Internet Engineering Task Force SIPPING WG Internet Draft J. Rosenberg dynamicsoft draft-ietf-sipping-reg-event-00.txt October 28, 2002 Expires: April 2003 A Session Initiation Protocol (SIP) Event Package for Registrations STATUS OF THIS MEMO This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC2026. 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 To view the list Internet-Draft Shadow Directories, see http://www.ietf.org/shadow.html. Abstract This document defines a Session Initiation Protocol (SIP) event package for registrations. Through its REGISTER method, SIP allows a user agent to create, modify, and delete registrations. Registrations can also be altered by administrators in order to enforce policy. As a result, these registrations represent a piece of state in the network that can change dynamically. There are many cases where a user agent would like to be notified of changes in this state. This event package defines a mechanism by which those user agents can request and obtain such notifications. J. Rosenberg [Page 1] Internet Draft reg-event October 28, 2002 Table of Contents 1 Introduction ........................................ 3 2 Terminology ......................................... 3 3 Usage Scenarios ..................................... 3 3.1 Forcing Re-Authentication ........................... 3 3.2 Composing Presence .................................. 4 3.3 Welcome Notices ..................................... 4 4 Package Definition .................................. 5 4.1 Event Package Name .................................. 5 4.2 Event Package Parameters ............................ 5 4.3 SUBSCRIBE Bodies .................................... 5 4.4 Subscription Duration ............................... 6 4.5 NOTIFY Bodies ....................................... 6 4.6 Notifier Processing of SUBSCRIBE Requests ........... 7 4.7 Notifier Generation of NOTIFY Requests .............. 7 4.7.1 The Registration State Machine ...................... 7 4.7.2 Applying the state machine .......................... 9 4.8 Subscriber Processing of NOTIFY Requests ............ 10 4.9 Handling of Forked Requests ......................... 10 4.10 Rate of Notifications ............................... 10 4.11 State Agents ........................................ 11 5 Registration Information ............................ 11 5.1 Structure of Registration Information ............... 11 5.2 Computing Registrations from the Document ........... 13 5.3 Example ............................................. 14 5.4 XML Schema .......................................... 15 6 Example Call Flow ................................... 17 7 Security Considerations ............................. 20 8 IANA Considerations ................................. 20 8.1 SIP Event Package Registration ...................... 20 8.2 application/reginfo+xml MIME Registration ........... 20 8.3 URN Sub-Namespace Registration for urn:ietf:params:xml:ns:reginfo ................................. 21 9 Changes since draft-rosenberg-sip-reg-event-00.txt ................................................................ 22 10 Contributors ........................................ 22 11 Acknowledgements .................................... 23 12 Authors Addresses ................................... 23 13 Normative References ................................ 24 14 Informative References .............................. 24 J. Rosenberg [Page 2] Internet Draft reg-event October 28, 2002 1 Introduction The Session Initiation Protocol (SIP) [1] provides all of the functions needed for the establishment and maintenance of communications sessions between users. One of the functions it provides is a registration operation. A registration is a binding between a SIP URI, called an address-of-record, and one or more contact URIs. These contact URIs represent additional resources that can be contacted in order to reach the user identified by the address-of-record. When a proxy receives a request within its domain of administration, it uses the Request-URI as an address-of-record, and uses the contacts bound to the address-of-record to forward (or redirect) the request. The SIP REGISTER method provides a way for a user agent to manipulate registrations. Contacts can be added or removed, and the current set of contacts can be queried. Registrations can also change as a result of administrator policy. For example, if a user is suspected of fraud, their registration can be deleted so that they cannot receive any requests. Registrations also expire after some time if not refreshed. Registrations represent a dynamic piece of state maintained by the network. There are many cases in which user agents would like to know about changes to the state of registrations. The SIP Events Framework [2] defines a generic framework for subscription to, and notification of, events related to SIP systems. The framework defines the methods SUBSCRIBE and NOTIFY, and introduces the notion of a package. A package is a concrete application of the event framework to a particular class of events. Packages have been defined for user presence [9], for example. This specification defines a package for registration state. 2 Terminology In this document, the key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" are to be interpreted as described in RFC 2119 [3] and indicate requirement levels for compliant implementations. 3 Usage Scenarios There are many applications of this event package. A few are documented here for illustrative purposes. 3.1 Forcing Re-Authentication It is anticipated that many SIP devices will be wireless devices that J. Rosenberg [Page 3] Internet Draft reg-event October 28, 2002 will be always-on, and therefore, continually registered to the network. Unfortunately, history has shown that these devices can be compromised. To deal with this, an administrator will want to terminate or shorten a registration, and ask the device to re- register so it can be re-authenticated. To do this, the device subscribes to the registration event package for the address-of- record that it is registering contacts against. When the administrator shortens registration (for example, when fraud is suspected) the registration server sends a notification to the device. It can then re-register and re-authenticate itself. If it cannot re-authenticate, the expiration will terminate shortly thereafter. 3.2 Composing Presence An important concept to understand is the relationship between this event package and the event package for user presence [9]. User presence represents the willingness and ability of a user to communicate with other users on the network. It is composed of a set of contact addresses that represent the various means for contacting the user. Those contact addresses might represent the contact address for voice, for example. Typically, the contact address listed for voice will be an address-of-record. The status of that contact (whether its open or closed) may depend on any number of factors, including the state of any registrations against that address-of- record. As a result, registration state can be viewed as an input to the process which determines the presence state of a user. Effectively, registration state is "raw" data, which is combined with other information about a user to generate a document that describes the user presence. In fact, this event package allows for a presence server to be separated from a SIP registration server, yet still use registration information to construct a presence document. When a presence server receives a presence subscription for some user, the presence server itself would generate a subscription to the registration server for the registration event package. As a result, the presence server would learn about the registration state for that user, and it could use that information to generate presence documents. 3.3 Welcome Notices A common service in current mobile networks are "welcome notices". When the user turns on their phone in a foreign country, they receive a message that welcomes them to the country, and provides information on transportation services, for example. In order to implement this service in a SIP system, an application J. Rosenberg [Page 4] Internet Draft reg-event October 28, 2002 server can subscribe to the registration state of the user. When the user turns on their phone, the phone will generate a registration. This will result in a notification being sent to the application that the user has registered. The application can then send a SIP MESSAGE request [10] to the device, welcoming the user and providing any necessary information. 4 Package Definition This section fills in the details needed to specify an event package as defined in Section 5.4 of [2]. 4.1 Event Package Name The SIP Events specification requires package definitions to specify the name of their package or template-package. The name of this package is "reg". As specified in [2], this value appears in the Event header present in SUBSCRIBE and NOTIFY requests. Example: Event: reg 4.2 Event Package Parameters The SIP Events specification requires package and template-package definitions to specify any package specific parameters of the Event header that are used by it. No package specific Event header parameters are defined for this event package. 4.3 SUBSCRIBE Bodies The SIP Events specification requires package or template-package definitions to define the usage, if any, of bodies in SUBSCRIBE requests. A SUBSCRIBE for registration events MAY contain a body. This body would serve the purpose of filtering the subscription. The definition of such a body is outside the scope of this specification. A SUBSCRIBE for the registration package MAY be sent without a body. This implies that the default registration filtering policy has been J. Rosenberg [Page 5] Internet Draft reg-event October 28, 2002 requested. The default policy is: o Notifications are generated every time there is any change in the state of any of the registered contacts for the resource being subscribed to. Those notifications only contain information on the contacts whose state has changed. o Notifications triggered from a SUBSCRIBE contain full state (the list of all contacts bound to the address-of-record). Of course, the server can apply any policy it likes to the subscription. 4.4 Subscription Duration The SIP Events specification requires package definitions to define a default value for subscription durations, and to discuss reasonable choices for durations when they are explicitly specified. Registration state changes as contacts are created through REGISTER requests, and then time out due to lack of refresh. Their rate of change is therefore related to the typical registration expiration. Since the default expiration for registrations is 3600 seconds, the default duration of subscriptions to registration state is also 3600 seconds. Of course, clients MAY include an Expires header in the SUBSCRIBE request asking for a different duration. 4.5 NOTIFY Bodies The SIP Events specification requires package definitions to describe the allowed set of body types in NOTIFY requests, and to specify the default value to be used when there is no Accept header in the SUBSCRIBE request. The body of a notification of a change in registration state contains a registration information document. This document describes some or all of the contacts associated with a particular address-of-record. All subscribers to registration state MUST support the application/reginfo+xml format described in Section 5, and MUST list its MIME type, application/reginfo+xml, in an Accept header present in the SUBSCRIBE request. Other registration information formats might be defined in the future. In that case, the subscriptions MAY indicate support for other formats. However, they MUST always support and list application/reginfo+xml as an allowed format. Of course, the notifications generated by the server MUST be in one J. Rosenberg [Page 6] Internet Draft reg-event October 28, 2002 of the formats specified in the Accept header in the SUBSCRIBE request. 4.6 Notifier Processing of SUBSCRIBE Requests The SIP Events framework specifies that packages should define any package-specific processing of SUBSCRIBE requests at a notifier, specifically with regards to authentication and authorization. Registration state can be sensitive information. Therefore, all subscriptions to it SHOULD be authenticated and authorized before approval. Authentication MAY be performed using any of the techniques available through SIP, including digest, S/MIME, TLS or other transport specific mechanisms [1]. Authorization policy is at the discretion of the administrator, as always. However, a few recommendations can be made. It is RECOMMENDED that a user be allowed to subscribe to their own registration state. Such subscriptions are useful when there are many devices that represent a user, each of which needs to learn the registration state of the other devices. We also anticipate that applications and automata will frequently be subscribers to the registration state. In those cases, authorization policy will typically be provided ahead of time. 4.7 Notifier Generation of NOTIFY Requests The SIP Event framework requests that packages specify the conditions under which notifications are sent for that package, and how such notifications are constructed. To determine when a notifier should send notifications of changes in registration state, we define a finite state machine (FSM) that represents the state of a contact for a particular address-of-record. Transitions in this state machine MAY result in the generation of notifications. These notifications will carry information on the new state and the event which triggered the state change. It is important to note that this FSM is just a model of the registration state machinery maintained by a server. An implementation would map its own state machines to this one in an implementation-specific manner. 4.7.1 The Registration State Machine The underlying state machine for a registration is shown in Figure 1. The machine is very simple. An instance of this machine is associated with each address-of-record. When the first contact is registered to that address-of-record, the state machine moves from init to active. J. Rosenberg [Page 7] Internet Draft reg-event October 28, 2002 +------------+ | | | Init | | | +------------+ | V +------------+ | | | Active | | | +------------+ | V +------------+ | | | Terminated | | | +------------+ Figure 1: Registration State Machine As long as there is at least one contact bound to the address-of- record, the state machine remains in the active state. When the last contact expires or is removed, the registration transitions to terminated. In addition to this state machine, each registration is associated with a set of contacts, each of which is modelled with its own state machine. The diagram for the per-contact state machine is shown in Figure 2. This FSM is identical to the registration state machine in terms of its states, but has many more transition events. When a new contact is added, the FSM moves from the init state into the active state. There are two ways in which it can become active. One is through an actual SIP REGISTER request (correspoding to the registered event), and the other is when the contact is created administratively, or through some non-SIP means (the created event). J. Rosenberg [Page 8] Internet Draft reg-event October 28, 2002 +------+ | | refreshed | | shortened V | +------------+ +------------+ +------------+ | | | | | | | Init |----------->| Active |----------->| Terminated | | | | | | | +------------+ registered +------------+ expired +------------+ created deactivated probation unregistered rejected Figure 2: Contact State Machine The FSM remains in the active state so long as the contact is bound to the address-of-record. When a contact is refreshed through a REGISTER request, the FSM stays in the same state, but a refreshed event is generated. Likewise, when an administrator modifies the expiration time of a binding (without deleting the binding) to trigger the contact to re-register and possibly re-authenticate, the FSM stays in the active state, but a shortened event is generated. When the contact is no longer bound to the address-of-record, the FSM moves to the terminated state. There are several reasons this can happen. The first is an expiration, which occurs when the contact was not refreshed by a REGISTER request. The second reason is deactivated. This occurs when the administrator has removed the contact as a valid binding, but still wishes the client to attempt to re-register the contact. In contast, the rejected event occurs when an active contact is removed by the administrator, but re- registrations will not help to re-establish it. This might occur if a user does not pay their bills, for example. The probation event occurs when an active contact is removed by the administrator, and the administrator wants the client to re-register, but to do so at a later time. The unregistered event occurs when a REGISTER request sets the expiration time of that contact to zero. 4.7.2 Applying the state machine The server MAY generate a notification to subscribers when any event occurs in the state machine. Whether it does or does not is policy J. Rosenberg [Page 9] Internet Draft reg-event October 28, 2002 dependent. However, several guidelines are defined. As a general rule, when a subscriber is authorized to receive notifications about a set of registrations, it is RECOMMENDED that notifications contain information about those contacts which have changed state (and thus triggered a notification), instead of delivering the current state of every contact in all registrations. However, notifications triggered as a result of a fetch operation (a SUBSCRIBE with Expires of 0) SHOULD result in the full state of all contacts for all registrations to be present in the NOTIFY. 4.8 Subscriber Processing of NOTIFY Requests The SIP Events framework expects packages to specify how a subscriber processes NOTIFY requests in any package specific ways, and in particular, how it uses the NOTIFY requests to contruct a coherent view of the state of the subscribed resource. Typically, the NOTIFY will only contain information for contacts whose state has changed. To construct a coherent view of the total state of all registrations, the subscriber will need to combine NOTIFYs received over time. The details of this process depend on the document format used to convey registration state. Section 5 outlines the process for the application/reginfo+xml format. 4.9 Handling of Forked Requests The SIP Events framework mandates that packages indicate whether or not forked SUBSCRIBE requests can install multiple subscriptions. Registration state is normally stored in some repository (whether it be co-located with a proxy/registrar or in a separate database). As such, there is usually a single place where the contact information for a particular address-of-record is resident. This implies that a subscription for this information is readily handled by a single element with access to this repository. There is, therefore, no compelling need for a subscription to registration information to fork. As a result, a subscriber MUSTNOT create multiple dialogs as a result of a single subscription request. The required processing to guarantee that only a single dialog is established is described in Section 5.4.9 of the SIP Events framework [2]. 4.10 Rate of Notifications The SIP Events framework mandates that packages define a maximum rate of notifications for their package. For reasons of congestion control, it is important that the rate of notifications not become excessive. As a result, it is RECOMMENDED J. Rosenberg [Page 10] Internet Draft reg-event October 28, 2002 that the server not generate notifications for a single subscriber at a rate faster than once every 5 seconds. 4.11 State Agents The SIP Events framework asks packages to consider the role of state agents in their design. State agents have no role in the handling of this package. 5 Registration Information 5.1 Structure of Registration Information Registration information is an XML document [4] that MUST be well- formed and SHOULD be valid. Registration information documents MUST be based on XML 1.0 and MUST be encoded using UTF-8. This specification makes use of XML namespaces for identifying registration information documents and document fragments. The namespace URI for elements defined by this specification is a URN [5], using the namespace identifier 'ietf' defined by [6] and extended by [7]. This URN is: urn:ietf:params:xml:ns:reginfo A registration information document begins with the root element tag "reginfo". It consists of any number of "registration" sub-elements, each of which contains the registration state for a particular address-of-record. Other elements from different namespaces MAY be present for the purposes of extensibility; elements or attributes from unknown namespaces MUST be ignored. There are two attributes associated with the "reginfo" element, both of which MUST be present: version: This attribute allows the recipient of registration information documents to properly order them. Versions start at 0, and increment by one for each new document sent to a subscriber. Versions are scoped within a subscription. Versions MUST be representable using a 32 bit integer. state: This attribute indicates whether the document contains the full registration state, or whether it contains only information on those registrations which have changed since the previous document (partial). Note that the document format explicitly allows for conveying J. Rosenberg [Page 11] Internet Draft reg-event October 28, 2002 information on multiple addresses-of-record. This enables subscriptions to groups of registrations, where such a group is identified by some kind of URI. For example, a domain might define sip:allusers@example.com as a subscribable resource that generates notifications when the state of any address-of-record in the domain changes. The "reginfo" element has a list of "registration" sub-elements. The "registration" element contains information on a single registration. Other elements from different namespaces MAY be present for the purposes of extensibility; elements or attributes from unknown namespaces MUST be ignored. There are three attributes associated with the "registration" element, all of which MUST be present: aor: The aor attribute contains a URI which is the address-of- record this registration refers to. id: The id attribute identifies this registration. It MUST be unique amongst all other id attributes present in other registration elements conveyed to the subscriber within the scope of their subscription. state: The state attribute indicates the state of the registration. The valid values are "init", "active" and "terminated". The "registration" element has a list of "contact" sub-elements. Other elements from different namespaces MAY be present for the purposes of extensibility; elements or attributes from unknown namespaces MUST be ignored. There are several attributes associated with the "contact" element which MUST be present: id: The id attribute identifies this contact. It MUST be unique amongst all other id attributes present in other contact elements conveyed to the subscriber within the scope of their subscription. state: The state attribute indicates the state of the contact. The valid values are "active" and "terminated". event: The event attribute indicates the event which caused the contact state machine to go into its current state. Valid values are registered, created, refreshed, shortened, expired, deactivated, probation, unregistered and rejected. If the event attribute has a value of shortened, the "expires" attribute MUST be present. It contains an unsigned long integer which indicates the number of seconds remaining until the binding is due to J. Rosenberg [Page 12] Internet Draft reg-event October 28, 2002 expire. This attribute MAY be included with any event attribute value for which the state of the contact is active. If the event attribute has a value of probation, the "retry-after" attribute MUST be present. It contains an unsigned long integer which indicates the amount of seconds after which the owner of the contact is expected to retry its registration. The optional "duration-registered" attribute conveys the amount of time that the contact has been bound to the address-of-record, in seconds. The optional "q" attribute conveys the relative priority of this contact compared to other registered contacts. The optional "params" attribute conveys any contact parameters that have been associated with this contact. As an example, contact parameters can be specified through the caller preferences extension [11]. The optional "callid" attribute contains the current Call-ID carried in the REGISTER that was last used to update this contact, and the optional "cseq" attribute contains the last CSeq value present in a REGISTER request that updated this contact value. The optional "display-name" attribute contains the textual display name associated with this contact. The xml:lang attribute MAY be present to indicate the language of the display-name. The value of the contact element is the URI of that contact. 5.2 Computing Registrations from the Document Typically, the NOTIFY for registration information will only contain information about those contacts whose state has changed. To construct a coherent view of the total state of all registration, a subscriber will need to combine NOTIFYs received over time. The subscriber maintains a table for each registration it receives information for. Each registration is uniquely identified by the "id" attribute in the "registration" element. Each table contains a row for each contact in that registration. Each row is indexed by the unique ID for that contact. It is conveyed in the "id" attribute of the "contact" element. The contents of each row contain the state of that contact as conveyed in the "contact" element. The tables are also associated with a version number. The version number MUST be initialized with the value of the "version" attribute from the "reginfo" element in the first document received. Each time a new document is received, the value of the local version number, and the "version" attribute in the new document, are compared. If the value in the new document is one higher than the local version number, the local version number is increased by one, and the document is processed. If the value in the document is more than one higher than the local version number, the local version number is set to the value in the new document, the document is processed, and the J. Rosenberg [Page 13] Internet Draft reg-event October 28, 2002 subscriber SHOULD generate a refresh request to trigger a full state notification. If the value in the document is less than the local version, the document is discarded without processing. The processing of the document depends on whether it contains full or partial state. If it contains full state, indicated by the value of the "state" attribute in the "reginfo" element, the contents of all tables associated with this subscription are flushed. They are repopulated from the document. A new table is created for each "registration" element, and a new row in each table is created for each "contact" element. If the reginfo contains partial state, as indicated by the value of the "state" attribute in the "reginfo" element, the document is used to update the existing tables. For each "registration" element, the subscriber checks to see if a table exists for that list. This check is done by comparing the value in the "id" attribute of the "registration" element with the ID associated with the table. If a table doesn't exist for that list, one is created. For each "contact" element in the list, the subscriber checks to see whether a row exists for that contact. This check is done by comparing the ID in the "id" attribute of the "contact" element with the ID associated with the row. If the contact doesn't exist in the table, a row is added, and its state is set to the information from that "contact" element. If the contact does exist, its state is updated to be the information from that "contact" element. If a row is updated or created, such that its state is now terminated, that entry MAY be removed from the table at any time. 5.3 Example The following is an example registration information document: sip:user@pc887.example.com sip:user@university.edu J. Rosenberg [Page 14] Internet Draft reg-event October 28, 2002 5.4 XML Schema The following is the schema definition of the reginfo format: J. Rosenberg [Page 15] Internet Draft reg-event October 28, 2002 J. Rosenberg [Page 16] Internet Draft reg-event October 28, 2002 6 Example Call Flow User Registrar Application | |(1) SUBSCRIBE | | |Event:reg | | |<------------------| | |(2) 200 OK | | |------------------>| | |(3) NOTIFY | | |------------------>| | |(4) 200 OK | | |<------------------| |(5) REGISTER | | |------------------>| | |(6) 200 OK | | |<------------------| | | |(7) NOTIFY | | |------------------>| | |(8) 200 OK | | |<------------------| |(9) MESSAGE | | |<--------------------------------------| Figure 3: Example Call Flow This section provides an example call flow, shown in Figure 3. It shows an implementation of the welcome notice application described in Section 3.3. First, the application SUBSCRIBEs to the registration event package for the desired user (1): SUBSCRIBE sip:joe@bar.com SIP/2.0 Via: SIP/2.0/UDP app.bar.com;branch=z9hG4bKnashds7 From: sip:app.bar.com;tag=123aa9 To: sip:joe@bar.com Call-ID: 9987@app.bar.com CSeq: 9887 SUBSCRIBE J. Rosenberg [Page 17] Internet Draft reg-event October 28, 2002 Contact: sip:app.bar.com Event: reg Max-Forwards: 70 Accept: application/reginfo+xml The registrar (which is acting as the notifier for the registration event package) generates a 200 OK to the SUBSCRIBE: SIP/2.0 200 OK Via: SIP/2.0/UDP app.bar.com;branch=z9hG4bKnashds7 ;received=1.2.3.4 From: sip:app.bar.com;tag=123aa9 To: sip:joe@bar.com;tag=xyzygg Call-ID: 9987@app.bar.com CSeq: 9987 SUBSCRIBE Contact: sip:server19.bar.com Expires: 3600 The registrar then generates a notification (3) with the current state. Since there is no active registration, the state of the registration is "init": NOTIFY sip:app.bar.com SIP/2.0 Via: SIP/2.0/UDP server19.bar.com;branch=z9hG4bKnasaii From: sip:joe@bar.com;tag=xyzygg To: sip:app.bar.com;tag=123aa9 Call-ID: 9987@app.bar.com CSeq: 1288 NOTIFY Contact: sip:server19.bar.com Event: reg Max-Forwards: 70 Content-Type: application/reginfo+xml Content-Length: ... J. Rosenberg [Page 18] Internet Draft reg-event October 28, 2002 Later on, the user registers (5): REGISTER sip:joe@bar.com SIP/2.0 Via: SIP/2.0/UDP pc34.bar.com;branch=z9hG4bKnaaff From: sip:joe@bar.com;tag=99a8s To: sip:joe@bar.com Call-ID: 88askjda9@pc34.bar.com CSeq: 9976 REGISTER Contact: sip:joe@pc34.bar.com This results in a NOTIFY being generated to the application (7): NOTIFY sip:app.bar.com SIP/2.0 Via: SIP/2.0/UDP server19.bar.com;branch=z9hG4bKnasaij From: sip:joe@bar.com;tag=xyzygg To: sip:app.bar.com;tag=123aa9 Call-ID: 9987@app.bar.com CSeq: 1289 NOTIFY Contact: sip:server19.bar.com Event: reg Max-Forwards: 70 Content-Type: application/reginfo+xml Content-Length: ... sip:joe@pc34.bar.com The application can then send its instant message to the device (9): MESSAGE sip:joe@pc34.bar.com SIP/2.0 Via: SIP/2.0/UDP app.bar.com;branch=z9hG4bKnashds8 From: sip:app.bar.com;tag=123aa10 To: sip:joe@bar.com Call-ID: 9988@app.bar.com CSeq: 82779 MESSAGE J. Rosenberg [Page 19] Internet Draft reg-event October 28, 2002 Max-Forwards: 70 Content-Type: text/plain Content-Length: ... Welcome to the bar.com service! 7 Security Considerations Security considerations for SIP event packages are discussed in RFC 3265 [2], and those considerations apply here. Registration information is sensitive, potentially private, information. Subscriptions to this event package SHOULD be authenticated and authorized according to local policy. Some policy guidelines are suggested in Section 4.6. In addition, notifications SHOULD be sent in such a way to ensure confidentiality, message integrity and verification of subscriber identity, such as sending subscriptions and notifications using a SIPS URL or protecting the notification bodies with S/MIME. 8 IANA Considerations This document registers a new SIP Event Package, a new MIME type (application/reginfo+xml), and a new XML namespace. 8.1 SIP Event Package Registration Package name: reg Type: package Contact: Jonathan Rosenberg, Published Specification: RFC XXXX (Note to RFC Editor: Please fill in XXXX with the RFC number of this specification). 8.2 application/reginfo+xml MIME Registration MIME media type name: application MIME subtype name: reginfo+xml Mandatory parameters: none Optional parameters: Same as charset parameter application/xml as specified in RFC 3023 [8]. J. Rosenberg [Page 20] Internet Draft reg-event October 28, 2002 Encoding considerations: Same as encoding considerations of application/xml as specified in RFC 3023 [8]. Security considerations: See Section 10 of RFC 3023 [8] and Section 7 of this specification. Interoperability considerations: none. Published specification: This document. Applications which use this media type: This document type is being used in notifications to alert SIP user agents that their registrations have expired and must be redone. Additional Information: Magic Number: None File Extension: .rif or .xml Macintosh file type code: "TEXT" Personal and email address for further information: Jonathan Rosenberg, Intended usage: COMMON Author/Change controller: The IETF. 8.3 URN Sub-Namespace Registration for urn:ietf:params:xml:ns:reginfo This section registers a new XML namespace, as per the guidelines in [7]. URI: The URI for this namespace is urn:ietf:params:xml:ns:reginfo. Registrant Contact: IETF, SIMPLE working group, , Jonathan Rosenberg . XML: BEGIN J. Rosenberg [Page 21] Internet Draft reg-event October 28, 2002 Registration Information Namespace

Namespace for Registration Information

application/reginfo+xml

See RFCXXXX.

END 9 Changes since draft-rosenberg-sip-reg-event-00.txt o Added to the contact state machine a "shortened" event which requests reregistration but keeps the binding state active. o Added an "expires" parameter, to indicate the number of seconds remaining for a binding. o Updated the Security Considerations section. o An IANA registration template was added for the "reg" package. 10 Contributors This document is based heavily on the registration event package originally proposed by Beckmann and Mayer in [12]. They can be contacted at: Georg Mayer Siemens AG Hoffmannstr. 51 Munich 81359 Germany EMail: Georg.Mayer@icn.siemens.de Mark Beckmann Siemens AG P.O. Box 100702 Salzgitter 38207 Germany EMail: Mark.Beckmann@siemens.com J. Rosenberg [Page 22] Internet Draft reg-event October 28, 2002 Rohan Mahy provided editorial work in order to progress this specification. His contact address is: Rohan Mahy Cisco Systems 170 West Tasman Dr, MS: SJC-21/3/3 Phone: +1 408 526 8570 Email: rohan@cisco.com 11 Acknowledgements We would like to thank Dean Willis for his support. 12 Authors Addresses Jonathan Rosenberg dynamicsoft 72 Eagle Rock Avenue First Floor East Hanover, NJ 07936 email: jdrosen@dynamicsoft.com Full Copyright Statement Copyright (c) The Internet Society (2002). All Rights Reserved. This document and translations of it may be copied and furnished to others, and derivative works that comment on or otherwise explain it or assist in its implementation may be prepared, copied, published and distributed, in whole or in part, without restriction of any kind, provided that the above copyright notice and this paragraph are included on all such copies and derivative works. However, this document itself may not be modified in any way, such as by removing the copyright notice or references to the Internet Society or other Internet organizations, except as needed for the purpose of developing Internet standards in which case the procedures for copyrights defined in the Internet Standards process must be followed, or as required to translate it into languages other than English. The limited permissions granted above are perpetual and will not be J. Rosenberg [Page 23] Internet Draft reg-event October 28, 2002 revoked by the Internet Society or its successors or assigns. This document and the information contained herein is provided on an "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIMS 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. 13 Normative References [1] J. Rosenberg, H. Schulzrinne, G. Camarillo, A. Johnston, J. Peterson, R. Sparks, M. Handley, and E. Schooler, "SIP: session initiation protocol," RFC 3261, Internet Engineering Task Force, June 2002. [2] A. B. Roach, "Session initiation protocol (sip)-specific event notification," RFC 3265, Internet Engineering Task Force, June 2002. [3] S. Bradner, "Key words for use in RFCs to indicate requirement levels," RFC 2119, Internet Engineering Task Force, Mar. 1997. [4] W. W. W. C. (W3C), "Extensible markup language (xml) 1.0." The XML 1.0 spec can be found at http://www.w3.org/TR/1998/REC-xml- 19980210. [5] R. Moats, "URN syntax," RFC 2141, Internet Engineering Task Force, May 1997. [6] R. Moats, "A URN namespace for IETF documents," RFC 2648, Internet Engineering Task Force, Aug. 1999. [7] M. Mealling, "The IETF XML registry," Internet Draft, Internet Engineering Task Force, July 2002. Work in progress. [8] M. Murata, S. S. Laurent, and D. Kohn, "XML media types," RFC 3023, Internet Engineering Task Force, Jan. 2001. 14 Informative References [9] J. Rosenberg, "Session initiation protocol (SIP) extensions for presence," Internet Draft, Internet Engineering Task Force, May 2002. Work in progress. [10] B. Campbell and J. Rosenberg, "Session initiation protocol extension for instant messaging," Internet Draft, Internet Engineering Task Force, Sept. 2002. Work in progress. J. Rosenberg [Page 24] Internet Draft reg-event October 28, 2002 [11] H. Schulzrinne and J. Rosenberg, "Session initiation protocol (SIP) caller preferences and callee capabilities," Internet Draft, Internet Engineering Task Force, July 2002. Work in progress. [12] G. Mayer and M. Beckmann, "Registration event package," Internet Draft, Internet Engineering Task Force, May 2002. Work in progress. J. Rosenberg [Page 25]