WS-Notification Overview Alan Weissberger NEC-Labs America 1 408 863 6042

1. WS-Notification OverviewAlan WeissbergerNEC-Labs America1 408 863 6042 GGF11 June 8, 2004

2. Purpose and Mission of OASIS WS-N TC • Define a set of specifications that standardize the way Web Services interact using the “Notification pattern.” -provides interoperability between different pub/ sub messaging middleware providers -notification pattern may be used in systems or device management, or in commercial apps like electronic trading • Leverage off the 3 specs and white papers submitted by various co-authors http://www.oasis-open.org/apps/org/workgroup/wsn/

3. History of WS-N • Introduced in Jan 04 at Globus World, as part of the WS-RF package to replace OGSI. • Feb 25 Feedback workshop on monolithic WS-Notification spec. Intent to form an OASIS TC. Spec later sub-divided. • March 5: Steve Graham splits WS-N into 3 specs: WS Base Notification, WS Brokered Notification, WS Topics

4. WS-N History (continued) • April 21 Interop event at IBM, RTP, NC • April 29 1st meeting of OASIS WS-N TC; [WS-RF TC met the previous day] in New Orleans, LA • May-June Bi-weekly conference calls -------------------------------------------------------- • Next f2f: July 29-30 2nd meeting of OASIS WS-N TC at Fujitsu-UK, near Heathrow airport. [WS-RF meets previous 2 days]

5. The Notification pattern • A Web Service (WS) or other entity (“producer”) disseminates information to a set of other WS’s (“consumers”), without having prior knowledge of these other WS’s • The “consumers” are registered with the “producers” either directly or via a subscription agent (“subscriber” or “initiator”). • Subscriber sends a “Subscription Request” message to Producer/Broker; an End Point Reference (EPR) is returned (defined in WS Addressing spec) to confirm the subscription • Both direct and brokered notification are possible and are dealt with in different specs

6. Subscription Request to a Notification Service

7. 3 players: Subscriber, Producer, and Consumer of Notifications

8. Pub/Sub example of Brokered NotificationBroker receives subscriptions and redirects notifications

9. 4th Player: the Notification Broker-an Intermediary that processes subscription requests and re-directs notification messages to the designated consumer(s)

10. The Subscription Process • A Subscriber sends a Subscribe Request message to a Notification Producer in order to register the interest of a Notification Consumer for Notification Messages related to one or more Topics. • Notification Producer MUST (???) create a Subscription resource representing the Subscription • Producer returns an Endpoint Reference* in the response to the Subscribe request. This EndpointReference is a WS-Resource-Qualified Endpoint Reference and includes the address of a Subscription Manager service and a reference property containing the identity of the Subscription resource. * At the April 29 f2f meeting, Oracle challenged the use of EPR and proposed another mechanism submitted to W3C

11. Dependency of WS-N on WS-RF? • There are 2 relevant WS-RF specs for WS-N: WS Resource Properties and WS Resource Lifetime (destruction only) • Key question: can direct (non- brokered) notification exist without these 2 specs: -for pub/sub systems? -for Grids using stateful resources associated with the web service(s)? • What is the implicit resource pattern?

12. Relationship of WS Agreement to WS-N and WS-RF specs? • On its own, WS Base (direct) Notification includes a “lightweight” subscription agreement, but only for dissemination of notification messages (typically on a state change or some number of designated event occurrences) • When WS-N is combined with WS Topics, WS Resource Properties, and WS Resource Lifetime, it has the potential to be a more robust, comprehensive agreement (depending on the types of resources available) • Some WS applications may use that package, rather than WS Agreement, to subscribe to a Web Service that produces notification messages

13. Status of the WS-N documents • WS Base Notification - to be voted on during the June 7, 2004 telecon (Editor: Steve Graham of IBM) • WS Brokered Notification – draft available (Editor: Dave Chappell of Sonic Systems) • WS Topics – no draft yet. Pre-OASIS TC draft: http://www.oasis-open.org/apps/org/workgroup/wsn/download.php/6600/WS-Topics-1-0.pdf • Also a ppt presentation by Peter Niblett at April 29 f2f meeting

14. WS Topics Overview [From Peter Niblett .ppt] • Information space taxonomy • Mechanism to organize and categorize things which can be subscribed to • Topics have metadata, and a naming scheme. • Topics are grouped into Topic Spaces • Three TopicExpressions used to identify topic(s) • Simple • ConcreteTopicPath • FullTopicPath • XML document for describing topic metadata

15. What are Topics used for? • Used by a subscriber to identify the subject area it wishes to cover in a subscription • A Producer/Broker only delivers if notification of the list of topics associated with the subscription, intersects with the list of topics associated with the message • Used to identify the set of subjects that a given Producer/Broker deals in • Useful information for a prospective publisher or subscriber • A producer may support only one topic • Can be associated with metadata, e.g. • Notification message schema • Semantic information • Could be used as part of an access control scheme

16. More information on WS-N • WS-RF and WS-N Update at GGF11- June 8th 12:30PM: Presented by David Snelling of Fujitsu, co-chair of WS-RF TC • Join the OASIS WS-N TC as either a prospective member (must attend telecons) or observer: get access to email archives, documents and specs; participate in telecons, f2f meetings, email discussions, etc.