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

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WS-Notification OverviewAlan WeissbergerNEC-Lab
s America1 408 863 6042

• GGF11
• June 8, 2004

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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/

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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

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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

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The Notification pattern

• A Web Service (WS) or other entity (producer)
  disseminates information to a set of other WSs
  (consumers), without having prior knowledge of
  these other WSs
• 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

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3 players Subscriber, Producer, and Consumer of
Notifications
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Subscription Request to a Notification Service
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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

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4th Player the Notification Broker-an
Intermediary that processes subscription requests
and re-directs notification messages to the
designated consumer(s)
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Pub/Sub example of Brokered NotificationBroker
receives subscriptions and redirects notifications
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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?

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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

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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
• Notification message schema
• Semantic information
• Could be used as part of an access control scheme
  or in conjunction with WS Agreement?

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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

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More information on WS-N

• WS-RF and WS-N Update at GGF11- June 8th 1230PM
  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.