RESTCONF and HTTP Transport for Event Notifications
draft-ietf-netconf-restconf-notif-04
The information below is for an old version of the document.
Document | Type |
This is an older version of an Internet-Draft that was ultimately published as RFC 8650.
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Authors | Eric Voit , Ambika Tripathy , Einar Nilsen-Nygaard , Alexander Clemm , Alberto Gonzalez Prieto , Andy Bierman | ||
Last updated | 2018-01-31 | ||
Replaces | draft-voit-netconf-restconf-notif | ||
RFC stream | Internet Engineering Task Force (IETF) | ||
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draft-ietf-netconf-restconf-notif-04
NETCONF E. Voit Internet-Draft A. Tripathy Intended status: Standards Track E. Nilsen-Nygaard Expires: August 4, 2018 Cisco Systems A. Clemm Huawei A. Gonzalez Prieto VMWare A. Bierman YumaWorks January 31, 2018 RESTCONF and HTTP Transport for Event Notifications draft-ietf-netconf-restconf-notif-04 Abstract This document defines RESTCONF, HTTP2, and HTTP1.1 bindings for the transport of subscription requests and corresponding push updates. Being subscribed may be either publisher defined event streams or nodes/subtrees of YANG Datastores. 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 https://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 August 4, 2018. Copyright Notice Copyright (c) 2018 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info) in effect on the date of Voit, et al. Expires August 4, 2018 [Page 1] Internet-Draft RESTCONF-Notif January 2018 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 . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Solution . . . . . . . . . . . . . . . . . . . . . . . . . . 3 3.1. Dynamic YANG Subscription with RESTCONF control . . . . . 3 4. Mandatory JSON and datastore support . . . . . . . . . . . . 6 5. Notification Messages . . . . . . . . . . . . . . . . . . . . 7 6. Security Considerations . . . . . . . . . . . . . . . . . . . 7 7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 7 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 7 8.1. Normative References . . . . . . . . . . . . . . . . . . 7 8.2. Informative References . . . . . . . . . . . . . . . . . 8 Appendix A. End-to-End Deployment Guidance . . . . . . . . . . . 9 A.1. Call Home . . . . . . . . . . . . . . . . . . . . . . . . 9 A.2. TLS Heartbeat . . . . . . . . . . . . . . . . . . . . . . 9 Appendix B. RESTCONF over GRPC . . . . . . . . . . . . . . . . . 9 Appendix C. Encoded Subscription and Notification Message Examples . . . . . . . . . . . . . . . . . . . . . . 10 C.1. RESTCONF Subscription and Events over HTTP1.1 . . . . . . 10 C.2. Event Notification over HTTP2 . . . . . . . . . . . . . . 14 Appendix D. Changes between revisions . . . . . . . . . . . . . 14 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 15 1. Introduction Mechanisms to support event subscription and push are defined in [I-D.draft-ietf-netconf-subscribed-notifications]. Enhancements to [I-D.draft-ietf-netconf-subscribed-notifications] which enable YANG Datastore subscription and push are defined in [I-D.ietf-netconf-yang-push]. This document provides a transport specification for these protocols over RESTCONF and HTTP. Driving these requirements is [RFC7923]. The streaming of notifications encapsulating the resulting information push can be done with either HTTP1.1 and HTTP2. When using HTTP2 [RFC7540] benefits which can be realized include: o Elimination of head-of-line blocking Voit, et al. Expires August 4, 2018 [Page 2] quot;Organizer", making it easy to separate a calendar user organizing a meeting from calendar users attending the meeting. Additionally, iCalendar provides descriptive roles for each "Attendee". For instance, a role of "chair" may be ascribed to one or more "Attendees". The "chair" and the "Organizer" may or may not be the same calendar user. This maps well to scenarios where an assistant may manage meeting logistics for another individual who chairs a meeting. Second, a "sent-by" parameter may be specified in either the "Organizer" or "Attendee" properties. When specified, the "sent-by" parameter indicates that the responding CU acted on behalf of the specified "Attendee" or "Organizer". 2.1.4 Component Revisions The "SEQUENCE" property is used by the "Organizer" to indicate revisions to the calendar component. The rules for incrementing the "SEQUENCE" number are defined in [iCAL]. For clarity, these rules are paraphrased Silverberg/Mansour/Dawson/Hopson - 9 - Expires March 1999 Internet Draft iTIP September 15, 1998 here in terms of how they are applied in [iTIP]. For a given "UID" in a calendar component: . For the "PUBLISH" and "REQUEST" methods, the "SEQUENCE" property value is incremented according to the rules defined in [iCAL]. . The "SEQUENCE" property value MUST be incremented each time the "Organizer" uses the "ADD" or "CANCEL" methods. . The "SEQUENCE" property value MUST NOT be incremented when using "REPLY", "REFRESH", "COUNTER", "DECLINECOUNTER", or when sending a delegation "REQUEST". In some circumstances the "Organizer" may not have received responses to the final revision sent out. In this situation, the "Organizer" may wish to send an update "REQUEST", and set "RSVP=TRUE" for all "Attendees", so that current responses can be collected. The value of the "SEQUENCE" property contained in a response from an "Attendee" may not always match the "Organizer's" revision. Implementations may choose to have the CUA indicate to the CU that the response is to an entry that has been revised and allow the CU to decide whether or not to accept the response. 2.1.5 Message Sequencing CUAs that handle the [iTIP] application protocol must often correlate a component in a calendar store with a component received in the [iTIP] message. For example, an event may be updated with a later revision of the same event. To accomplish this, a CUA must correlate the version of the event already in its calendar store with the version sent in the [iTIP] message. In addition to this correlation, there are several factors that can cause [iTIP] messages to arrive in an unexpected order. That is, an "Organizer" could receive a reply to an earlier revision of a component AFTER receiving a reply to a later revision. To maximize interoperability and to handle messages that arrive in an unexpected order, use the following rules: 1. The primary key for referencing a particular iCalendar component is the "UID" property value. To reference an instance of a recurring component, the primary key is composed of the "UID" and the "RECURRENCE-ID" properties. 2. The secondary key for referencing a component is the "SEQUENCE" property value. For components where the "UID" is the same, the component with the highest numeric value for the "SEQUENCE" property obsoletes all other revisions of the component with lower values. 3. "Attendees" send "REPLY" messages to the "Organizer". For replies where the "UID" property value is the same, the value of the "SEQUENCE" property indicates the revision of the component to which Silverberg/Mansour/Dawson/Hopson - 10 - Expires March 1999 Internet Draft iTIP September 15, 1998 the "Attendee" is replying. The reply with the highest numeric value for the "SEQUENCE" property obsoletes all other replies with lower values. 4. In situations where the "UID" and "SEQUENCE" properties match, the "DTSTAMP" property is used as the tie-breaker. The component with the latest "DTSTAMP" overrides all others. Similarly, for "Attendee" responses where the "UID" property values match and the "SEQUENCE" property values match, the response with the latest "DTSTAMP" overrides all others. Hence, CUAs must persist the following component properties: "UID", "RECURRENCE-ID", "SEQUENCE", and "DTSTAMP". Furthermore, for each "ATTENDEE" property of a component CUAs must persist the "SEQUENCE" and "DTSTAMP" property values associated with the "Attendee's" response. 3 Application Protocol Elements ITIP messages are "text/calendar" MIME entities that contain calendaring and scheduling information. The particular type of [iCAL] message is referred to as the "method type". Each method type is identified by a "METHOD&Internet-Draft RESTCONF-Notif January 2018 o Weighting and proportional dequeuing of Events from different subscriptions o Explicit precedence in subscriptions so that events from one subscription must be sent before another dequeues 2. Terminology 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]. The following terms use the definitions from [I-D.draft-ietf-netconf-subscribed-notifications]: configured subscription, dynamic subscription, notification message, publisher, receiver, subscriber, and subscription. 3. Solution Subscribing to event streams is defined in [I-D.draft-ietf-netconf-subscribed-notifications], YANG Datastore subscription is defined in [I-D.ietf-netconf-yang-push]. This section specifies transport mechanisms applicable to both. 3.1. Dynamic YANG Subscription with RESTCONF control Dynamic subscriptions for both [I-D.draft-ietf-netconf-subscribed-notifications] and its [I-D.ietf-netconf-yang-push] augmentations are configured and managed via signaling messages transported over [RFC8040]. These interactions will be accomplished via a RESTCONF POST into RPCs located on the publisher. HTTP responses codes will indicate the results of the interaction with the publisher. An HTTP status code of 200 is the proper response to a successful <establish- subscription> RPC call. The successful <establish-subscription> will result in a HTTP message with returned subscription URI on a logically separate mechanism than was used for the original RESTCONF POST. This mechanism is via a parallel TCP connection in the case of HTTP 1.x, or in the case of HTTP2 via a separate HTTP stream within the HTTP connection. When a being returned by the publisher, failure will be indicated by 4xx range status codes transported in payload. Anytime hints are returned from the publisher status code 412 is used with the error-tag "operation-failed". Once established, the resulting stream of notification messages are then delivered via SSE for HTTP1.1 and via an HTTP2 DATA frame for HTTP2. Voit, et al. Expires August 4, 2018 [Page 3] Internet-Draft RESTCONF-Notif January 2018 3.1.1. Call Flow for HTTP2 Requests to [I-D.draft-ietf-netconf-subscribed-notifications] or [I-D.ietf-netconf-yang-push] augmented RPCs are sent on one or more HTTP2 streams indicated by (a) in Figure 2. Notification messages related to a single subscription are pushed on a unique logical channel (b). In the case below, a newly established subscription has its associated messages pushed over HTTP2 stream (7). +------------+ +------------+ | Subscriber | | Publisher | |HTTP2 Stream| |HTTP2 Stream| | (a) (b) | | (a) (b) | +------------+ +------------+ | RESTCONF POST (RPC:establish-subscription) | |--------------------------------------------->| | HTTP 200 OK (URI)| |<---------------------------------------------| | (7)HTTP POST (URI) (7) | |--------------------------------------------->| | | HTTP 200 OK| | |<---------------------------------------------| | | HTTP Data (event-notif)| | |<---------------------------------------------| | RESTCONF POST (RPC:modify-subscription) | | |--------------------------------------------->| | | | HTTP 200 OK| | |<---------------------------------------------| | | | HTTP Data (subscription-modified)| | |<---------------------------------------------| | | HTTP Data (event-notif)| | |<---------------------------------------------| | RESTCONF POST (RPC:delete-subscription) | | |--------------------------------------------->| | | | HTTP 200 OK| | |<---------------------------------------------| | | | HTTP Headers (end of stream)| | (/7)<-----------------------------------------(/7) | Figure 1: Dynamic with HTTP2 3.1.2. Call flow for HTTP1.1 Requests to [I-D.ietf-netconf-yang-push] RPCs are sent on the TCP connection indicated by (a). Notification messages are pushed on a separate connection (b). This connection (b) will be used for all notification messages across all subscriptions. Voit, et al. Expires August 4, 2018 [Page 4] Internet-Draft RESTCONF-Notif January 2018 +--------------+ +--------------+ | Subscriber | | Publisher | |TCP connection| |TCP connection| | (a) (b) | | (a) (b) | +--------------+ +--------------+ | RESTCONF POST (RPC:establish-subscription) | |--------------------------------------------->| | HTTP 200 OK (URI)| |<---------------------------------------------| | |HTTP GET (URI) | | |--------------------------------------------->| | | HTTP 200 OK| | |<---------------------------------------------| | | SSE (event-notif)| | |<---------------------------------------------| | RESTCONF POST (RPC:modify-subscription) | | |--------------------------------------------->| | | | HTTP 200 OK| | |<---------------------------------------------| | | | SSE (subscription-modified)| | |<---------------------------------------------| | | SSE (event-notif)| | |<---------------------------------------------| | RESTCONF POST (RPC:delete-subscription) | | |--------------------------------------------->| | | | HTTP 200 OK| | |<---------------------------------------------| | | | | | | Figure 2: Dynamic with HTTP1.1 3.1.3. Configured Subscription over HTTP2 With a configured subscription, all information needed to establish a secure relationship with that receiver is available on the publisher. With this information, the publisher will establish a secure transport connection with the receiver and then begin pushing notification messages to the receiver. Since RESTCONF might not exist on the receiver, it is not desirable to require that subscribed content be pushed with any dependency on RESTCONF. Therefore in place of RESTCONF, a TLS secured HTTP2 Client connection must be established with an HTTP2 Server located on the receiver. Notification messages will then be sent as part of an extended HTTP POST to the receiver. POST messages will be addressed to HTTP augmentation code on the receiver capable of accepting and responding to state change Voit, et al. Expires August 4, 2018 [Page 5] Internet-Draft RESTCONF-Notif January 2018quot; property specified as part of the "text/calendar" content type. The table below shows various combinations of calendar components and the method types that this memo supports. +=================================================+ | | VEVENT | VTODO | VJOURNAL | VFREEBUSY | |=================================================| |Publish | Yes | Yes | Yes | Yes | |Request | Yes | Yes | No | Yes | |Refresh | Yes | Yes | No | No | |Cancel | Yes | Yes | Yes | No | |Add | Yes | Yes | Yes | No | |Reply | Yes | Yes | No | Yes | |Counter | Yes | Yes | No | No | |Decline- | | | | | |Counter | Yes | Yes | No | No | +=================================================+ Each method type is defined in terms of its associated components and properties. Some components and properties are required, some are optional and others are excluded. The restrictions are expressed in this document using a simple "restriction table". The first column indicates the name of a component or property. Properties of the iCalendar object are not indented. Properties of a component are indented. The second column contains "MUST" if the component or property must be present, "MAY" if the component or property is optional, and "NOT" if the component or property must not be present. Entries in the second column sometimes contain comments for further clarification. Silverberg/Mansour/Dawson/Hopson - 11 - Expires March 1999 Internet Draft iTIP September 15, 1998 3.1 Common Component Restriction Tables The restriction table below applies to properties of the iCalendar object. That is, the properties at the outermost scope. The presence column uses the following values to assert whether a property is required, is optional and the number of times it may appear in the iCalendar object. Presence Value Description -------------------------------------------------------------- 1 One instance MUST be present 1+ At least one instance MUST be present 0 Instances of this property Must NOT be present 0+ Multiple instances MAY be present 0 or 1 Up to 1 instance of this property MAY be present --------------------------------------------------------------- The tables also call out "X-PROPERTY" and "X-COMPONENT" to show where vendor-specific properties and components can appear. The tables do not lay out the restrictions of property parameters. Those restrictions are defined in [iCAL]. Component/Property Presence ------------------- ---------------------------------------------- CALSCALE 0 or 1 PRODID 1 VERSION 1 Value MUST be "2.0" X-PROPERTY 0+ DateTime values MAY refer to a "VTIMEZONE" component. The property restrictions in the table below apply to any "VTIMEZONE" component in an ITIP message. Component/Property Presence ------------------- ---------------------------------------------- VTIMEZONE 0+ MUST be present if any date/time refers to timezone DAYLIGHT 0+ MUST be one or more of either STANDARD or DAYLIGHT COMMENT 0 or 1 DTSTART 1 MUST be local time format RDATE 0+ if present RRULE MUST NOT be present RRULE 0+ if present RDATE MUST NOT be present TZNAME 0 or 1 TZOFFSET 1 TZOFFSETFROM 1 TZOFFSETTO 1 X-PROPERTY 0+ LAST-MODIFIED 0 or 1 STANDARD 0+ MUST be one or more of either STANDARD or DAYLIGHT COMMENT 0 or 1 Silverberg/Mansour/Dawson/Hopson - 12 - Expires March 1999 Internet Draft iTIP September 15, 1998 DTSTART 1 MUST be local time format RDATE 0+ if present RRULE MUST NOT be present RRULE 0+ if present RDATE MUST NOT be present TZNAME 0 or 1 TZOFFSETFROM 1 TZOFFSETTO 1 X-PROPERTY 0+ TZID 1 TZURL 0 or 1 X-PROPERTY 0+ The property restrictions in the table below apply to any "VALARM" component in an ITIP message. Component/Property Presence ------------------- ---------------------------------------------- VALARM 0+ ACTION 1 ATTACH 0+ DESCRIPTION 0 or 1 DURATION 0 or 1 if present REPEAT MUST be present REPEAT 0 or 1 if present DURATION MUST be present SUMMARY 0 or 1 TRIGGER 1 X-PROPERTY 0+ 3.2 Methods for VEVENT Calendar Components This section defines the property set restrictions for the method types that are applicable to the "VEVENT" calendar component. Each method is defined using a table that clarifies the property constraints that define the particular method. The following summarizes the methods that are defined for the "VEVENT" calendar component. +================+==================================================+ | Method | Description | |================+==================================================| | PUBLISH | Post notification of an event. Used primarily as | | | a method of advertising the existence of an | | | event. | | | | | REQUEST | Make a request for an event. This is an explicit | | | invitation to one or more "Attendees". Event | | | Requests are also used to update or change an | | | existing event. Clients that cannot handle | | | REQUEST may degrade the event to view it as an | | | PUBLISH. | | | | | REPLY | Reply to an event request. Clients may set their | | | status ("partstat") to ACCEPTED, DECLINED, | Silverberg/Mansour/Dawson/Hopson - 13 - Expires March 1999 Internet Draft iTIP September 15, 1998 | | TENTATIVE, or DELEGATED. | | | | | ADD | Add one or more instances to an existing event. | | | | | CANCEL | Cancel one or more instances of an existing | | | event. | | | | | REFRESH | A request is sent to an "Organizer" by an | | | "Attendee" asking for the latest version of an | | | event to be resent to the requester. | | | | | COUNTER | Counter a REQUEST with an alternative proposal, | | | Sent by an "Attendee" to the "Organizer". | | | | | DECLINECOUNTER | Decline a counter proposal. Sent to an | | | "Attendee" by the "Organizer". | +================+==================================================+ 3.2.1 PUBLISH The "PUBLISH" method in a "VEVENT" calendar component is an unsolicited posting of an iCalendar object. Any CU may add published components to their calendar. The "Organizer" MUST be present in a published iCalendar component. "Attendees" MUST NOT be present. Its expected usage is for encapsulating an arbitrary event as an iCalendar object. The "Organizer" may subsequently update (with another "PUBLISH" method), add instances to (with an "ADD" method), or cancel (with a "CANCEL" method) a previously published "VEVENT" calendar component. This method type is an iCalendar object that conforms to the following property constraints: Component/Property Presence ------------------- ---------------------------------------------- METHOD 1 MUST equal "PUBLISH" VEVENT 1+ DTSTAMP 1 DTSTART 1 ORGANIZER 1 SUMMARY 1 Can be null. UID 1 RECURRENCE-ID 0 or 1 only if referring to an instance of a recurring calendar component. Otherwise it MUST NOT be present. SEQUENCE 0 or 1 MUST be present if value is greater than 0, MAY be present if 0 ATTACH 0+ CATEGORIES 0 or 1 This property may contain a list of values CLASS 0 or 1 COMMENT 0 or 1 CONTACT 0+ CREATED 0 or 1 DESCRIPTION 0 or 1 Can be null Silverberg/Mansour/Dawson/Hopson - 14 - Expires March 1999 Internet Draft iTIP September 15, 1998 DTEND 0 or 1 if present DURATION MUST NOT be present DURATION 0 or 1 if present DTEND MUST NOT be present EXDATE 0+ EXRULE 0+ GEO 0 or 1 LAST-MODIFIED 0 or 1 LOCATION 0 or 1 PRIORITY 0 or 1 RDATE 0+ RELATED-TO 0+ RESOURCES 0 or 1 This property MAY contain a list of values RRULE 0+ STATUS 0 or 1 MAY be one of TENTATIVE/CONFIRMED/CANCELLED TRANSP 0 or 1 URL 0 or 1 X-PROPERTY 0+ ATTENDEE 0 REQUEST-STATUS 0 VALARM 0+ VFREEBUSY 0 VJOURNAL 0 VTODO 0 VTIMEZONE 0+ MUST be present if any date/time refers to a timezone X-COMPONENT 0+ 3.2.2 REQUEST The "REQUEST" method in a "VEVENT" component provides the following scheduling functions: . Invite "Attendees" to an event; . Reschedule an existing event; . Response to a REFRESH request; . Update the details of an existing event, without rescheduling it; . Update the status of "Attendees" of an existing event, without rescheduling it; . Reconfirm an existing event, without rescheduling it; . Forward a "VEVENT" to another uninvited CU. . For an existing "VEVENT" calendar component, delegate the role of "Attendee" to another CU; . For an existing "VEVENT" calendar component, changing the role of "Organizer" to another CU. The "Organizer" originates the "REQUEST". The recipients of the "REQUEST" method are the CUs invited to the event, the "Attendees". "Attendees" use the "REPLY" method to convey attendance status to the "Organizer". The "UID" and "SEQUENCE" properties are used to distinguish the various uses of the "REQUEST" method. If the "UID" property value in the Silverberg/Mansour/Dawson/Hopson - 15 - Expires March 1999 Internet Draft iTIP September 15, 1998 "REQUEST" is not found on the recipient's calendar, then the "REQUEST" is for a new "VEVENT" calendar component. If the "UID" property value is found on the recipient's calendar, then the "REQUEST& notifications and subscribed content notification messages. The first POST message must be a subscription-started notification. Notifications which include any subscribed content must not be sent until the receipt of an HTTP 200 OK for this initial notification. The 200 OK will indicate that the receiver is ready for the delivery of subscribed content. At this point a subscription must be allocated its own HTTP2 stream. Figure 4 depicts this message flow. +------------+ +------------+ | Receiver | | Publisher | |HTTP2 Stream| |HTTP2 Stream| | (a) (b) | | (a) (b) | +------------+ +------------+ | HTTP Post Headers, Data (sub-start, SubID)| |<---------------------------------------------| | HTTP 200 OK | |--------------------------------------------->| | | HTTP Post Headers, Data (event-notif)| | |<---------------------------------------------| | | HTTP Data (event-notif)| | |<---------------------------------------------| | | HTTP Data (sub-terminate)| | |<---------------------------------------------| | |HTTP 200 OK | | |--------------------------------------------->| Figure 3: Configured over HTTP2 As the HTTP2 transport is available to the receiver, the publisher should: o take any subscription-priority and copy it into the HTTP2 stream priority, and o take a subscription-dependency if it has been provided and map the HTTP2 stream for the parent subscription into the HTTP2 stream dependency. 4. Mandatory JSON and datastore support A publisher MUST support JSON encoding of RPCs and Notifications. A publisher supporting [I-D.ietf-netconf-yang-push] MUST support the "operational" datastore as defined by [I.D.draft-ietf-netmod-revised-datastores]. Voit, et al. Expires August 4, 2018 [Page 6] Internet-Draft RESTCONF-Notif January 2018 5. Notification Messages Notification messages transported over NETCONF will be identical in format and content to those encoded using one-way operations defined within [RFC5277], section 4. 6. Security Considerations One or more publishers of configured subscriptions could be used to overwhelm a receiver which doesn't even support subscriptions. There are two protections needing support on a publisher. First, notification messages for configured subscriptions MUST only be transmittable over encrypted transports. Clients which do not want pushed content need only terminate or refuse any transport sessions from the publisher. Second, the HTTP transport augmentation on the receiver must send an HTTP 200 OK to a subscription started notification before the publisher starts streaming any subscribed content. One or more publishers could overwhelm a receiver which is unable to control or handle the volume of Event Notifications received. In deployments where this might be a concern, HTTP2 transport such as HTTP2) should be selected. The NETCONF Authorization Control Model [RFC6536] SHOULD be used to control and restrict authorization of subscription configuration. 7. Acknowledgments We wish to acknowledge the helpful contributions, comments, and suggestions that were received from: Susan Hares, Tim Jenkins, Balazs Lengyel, Kent Watsen, Michael Scharf, and Guangying Zheng. 8. References 8.1. Normative References [I-D.draft-ietf-netconf-subscribed-notifications] Voit, E., Clemm, A., Gonzalez Prieto, A., Tripathy, A., and E. Nilsen-Nygaard, "Custom Subscription to Event Streams", draft-ietf-netconf-subscribed-notifications-06 (work in progress), January 2018. [I.D.draft-ietf-netmod-revised-datastores] Bjorklund, M., Schoenwaelder, J., Shafer, P., Watsen, K., and R. Wilton, "Network Management Datastore Architecture", draft-ietf-netmod-revised-datastores-04 (work in progress), August 2017. Voit, et al. Expires August 4, 2018 [Page 7] Internet-Draft RESTCONF-Notif January 2018 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, <https://www.rfc-editor.org/info/rfc2119>. [RFC5277] Chisholm, S. and H. Trevino, "NETCONF Event Notifications", RFC 5277, DOI 10.17487/RFC5277, July 2008, <https://www.rfc-editor.org/info/rfc5277>. [RFC6520] Seggelmann, R., Tuexen, M., and M. Williams, "Transport Layer Security (TLS) and Datagram Transport Layer Security (DTLS) Heartbeat Extension", RFC 6520, DOI 10.17487/RFC6520, February 2012, <https://www.rfc-editor.org/info/rfc6520>. [RFC6536] Bierman, A. and M. Bjorklund, "Network Configuration Protocol (NETCONF) Access Control Model", RFC 6536, DOI 10.17487/RFC6536, March 2012, <https://www.rfc-editor.org/info/rfc6536>. [RFC7540] Belshe, M., Peon, R., and M. Thomson, Ed., "Hypertext Transfer Protocol Version 2 (HTTP/2)", RFC 7540, DOI 10.17487/RFC7540, May 2015, <https://www.rfc-editor.org/info/rfc7540>. [RFC8040] Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017, <https://www.rfc-editor.org/info/rfc8040>. 8.2. Informative References [GRPC] "RPC framework that runs over HTTP2", August 2017, <https://grpc.io/>. [I-D.ietf-netconf-yang-push] Clemm, A., Voit, E., Gonzalez Prieto, A., Prasad Tripathy, A., Nilsen-Nygaard, E., Bierman, A., and B. Lengyel, "Subscribing to YANG datastore push updates", March 2017, <https://datatracker.ietf.org/doc/ draft-ietf-netconf-yang-push/>. [RFC7923] Voit, E., Clemm, A., and A. Gonzalez Prieto, "Requirements for Subscription to YANG Datastores", RFC 7923, DOI 10.17487/RFC7923, June 2016, <https://www.rfc-editor.org/info/rfc7923>. Voit, et al. Expires August 4, 2018 [Page 8] Internet-Draft RESTCONF-Notif January 2018 [RFC7951] Lhotka, L., "JSON Encoding of Data Modeled with YANG", RFC 7951, DOI 10.17487/RFC7951, August 2016, <https://www.rfc-editor.org/info/rfc7951>. [RFC8071] Watsen, K., "NETCONF Call Home and RESTCONF Call Home", RFC 8071, DOI 10.17487/RFC8071, February 2017, <https://www.rfc-editor.org/info/rfc8071>. [W3C-20150203] "Server-Sent Events, World Wide Web Consortium CR CR- eventsource-20121211", February 2015, <https://www.w3.org/TR/2015/REC-eventsource-20150203/" is for a rescheduling, an update, or a reconfirm of the "VEVENT" calendar component. For the "REQUEST" method, multiple "VEVENT" components in a single iCalendar object are only permitted when for components with the same "UID" property. That is, a series of recurring events may have instance-specific information. In this case, multiple "VEVENT" components are needed to express the entire series. This method type is an iCalendar object that conforms to the following property constraints: Component/Property Presence ----------------------------------------------------------------- METHOD 1 MUST be "REQUEST" VEVENT 1+ All components MUST have the same UID ATTENDEE 1+ DTSTAMP 1 DTSTART 1 ORGANIZER 1 SEQUENCE 0 or 1 MUST be present if value is greater than 0, MAY be present if 0 SUMMARY 1 Can be null UID 1 ATTACH 0+ CATEGORIES 0 or 1 This property may contain a list of values CLASS 0 or 1 COMMENT 0 or 1 CONTACT 0+ CREATED 0 or 1 DESCRIPTION 0 or 1 Can be null DTEND 0 or 1 if present DURATION MUST NOT be present DURATION 0 or 1 if present DTEND MUST NOT be present EXDATE 0+ EXRULE 0+ GEO 0 or 1 LAST-MODIFIED 0 or 1 LOCATION 0 or 1 PRIORITY 0 or 1 RDATE 0+ RECURRENCE-ID 0 or 1 only if referring to an instance of a recurring calendar component. Otherwise it MUST NOT be present. RELATED-TO 0+ REQUEST-STATUS 0+ RESOURCES 0 or 1 This property MAY contain a list of values RRULE 0+ STATUS 0 or 1 MAY be one of TENTATIVE/CONFIRMED TRANSP 0 or 1 URL 0 or 1 Silverberg/Mansour/Dawson/Hopson - 16 - Expires March 1999 Internet Draft iTIP September 15, 1998 X-PROPERTY 0+ VALARM 0+ VTIMEZONE 0+ MUST be present if any date/time refers to a timezone X-COMPONENT 0+ VFREEBUSY 0 VJOURNAL 0 VTODO 0 3.2.2.1 Rescheduling an Event The "REQUEST" method may be used to reschedule an event. A rescheduled event involves a change to the existing event in terms of its time or recurrence intervals and possibly the location or description. If the recipient CUA of a "REQUEST" method finds that the "UID" property value already exists on the calendar, but that the "SEQUENCE" (or "DTSTAMP") property value in the "REQUEST" method is greater than the value for the existing event, then the "REQUEST" method describes a rescheduling of the event. 3.2.2.2 Updating or Reconfirmation of an Event The "REQUEST" method may be used to update or reconfirm an event. An update to an existing event does not involve changes to the time or recurrence intervals, and might not involve a change to the location or description for the event. If the recipient CUA of a "REQUEST" method finds that the "UID" property value already exists on the calendar and that the "SEQUENCE" property value in the "REQUEST" is the same as the value for the existing event, then the "REQUEST" method describes an update of the event details, but no rescheduling of the event. The update "REQUEST" method is the appropriate response to a "REFRESH" method sent from an "Attendee" to the "Organizer" of an event. The "Organizer" of an event may also send unsolicited "REQUEST" methods. The unsolicited "REQUEST" methods may be used to update the details of the event without rescheduling it, to update the "partstat" parameter of "Attendees", or to reconfirm the event. 3.2.2.3 Delegating an Event to another CU Some calendar and scheduling systems allow "Attendees" to delegate their presence at an event to another calendar user. ITIP supports this concept using the following workflow. Any "Attendee" may delegate their right to participate in a calendar VEVENT to another CU. The implication is that the delegate participates in lieu of the original "Attendee"; NOT in addition to the "Attendee". The delegator MUST notify the "Organizer" of this action using the steps outlined below. Implementations may support or restrict delegation as they see fit. For Silverberg/Mansour/Dawson/Hopson - 17 - Expires March 1999 Internet Draft iTIP September 15, 1998 instance, some implementations may restrict a delegate from delegating a "REQUEST" to another CU. The "Delegator" of an event forwards the existing "REQUEST" to the "Delegate". The "REQUEST" method MUST include an "ATTENDEE" property with the calendar address of the "Delegate". The "Delegator" MUST also send a "REPLY" method to the "Organizer" with the "Delegator's" "ATTENDEE" property "partstat" parameter value set to "delegated". In addition, the "delegated-to" parameter MUST be included with the calendar address of the "Delegate". In response to the request, the "Delegate" MUST send a "REPLY" method to the "Organizer" and optionally, to the "Delegator". The "REPLY" method " SHOULD include the "ATTENDEE" property with the "delegated-from" parameter value of the "Delegator's" calendar address. The "Delegator" may continue to receive updates to the event even though they will not be attending. This is accomplished by the "Delegator" setting their "role" attribute to " NON-PARTICIPANT" in the "REPLY" to the "Organizer" 3.2.2.4 Changing the Organizer The situation may arise where the "Organizer" of a VEVENT is no longer able to perform the "Organizer>. Appendix A. End-to-End Deployment Guidance Several technologies are expected to be seen within a deployment to achieve security and ease-of-use requirements. These are not necessary for an implementation of this specification, but will be useful to consider when considering the operational context. A.1. Call Home Implementations should include the ability to transparently incorporate 'call home' [RFC8071] so that secure TLS connections can originate from the desired device. A.2. TLS Heartbeat HTTP sessions might not quickly allow a subscriber to recognize when the communication path has been lost from the publisher. To recognize this, it is possible for a receiver to establish a TLS heartbeat [RFC6520]. In the case where a TLS heartbeat is included, it should be sent just from receiver to publisher. Loss of the heartbeat should result in any subscription related TCP sessions between those endpoints being torn down. The subscription can then attempt to re-establish. Appendix B. RESTCONF over GRPC An initial goal for this document was to support [GRPC] transport seamlessly without any mapping or extra layering. However there is an incompatibility of RESTCONF and GRPC. RESTCONF uses HTTP GET, and GRPC uses HTTP2's POST rather than GET. As GET is used across RESTCONF for things like capabilities exchange, a seamless mapping depends on specification changes outside the scope of this document. If/when GRPC supports GET, or RESTCONF is updated to support POST, this should be revisited. It is hoped that the resulting fix will be transparent to this document. Voit, et al. Expires August 4, 2018 [Page 9] Internet-Draft RESTCONF-Notif January 2018 Appendix C. Encoded Subscription and Notification Message Examples (Note: examples in this section need significant updates) C.1. RESTCONF Subscription and Events over HTTP1.1 Subscribers can dynamically learn whether a RESTCONF server supports various types of Event or Yang datastore subscription capabilities. This is done by issuing an HTTP request OPTIONS, HEAD, or GET on the stream. Some examples building upon the Call flow for HTTP1.1 from Section 3.2.2 are: GET /restconf/data/ietf-restconf-monitoring:restconf-state/ streams/stream=yang-push HTTP/1.1 Host: example.com Accept: application/yang.data+xml If the server supports it, it may respond HTTP/1.1 200 OK Content-Type: application/yang.api+xml <stream xmlns="urn:ietf:params:xml:ns:yang:ietf-restconf-monitoring"> <name>yang-push</name> <description>Yang push stream</description> <access> <encoding>xml</encoding> <location>https://example.com/streams/yang-push-xml </location> </access> <access> <encoding>json</encoding> <location>https://example.com/streams/yang-push-json </location> </access> </stream> If the server does not support any form of subscription, it may respond HTTP/1.1 404 Not Found Date: Mon, 25 Apr 2012 11:10:30 GMT Server: example-server Subscribers can determine the URL to receive updates by sending an HTTP GET as a request for the "location" leaf with the stream list entry. The stream to use for may be selected from the Event Stream list provided in the capabilities exchange. Note that different Voit, et al. Expires August 4, 2018 [Page 10] Internet-Draft RESTCONF-Notif January 2018 encodings are supporting using different Event Stream locations. For example, the subscriber might send the following request: GET /restconf/data/ietf-restconf-monitoring:restconf-state/ streams/stream=yang-push/access=xml/location HTTP/1.1 Host: example.com Accept: application/yang.data+xml The publisher might send the following response: HTTP/1.1 200 OK Content-Type: application/yang.api+xml <location xmlns="urn:ietf:params:xml:ns:yang:ietf-restconf-monitoring"> https://example.com/streams/yang-push-xml </location> To subscribe and start receiving updates, the subscriber can then send an HTTP GET request for the URL returned by the publisher in the request above. The accept header must be "text/event-stream". The publisher uses the Server Sent Events [W3C-20150203] transport strategy to push filtered events from the event stream. The publisher MUST support individual parameters within the POST request body for all the parameters of a subscription. The only exception is the encoding, which is embedded in the URI. An example of this is: // subtree filter = /foo // periodic updates, every 5 seconds POST /restconf/operations/ietf-subscribed-notifications: establish-subscription HTTP/1.1 Host: example.com Content-Type: application/yang-data+json { "ietf-subscribed-notifications:input" : { "stream": "push-data" "period" : 5, "xpath-filter" : "/ex:foo[starts-with('bar'.'some']" } } Should the publisher not support the requested subscription, it may reply: Voit, et al. Expires August 4, 2018 [Page 11] Internet-Draft RESTCONF-Notif January 2018 HTTP/1.1 501 Not Implemented Date: Mon, 23 Apr 2012 17:11:00 GMT Server: example-server Content-Type: application/yang.errors+xml <errors xmlns="urn:ietf:params:xml:ns:yang:ietf-restconf"> <error> <error-type>application</error-type> <error-tag>operation-not-supported</error-tag> <error-severity>error</error-severity> <error-message>Xpath filters not supported</error-message> <error-info> <supported-subscription xmlns="urn:ietf:params:xml:ns: netconf:datastore-push:1.0"> <subtree-filter/> </supported-subscription> </error-info> </error> </errors> with an equivalent JSON encoding representation of: HTTP/1.1 501 Not Implemented Date: Mon, 23 Apr 2012 17:11:00 GMT Server: example-server Content-Type: application/yang.errors+json { "ietf-restconf:errors": { "error": { "error-type": "protocol", "error-tag": "operation-not-supported", "error-message": "Xpath filters not supported." "error-info": { "datastore-push:supported-subscription": { "subtree-filter": [null] } } } } } The following is an example of a pushed content for the subscription above. It contains a subtree with root foo that contains a leaf called bar: Voit, et al. Expires August 4, 2018 [Page 12] quot; role and abdicates without passing on the "Organizer" role to someone else. When this occurs the "Attendees" of the VEVENT may use out-of-band mechanisms to communicate the situation and agree upon a new "Organizer". The new "Organizer" should then send out a new "REQUEST" with a modified version of the VEVENT in which the "SEQUENCE" number has been incremented and value of the "ORGANIZER" property has been changed to the calendar address of the new "Organizer". 3.2.2.5 Sending on Behalf of the Organizer There are a number of scenarios that support the need for a calendar user to act on behalf of the "Organizer" without explicit role changing. This might be the case if the CU designated as "Organizer" was sick or unable to perform duties associated with that function. In these cases iTIP supports the notion of one CU acting on behalf of another. Using the "sent-by" parameter, a calendar user could send an updated "VEVENT" REQUEST. In the case where one CU sends on behalf of another CU, the "Attendee" responses are still directed back towards the CU designated as "Organizer". 3.2.2.6 Forwarding to An Uninvited CU An "Attendee" invited to an event may invite another uninvited CU to the event. The invited "Attendee" accomplishes this by forwarding the original "REQUEST" method to the uninvited CU. The "Organizer" decides whether or not the uninvited CU is added to the attendee list. If the Silverberg/Mansour/Dawson/Hopson - 18 - Expires March 1999 Internet Draft iTIP September 15, 1998 "Organizer" decides not to add the uninvited CU no further action is required, however the "Organizer" MAY send the uninvited CU a "CANCEL" message. If the "Organizer" decides to add an uninvited CU, a new "ATTENDEE" property is added for the uninvited CU with its property parameters set as the "Organizer" deems appropriate. When forwarding a "REQUEST" to another CU, the forwarding "Attendee" MUST NOT make changes to the VEVENT property set. 3.2.2.7 Updating Attendee Status The "Organizer" of an event may also request updated status from one or more "Attendees. The "Organizer" sends a "REQUEST" method to the "Attendee" and sets the "ATTENDEE;RSVP=TRUE" property parameter. The "SEQUENCE" property for the event is not changed from its previous value. A recipient will determine that the only change in the "REQUEST" is that their "RSVP" property parameter indicates a request for updated status. The recipient SHOULD respond with a "REPLY" method indicating their current status with respect to the "REQUEST". 3.2.3 REPLY The "REPLY" method in a "VEVENT" calendar component is used to respond (e.g., accept or decline) to a "REQUEST" or to reply to a delegation "REQUEST". When used to provide a delegation response, the "Delegator" SHOULD include the calendar address of the "Delegate" on the "delegated- to" property parameter of the "Delegator's" "ATTENDEE" property. The "Delegate" SHOULD include the calendar address of the "Delegator" on the "delegated-from" property parameter of the "Delegate's" "ATTENDEE" property. The "REPLY" method may also be used to respond to an unsuccessful "REQUEST" method. Depending on the value of the "REQUEST-STATUS" property no scheduling action may have been performed. The "Organizer" of an event may receive the "REPLY" method from a CU not in the original "REQUEST". For example, a "REPLY" may be received from a "Delegate" to an event. In addition, the "REPLY" method may be received from an unknown CU (a "Party Crasher"). This uninvited "Attendee" may be accepted, or the "Organizer" may cancel the event for the uninvited "Attendee" by sending a "CANCEL" method to the uninvited "Attendee". An "Attendee" can include a message to the "Organizer" using the "COMMENT" property. For example, if the user indicates tentative acceptance and wants to let the "Organizer" know why, the reason can be expressed in the "COMMENT" property value. The "OrganizerInternet-Draft RESTCONF-Notif January 2018 XML encoding representation: <?xml version="1.0" encoding="UTF-8"?> <notification xmlns="urn:ietf:params:xml:ns:yang:ietf-restconf"> <subscription-id xmlns="urn:ietf:params:xml:ns:restconf: datastore-push:1.0"> my-sub </subscription-id> <eventTime>2015-03-09T19:14:56.233Z</eventTime> <datastore-contents xmlns="urn:ietf:params:xml:ns:restconf: datastore-push:1.0"> <foo xmlns="http://example.com/yang-push/1.0"> <bar>some_string</bar> </foo> </datastore-contents> </notification> Or with the equivalent YANG over JSON encoding representation as defined in [RFC7951]: { "ietf-restconf:notification": { "datastore-push:subscription-id": "my-sub", "eventTime": "2015-03-09T19:14:56.233Z", "datastore-push:datastore-contents" may also receive a "REPLY" from one CU on behalf of another. Like the scenario enumerated above for the "Organizer", "Attendees" may have another CU respond on their behalf. This is done using the "sent-by" parameter. Silverberg/Mansour/Dawson/Hopson - 19 - Expires March 1999 Internet Draft iTIP September 15, 1998 The optional properties listed in the table below (those listed as "0+" or "0 or 1") MUST NOT be changed from those of the original request. If property changes are desired the COUNTER message must be used. This method type is an iCalendar object that conforms to the following property constraints: Component/Property Presence ------------------- ---------------------------------------------- METHOD 1 MUST be "REPLY" VEVENT 1+ All components MUST have the same UID ATTENDEE 1 MUST be the address of the Attendee replying. DTSTAMP 1 ORGANIZER 1 RECURRENCE-ID 0 or 1 only if referring to an instance of a recurring calendar component. Otherwise it must NOT be present. UID 1 MUST be the UID of the original REQUEST SEQUENCE 0 or 1 MUST if non-zero, MUST be the sequence number of the original REQUEST. MAY be present if 0. ATTACH 0+ CATEGORIES 0 or 1 This property may contain a list of values CLASS 0 or 1 COMMENT 0 or 1 CONTACT 0+ CREATED 0 or 1 DESCRIPTION 0 or 1 DTEND 0 or 1 if present DURATION MUST NOT be present DTSTART 0 or 1 DURATION 0 or 1 if present DTEND MUST NOT be present EXDATE 0+ EXRULE 0+ GEO 0 or 1 LAST-MODIFIED 0 or 1 LOCATION 0 or 1 PRIORITY 0 or 1 RDATE 0+ RELATED-TO 0+ RESOURCES 0 or 1 This property MAY contain a list of values REQUEST-STATUS 0+ RRULE 0+ STATUS 0 or 1 SUMMARY 0 or 1 TRANSP 0 or 1 URL 0 or 1 X-PROPERTY 0+ VTIMEZONE 0 or 1 MUST be present if any date/time refers to a timezone Silverberg/Mansour/Dawson/Hopson - 20 - Expires March 1999 Internet Draft iTIP September 15, 1998 X-COMPONENT 0+ VALARM 0 VFREEBUSY 0 VJOURNAL 0 VTODO 0 3.2.4 ADD The "ADD" method in a "VEVENT" calendar component is used to add one or more instances to an existing "VEVENT". Unlike the "REQUEST" method, when using issuing an "ADD" method, the "Organizer" does not send the full "VEVENT" description; only the new instance(s). The "ADD" method is especially useful if there are instance-specific properties to be preserved in a recurring "VEVENT". For instance, an "Organizer" may have originally scheduled a weekly Thursday meeting. At some point, several instances changed. Location or start time may have changed, or some instances may have unique "DESCRIPTION" properties. The "ADD" method allows the "Organizer" to add new instances to an existing event using a single ITIP message without redefining the entire recurring pattern. The "UID" must be that of the existing event. If the "UID" property value in the "ADD" is not found on the recipient's calendar, then the recipient SHOULD send a "REFRESH" to the "Organizer" in order to be updated with the latest version of the "VEVENT". If an "Attendee" implementation does not support the "ADD" method it should respond with a "REQUEST-STATUS" value of 3.14 and ask for a "REFRESH". This method type is an iCalendar object that conforms to the following property constraints: Component/Property Presence ------------------- ---------------------------------------------- METHOD 1 MUST be "ADD" VEVENT 1 DTSTAMP 1 DTSTART 1 ORGANIZER 1 SEQUENCE 1 MUST be greater than 0 SUMMARY 1 Can be null UID 1 MUST match that of the original event ATTACH 0+ ATTENDEE 0+ CATEGORIES 0 or 1 This property MAY contain a list of values CLASS 0 or 1 COMMENT 0 or 1 CONTACT 0+ CREATED 0 or 1 DESCRIPTION 0 or 1 Can be null DTEND 0 or 1 if present DURATION MUST NOT be present DURATION 0 or 1 if present DTEND MUST NOT be present EXDATE 0+ Silverberg/Mansour/Dawson/Hopson - 21 - Expires March 1999 Internet Draft iTIP September 15, 1998 EXRULE 0+ GEO 0 or 1 LAST-MODIFIED 0 or 1 LOCATION 0 or 1 PRIORITY 0 or 1 RDATE 0+ RELATED-TO 0+ RESOURCES 0 or 1 This property MAY contain a list of values RRULE 0+ STATUS 0 or 1 MAY be one of TENTATIVE/CONFIRMED TRANSP 0 or 1 URL 0 or 1 X-PROPERTY 0+ RECURRENCE-ID 0 REQUEST-STATUS 0 VALARM 0+ VTIMEZONE 0+ MUST be present if any date/time refers to a timezone X-COMPONENT 0+ VFREEBUSY 0 VTODO 0 VJOURNAL 0 3.2.5 CANCEL The "CANCEL" method in a "VEVENT" calendar component is used to send a cancellation notice of an existing event request to the "Attendees". The message is sent by the "Organizer" of the event. For a recurring event, either the whole event or instances of an event may be cancelled. To cancel the complete range of recurring event, the "UID" property value for the event MUST be specified and a "RECURRENCE-ID" MUST NOT be specified in the "CANCEL" method. In order to cancel an individual instance of the event, the "RECURRENCE-ID" property value for the event MUST be specified in the "CANCEL" method. There are two options for canceling a sequence of instances of a recurring "VEVENT" calendar component: (a) the "RECURRENCE-ID" property for an instance in the sequence MUST be specified with the "RANGE" property parameter value of THISANDPRIOR (or THISANDFUTURE) to indicate cancellation of the specified "VEVENT" calendar component and all instances before (or after); or (b) individual recurrence instances may be cancelled by specifying multiple "RECURRENCE-ID" properties corresponding to the instances to be cancelled. When a "VEVENT" is cancelled, the "SEQUENCE" property value MUST be incremented. Silverberg/Mansour/Dawson/Hopson - 22 - Expires March 1999 Internet Draft iTIP September 15, 1998 This method type is an iCalendar object that conforms to the following property constraints: Component/Property Presence ------------------- ---------------------------------------------- METHOD 1 MUST be "CANCEL" VEVENT 1+ All must have the same UID ATTENDEE 0+ MUST include all "Attendees" being removed the event. MUST include all "Attendees" if the entire event is cancelled. DTSTAMP 1 ORGANIZER 1 SEQUENCE 1 UID 1 MUST be the UID of the original REQUEST COMMENT 0 or 1 ATTACH 0+ CATEGORIES 0 or 1 This property may contain a list of values CLASS 0 or 1 CONTACT 0+ CREATED 0 or 1 DESCRIPTION 0 or 1 DTEND 0 or 1 if present DURATION MUST NOT be present DTSTART 0 or 1 DURATION 0 or 1 if present DTEND MUST NOT be present EXDATE 0+ EXRULE 0+ GEO 0 or 1 LAST-MODIFIED 0 or 1 LOCATION 0 or 1 PRIORITY 0 or 1 RDATE 0+ RECURRENCE-ID 0 or 1 MUST be present if referring to one or more or more recurring instances. Otherwise it MUST NOT be present RELATED-TO 0+ RESOURCES 0 or 1 RRULE 0+ STATUS 0 or 1 MUST be set to CANCELLED. If uninviting specific "Attendees" then MUST NOT be included. SUMMARY 0 or 1 TRANSP 0 or 1 URL 0 or 1 X-PROPERTY 0+ REQUEST-STATUS 0 VTIMEZONE 0+ MUST be present if any date/time refers to a timezone X-COMPONENT 0+ VTODO 0 VJOURNAL 0 Silverberg/Mansour/Dawson/Hopson - 23 - Expires March 1999 Internet Draft iTIP September 15, 1998 VFREEBUSY 0 VALARM 0 3.2.6 REFRESH The "REFRESH" method in a "VEVENT" calendar component is used by "Attendees" of an existing event to request an updated description from the event "Organizer". The "REFRESH" method must specify the "UID" property of the event to update. A recurrence instance of an event may be requested by specifying the "RECURRENCE-ID" property corresponding to the associated event. The "Organizer" responds with the latest description and version of the event. This method type is an iCalendar object that conforms to the following property constraints: Component/Property Presence ------------------- ---------------------------------------------- METHOD 1 MUST be "REFRESH" VEVENT 1 ATTENDEE 1 MUST be the address of requestor DTSTAMP 1 ORGANIZER 1 UID 1 MUST be the UID associated with original REQUEST COMMENT 0 or 1 RECURRENCE-ID 0 or 1 MUST only if referring to an instance of a recurring calendar component. Otherwise it must NOT be present. X-PROPERTY 0+ ATTACH 0 CATEGORIES 0 CLASS 0 CONTACT 0 CREATED 0 DESCRIPTION 0 DTEND 0 DTSTART 0 DURATION 0 EXDATE 0 EXRULE 0 GEO 0 LAST-MODIFIED 0 LOCATION 0 PRIORITY 0 RDATE 0 RELATED-TO 0 REQUEST-STATUS 0 RESOURCES 0 RRULE 0 SEQUENCE 0 Silverberg/Mansour/Dawson/Hopson - 24 - Expires March 1999 Internet Draft iTIP September 15, 1998 STATUS 0 SUMMARY 0 TRANSP 0 URL 0 X-COMPONENT 0+ VTODO 0 VJOURNAL 0 VFREEBUSY 0 VTIMEZONE 0 VALARM 0 3.2.7 COUNTER The "COUNTER" method for a "VEVENT" calendar component is used by an "Attendee" of an existing event to submit to the "Organizer" a counter proposal to the event description. The "Attendee" sends this message to the "Organizer" of the event. The counter proposal is an iCalendar object consisting of a VEVENT calendar component describing the complete description of the alternate event. The "Organizer" rejects the counter proposal by sending the "Attendee": { "example-mod:foo": { "bar": "some_string" } } } } To modify a subscription, the subscriber issues another POST request on the provided URI using the same subscription-id as in the original request. For example, to modify the update period to 10 seconds, the subscriber may send: POST /restconf/operations/ietf-subscribed-notifications: modify-subscription HTTP/1.1 Host: example.com Content-Type: application/yang-data+json { "ietf-subscribed-notifications:input" : { "subscription-id": 100, "period" : 10 } } Voit, et al. Expires August 4, 2018 [Page 13] Internet-Draft RESTCONF-Notif January 2018 To delete a subscription, the subscriber issues a DELETE request on the provided URI using the same subscription-id as in the original request C.2. Event Notification over HTTP2 The basic encoding will look as below. It will consists of a JSON representation wrapped in an HTTP2 header. HyperText Transfer Protocol 2 Stream: HEADERS, Stream ID: 5 Header: :method: POST Stream: HEADERS, Stream ID: 5 { "ietf-yangpush:notification": { "datastore-push:subscription-id": "my-sub", "eventTime": "2015-03-09T19:14:56.233Z", "datastore-push:datastore-contents": { "foo": { "bar": "some_string" } } } } Appendix D. Changes between revisions (To be removed by RFC editor prior to publication) v03 - v04 o Draft not fully synched to new version of subscribed-notifications yet. o References updated v02 - v03 o Event notification reframed to notification message. o Tweaks to wording/capitalization/format. v01 - v02 o Removed sections now redundant with [I-D.draft-ietf-netconf-subscribed-notifications] and [I-D.ietf-netconf-yang-push] such as: mechanisms for subscription maintenance, terminology definitions, stream discovery. Voit, et al. Expires August 4, 2018 [Page 14] Internet-Draft RESTCONF-Notif January 2018 o 3rd party subscriptions are out-of-scope. o SSE only used with RESTCONF and HTTP1.1 dynamic subscriptions o Timeframes for event tagging are self-defined. o Clean-up of wording, references to terminology, section numbers. v00 - v01 o Removed the ability for more than one subscription to go to a single HTTP2 stream. o Updated call flows. Extensively. o SSE only used with RESTCONF and HTTP1.1 dynamic subscriptions o HTTP is not used to determine that a receiver has gone silent and is not Receiving Event Notifications o Many clean-ups of wording and terminology Authors' Addresses Eric Voit Cisco Systems Email: evoit@cisco.com Ambika Prasad Tripathy Cisco Systems Email: ambtripa@cisco.com Einar Nilsen-Nygaard Cisco Systems Email: einarnn@cisco.com Alexander Clemm Huawei Email: ludwig@clemm.org Voit, et al. Expires August 4, 2018 [Page 15] Internet-Draft RESTCONF-Notif January 2018 Alberto Gonzalez Prieto VMWare Email: agonzalezpri@vmware.com Andy Bierman YumaWorks Email: andy@yumaworks.com Voit, et al. Expires August 4, 2018 [Page 16]