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. 8.3. Privacy The CI/T protocol does not carry any information about individual End Users of a CDN, there are no privacy concerns for End Users. The CI/T protocol does carry information which could be considered commercially sensitive by CDN operators and content owners. The use of mutually authenticated TLS to establish a secure session for the transport of CI/T data, as discussed in Section 8.1, provides confidentiality while the CI/T data is in transit, and prevents parties other party than the authorised dCDN from gaining access to that data. The dCDN MUST ensure that it only exposes CI/T data related to a uCDN to clients it has authenticated as belonging to that uCDN. 9. Acknowledgements The authors thank Kevin Ma for his input, and Carsten Bormann for his review and formalization of the JSON data. 10. References 10.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/ RFC2119, March 1997, . [RFC7159] Bray, T., Ed., "The JavaScript Object Notation (JSON) Data Interchange Format", RFC 7159, DOI 10.17487/RFC7159, March 2014, . [RFC7230] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer Protocol (HTTP/1.1): Message Syntax and Routing", RFC 7230, DOI 10.17487/RFC7230, June 2014, . Murray & Niven-Jenkins Expires April 18, 2016 [Page 41] Internet-Draft CDN Interconnect Triggers October 2015 [RFC7231] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content", RFC 7231, DOI 10.17487/RFC7231, June 2014, . [RFC7232] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer Protocol (HTTP/1.1): Conditional Requests", RFC 7232, DOI 10.17487/RFC7232, June 2014, . [RFC7525] Sheffer, Y., Holz, R., and P. Saint-Andre, "Recommendations for Secure Use of Transport Layer Security (TLS) and Datagram Transport Layer Security (DTLS)", BCP 195, RFC 7525, DOI 10.17487/RFC7525, May 2015, . 10.2. Informative References [I-D.greevenbosch-appsawg-cbor-cddl] Vigano, C. and H. Birkholz, "CBOR data definition language: a notational convention to express CBOR data structures.", draft-greevenbosch-appsawg-cbor-cddl-06 (work in progress), July 2015. [I-D.ietf-cdni-media-type] Ma, K., "CDNI Media Type Registration", draft-ietf-cdni- media-type-06 (work in progress), October 2015. [I-D.ietf-cdni-metadata] Niven-Jenkins, B., Murray, R., Caulfield, M., and K. Ma, "CDN Interconnection Metadata", draft-ietf-cdni- metadata-11 (work in progress), July 2015. [I-D.ietf-cdni-redirection] Niven-Jenkins, B. and R. Brandenburg, "Request Routing Redirection Interface for CDN Interconnection", draft- ietf-cdni-redirection-13 (work in progress), October 2015. [RFC2818] Rescorla, E., "HTTP Over TLS", RFC 2818, DOI 10.17487/ RFC2818, May 2000, . [RFC6707] Niven-Jenkins, B., Le Faucheur, F., and N. Bitar, "Content Distribution Network Interconnection (CDNI) Problem Statement", RFC 6707, DOI 10.17487/RFC6707, September 2012, . Murray & Niven-Jenkins Expires April 18, 2016 [Page 42] Internet-Draft CDN Interconnect Triggers October 2015 [RFC7336] Peterson, L., Davie, B., and R. van Brandenburg, Ed., "Framework for Content Distribution Network Interconnection (CDNI)", RFC 7336, DOI 10.17487/RFC7336, August 2014, . [RFC7337] Leung, K., Ed. and Y. Lee, Ed., "Content Distribution Network Interconnection (CDNI) Requirements", RFC 7337, DOI 10.17487/RFC7337, August 2014, . Authors' Addresses Rob Murray Velocix (Alcatel-Lucent) 3 Ely Road Milton, Cambridge CB24 6DD UK Email: rob.murray@alcatel-lucent.com Ben Niven-Jenkins Velocix (Alcatel-Lucent) 3 Ely Road Milton, Cambridge CB24 6DD UK Email: ben.niven-jenkins@alcatel-lucent.com Murray & Niven-Jenkins Expires April 18, 2016 [Page 43]