Understanding WAS V8.5 Publish Subscribe

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WebSphere^® Support Technical Exchange

Ask the Experts

Understanding WAS V8.5 Publish Subscribe

21 August 2013

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WebSphere^® Support Technical Exchange 22

Agenda

Introduce the panel of experts

^IntroduceSIB Publish/Subscribe Topics

Answer questions submitted by email (5 questions)

Open telephone lines for questions

Summarize highlights

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Panel of Experts

Panelist Role at IBM

Paul O'Donnell Senior Software Engineer Jhansi Kolla Staff Software Engineer

Padmashree Sampathkumar

Software Developer

Anil K Maddipatla Software Developer

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Introduction

In our discussion today, we would be covering a brief introduction to Publish Subscribe mechanism and the common questions around:

Topics and Topic Spaces

Remote Publication Points

Broker Profiles

Message flow

This presentation is applicable for all platforms and all

version of WebSphere Application Server V6.0 and above.

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Question 1

How do Topics and Topic Spaces relate to each other?

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Answer to Question 1

Topic is the JMS destination for Publish/Subscribe.

Topic space is the SIBus destination for the Publish/Subscribe.

A topic space is a hierarchy of publish/subscribe topics across the SIBus.

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Answer to Question 1 (continued)

Topic space is defined for the whole bus and is owned by the Bus.

When a topic space is created in a Bus, a publication point gets automatically created on each messaging engine in that Bus

.

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Question 2

What is the difference between Remote Publication Points and Known Remote Publication Points?

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Answer to Question 2

A Remote Publication Point is a Publication Point of a remote messaging engine to which the messages published locally are sent.

A Known Remote Publication Point (KRPP):

Is a publication point on a remote messaging engine

Has a publishing application connected to it

Sends messages to the local messaging engine

KRPPs can be viewed through the admin console here:

Service integration -> Buses -> bus_name -> [Topology] Messaging engines -> engine_name ->

Runtime -> [Message Points] Publication points -> identifier_name -> Runtime -> [Additional Properties] Known remote publication points

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Answer to Question 2 (continued)

In this example, ME1 is the Known Remote Publication Point from the perspective of ME2 and ME3

ME2 and ME3 are the

Remote Publication Points to ME1.

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Question 3

How are Topic space Mappings used?

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Answer to Question 3

A Topic Space Mapping (TSM) allows a subscriber to receive messages that are published on a foreign bus.

The foreign bus can be adjacent, or indirectly connected through a hierarchy of buses and TSMs.

TSMs are unidirectional

TSMs are created using the bus link creation wizard. Check this box on the “Foreign bus details” panel:

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Answer to Question 3 (continued)

Subscriber on bus 1 receives publications from publisher on bus 2

Subscribers on buses 2 and 3 receive publications from publishers on buses 2 and 3, through bus 1

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Question 4

What is a Publish Subscribe Broker Profile?

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Answer to Question 4

Bridge between WebSphere Application Server and a message broker in WebSphere MQ.

Publish subscribe messaging on a WebSphere MQ link.

Multiple profiles to connect to multiple queue managers.

Topic mapping for broker profile

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Question 5

What happens to a message when it is published?

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Answer to Question 5 (continued)

There are four message flow scenarios in the SIB Publish/Subscribe model -

Subscriber is connected to the same ME where publisher is connected.

Subscriber is connected to the remote ME with in the same Bus.

Subscriber is connected to the remote Bus.

Remote subscribers.

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Subscriber1 is connected to the same ME.

Subscriber2 is connected to the different ME with in the same Bus

Subscriber3 is connected to the remote Bus

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Answer to Question 5 (continued)

Remote Subscribers

Durable subscriber registered to one ME and later connect to a different ME to get the

messages.

Messages are routed to the ME where durable subscription home is registered.

The subscribing application would access its subscription through a remote subscription.

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Open Lines for Questions

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Summary

High level points of presentation

High level points of presentation:

Difference between topic and topic space.

What is a publication point, difference between the Remote Publication Point and Known Remote Publication Point.

Topic space mappings.

Publish Subscribe Broker Profile.

End to end message flow in pub/sub messaging model.

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References and Useful Links (Optional)

Reference 1:

http://www.ibm.com/developerworks/websphere/community/

Reference 2:

http://www.ibm.com/software/websphere/events_1.html

Reference 3:

http://www.websphere.org

Reference 4:

http://www.ibm.com/software/info/education/assistant

Reference 5:

http://www.ibm.com/software/websphere/support/d2w.html

Reference 6:

http://www.ibm.com/software/support/einfo.html

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