SIMPLE E. Burger Internet-Draft BEA Systems, Inc. Intended status: Standards Track H. Khartabil Expires: October 4, 2008 April 2, 2008 Instant Message Disposition Notification draft-ietf-simple-imdn-07 Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. 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." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on October 4, 2008. Abstract Instant Messaging (IM) refers to the transfer of messages between users in real-time. This document provides a mechanism whereby endpoints can request Instant Message Disposition Notifications (IMDN), including delivery, processing, and read notifications, for page-mode instant messages. The Common Profile for Instant Messaging (CPIM) data format specified in RFC 3862 is extended with new header fields that enable endpoints to request IMDNs. A new message format is also defined to convey IMDNs. This document also describes how SIP entities behave using this Burger & Khartabil Expires October 4, 2008 [Page 1] Internet-Draft IMDN April 2008 extension. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 2. Conventions . . . . . . . . . . . . . . . . . . . . . . . . . 4 3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5 4. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 5. Disposition Types . . . . . . . . . . . . . . . . . . . . . . 6 5.1. Delivery . . . . . . . . . . . . . . . . . . . . . . . . . 6 5.2. Processing . . . . . . . . . . . . . . . . . . . . . . . . 7 5.3. Read . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 6. New CPIM Header Fields . . . . . . . . . . . . . . . . . . . . 7 6.1. CPIM Header Field Namespace . . . . . . . . . . . . . . . 7 6.2. Disposition-Notification . . . . . . . . . . . . . . . . . 8 6.3. Message-ID . . . . . . . . . . . . . . . . . . . . . . . . 8 6.4. Original-To . . . . . . . . . . . . . . . . . . . . . . . 8 6.5. IMDN-Record-Route . . . . . . . . . . . . . . . . . . . . 8 6.6. IMDN-Route . . . . . . . . . . . . . . . . . . . . . . . . 9 7. Endpoint Behaviour . . . . . . . . . . . . . . . . . . . . . . 9 7.1. IM Sender . . . . . . . . . . . . . . . . . . . . . . . . 9 7.1.1. Constructing Instant Messages . . . . . . . . . . . . 9 7.1.2. Matching IMs with IMDNs . . . . . . . . . . . . . . . 10 7.1.3. Keeping State . . . . . . . . . . . . . . . . . . . . 11 7.1.4. Aggregation of IMDNs . . . . . . . . . . . . . . . . . 12 7.2. IM Recipient . . . . . . . . . . . . . . . . . . . . . . . 12 7.2.1. Constructing IMDNs . . . . . . . . . . . . . . . . . . 12 8. Intermediary Behaviour . . . . . . . . . . . . . . . . . . . . 15 8.1. Constructing Processing Notifications . . . . . . . . . . 15 8.2. Aggregation of IMDNs . . . . . . . . . . . . . . . . . . . 17 9. Identifying Messages . . . . . . . . . . . . . . . . . . . . . 19 10. Header Fields Formal Syntax . . . . . . . . . . . . . . . . . 19 11. IMDN Format . . . . . . . . . . . . . . . . . . . . . . . . . 20 11.1. Structure of XML-Encoded IMDN Payload . . . . . . . . . . 20 11.1.1. The Element . . . . . . . . . . . . . . . 21 11.1.2. The Element . . . . . . . . . . . . . . . . 21 11.1.3. The Element . . . . . . . . . . . . . 21 11.1.4. The Element . . . . . . . . . 21 11.1.5. The Element . . . . . . . . . . . . . . . . 21 11.1.6. The Element . . . . . . . . . . . . . . 21 11.1.7. The Element . . . . . . . . . . . . . . . . . 21 11.1.8. The Element . . . . . . . . . . . . . . . . . . 22 11.2. MIME Type for IMDN Payload . . . . . . . . . . . . . . . . 22 11.3. The RelaxNG Schema . . . . . . . . . . . . . . . . . . . . 22 12. Transporting Messages using SIP . . . . . . . . . . . . . . . 26 12.1. Endpoint Behaviour . . . . . . . . . . . . . . . . . . . . 26 12.1.1. Sending Requests . . . . . . . . . . . . . . . . . . . 26 Burger & Khartabil Expires October 4, 2008 [Page 2] Internet-Draft IMDN April 2008 12.1.2. Sending Responses . . . . . . . . . . . . . . . . . . 26 12.1.3. Receiving Requests . . . . . . . . . . . . . . . . . . 26 12.2. Intermediary Behaviour . . . . . . . . . . . . . . . . . . 27 13. Transporting Messages using MSRP . . . . . . . . . . . . . . . 28 14. Security Considerations . . . . . . . . . . . . . . . . . . . 29 14.1. Forgery . . . . . . . . . . . . . . . . . . . . . . . . . 31 14.2. Confidentiality . . . . . . . . . . . . . . . . . . . . . 31 14.3. Non-Repudiation . . . . . . . . . . . . . . . . . . . . . 32 15. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 32 15.1. message/imdn+xml MIME TYPE . . . . . . . . . . . . . . . . 32 15.2. URN Sub-Namespace Registration for urn:ietf:params:xml:ns:imdn . . . . . . . . . . . . . . . 33 15.3. Schema Registration . . . . . . . . . . . . . . . . . . . 33 15.4. Registration for urn:ietf:params:imdn . . . . . . . . . . 34 15.5. Message/CPIM Header Field Registration . . . . . . . . . . 34 15.6. Content-Disposition: notification . . . . . . . . . . . . 34 16. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 35 17. References . . . . . . . . . . . . . . . . . . . . . . . . . . 35 17.1. Normative References . . . . . . . . . . . . . . . . . . . 35 17.2. Informative References . . . . . . . . . . . . . . . . . . 35 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 36 Intellectual Property and Copyright Statements . . . . . . . . . . 37 Burger & Khartabil Expires October 4, 2008 [Page 3] Internet-Draft IMDN April 2008 1. Introduction In many user-to-user message exchange systems, message senders often wish to know if the human recipient actually received or read a message. Electronic Mail [RFC2821] deals with this situation with Message Delivery Notifications [RFC3798]. After the recipient views the message, her mail user agent generates a Message Delivery Notification, or MDN. The MDN is an e-mail that follows the format prescribed by RFC 3798 [RFC3798]. The fixed format ensures that an automaton can process the message. The common presence and instant messaging (CPIM) format, Message/CPIM [RFC3862], is a message format used to generate instant messages. The session initiation protocol, SIP [RFC3261], can carry instant messages generated using message/CPIM in SIP MESSAGE requests [RFC3428]. This document extends the Message/CPIM message format in much the same way Message Delivery Notifications extends Electronic Mail. This extension enables Instant Message Senders to request, create, and send Instant Message Disposition Notifications (IMDN). This mechanism works for page-mode as well as session mode instant messages. This document only discusses page-mode. Session mode is left for future standardisation efforts. IMDNs include positive delivery, negative delivery (i.e., a message did not get delivered successfully), read notifications (i.e., a message was rendered) as well as processed notifications. By using CPIM header fields, the IMDN request and delivery are abstracted outside the transport protocol allowing interoperability between different IM systems. 2. Conventions 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]. This document refers generically to the sender of a message in the masculine (he/him/his) and the recipient of the message in the feminine (she/her/hers). This convention is purely for convenience and makes no assumption about the gender of a message sender or recipient. Burger & Khartabil Expires October 4, 2008 [Page 4] Internet-Draft IMDN April 2008 3. Terminology o IM: An Instant Message generated using the Message/CPIM format. o IMDN: An Instant Message Disposition Notification generated using the Message/CPIM format that carries an IMDN XML document. o Message: an IM or an IMDN generated using the Message/CPIM format. o IM Sender: An endpoint (User Agent) generating and sending an IM. Also, the endpoint request IMDNs for an IM. Quite often, the IM Sender is the IMDN Recipient. However, that is not always the case, since the IMDN uses the From header in the CPIM message. That value is often the IM Sender's Address of Record (AOR). This address may in fact resolve to different User Agents. o IM Recipient: An endpoint (User Agent) that receives IMs. The IM Recipient, as the node that presumably renders the IM to the user, generates and sends delivery IMDNs to IMs, if requested by the IM Sender and allowed by the IM Recipient. o Endpoint: An IM Sender or an IM Recipient. o Intermediary: An entity in the network, most often an application server, including URI-List servers and Store-and-Forward servers, that forwards an IM to its final destination. Intermediaries also can generate and send processing IMDNs to IMs, if requested by the IM Sender and allowed by policy. o Gateway: An intermediary that translates between different IM systems that use different protocols. o IMDN Payload: An XML document carrying the disposition notification information. In this specification, it is of MIME type "message/imdn+xml". o Disposition type: the type of IMDN that can be requested. This specification defines three, namely "delivery", "processing" and "read" disposition types. o Transport Protocol Message: A SIP or other protocol message that contains an IM or IMDN. 4. Overview The diagram below shows the basic protocol flow. An IM Sender creates an IM, adds IMDN request information the IM Sender is interested in receiving and then sends the IM. At a certain point in time, the IM Recipient or an intermediary determines that the user or application has received, did not receive, read, or otherwise disposed the IM. The mechanism by which an IM Recipient determines its user has read an IM is beyond the scope of this document. At that point, the IM Recipient or intermediary automatically generates a notification message to the IM Sender. This notification message is the Instant Message Disposition Notification (IMDN). Burger & Khartabil Expires October 4, 2008 [Page 5] Internet-Draft IMDN April 2008 +--------------+ +--------------+ | IM Sender | | IM Recipient | |IMDN Recipient| | IMDN Sender | +--------------+ +--------------+ | | | | | 1. IM requesting IMDN | |-------------------------------------->| | | | | | 2. IMDN (disposition) | |<--------------------------------------| | | | | Basic IMDN Message Flow Note that the recipient of an IMDN, in some instances, may not be the IM Sender. This is specifically true for page-mode IMs where the Address of Record (AOR) of the IM Sender, that is present in the IM, resolves to a different location or user agent than the IM originated. This could happen, for example, if resolving the AOR results in forking the request to multiple user agents. For simplicity, the rest of this document assumes that the IM Sender and the IMDN Recipient are the same and therefore will refer to both as the IM Sender. 5. Disposition Types There are three broad categories of disposition states. They are delivery, processing, and read. 5.1. Delivery The delivery notification type indicates whether the IM has been delivered to the IM Recipient or not. The delivery notification type can have the following states: o "delivered" to indicate successful delivery. o "failed" to indicate failure in delivery. o "forbidden" indicate denial for the IM Sender to receive the requested IMDN. The IM Recipient can send the "forbidden" state, but usually it is an intermediary that sends the message if one configures it to do so. For example, it is possible the administrator has disallowed IMDNs. Burger & Khartabil Expires October 4, 2008 [Page 6] Internet-Draft IMDN April 2008 o "error" to indicate an error in determining the fate of an IM. 5.2. Processing The processing notification type indicates that an intermediary has processed an IM. The processing notification type can have the following states: o "processed" is a general state of the IM indicating that the intermediary has performed its task on the IM. o "stored" state indicates that the intermediary stored the IM for later delivery. o "forbidden" indicate denial for the IM Sender to receive the requested IMDN. The "forbidden" state is sent by an intermediary that is configured to do so. For example, the administrator has disallowed IMDNs. o "error" to indicate an error in determining the fate of an IM. 5.3. Read The read notification type indicates whether the IM Recipient rendered the IM to the user or not. The read notification type can have the following states: o "read" is a state indicating that the IM has been rendered to the user. o "forbidden" indicate denial, by the IM Recipient, for the IM Sender to receive the requested IMDN. o "error" to indicate an error in determining the fate of an IM. In addition to text, some IMs may contain audio, video, and still images. Therefore, the state "read" includes playing the audio or video file to the user. Since there is no positive acknowledgement from the user, one cannot determine _a priori_ the user actually read the IM. Thus, one cannot use the protocol described here as a non-repudiation service. 6. New CPIM Header Fields This specification extends the CPIM data format specified in RFC 3862 [RFC3862]. A new name space is created as well as a number of new CPIM header fields. 6.1. CPIM Header Field Namespace Per CPIM [RFC3862], this specification defines a new name space for the CPIM extension header fields defined in the following sections. The name space is: Burger & Khartabil Expires October 4, 2008 [Page 7] Internet-Draft IMDN April 2008 urn:ietf:params:imdn As per CPIM [RFC3862] requirements, the new header fields defined in the following sections are prepended, in CPIM messages, by a prefix assigned to the URN through the NS header field of the CPIM message. The remaining of this specification always assumes an NS header field like this one: NS: imdn . Of course, clients are free to use any prefix while servers and intermediaries must accept any legal name space prefix specification. 6.2. Disposition-Notification The IM Sender MUST include the Disposition-Notification header field to indicate the desire to receive IMDNs from the IM Recipient, for that specific IM. Section 10 defines the syntax. 6.3. Message-ID The IM Sender MUST include the Message-ID header field in the IM that he wishes to receive an IMDN on. The Message-ID contains a globally unique message identifier the IM Sender can use to correlate received IMDNs. When the IM Sender receives an IMDN, it can compare its value with the value of the element present in the IMDN payload. IMDNs also carry this header field. Note that since the IMDN is itself an IM, the Message-ID of the IMDN will be different than the Message-ID of the original IM. Section 10 defines the syntax. 6.4. Original-To An intermediary MAY insert an Original-To header field to the IM. The value of the Original-To field MUST be the address of the IM Receiver. The IM Recipient uses this header to indicate the original IM address in the IMDNs. The IM Recipient does this by populating the element in the IMDN. The intermediary MUST insert this header if the intermediary changes the CPIM To header field value. The header field MUST NOT appear more than once in an IM. The intermediary MUST NOT change this header field value if it is already present. Section 10 defines the syntax. 6.5. IMDN-Record-Route An intermediary MAY insert an IMDN-Record-Route header field to the IM. The value of the IMDN-Record-Route header field MUST be the address of the intermediary. Multiple IMDN-Record-Route header Burger & Khartabil Expires October 4, 2008 [Page 8] Internet-Draft IMDN April 2008 fields can appear in an IM. Section 10 defines the syntax. 6.6. IMDN-Route The IMDN-Route header field provides routing information by including one or more addresses where to route the IMDN. An intermediary that needs the IMDN to flow back through the same intermediary MUST add the IMDN-Record-Route header. When the IM Recipient creates the corresponding IMDN, the IM Recipient copies the IMDN-Record-Route headers into corresponding IMDN-Route header fields. Section 10 defines the syntax. 7. Endpoint Behaviour 7.1. IM Sender 7.1.1. Constructing Instant Messages An IM is constructed using CPIM Message Format defined in RFC 3862 [RFC3862]. 7.1.1.1. Adding a Message-ID Header Field If the IM sender requests the reception of IMDNs, the IM sender MUST include a Message-ID header field. The Message-ID field is populated with a value that is unique with at least 32 bits of randomness. This header field enables the IM Sender to match any IMDNs with their corresponding IMs. 7.1.1.2. Adding a DateTime Header Field Some devices are not able to retain state over long periods. For example, mobile devices may have memory limits or battery limits. These limits may mean these devices may not be able to, or may chose not to, keep sent messages for the purposes of correlating IMDNs with sent IMs. To make some use of IMDN in this case, we add a time stamp to the IM to indicate when the user sent the message. The IMDN returns this time stamp to enable the user to correlate the IM with the IMDN at the human level. We use the DateTime CPIM header field for this purpose. Thus, if the IM Sender would like an IMDN, the IM Sender MUST include the DateTime CPIM header field. 7.1.1.3. Adding a Disposition-Notification Header Field The Disposition-Notification conveys the type of disposition notification requested by the IM sender. There are three types of disposition notification: delivery, processing, and read. The Burger & Khartabil Expires October 4, 2008 [Page 9] Internet-Draft IMDN April 2008 delivery notification is further subdivided into failure and success delivery notifications. An IM Sender requests failure delivery notification by including a Disposition-Notification header field with value "negative-delivery". Similarly, a success notification is requested by including a Disposition-Notification header field with value "positive-delivery". The IM Send can request both types of delivery notifications for the same IM. The IM Sender can request a processing notification by including a Disposition-Notification header field with value "processing". The IM Sender can also request a read notification. The IM Sender MUST include a Disposition-Notification header field with the value "read" to request a read request. The absence of this header field or the presence of the header field with an empty value indicates that the IM Sender is not requesting any IMDNs. Disposition-Notification header field values are comma separated. The IM Sender MAY request more than one type of IMDN for a single IM. Future extensions may define other disposition notifications not defined in this document. Section 10 describes the formal syntax for the Disposition- Notification header field. The following is an example CPIM body of an IM where the IM Sender requests positive and negative delivery notifications, but neither read notification nor processing notifications: From: Alice To: Bob NS: imdn imdn.Message-ID: 34jk324j DateTime: 2006-04-04T12:16:49-05:00 imdn.Disposition-Notification: positive-delivery, negative-delivery Content-type: text/plain Content-length: 12 Hello World 7.1.2. Matching IMs with IMDNs An IM Sender matches an IMDN to an IM by matching the Message-ID header field value in the IM with the element value in the body of the IMDN. If the IM was delivered to multiple recipients, the IM Sender uses the element and the Burger & Khartabil Expires October 4, 2008 [Page 10] Internet-Draft IMDN April 2008 element in the XML body of the IMDN it received to determine if the IM was sent to multiple recipients and to identify the IM Recipient that sent the IMDN. An IM Sender can determine an IMDN is a disposition notification by noting the Content-Disposition in the IMDN is "notification". This does mean the IM Sender MUST understand the Content-Disposition MIME header in CPIM messages. 7.1.3. Keeping State This specification does not mandate the IM Sender to keep state for a sent IM. Once an IM Sender sends an IM containing an IMDN request, it MAY preserve the IM context, principally the Message-ID, and other user- identifiable information such as the IM subject or content, and date and time it was sent. Without preservation of the IM context, the IM Sender will not be able to correlate the IMDN with the IM it sent. The IM Sender may find it impossible to preserve IM state if it has limited resources or does not have non-volatile memory and then loses power. There is, however, the concept of "Sent Items" box in an application that stores sent IMs. This "Sent Items" box has the necessary information and may have a fancy user interface indicating the state of a sent IM. A unique Message-ID for this purpose proves to be useful. The length of time for items to remain in the "Sent Items" box is a user choice. The user is usually free to keep or delete items from the "Sent Items" box as she pleases or as the memory on the device reaches capacity. Clearly, if an IM Sender loses its sent items state, for example, the user deletes items from the "Send Items" box, the client may use a different display strategy in response to apparently unsolicited IMDNs. This specification also does not mandate an IM Sender to run any timers waiting for an IMDN. There are no time limits associated with when IMDNs may be received. IMDNs may legitimately never be received. Likewise, the recipient may take a long time to actually read the message, so the time between the sending of an IM and the generation and ultimate receipt of the IMDN may simply take a very long time. Some clients may choose to purge the state associated with the sent IM. This is the reason for adding the time stamp in the IM and having it returned in the IMDN. This gives the user some opportunity of remembering what Burger & Khartabil Expires October 4, 2008 [Page 11] Internet-Draft IMDN April 2008 IM was sent. For example if the IMDN indicates that the IM the user sent at 2 p.m. last Thursday was delivered, the user has a chance of remembering that they sent an IM at 2 p.m. last Thursday. 7.1.4. Aggregation of IMDNs An IM Sender may send an IM to multiple recipients in one Transport Protocol Message (typically using a URI-List server [I-D.ietf-sip-uri-list-message]) and request IMDNs. An IM Sender that requested IMDNs MUST be prepared to receive multiple aggregated or non-aggregated IMDNs. See Section 8.2 for details. 7.2. IM Recipient 7.2.1. Constructing IMDNs IM recipients examine the contents of the Disposition-Notification header field of the CPIM message to determine if the recipient needs to generate an IMDN for that IM. Disposition-Notification header fields of CPIM messages can include one or more values. IM recipients may need to generate zero, one, or more IMDNs for that IM, for example a delivery notification as well as a read notification. In this case, the IM Recipient MUST be able to construct multiple IMDNs per IM. An IM Recipient MUST NOT construct more than one IMDN per disposition type. That is, it must not generate a delivery notification indicating "delivered" then followed by a delivery notification indicating "failed" for the same IM. If the IM Sender requested only failure notifications and the IM was successfully delivered, then no IMDNs will be generated. If the IM recipient does not understand a value of the Disposition-Notification header field, the IM recipient ignores that value. The IM Recipient MUST NOT generate "processing" notifications. A Disposition-Notification header field MUST NOT appear in an IMDN since it is forbidden to request an IMDN for an IMDN. An IM Sender MUST ignore a delivery notification request in an IMDN if present. The IM Sender MUST NOT send an IMDN for an IMDN. An IMDN MUST contain a Message-ID header field. The same rules of uniqueness for the Message-ID header field that appears in an IM apply to an IMDN. The Message-ID header field in the IMDN is different and unrelated to the one in the IM. An IM may contain an IMDN-Record-Route header field (see Section 8 for details). If IMDN-Record-Route header fields appear in the IM, the IM Recipient constructing the IMDN MUST copy the contents of the IMDN-Record-Route header fields into IMDN-Route header fields in the Burger & Khartabil Expires October 4, 2008 [Page 12] Internet-Draft IMDN April 2008 IMDN and maintain the order. The IMDN is then sent to the URI in the top IMDN-Route header field. IMDN-Record-Route header fields do not make sense in an IMDN and therefore MUST NOT be placed in an IMDN. IMDN Recipients MUST ignore it if present. As stated in CPIM [RFC3862], CPIM messages may need to support MIME headers other than Content-type. IM Recipients MUST insert a Content-Disposition header field, set to the value "notification". This indicates to the IM Sender that the message is an IMDN to an IM it has earlier sent. 7.2.1.1. Constructing Delivery Notifications The IM Recipient constructs a delivery notification in a similar fashion as an IM, using a CPIM body [RFC3862] that carries a Disposition Notification XML document formatted according to the rules specified in Section 11. The MIME type of the Disposition Notification XML document is "message/imdn+xml". Section 10 defines the schema for an IMDN. An example CPIM body of IMDN looks like the following: From: Bob To: Alice NS: imdn imdn.Message-ID: d834jied93rf Content-type: message/imdn+xml Content-Disposition: notification Content-length: ... 34jk324j 2006-04-04T12:16:49-05:00 im:bob@example.com im:bob@example.com The IM was successfully Delivered Burger & Khartabil Expires October 4, 2008 [Page 13] Internet-Draft IMDN April 2008 7.2.1.2. Constructing Read Notifications The IM Recipient constructs a read notification in a similar fashion as the delivery notification. See Section 7.2.1.1 for details. Section 10 defines the schema for an IMDN. An example looks like the following: From: Bob To: Alice NS: imdn imdn.Message-ID: dfjkleriou432333 Content-type: message/imdn+xml Content-Disposition: notification Content-length: ... 34jk324j 2006-04-04T12:16:49-05:00 im:bob@example.com im:bob@example.com The IM has been read There are situations where the IM Recipient cannot determine if or when the IM has been read. The IM Recipient in this case generates a read notification with a value of "error" to indicate an internal error by the server. Note that the IM Recipient may choose to ignore any IMDN requests and not to send any IMDNs. An IM recipient may not wish to let a sender know she read, or did not read, a particular message. Likewise, she may not want anyone to know if she reads messages. This could be on a per-message, per- sender, or programmed policy choice. Burger & Khartabil Expires October 4, 2008 [Page 14] Internet-Draft IMDN April 2008 8. Intermediary Behaviour In this context, intermediaries are application servers (including URI-List servers and Store-and-Forward server) and gateways. A gateway is a server that translates between different IM systems that use different protocols. A URI-List server may change the IM Recipient address from its own to the address of the final recipient of that IM for every copy it makes that it sends to the list members (see [I-D.ietf-sip-uri-list-message] for details). In this case, if the IM Sender is requesting an IMDN, the intermediary SHOULD add an Original-To header field to the IM populating it with the address that was in the CPIM To header field before it was changed. That is, the intermediary populates the Original-To header field with the intermediary address. Of course, one may configure an intermediary to restrict it from re-writing or populating the Original-To field. An intermediary MUST NOT add an Original-To header field if one already exists. An intermediary MAY have an administrative configuration to not reveal the original Request-URI, and as such, MUST NOT add an Original-To header. An intermediary MAY choose to remain on the path of IMDNs for a specific IM. It can do so by adding a CPIM IMDN-Record-Route header field as the top IMDN-Record-Route header field and populating it with its own address. An intermediary that does not support this extension will obviously not add the IMDN-Record-Route header field. This allows IMDNs to traverse directly from the IM Recipient to the IM Sender even if the IM traversed an intermediary not supporting this extension. An intermediary receiving an IMDN checks the top IMDN-Route header field. If that header field carries the intermediary address, the intermediary removes that value and forwards the IMDN to the address indicated in the now top IMDN-Route header field. If no additional IMDN-Route header fields are present, the IMDN is forwarded to the address in the CPIM To header field. An intermediary MUST remove any information about the final recipients of a list if the list membership is not disclosed. The intermediary does that by removing the element and/or element from the body of the IMDN before forwarding it to the IM Sender. 8.1. Constructing Processing Notifications Intermediaries are the only entities that construct processing notifications. They do so only if the IM Sender has requested a Burger & Khartabil Expires October 4, 2008 [Page 15] Internet-Draft IMDN April 2008 "processing" notification by including a Disposition-Notification header field with value "processing". The intermediary can create and send "processing" notifications indicating that an IM has been processed or stored. The intermediary MUST NOT send more than one IMDN for the same disposition type. I.e., it must not send a "processing" notification indicating that an IM is being "processed" followed by another IMDN indicating that the same IM is "stored". An intermediary constructs a "processing" notification in a similar fashion as the delivery notification. See Section 7.2.1.1 for details. An example looks like the following: Content-type: Message/CPIM From: Bob To: Alice Content-type: message/imdn+xml Content-Disposition: notification Content-length: ... 34jk324j 2006-04-04T12:16:49-05:00 im:bob@example.com im:bob@example.com The IM has been processed There are situations where the intermediary cannot know the fate of an IM. The intermediary in this case generates a processing notification with a value of "error" to indicate so. Burger & Khartabil Expires October 4, 2008 [Page 16] Internet-Draft IMDN April 2008 8.2. Aggregation of IMDNs As previously described, URI-List servers are intermediaries. A URI-List server may choose to aggregate IMDNs using local policy for making such a decision or it may send individual IMDNs instead. When a URI-List server receives an IM and decides to aggregate IMDNs, it can wait for a configurable period of time or until all recipients have sent the IMDN, whichever comes first, before the URI-List server sends an aggregated IMDN. Note that some IMDNs, for example "read" notifications, may never come due to user settings. It is an administrator configuration and an implementation issue how long to wait before sending an aggregated IMDN and before a URI-List server removes state for that IM. A URI-List server MAY choose to send multiple aggregated IMDNs. A timer can be started and when it fires, the URI-List server can aggregate whatever IMDNs it has so far for that IM, send the aggregated IMDN and restart the timer for the next batch. This is needed for scenarios where the IM Sender has requested more than one IMDN for a specific IM, for example, delivery notifications as well as read notifications, or when the URI-List server is short on resources and chooses to prioritise forwarding IMs over IMDNs. A second timer can be running and when it fires, the state of the IM is deleted. In this case, the URI-List server consumes any IMDNs that might arrive after that time. Please note the references to timers in the above paragraphs are not normative and are only present to help describe one way one might implement aggregation. A URI-List server MAY aggregate IMDNs for the case where the list membership information is not disclosed. There may be scenarios where the URI-List server starts sending aggregated IMDNs and switch to individual ones or visa versa. A timer firing so often may in fact have that effect. The aggregated IMDN is constructed using the multipart/mixed MIME type and including all the received IMDNs as message/imdn+xml as individual payloads. Below is an example of aggregated IMDNs. From: Bob To: Alice NS: imdn imdn.Message-ID: d834jied93rf Burger & Khartabil Expires October 4, 2008 [Page 17] Internet-Draft IMDN April 2008 Content-type: multipart/mixed; boundary="imdn-boundary" Content-Disposition: notification Content-length: ... --imdn-boundary Content-type: message/imdn+xml 34jk324j 2006-04-04T12:16:49-05:00 im:bob@example.com im:bob@example.com The IM was successfully Delivered --imdn-boundary Content-type: message/imdn+xml 34jk324j 2006-04-04T12:16:49-05:00 im:bob@example.com im:bob@example.com The IM was successfully Delivered --imdn-boundary Burger & Khartabil Expires October 4, 2008 [Page 18] Internet-Draft IMDN April 2008 9. Identifying Messages Messages are typically carried in a transport protocol like SIP [RFC3261]. If the payload carried by the transport protocol does not contain any parts of type Message/CPIM then the message is an IM. If the payload contains any parts of type Message/CPIM, and none of those parts contains a payload that is of type "message/imdn+xml", the message is an IM. It is not valid to attempt to carry both an IM and an IMDN in a multipart payload in a single transport protocol message. A message is identified as a delivery notification by examining its contents. The message is a delivery notification if the Content-type header field present has a value of "message/imdn+xml", the Content- Disposition header field has a value of "notification", and the element in that xml body has a sub-element . A message is identified as a processing notification or read notification in a similar fashion as a delivery notification. The difference is that the element in that xml body has a sub-element of and respectively. 10. Header Fields Formal Syntax The following syntax specification uses the message header field syntax as described in Section 3 of RFC 3862 [RFC3862]. Header field syntax is described without a name space qualification. Following the rules in RFC 3862 [RFC3862], header field names and other text are case sensitive and MUST be used as given, using exactly the indicated upper case and lower case letters. Burger & Khartabil Expires October 4, 2008 [Page 19] Internet-Draft IMDN April 2008 Disposition-Notification = "Disposition-Notification" ": " [(notify-req *(COMMA notify-req))] notify-req = ("negative-delivery" / "positive-delivery" / "processing" / "read" / Token) *(SEMI disp-notif-params) disp-notify-params = generic-param Message-ID = "Message-ID" ": " Token Original-To = "Original-To" ": " [ Formal-name ] "<" URI ">" IMDN-Record-Route = "IMDN-Record-Route" ": " [ Formal-name ] "<" URI ">" IMDN-Route = "IMDN-Route" ": " [ Formal-name ] "<" URI ">" 11. IMDN Format 11.1. Structure of XML-Encoded IMDN Payload An IMDN Payload is an XML document [XML] that MUST be well formed and MUST be valid according to schemas, including extension schemas, available to the validater and applicable to the XML document. The IMDN Payload MUST be based on XML 1.0 and MUST be encoded using UTF-8. The name space identifier for elements defined by this specification is a URN [URN], using the name space identifier 'ietf' defined by [URN_NS] and extended by [IANA]. This urn is: urn:ietf:params:xml:ns:imdn. This name space declaration indicates the name space on which the IMDN is based. The root element is . The element has sub-elements, namely , , , , , , , and . Those elements are described in details in the following sections. and can be extended in the future to include new sub-elements not defined in this document, as described in Section 15.3. Burger & Khartabil Expires October 4, 2008 [Page 20] Internet-Draft IMDN April 2008 11.1.1. The Element The element is mandatory according to the XML schema and carries the message id that appeared in the Message-ID header field of the IM. 11.1.2. The Element The element is mandatory and carries the date and time the IM was sent (not the IMDN). This information is obtained from the DateTime header field of the IM. 11.1.3. The Element The element is optional and carries the URI of the final recipient. This information is obtained from the CPIM To header field of the IM. 11.1.4. The Element The element is optional and carries the URI of the original recipient. It MUST be present if the IM carried the Original-To header field. This information is obtained from the Original-To header field of the IM. 11.1.5. The Element The element is optional and carries the text that was in the Subject header field, if any. This allows for a human level correlation between an IM and an IMDN. 11.1.6. The Element The element is mandatory and carries the disposition type that the IM Sender requested and is being reported. It can carry one of the sub-elements , , or any other future extension. 11.1.7. The Element The element is mandatory and carries the result of the disposition request in the element. For disposition type , it can carry one of the sub-elements , , or . For disposition type , it can carry one of the sub-elements , or . For disposition type , it can carry one of the sub- elements , , or . means the disposition was denied. means internal server Burger & Khartabil Expires October 4, 2008 [Page 21] Internet-Draft IMDN April 2008 error. It can also carry any other future extension. 11.1.8. The Element The element is optional and carries a human readable text. It has the "lang" attribute that indicates the language the text is written in. 11.2. MIME Type for IMDN Payload The MIME type for the IMDN Payload is "message/imdn+xml". The IMDN MUST identify the payload as MIME type "message/imdn+xml" in the Content-type header field. 11.3. The RelaxNG Schema Burger & Khartabil Expires October 4, 2008 [Page 22] Internet-Draft IMDN April 2008 Burger & Khartabil Expires October 4, 2008 [Page 23] Internet-Draft IMDN April 2008 Burger & Khartabil Expires October 4, 2008 [Page 24] Internet-Draft IMDN April 2008 lang Burger & Khartabil Expires October 4, 2008 [Page 25] Internet-Draft IMDN April 2008 12. Transporting Messages using SIP 12.1. Endpoint Behaviour 12.1.1. Sending Requests The IM Sender constructs a SIP MESSAGE request using RFC 3428 [RFC3428]. The Content-type header field indicates the MIME type of the request payload. When using this extension, the Content-type header field MUST be of MIME type "message/cpim" [RFC3862] for both IMs and IMDNs. The IM Sender constructs the payload according to Section 7. The IM Sender constructs a SIP MESSAGE request to multiple recipients in a similar manner as a SIP MESSAGE request to a single recipient. Multiple-Recipient MESSAGE Requests in SIP [I-D.ietf-sip-uri-list-message] describes the differences. IM senders can remain anonymous. For example, the sender can set the SIP From header field of the SIP message to an anonymous URI. As there is no return address, anonymous IM senders SHOULD NOT request disposition notifications. An IM Recipient can ignore such request if the IM Sender is anonymous. 12.1.2. Sending Responses An endpoint receiving a SIP MESSAGE request constructs a SIP response according to RFC 3428 [RFC3428]. Of course, an endpoint will send a SIP response to the MESSAGE request regardless of the type of message (IM or IMDN) is has received, or the disposition type it has been asked for. 12.1.3. Receiving Requests 12.1.3.1. Instant Message A SIP MESSAGE request is identified as an IM by examining its contents according to Section 9. If an IM Recipient received a SIP MESSAGE request that is an IM that requested a positive-delivery notification, and that IM Recipient has constructed and sent a SIP 2xx class response, it MAY generate a positive-delivery notification after making sure that the IM has been delivered to the user or application. A gateway, for example, can generate a 2xx response before the final recipient received the IM. The IM Recipient constructs a positive-delivery notification according to Section 7.2.1.1. The IM Recipient places the message as the payload in a SIP MESSAGE request. Burger & Khartabil Expires October 4, 2008 [Page 26] Internet-Draft IMDN April 2008 If an IM Recipient received a SIP MESSAGE request that is an IM that requested a negative-delivery, and that IM Recipient has constructed and sent a 2xx class response, it SHOULD generate a negative-delivery notification if it learnt that the final recipient or application did not receive the IM (a gateway, for example, can generate a 2xx response before it has an error response from downstream or before any internal timers fire waiting for a response). The negative- delivery notification is constructed according to Section 7.2.1.1. The message is then placed as the payload in a SIP MESSAGE request. If an IM Recipient received a SIP MESSAGE request that is an IM that requested a negative-delivery notification, and the IM Recipient has constructed and sent an non-2xx final response, it MUST NOT generate a negative-delivery notification. If an IM Recipient received a SIP MESSAGE request that is an IM that requested a read notification, and that IM Recipient has constructed and sent a SIP 2xx class response, it MAY generate a read notification after making sure that the IM has been presented to the user or application. It is outside the scope of this document how such determination can be made. Note that the option to send a read notification or not can be left to the user. An application may allow a user to configure such choice. The IM Recipient constructs the read notification according to Section 7.2.1.2. The IM Recipient places the message as the payload in a SIP MESSAGE request. For IMDNs, the IM Recipient populates the SIP Request-URI and the SIP To header field using the address that appeared in the SIP From header field in the IM. 12.1.3.2. Delivery Notification A SIP MESSAGE request is identified as delivery notification by examining its contents according to Section 9. 12.1.3.3. Read Notification A SIP MESSAGE request is identified as read notification by examining its contents according to Section 9. 12.2. Intermediary Behaviour In this context, intermediaries include application servers, including URI-List servers, Store-and-Forward servers, and gateways. SIP Proxies MUST NOT generate IMDNs but MUST forward them like any other SIP request. Intermediaries forward a SIP MESSAGE request to multiple recipients Burger & Khartabil Expires October 4, 2008 [Page 27] Internet-Draft IMDN April 2008 according to [I-D.ietf-sip-uri-list-message]. If an intermediary receives an IM, the intermediary examines the body. If the body is of type "message/cpim" the intermediary then looks for a Disposition-Notification CPIM header field in the message. If the Disposition-Notification CPIM header field has either the value "positive-delivery" or "negative-delivery", and, in processing the IM, the intermediary generates a SIP 2xx class response to the MESSAGE request, then the intermediary performs the following actions. If the Disposition-Notification header field contains a value of "positive-delivery", the intermediary MUST NOT generate a delivery notification if it receives a SIP 2xx class response for the sent IM. Just because a downstream entity received a MESSAGE request does not mean the message was relayed to its ultimate destination or was delivered. Thus, the intermediary cannot say delivery occurred just because it received a 2xx response. If the Disposition-Notification header field contains a value of "negative-delivery", the intermediary SHOULD generate a delivery notification if it receives a SIP 4xx, 5xx or 6xx class final response for the sent IM. If it has received a SIP 2xx class response followed by a negative-delivery notification, the intermediary forwards that negative-delivery notification or aggregates it. If the Disposition-Notification header field contains a value of "processing", the intermediary MAY generate a processing notification after it has forwarded or stored the IM. The rest of the procedures in Section 8.1 apply. The procedure for generating such IMDN is the same as that of an IM Recipient (Section 7.2.1.1). The element of the XML body is populated with the URI of the IM Recipient. If an intermediary receives a SIP MESSAGE request carrying a positive delivery notification or a read notification, it forwards it using the rules in Section 8. 13. Transporting Messages using MSRP MSRP already provides a built-in mechanism to supply positive and negative delivery reports. These reports do not provide built-in Read or Processing notifications. However, these notifications in Burger & Khartabil Expires October 4, 2008 [Page 28] Internet-Draft IMDN April 2008 session mode are not as useful as they are for page-mode. This is because the base use case for MSRP is that the recipient user agent immediately renders SEND requests sequentially, providing the session experience. This is unlike page-mode requests where a user has to actively read the message. That is, they need to click on a button, open a message, and so on to read the message. If new requirements arise in the future determining the need for IMDN in MSRP, new specifications can be drafted. 14. Security Considerations IMDNs provide a fine-grained view of the activity of the IM Recipient and thus deserves particularly careful confidentiality protection so that only the intended recipient of the IMDN will receive the IMDN. In most cases, the intended recipient of the IMDN is the IM Sender. Since the IM transport protocol carries the IMDN, all security considerations of the underlying IM protocol also apply to the IMDNs. The threats in the IMDN system, over and beyond the threats inherent to IM include the following: o A malicious endpoint attempts to send messages to a user that would normally not wish to receive messages from that endpoint by convincing the IMDN system to "bounce" an IMDN from an unsuspecting endpoint to the user. o A malicious endpoint attempts to flood an IM Sender with IMDNs by convincing a URI-List server to send IMDNs to an unsuspecting IM Sender. o A malicious node in the network that attempts to modify an IMDN from an IM Recipient. o A malicious intermediary attempts to forward an IMDN from an IM Recipient to the IM Sender, where the IM Recipient would not normally forward the IMDN to that IM Sender if the IM Recipient knew the identity of the IM Sender. o A malicious endpoint that attempts to discover for a Request-URI of an endpoint beyond an intermediary, where the endpoint would normally wish to keep its identity private from the malicious endpoint. o A malicious node in the network that attempts to eavesdrop on IMDN traffic to, for example, learn Request-URI or traffic pattern information. o A malicious node in the network attempts to stage a denial of service attack on an intermediary by requesting a large list expansion. The protocol cannot protect against attacks that include the Burger & Khartabil Expires October 4, 2008 [Page 29] Internet-Draft IMDN April 2008 following: o A malicious intermediary directly revealing the identity of a downstream endpoint that would not normally wish its identity revealed. Keeping such information private is an intermediary implementation issue. o A malicious IM Recipient that alters the time of the IMDN. There is no protocol mechanism for ensuring that the IM Recipient does not lie about the time or purposely holds an IMDN for transmission to make it appear that the user read an IM later than they actually did. o A deletion attack on an IMDN. This is a trade-off between privacy and security. The privacy considerations allow the IM Recipient to silently ignore an IMDN request. Any mechanism that would reliably indicate that a malicious node deleted an IM Recipient's IMDN would also serve the purpose of detecting an IM Recipient that chose not to issue an IMDN. To combat eavesdropping, modification, and man-in-the-middle attacks, we require some level of authentication and integrity protections. That said, there are circumstances where strong integrity would be overkill. The presumption is the IM Sender has and sets the expectation for the level of protection. The procedures for integrity protection are as follows. o If the IM Recipient has a certificate, it MUST sign the IMDN. Signing the IMDN provides integrity protection. While an intermediary can replace the IMDN body, the IM Sender (the recipient of the IMDN) can validate the signature and note the IMDN does not come directly from the IM Receiver. This is not a problem if the IM Sender trusts the intermediary. Likewise, an IMDN in response to a signed IM without a signature indicates something bad might have happened. o If the IM is encrypted, the IM Recipient or intermediary MUST encrypt the IMDN body, as an attacker may attempt to discern the user's activity profile and identity from sniffing IMDNs on the network. o The two above rules are cumulative. The IM Recipient or intermediary MUST be capable of accessing the IM Sender's public certificate in order to verify the signature in the IM. CPIM security considerations [RFC3862] apply here, as this is an extension of CPIM. In order to make the IMDN mechanism independent of the transport protocol, the Work Group made the design choice of putting routing information into the IMDN application layer payload. One consequence of this choice is it eliminates the possibility of having end-to-end encryption. An attacker can mount a distributed denial of service attack on a Burger & Khartabil Expires October 4, 2008 [Page 30] Internet-Draft IMDN April 2008 node by sending lots of IMs to the node with IMDN requests. Note that this is the same problem as there is without IMDN; IMDN simply linearly increases the load on the node under attack. One can mitigate, but not eliminate this threat by the endpoint immediately ignoring requests that are not authenticated. Likewise, an attacker can mount a denial of service attack on an intermediary by asking the intermediary to explode a large list. The following security considerations apply when using IMDNs: 14.1. Forgery IMs can be forged. To protect against that, an IM can be signed. An intermediary that receives a signed message and needs to modify any part of it that is included in the signature (like adding an Original-To header field to the CPIM header fields), MUST consume the IM and create a new copy of it that the intermediary signs itself. IMDNs may be forged as easily as ordinary IMs. Endpoints and intermediaries that wish to make automatic use of IMDNs should take appropriate precautions to minimize the potential damage from denial- of-service attacks. Security threats related to forged IMDNs include the sending of a falsified IMDN when the indicated disposition of the IM has not actually occurred. For example, read notification could be forged to indicate that an IM Recipient has read the IM. Unsolicited IMDNs is also another form of forgery. 14.2. Confidentiality There may be cases where an IM Recipient does not wish to reveal the information that he has received or in fact read the IM. In this situation, it is acceptable for the IM Recipient to silently ignore requests for an IMDN. It is strongly RECOMMENDED that the IM Recipient obtain the user's consent before sending an IMDN. Circumstances where the IM Recipient does not ask for the user's consent include IM systems that, for regulatory reasons, are required to issue an IMDN, such as in the health care field or financial community. An IM Recipient can obtain such consent by a prompt or dialog box on a per-IM basis, globally through the user's setting of a preference, or other, user-configurable mechanism. The user might also indicate globally that IMDNs are never to be sent or that a "forbidden" IMDN status is always sent in response to a request for an IMDN. There are situations where a user sends an IM and requests IMDNs to a list whose member information is not disclosed. In this situation, Burger & Khartabil Expires October 4, 2008 [Page 31] Internet-Draft IMDN April 2008 the user will learn of the list members. Therefore, in this case, the URI-List server MUST remove any information about list members. If the number of members in the list is also not disclosed, the URL- List server MUST only deliver one aggregated IMDN. Alternatively, the URI-list server MAY reject the IM. It is possible for a list server to not understand IMDN. IM Recipients may note the To is a list name and not the IM Recipient's name. In this case, the IM Recipient can take the appropriate action if it wishes to keep its identity private. An unencrypted IMDN could reveal confidential information about an encrypted IM. The same level of security applied to an IM MUST be applied to its IMDNs. For example, if an IM is signed and encrypted, the IMDN must be signed and encrypted. 14.3. Non-Repudiation IMDNs cannot be relied on as a guarantee that an IM was or was not seen by the user. Even if IMDNs are not actively forged, they may be lost in transit. Moreover, the IM Recipient may bypass the IMDN issuing mechanism through policy or manipulation of their User Agent Server. 15. IANA Considerations 15.1. message/imdn+xml MIME TYPE This document registers a new MIME type "message/imdn+xml", and registers a new XML name space. This specification follows the guidelines of RFC 3023 [RFC3023]. MIME media type: message MIME subtype name: imdn+xml Mandatory parameters: none Optional parameters: Same as charset parameter application/xml as specified in RFC 3023 [RFC3023]. Encoding considerations: Same as encoding considerations of application/xml as specified in RFC 3023 [RFC3023]. Security considerations: See section 10 of RFC 3023 [RFC3023] and Section 14 of this document. Burger & Khartabil Expires October 4, 2008 [Page 32] Internet-Draft IMDN April 2008 Interoperability considerations: none. Published specification: This document. Applications which use this media type: This document type is used to support CPIM based instant messaging. Additional information: None Magic number: None File extension: .cl or .xml Macintosh file type code: "TEXT" Personal and email address for further information: Hisham Khartabil (hisham.khartabil@gmail.com) Intended Usage: COMMON Author/change controller: The IETF . 15.2. URN Sub-Namespace Registration for urn:ietf:params:xml:ns:imdn This section registers a new XML name space, as per guidelines in the IETF XML Registry [IANA]. URI: The URI for this name space is urn:ietf:params:xml:ns:imdn. Registrant Contact: IETF, SIMPLE working group, Hisham Khartabil (hisham.khartabil@gmail.com) . 15.3. Schema Registration This section registers a new XML schema per the procedures in [IANA]. Extensions MUST be standards track documents. URI: urn:ietf:params:xml:ns:imdn Registrant Contact: IETF, SIMPLE working group, Hisham Khartabil (hisham.khartabil@gmail.com) The XML for this schema can be found as the sole content of Section 11.3. Burger & Khartabil Expires October 4, 2008 [Page 33] Internet-Draft IMDN April 2008 15.4. Registration for urn:ietf:params:imdn Registry name: imdn Specification: RFC XXXX. Additional values may be defined by standards track RFCs that update or obsolete RFC XXXX (Specification Required). Repository: http://www.iana.org/assignments/imdn Index value: The index value is a CPIM message IMDN header name, which may consist of a sequence from a restricted set of US-ASCII characters, as defined above. URN Formation: The URI for a header is formed from its name by: a) replacing any non-URN characters (as defined by RFC 2141[URN]) with the corresponding '%hh' escape sequence (per RFC 3986 [RFC2396]); and b) prepending the resulting string with 'urn:ietf:params:imdn:'. Thus, the URI corresponding to the CPIM message IMDN header 'Disposition-Notification:' would be 'urn:ietf:params:imdn:Disposition-Notification'. 15.5. Message/CPIM Header Field Registration This document registers the following message/cpim header fields in the imdn fields registry: Disposition-Notification - [RFCXXXX] Message-ID - [RFCXXXX] Original-To - [RFCXXXX] IMDN-Record-Route - [RFCXXXX] IMDN-Route - [RFCXXXX] 15.6. Content-Disposition: notification This document registers one new Content-Disposition header field "disposition-types": notification. The authors request that this value be recorded in the IANA registry for Content-Dispositions. Descriptions of this "disposition-types", including motivation and examples, are given in Section 7.2.1.1 and Section 9. Burger & Khartabil Expires October 4, 2008 [Page 34] Internet-Draft IMDN April 2008 Short descriptions suitable for the IANA registry are: notification the body of the message is a notification according to an earlier request for a disposition notification to an instant message 16. Acknowledgements The authors would like to thank Paul Kyzivat, Ben Campbell, Adam Roach, Gonzalo Camarillo, Sean Olson, Eva Leppanen, Miguel Garcia, Eric McMurry, Jari Urpalainen, Jon Peterson, and Robert Sparks for their comments and support. In addition, we would like to thank the Gen-Art reviewer extrodinaire, Spencer Dawkins. 17. References 17.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC3862] Klyne, G. and D. Atkins, "Common Presence and Instant Messaging (CPIM): Message Format", RFC 3862, August 2004. [IANA] Mealling, M., "The IETF XML Registry", RFC 3688, January 2004. [URN] Moats, R., "The URN Syntax", RFC 2141, May 1997. [RFC3023] Murata, M., "XML Media Types", RFC 3023, March 1997. [XML] Bray, T., "Extensible Markup Language (XML) 1.0 (Second Edition)", W3C CR CR-xml11-20011006, October 2000. [RFC2396] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform Resource Identifier (URI): Generic Syntax", STD 66, RFC 3986, January 2005. 17.2. Informative References [RFC3261] Rosenberg et al., J., Shulzrinne, H., Camarillo, G., Johnston, A., Peterson, J., Sparks, R., Handley, M., and E. Schooler, "SIP: Session Initiation Protocol", RFC 3261, June 2002. [RFC3428] Campbell, B., "SIP Extension for Instant Messaging", Burger & Khartabil Expires October 4, 2008 [Page 35] Internet-Draft IMDN April 2008 RFC 3428, December 2002. [RFC2821] Klensin, J., "Simple Mail Transfer Protocol", RFC 2821, April 2001. [RFC3798] Hansen, T. and G. Vaudreuil, "Message Disposition Notification", RFC 3798, May 2004. [URN_NS] Moats, R., "The URN Namespace for IETF Documents", RFC 2648, August 1999. [I-D.ietf-sip-uri-list-message] Garcia-Martin, M. and G. Camarillo, "Multiple-Recipient MESSAGE Requests in the Session Initiation Protocol (SIP)", draft-ietf-sip-uri-list-message-03 (work in progress), December 2007. Authors' Addresses Eric Burger BEA Systems, Inc. 4 Van de Graaff Dr. Burlington, MA 01803 USA Phone: +1 781 993 7437 Fax: +1 603 457 5933 Email: eric.burger@bea.com Hisham Khartabil Melbourne Australia Phone: +61 416 108 890 Email: hisham.khartabil@gmail.com Burger & Khartabil Expires October 4, 2008 [Page 36] Internet-Draft IMDN April 2008 Full Copyright Statement Copyright (C) The IETF Trust (2008). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. This document and the information contained herein are provided on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Intellectual Property The IETF takes no position regarding the validity or scope of any Intellectual Property Rights or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; nor does it represent that it has made any independent effort to identify any such rights. Information on the procedures with respect to rights in RFC documents can be found in BCP 78 and BCP 79. Copies of IPR disclosures made to the IETF Secretariat and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementers or users of this specification can be obtained from the IETF on-line IPR repository at http://www.ietf.org/ipr. The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights that may cover technology that may be required to implement this standard. Please address the information to the IETF at ietf-ipr@ietf.org. Burger & Khartabil Expires October 4, 2008 [Page 37]