SIPPING Working Group M. Garcia-Martin Internet-Draft M. Matuszewski Intended status: Standards Track Nokia Expires: December 15, 2006 N. Beijar J. Lehtinen Helsinki University of Technology June 13, 2006 A Framework for Sharing Resources with the Session Initiation Protocol (SIP) draft-garcia-sipping-resource-sharing-framework-00 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 December 15, 2006. Copyright Notice Copyright (C) The Internet Society (2006). Abstract This memo proposes a SIP framework used for advertising and searching for shared resources, such as services or files, within a given community. The memo defines the signaling used by users to signal the availability of resources stored in their User Agents (UA). It Garcia-Martin, et al. Expires December 15, 2006 [Page 1] Internet-Draft SIP Resource Sharing Framework June 2006 also provides the signaling for users to perform searches of available resources and monitor changes in existing resources. Additionally, we provide the signaling used to access a resource. These methods can be used in (but are not limited to) SIP peer-to- peer systems based on centralized, semi-centralized or fully distributed architectures. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Definitions and Document Conventions . . . . . . . . . . . . . 4 3. Overview of Operation . . . . . . . . . . . . . . . . . . . . 5 4. Resource Publication . . . . . . . . . . . . . . . . . . . . . 6 4.1. Initial resource metadata publication . . . . . . . . . . 6 4.2. Publication of modified resource metadata . . . . . . . . 7 4.3. Actions performed by the ESC . . . . . . . . . . . . . . . 8 5. Search Operation . . . . . . . . . . . . . . . . . . . . . . . 8 5.1. Sending a search request . . . . . . . . . . . . . . . . . 9 5.2. Reporting search results . . . . . . . . . . . . . . . . . 10 5.3. Propagating searches . . . . . . . . . . . . . . . . . . . 11 5.3.1. Searching based on flooding . . . . . . . . . . . . . 11 5.3.2. Searching based on distributed hash tables (DHT) . . . 12 5.4. Terminating a Search Request . . . . . . . . . . . . . . . 12 5.5. Example of a search filter . . . . . . . . . . . . . . . . 12 6. Accessing a Resource . . . . . . . . . . . . . . . . . . . . . 14 7. Security Considerations . . . . . . . . . . . . . . . . . . . 14 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 14 8.1. Normative References . . . . . . . . . . . . . . . . . . . 14 8.2. Informative References . . . . . . . . . . . . . . . . . . 15 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 15 Intellectual Property and Copyright Statements . . . . . . . . . . 17 Garcia-Martin, et al. Expires December 15, 2006 [Page 2] Internet-Draft SIP Resource Sharing Framework June 2006 1. Introduction The Session Initiation Protocol (SIP) [RFC3261] is a text-based protocol for initiating and managing communication sessions. The protocol is extended by the SIP-events framework [RFC3265] to provide a mechanism whereby a user can subscribe to state changes of resources and get notifications when the state of the resource changes. SIP also provides a publication mechanism [RFC3903] that allows a user to supply resource metadata related to the state and changes in the state of such resource. A 'resource' event package [I-D.draft-garcia-sipping-resource-event-package] is used to allow SIP User Agents to publish, subscribe, and get notifications of the availability of generic resources, where a resource can be, for example, a file (e.g., images, video files, audio files), a chat room, streaming content, a printer, a printer job, etc. All these building blocks can easily be combined to provide a generic mechanism whereby users can provide the availability at their user agents of resources of any kind. The mechanism can also provide a directory search within a publishing community, so that members of the community can search for the availability of resources that have been made available by other members of the same community, and then further access those resources (e.g., join a chat room or download a file, etc.). Think for example of a user, Alice, who wants to make a set of image files available to members of her family. She sets up a SIP peer-to- peer network with her family, and publishes the resouce metadata describing her available files. The resource metadata is stored in the peer nodes, in the user agents of Alice's family members. Then, Bob, a member of the same SIP peer-to-peer network, wants to acquire those pictures, tagged with a keyword 'vacation'. He defines the search criteria; his SIP UA creates an appropriate filter and sets up a short subscription by sending it to the SIP peer-to-peer network. Then he receives notifications from the different peer nodes, containing a metadata describing the searched files. In another scenario, a centralized server can be used to aggregate all the state resource metadata. This might be useful in cases where several instances of the same resource are available at different SIP user agents. The server will act as a state agent (defined in RFC 3265 [RFC3265]) and Event State Compositor (ESC) (defined in RFC 3903 [RFC3903]). The aggregation that the server relieves the endpoints from doing the aggregation itself, so this is an interesting scenario in deployments that involve endpoints with limited processing capability and network bandwidth. A hybrid scenario is also possible, where, for example, User Agents act as secondary nodes (ordinary peers) in a SIP peer-to-peer Garcia-Martin, et al. Expires December 15, 2006 [Page 3] Internet-Draft SIP Resource Sharing Framework June 2006 network. ESCs are primary nodes (super peers). In this scenario, publication of resource metadata and search operations takes place between the secondary and the primary nodes. The primary nodes keep the state consistent among themselves proactively according to a well-defined algorithm (e.g. Chord), or alternatively, distribute the search request among themselves reactively as a resource is needed. This memo describes a framework where SIP is used for advertising and searching for shared resources, such as services or files. The framework defines the signaling used for users to signal the availability of resources stored in their User Agents (UA). It also provides the signaling used for users to perform searches of available resources and monitor changes in existing resources. Additionally, signaling used to access a resource from a remote UA is provided. These methods can be used in (but are not limited to) SIP peer-to-peer systems based on centralized, semi-centralized or fully distributed architectures. While other protocols and mechanisms can be used to achieve similar purposes, it is a beneficial to provide the means to use SIP in order to minimize the protocol implementation support, especially in endpoints with limited resources. 2. Definitions and Document Conventions In addition to the definitions of RFC 3265 [RFC3265], and RFC 3903 [RFC3903], this document introduces the following new terms: Community: A collection of loosely coupled SIP user agents that agree to share resources among members of the community. A community can be composed of an enterprise, a group of friends, family members, or members of a club. Resource: An abstraction of a shared object, which can be a service or information, e.g. in the form of an audio/video stream or a static file. Resource metadata: A set of properties describing the resource. The resource metadata can include the hash (if resource is hashable), name, creation date, Uniform Resource Name (URN), Uniform Resource Identifier (URI), and other relevant information. Resource descriptor: A subset of the resource metadata that uniquely identifies one resource. Resource directory: A device storing the resource descriptors of a set of resources; also called ESC in this document. Search operation: Signalling issued by a user to get information of the available resources and its associated metadata. Typically search operations are delimited with search filters. Garcia-Martin, et al. Expires December 15, 2006 [Page 4] Internet-Draft SIP Resource Sharing Framework June 2006 Search filter: A set of properties used in search operations to set the limits of the search, based on user's input. A search filter can consist of, e.g., a file name, file type, a resource description, etc. File transfer operation: An operation whereby a User Agent gets a file resource from a remote UA. In this document, the key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" are to be interpreted as described in BCP 14, RFC 2119 [RFC2119] and indicate requirement levels for compliant implementations. Indented passages such as this one are used in this document to provide additional information and clarifying text. They do not contain descriptions of normative protocol behavior. 3. Overview of Operation Prior to starting any of the resource sharing operations, a SIP User Agent needs to join a community. Communities can be created around a given SIP peer-to-peer network, around a centralized server that keeps track of shared resources, in and ad-hoc network, or by some other means. A user may need to join the community explicitly, e.g. using some additional signaling or manual configuration. Alternatively, a community may be open, allowing implicit joining by making resources available to the community. Once a user has joined a given community, he decides to share one or more resources with the community. Due to security restrictions, we only consider resources that are hosted by the SIP UA that the user is using, for example, images and videoclips taken with a digital camera, streaming content, chat rooms hosted by the SIP UA, printers connected to the SIP UA, etc. Typically the operation of selecting the resources that are shared with a given community requires some initial configuration, so that the user decides which resources are made accesable to other users. This may imply selection of directories where files are available or individual selection of different resources. Once the selection of shared resources is done, the SIP UA may publish the availability of those resources towards an Event State Compositor (ESC). The ESC can be a central server or a node participating in a DHT. The step may require some configuration, such as the URL of the ESC. Resource publication is further discussed in Section 4.1. Garcia-Martin, et al. Expires December 15, 2006 [Page 5] Internet-Draft SIP Resource Sharing Framework June 2006 A user can perform a search operation, when he is interested in accessing (downloading, joining, or obtaining service from) a resource. Search operations are implemented as short-lived subscriptions that include a filter to define the searched resources. Results of search operations are conveyed in a series of notications. Additionally, in cases where monitoring of a resource is required, a longer-lived subscription can be installed. Search operations are further discussed in Section 5. Once a user has got knowledge of a resource and its availability, he can access it by joining the resource (e.g., if it is a conference), downloading it (if it is a file), or doing an appropriate action. Section 6 provides further discussion. 4. Resource Publication Resource publication is based on the PUBLISH method specified in RFC 3903 [RFC3903] together with the 'resource' event package [I-D.draft-garcia-sipping-resource-event-package]. 4.1. Initial resource metadata publication Initial resource metadata publication is perfomed to publish metadata about the availability of one or more resources to the ESC. Figure 1 presents the signaling flow required for an Event Publishing Agent (EPA) to publish the availability of one or more resources towards the Event State Compositor (ESC). EPA ESC | | | SIP/2.0 PUBLISH | | Event: resource | | (resource metadata in body) | | ------------------------------------> | | | | 200 OK SIP/2.0 | | SIP-ETag: x | | <------------------------------------ | | | Figure 1: Signaling flow for publication of resource metadata The EPA performs the initial resource metadata publication by sending a PUBLISH [RFC3903] request to the ESC. The PUBLISH request contains a full 'resource' document that contains metadata about one or more resources available at the EPA. The 'resource' document is defined in the 'resource' event package Garcia-Martin, et al. Expires December 15, 2006 [Page 6] Internet-Draft SIP Resource Sharing Framework June 2006 [I-D.draft-garcia-sipping-resource-event-package]. Each resource is described using a set of invariant metadata and a set of metadata specific to each instance of the resource, given in the and child elements of the element. In case of publishing availability of a file, the invariant metadata contains the following attributes: the Uniform Resource Name (URN), the MIME type (e.g., image/jpeg), the size and the SHA1 hash of the file. For each identical copy of the file, the instance-specific metadata contains any of: the SIP URI of the file, the file name, a short description, a set of keywords describing the file, the file creation date, the file modification date, the file read date, a link to an icon, and other resource metadata that is associated to the file. Additionally the instance-specific metadata contains the SIP AOR (e.g. URI) and GRUU of the user's endpoint where the file is stored. In case of publishing availablility of some other type of resource, the attributes are used as applicable. The PUBLISH request is routed to the ESC. The ESC sends a 200 OK response that, according to RFC 3903 [RFC3903], includes a SIP-ETag header that contains the entity-tag allocated to the resource. The EPA stores this entity-tag for future references to the publication. Note that the actual file is not transmitted at any point to the ESC: only the metadata associated with the file is transmitted. 4.2. Publication of modified resource metadata Whenever a resource is modified or new resources are added or deleted from the endpoint, the EPA refreshes the previous publication by sending a new PUBLISH request, as shown in Figure 2. This publication carries a partial 'resource' document that contains a number of XML patch operations that add, remove, or replace XML elements towards the last published 'resource' document. A resource modification occurs, e.g., when an image file is edited to suppress red eyes, an audio file is edited to suppress silence or apply some noise filter, or when some audio/music stream provided by the UE changes its bitrate. Any kind of modification to the resource owned by the UE implies a change in the metadata. RFC 3903 [RFC3903] contains provisions to allow the ESC to distinguish an initial publication from a refreshment-based one with the aid of the entity tags and the SIP-ETag and SIP-If-Match header fields. The SIP-Etags in conjunction with the 'version' attribute of the root element of the 'resource' document provide the means to Garcia-Martin, et al. Expires December 15, 2006 [Page 7] Internet-Draft SIP Resource Sharing Framework June 2006 synchronize versions. EPA ESC | | | SIP/2.0 PUBLISH | | SIP-If-Match: x | | Event: resource | | (resource description in body) | | ------------------------------------> | | | | 200 OK SIP/2.0 | | SIP-ETag: y | | <------------------------------------ | | | Figure 2: Signaling flow for publication of modified resource metadata If a resouce becomes unavailable at the EPA, e.g., as a result of a file deletion, the resource publication contains a partial 'resource' document that describes the resource to be removed. 4.3. Actions performed by the ESC As the ESC receives initial or updated publications, the ESC will typically locally store the published metadata, but in some cases, depending on the usage scenario, storage of metadata will take place in other nodes, for example, in other primary nodes which are members of the DHT. The ESC may act as a primary node in an overlay SIP P2P network. Thus, upon reception of a publication from one of its secondary nodes, the primary node may need to publish or update the metadata in the overlay SIP P2P network. This step heavily depends on the chosen peer-to-peer algorithm. For example, if the SIP P2P distribution algorithm is based on flooding, the primary node may not need to contact any other primary node, but just wait for search queries from them. However, if the overlay is based on a Distributed Hash Table (DHT) based algorithm, then the primary node may need to update resource metadata and store it in the appropriate node. The actual mechanism to update resource metadata is dependent on the specific algorithm and out of scope of this memo. 5. Search Operation The search of shared resources is implemented with the SIP event framework defined in RFC 3265 [RFC3265] in conjunction with the Garcia-Martin, et al. Expires December 15, 2006 [Page 8] Internet-Draft SIP Resource Sharing Framework June 2006 'resource' event package [I-D.draft-garcia-sipping-resource-event-package] and a filter document [I-D.ietf-simple-filter-format]. The signaling flow for a search operation is shown in Figure 3. Subscriber Notifier | | | SIP/2.0 SUBSCRIBE | | Event: resource | | (search filter in body) | | ------------------------------------> | | | | 200 OK SIP/2.0 | | <------------------------------------ | | | | SIP/2.0 NOTIFY | | Event: resource | | <------------------------------------ | | | | 200 OK SIP/2.0 | | ------------------------------------> | | | | SIP/2.0 NOTIFY | | Event: resource | | (resource descriptor in body) | | <------------------------------------ | | | | 200 OK SIP/2.0 | | ------------------------------------> | | | | SIP/2.0 NOTIFY | | Event: resource | | Subscription-State: terminated | | (resource descriptor in body) | | <------------------------------------ | | | | 200 OK SIP/2.0 | | ------------------------------------> | | | Figure 3: Signaling flow of a search operation 5.1. Sending a search request To search for a resource, the subscriber first builds a filter containing the data of the searched resource. The filter can contain, for example, keywords, file names, types of files, etc. The Garcia-Martin, et al. Expires December 15, 2006 [Page 9] Internet-Draft SIP Resource Sharing Framework June 2006 filter conforms to the XML format for filters [I-D.ietf-simple-filter-format]. Then it attaches the filter to a SUBSCRIBE request for the resource event package. The subscription duration will be short, typically on the order of a few minutes. This subscription time provides enough time for a primary node in a SIP peer-to-peer network to propagate the search within the overlay network and get responses before the subscription expires. Eventually, the SUBSCRIBE request is sent to a notifier (either a peer or an ESC) that will provide one or more NOTIFY requests including a 'resource' document according to the filtered content. 5.2. Reporting search results After receiving the SUBSCRIBE message, and acknowledging it with a 200 OK, the Notifier sends a NOTIFY request to the Subscriber. This request may contain a first collection of metadata about the searched resources, if such information is already available in the ESC, in a full 'resource' document. Information may be available immediately in case there is matching metadata stored in the ESC, due to push operations according to the peer-to-peer algorithm, or due to cached information from previous searches. In many cases, however, this NOTIFY request does not contain metadata about the searched resources, and it is sent just because the protocol (RFC 3265 [RFC3265]) requires an immediate NOTIFY after each successful SUBSCRIBE request. The NOTIFY request is acknowledged with a 200 OK response. The ESC may, depending on algorithm, invoke a search for additional resources, whose metadata is stored in other ESCs (see section 4.3). Due to this propagated search, additional matching resource descriptors may become known. New matching resource descriptors may also become known as a result of PUBLISH requests received by the ESC within the duration of the subscription. To report matching resources, the ESC sends NOTIFY requests to the Subscriber. The body of the initial NOTIFY contains a full 'resource' document that is formatted according to the 'resource' event package [I-D.draft-garcia-sipping-resource-event-package] and it can contain metadata about several resources that matched the search criteria. The 'resource' event package defines all the metadata associated to each resource, including the file name, size, type, icon, hash, SIP URI and UE (GRUU) of the users where the file is available, etc. In some cases, the metadata that describes a given resource will provide more than one location of the resource. This will typically be the case when a popular resource (e.g., a file) is available in several endpoints. Then the 'resource' XML document supplied in the NOTIFY request will contain more than one child element in a given element. It may also Garcia-Martin, et al. Expires December 15, 2006 [Page 10] Internet-Draft SIP Resource Sharing Framework June 2006 be necessary to divide a NOTIFY request into several smaller due to the user's preferences (rate of notifications, bandwidth consumption, and event throttling). The NOTIFY requests are acknowledged with a 200 OK response. The initial NOTIFY request contains a full 'resource' XML document. Once the notifier acquires more metadata, it sends partial 'resource' XML documents with additions, replacement, or removals. Upon reception of a new partial 'resource' document, the subscriber composes a full 'resource' XML document, based on the existing previous version plus the partial notification. Then, the subscriber UA has the new full 'resource' XML document at his disposal, so it can, e.g., display the metadata sequentially to the user, as soon as new results are received. 5.3. Propagating searches In many cases, such as in P2P systems, the metadata is distributed in several ESCs. We consider two special cases: 1. In a flooding based architecture, several or all ESCs need to be queried in order to find the matching resources. A given ESC is only aware of resources that have been published into its local database. 2. In a DHT based architecture, such as Chord, a specific ESC is responsible for a specific set of metadata. In both cases, the ESC/ESCs containing the required metadata may be another ESC than the one receiving the Subscribe request. 5.3.1. Searching based on flooding In a flooding based search, the SUBSCRIBE request is first processed by the local ESC itself, and then distributed to all ESCs in the system. The distribution is, however, limited by the value of the Max-Forwards header field. An ESC receiving the SUBSCRIBE consults its local database to find matching resources and it replies with a NOTIFY request that may contain a 'resource' document if matching resources are found locally. The ESC also acts as an URI-list server [I-D.ietf-simple-event-list] where the URI-list is locally stored. It then forwards a SUBSCRIBE request with the same filter document to each of the ESCs stored in its neighbor table, providing that the Max-Forwards header is still positive and provided that the ESC hasn't already processed the same request. The generation and maintenance of the neighbor table is out of scope of this memo. The ESC will receive NOTIFY requests from other neighbor nodes, each of the requests containing a different 'resource' document. The ESC Garcia-Martin, et al. Expires December 15, 2006 [Page 11] Internet-Draft SIP Resource Sharing Framework June 2006 will aggregates and composes a single 'resource' document, and sends partial notifications to the subscriber, according to the rate of notifications. The subscriber is getting periodic partial notifications, each one adding new resources or new instances of existing resources. 5.3.2. Searching based on distributed hash tables (DHT) In a DHT based system, a single node (a notifier) is responsible for the metadata related to a given search key (the resource). For file resources the search key is the hash. An ESC receiving a SUBSCRIBE request consults its routing table (finger table in Chord) to locate the notifier whose key is the closest one to the search key, and forwards the SUBSCRIBE to that ESC. Finally the SUBSCRIBE will reach the node responsible for the given search key. The definition of 'closest' is depending on the actual DHT used. 5.4. Terminating a Search Request When the last results are made available, or when the search operation expires, the server sends a last NOTIFY request to the user, containing the latest available results (if any), and setting the Subscription-State header field to "terminated" to indicate the end of the search operation, as per procedures of RFC 3265 [RFC3265]. The user can also cancel the search operation by sending a re- SUBSCRIBE request that contains a Expires header field set to zero, according also to the procedures of RFC 3265 [RFC3265]. 5.5. Example of a search filter Figure 3 provides the signaling flow for a search operation. The SUBSCRIBE request contains a filter body, formatted according to the filter data format [I-D.ietf-simple-filter-format]. Figure 4 shows an example of the SUBSCRIBE request carrying a filter. The filter selects a few XML elements of a resource that contains the string "vacation" in a element. SUBSCRIBE sip:bob@example.com SIP/2.0 Via: SIP/2.0/UDP alice.example.net;branch=z9hG4bKnashds7 Max-Forwards: 70 From: ;tag=31415 To: Call-ID: b89rjhnedlrfjflslj40a222 CSeq: 61 SUBSCRIBE Event: resource Expires: 180 Garcia-Martin, et al. Expires December 15, 2006 [Page 12] Internet-Draft SIP Resource Sharing Framework June 2006 Accept: application/resource+xml;q=0.3 Contact: Content-Type: application/simple-filter+xml Content-Length: [length] /rs:resource-set/rs:resource /rs:resource-set/rs:resource/rs:identity/rs:urn /rs:resource-set/rs:resource/rs:identity/rs:mime-type /rs:resource-set/rs:resource/rs:identity/rs:size /rs:resource-set/rs:resource/rs:identity/rs:sha-1 /rs:resource-set/rs:resource/rs:instance/rs:uri /rs:resource-set/rs:resource/rs:instance/rs:user-aor /rs:resource-set/rs:resource/rs:instance/rs:user-gruu /rs:resource-set/rs:resource/rs:instance/rs:description /rs:resource-set/rs:resource/rs:instance[rs:keyword="vacation"] Figure 4: Example of a search filter Garcia-Martin, et al. Expires December 15, 2006 [Page 13] Internet-Draft SIP Resource Sharing Framework June 2006 6. Accessing a Resource Once the search operation is complete, the user can select whether to do any further operation on a given resource, and if so, on which instance to operate. This heavily depends on the type of resource that has been shared. File resources can be downloaded, for example, by setting up an MSRP session towards the user's SIP URI, and providing a file description in the SDP. This mechanism is described in [I-D.garcia-mmusic-file-transfer-mech]. In this case, the SIP INVITE request is addressed (Request-URI) to the URI contained in a (preferred option) or elements of the chosen for that . The file requester creates an SDP description of an MSRP session that contains the SDP file description extensions to describe the file. If the hash of the file is available, it is RECOMMENDED to include it, as it uniquely identifies the file. In other cases, there can be a URN or URI that describes the resource in the or elements of that . The mechanism to retrieve or receive service from the resource is dependent on it. For example, an HTTP URI requires an HTTP GET request to retrieve the resource. Similarly FTP URIs require the establishment of an FTP session. 7. Security Considerations TBD 8. References 8.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC3261] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, A., Peterson, J., Sparks, R., Handley, M., and E. Schooler, "SIP: Session Initiation Protocol", RFC 3261, June 2002. [RFC3265] Roach, A., "Session Initiation Protocol (SIP)-Specific Event Notification", RFC 3265, June 2002. [RFC3903] Niemi, A., "Session Initiation Protocol (SIP) Extension for Event State Publication", RFC 3903, October 2004. Garcia-Martin, et al. Expires December 15, 2006 [Page 14] Internet-Draft SIP Resource Sharing Framework June 2006 [I-D.draft-garcia-sipping-resource-event-package] Garcia-Martin, M. and M. Matuszewski, "A Session Initiation Protocol (SIP) Event Package and Data Format for Publication and Searching Generic Resources", draft-garcia-sipping-resource-event-package-00 (work in progress), June 2006. 8.2. Informative References [I-D.garcia-mmusic-file-transfer-mech] Garcia-Martin, M., Isomaki, M., Camarillo, G., and S. Loreto, "Session Description Protocol (SDP) Offer/Answer Mechanism to Enable File Transfer", draft-garcia-mmusic-file-transfer-mech-00 (work in progress), June 2006. [I-D.ietf-simple-filter-format] Khartabil, H., "An Extensible Markup Language (XML) Based Format for Event Notification Filtering", draft-ietf-simple-filter-format-05 (work in progress), March 2005. [I-D.ietf-simple-event-list] Roach, A., Rosenberg, J., and B. Campbell, "A Session Initiation Protocol (SIP) Event Notification Extension for Resource Lists", draft-ietf-simple-event-list-07 (work in progress), January 2005. Authors' Addresses Miguel A. Garcia-Martin Nokia P.O.Box 407 NOKIA GROUP, FIN 00045 Finland Email: miguel.an.garcia@nokia.com Marcin Matuszewski Nokia P.O.Box 407 NOKIA GROUP, FIN 00045 Finland Email: marcin.matuszewski@nokia.com Garcia-Martin, et al. Expires December 15, 2006 [Page 15] Internet-Draft SIP Resource Sharing Framework June 2006 Nicklas Beijar Helsinki University of Technology P.O.Box 3000 TKK, FIN 02015 Finland Phone: +358 9 451 5303 Email: nbeijar@netlab.tkk.fi URI: http://www.netlab.tkk.fi/ Juuso Lehtinen Helsinki University of Technology P.O.Box 3000 TKK, FIN 02015 Finland Phone: +358 9 451 2472 Email: juuso@netlab.tkk.fi URI: http://www.netlab.tkk.fi/ Garcia-Martin, et al. Expires December 15, 2006 [Page 16] Internet-Draft SIP Resource Sharing Framework June 2006 Full Copyright Statement Copyright (C) The Internet Society (2006). 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 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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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. Acknowledgment Funding for the RFC Editor function is provided by the IETF Administrative Support Activity (IASA). Garcia-Martin, et al. Expires December 15, 2006 [Page 17]