Sieve Working Group P. Saint-Andre Internet-Draft XSF Expires: September 2, 2007 A. Melnikov Isode Limited March 1, 2007 Sieve Notification Mechanism: xmpp draft-ietf-sieve-notify-xmpp-04 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 September 2, 2007. Copyright Notice Copyright (C) The IETF Trust (2007). Abstract This document describes a profile of the Sieve extension for notifications, to allow notifications to be sent over the Extensible Messaging and Presence Protocol (XMPP), also known as Jabber. Saint-Andre & Melnikov Expires September 2, 2007 [Page 1] Internet-Draft SIEVE-XMPP March 2007 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.1. Overview . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Definition . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2.1. Notify parameter "method" . . . . . . . . . . . . . . . . . 3 2.2. Notify tag ":from" . . . . . . . . . . . . . . . . . . . . 4 2.3. Notify tag ":options" . . . . . . . . . . . . . . . . . . . 4 2.4. Notify tag ":importance" . . . . . . . . . . . . . . . . . 4 2.5. Notify tag ":message" . . . . . . . . . . . . . . . . . . . 4 3. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 4. Requirements Conformance . . . . . . . . . . . . . . . . . . . 5 5. Internationalization Considerations . . . . . . . . . . . . . . 6 6. Security Considerations . . . . . . . . . . . . . . . . . . . . 7 7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 7 7.1. Normative References . . . . . . . . . . . . . . . . . . . 7 7.2. Informative References . . . . . . . . . . . . . . . . . . 8 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 8 Intellectual Property and Copyright Statements . . . . . . . . . . 9 Saint-Andre & Melnikov Expires September 2, 2007 [Page 2] Internet-Draft SIEVE-XMPP March 2007 1. Introduction 1.1. Overview The [NOTIFY] extension to the [SIEVE] mail filtering language is a framework for providing notifications by employing URIs to specify the notification mechanism. This document defines how xmpp URIs (see [XMPP-URI]) are used to generate notifications via the Extensible Messaging and Presence Protocol (see [XMPP]), which is widely implemented in Jabber instant messaging technologies. 1.2. Terminology This document inherits terminology from [NOTIFY], [SIEVE], and [XMPP]. The capitalized key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [TERMS]. 2. Definition The xmpp mechanism results in the sending of an XMPP message to notify a recipient about an email message. The general XMPP syntax is as follows: o The notification MUST be an XMPP stanza. o The value of the XMPP 'type' attribute MUST be 'headline' or 'normal'. o The value of the XMPP 'from' attribute MUST be the XMPP address of the notification service. o The XMPP stanza MAY include a child element whose value is some configurable text indicating that the message is a Sieve notification. o The notification SHOULD include a URL for the recipient to use as a hint in locating the message, encapsulated as the XML character data of a child element of an element qualified by the 'jabber:x:oob' namespace as specified in [OOB]. The recommended mapping of the Sieve notify action into XMPP syntax is described in the following sections. 2.1. Notify parameter "method" The "method" parameter MUST be a URI that conforms to the xmpp URI scheme (as specified in [XMPP-URI]) and that identifies an XMPP Saint-Andre & Melnikov Expires September 2, 2007 [Page 3] Internet-Draft SIEVE-XMPP March 2007 account associated with the email inbox. The URI MAY include the resource identifier portion of an XMPP address but SHOULD NOT include an authority component, query component, or fragment identifier component. The processing application MUST extract an XMPP address from the URI in accordance with the processing rules specified in [XMPP-URI]. The resulting XMPP address MUST be encapsulated in XMPP syntax as the value of the XMPP 'to' attribute. 2.2. Notify tag ":from" The ":from" tag has no special meaning for this notification mechanism, and this specification puts no restriction on its use. As noted, the value of the XMPP 'from' attribute specified in the XMPP notification message MUST be the XMPP address of the notification service itself. The value of the ":from" tag MAY be transformed into XMPP syntax; if so, it SHOULD be encapsulated as the value of an XMPP [SHIM] header named "Reply-To". 2.3. Notify tag ":options" The ":options" tag has no special meaning for this notification mechanism. Any handling of this tag is the responsibility of an implementation. 2.4. Notify tag ":importance" The ":importance" tag has no special meaning for this notification mechanism, and this specification puts no restriction on its use. The value of the ":importance" tag MAY be transformed into XMPP syntax (in addition to or instead of including in the default message); if so, it MUST be encapsulated as the value of an XMPP [SHIM] header named "Urgency", and the XML character of that header MUST be "high" if the value of the ":importance" tag is "1", "medium" if the value of the ":importance" tag is "2", or "low" if the value of the ":importance" tag is "3". 2.5. Notify tag ":message" If included, the ":message" tag SHOULD be transformed into the XML character data of an XMPP element. If not included, the rule specified in [NOTIFY] SHOULD be followed, as shown in the examples below. 3. Examples In the following examples, the sender of the email has an address of , the entity to be notified has an XMPP Saint-Andre & Melnikov Expires September 2, 2007 [Page 4] Internet-Draft SIEVE-XMPP March 2007 address of , and the notification service has an XMPP address . The following is a basic Sieve notify action with only a method: notify "xmpp:romeo@example.com" The resulting XMPP stanza might be as follows: A Sieve instant notification! <juliet@example.org> Wherefore art thou? The following is a more advanced Sieve notify action with a method, importance, subject, and message, as well as a URL pointing to the message: notify :importance "1" :message "Contact Juliet immediately!" "xmpp:romeo@example.com?message;subject=SIEVE" The resulting XMPP stanza might be as follows: SIEVE Contact Juliet immediately!
high
 imap://romeo@example.com/INBOX;UIDVALIDITY=385759045/;UID=20 4. Requirements Conformance Section 3.8 of [NOTIFY] specifies a set of requirements for Sieve notification methods. The conformance of the xmpp notification mechanism is provided here. Saint-Andre & Melnikov Expires September 2, 2007 [Page 5] Internet-Draft SIEVE-XMPP March 2007 1. An implementation of the xmpp notification method MAY modify the final notification text (e.g., limit the length to a configurable number of characters, such as 200). Modification of characters themselves should not be necessary, since XMPP character data is encoded in [UTF-8]. 2. An implementation MAY ignore parameters specified in the ":from", ":options", ":importance", and ":message" tags. 3. The xmpp notification method does not recommend the default message to be used if the ":message" argument is not specified. 4. A notification sent via the xmpp notification method MAY include a timestamp in the textual message. 5. The value of the XMPP 'from' attribute MUST be the XMPP address of the xmpp notification service. The value of the Sieve ":from" tag MAY be transformed into the value of an XMPP [SHIM] header named "Reply-To". 6. An implementation MUST NOT include any other extraneous information not specified in parameters to the notify action. 7. In accordance with [XMPP-URI], an implementation MUST ignore any URI action or parameter it does not understand (i.e., the URI MUST be processed as if the action or parameter were not present). It is RECOMMENDED to support the "message" action and the associated "body" and "subject" parameters, which parameters SHOULD be mapped to the XMPP and child elements of the XMPP stanza type, respectively. 8. In response to a notify_method_capability test for the "online" notification-capability, an implementation SHOULD return a value of "yes" if it has knowledge of an active presence session for the specified notification-uri and a value of "no" if it does not have such knowledge. 9. An implementation SHOULD NOT attempt to retry delivery of a notification if it receives an XMPP error of type "auth" or "cancel", MAY attempt to retry delivery if it receives an XMPP error of type "wait", and MAY attempt to retry delivery if it receives an XMPP error of "modify" but only if it makes appropriate modifications to the notification (see [XMPP]); in any case the number of retries SHOULD be limited to a configurable number no less than 3 and no more than 10. An implementation MAY throttle notifications if the number of notifications within a given time period becomes excessive according to local service policy. Duplicate suppression (if any) is a matter of implementation and is not specified herein. 5. Internationalization Considerations Although an XMPP address may contain nearly any [UNICODE] character, the value of the "method" parameter MUST be a Uniform Resource Identifier (see [URI]) rather than an Internationalized Resource Saint-Andre & Melnikov Expires September 2, 2007 [Page 6] Internet-Draft SIEVE-XMPP March 2007 Identifier (see [IRI]). The rules specified in [XMPP-URI] MUST be followed when generating XMPP URIs. In accordance with Section 13 of RFC 3920, all data sent over XMPP MUST be encoded in [UTF-8]. 6. Security Considerations Depending on the information included, sending a notification can be comparable to forwarding mail to the notification recipient. Care must be taken when forwarding mail automatically, to ensure that confidential information is not sent into an insecure environment. In particular, implementations MUST conform to the security considerations given in [NOTIFY], [SIEVE], and [XMPP]. 7. References 7.1. Normative References [OOB] Saint-Andre, P., "Out of Band Data", XSF XEP 0066, January 2006. [NOTIFY] Melnikov, A., Leiba, B., Segmuller, W., and T. Martin, "Sieve Extension: Notifications", draft-ietf-sieve-notify-07 (work in progress), February 2007. [SHIM] Saint-Andre, P. and J. Hildebrand, "Stanza Headers and Internet Metadata", XSF XEP 0131, August 2005. [SIEVE] Showalter, T. and P. Guenther, "Sieve: An Email Filtering Language", draft-ietf-sieve-3028bis-12 (work in progress), February 2007. [TERMS] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [XMPP-URI] Saint-Andre, P., "Internationalized Resource Identifiers (IRIs) and Uniform Resource Identifiers (URIs) for the Extensible Messaging and Presence Protocol (XMPP)", RFC 4622, August 2006. Saint-Andre & Melnikov Expires September 2, 2007 [Page 7] Internet-Draft SIEVE-XMPP March 2007 7.2. Informative References [IRI] Duerst, M. and M. Suignard, "Internationalized Resource Identifiers (IRIs)", RFC 3987, January 2005. [UNICODE] The Unicode Consortium, "The Unicode Standard, Version 3.2.0", 2000. The Unicode Standard, Version 3.2.0 is defined by The Unicode Standard, Version 3.0 (Reading, MA, Addison- Wesley, 2000. ISBN 0-201-61633-5), as amended by the Unicode Standard Annex #27: Unicode 3.1 (http://www.unicode.org/reports/tr27/) and by the Unicode Standard Annex #28: Unicode 3.2 (http://www.unicode.org/reports/tr28/). [URI] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform Resource Identifier (URI): Generic Syntax", STD 66, RFC 3986, January 2005. [UTF-8] Yergeau, F., "UTF-8, a transformation format of ISO 10646", STD 63, RFC 3629, November 2003. [XMPP] Saint-Andre, P., "Extensible Messaging and Presence Protocol (XMPP): Core", RFC 3920, October 2004. Authors' Addresses Peter Saint-Andre XMPP Standards Foundation Email: stpeter@jabber.org Alexey Melnikov Isode Limited Email: Alexey.Melnikov@isode.com Saint-Andre & Melnikov Expires September 2, 2007 [Page 8] Internet-Draft SIEVE-XMPP March 2007 Full Copyright Statement Copyright (C) The IETF Trust (2007). 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. 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