WebSphere Message Brokers
File: ac04590_
Writer: Terry Cowling

Reference topic

This build: July 31, 2007 21:17:24

Publication node

This topic describes the Publication node.

This topic contains the following sections:

Purpose

Use the Publication node to filter output messages from a message flow and transmit them to subscribers who have registered an interest in a particular set of topics. The Publication node must always be an output node of a message flow and has no output terminals of its own.

Use the Publication node (or a user-defined node that provides a similar service) if your message flow supports publish/subscribe applications. Applications that expect to receive publications must register a subscription with a broker, and can optionally qualify the publications that they get by providing restrictive criteria (such as a specific publication topic).

If your subscriber applications use the WebSphere MQ Enterprise Transport to connect to the broker, you can define the queues to which messages are published as WebSphere MQ clustered queues or shared queues.

Publications can also be sent to subscribers within a WebSphere MQ cluster if a cluster queue is nominated as the subscriber queue. In this case, the subscriber should use the name of an "imaginary" queue manager that is associated with the cluster, and should ensure that a corresponding blank queue manager alias definition for this queue manager is made on the broker that satisfies the subscription.

The Publication node is contained in the Routing drawer of the palette, and is represented in the workbench by the following icon:

Publication node icon

Using this node in a message flow

Look at the following samples to see how to use this node:

You can view samples only when you use the information center that is integrated with the Message Brokers Toolkit.

For an example of how to use this node, assume that you have written a publishing application that publishes stock updates on a regular basis. The application sends the messages to the broker on an MQInput node, and the message flow provides a conversion from the input currency to a number of output currencies. Include a Publication node for each currency that is supported, and set the Subscription Point to a value that reflects the currency in which the stock price is published by the node; for example, Sterling, or USD.

Configuring the Publication node

When you have put an instance of the Publication node into a message flow, you can configure it; see Configuring a message flow node. The properties of the node are displayed in the Properties view.

All mandatory properties for which you must enter a value (those that do not have a default value defined) are marked with an asterisk.

Configure the Publication node as follows:

  1. On the Description tab. enter a short description, a long description, or both. You can also rename the node on this tab.
  2. On the Basic tab:
    1. Select Implicit Stream Naming to take the name of the WebSphere MQ queue on which the message was received by the message flow as the stream name. This property provides forward compatibility with WebSphere MQ Publish/Subscribe, and applies to messages with an MQRFH header when MQPSStream is not specified.

      Clear the check box if you do not want this action to be taken.

    2. Specify the Subscription Point for this Publication node. If you do not specify a value for this property, the default subscription point is assumed. This value uniquely identifies the node, and can be used by subscribers to get a specific publication (as described in the example scenario above).

      For more information, see Subscription points.

Terminals and properties

The Publication node terminals are described in the following table.

Terminal Description
In The input terminal that accepts a message for processing by the node.

The following tables describe the node properties. The column headed M indicates whether the property is mandatory (marked with an asterisk if you must enter a value when no default is defined); the column headed C indicates whether the property is configurable (you can change the value when you add the message flow to the bar file to deploy it).

The Publication node Description properties are described in the following table.

Property M C Default Description
Node name No No The node type. For example, Input The name of the node.
Short Description No No   A brief description of the node.
Long Description No No   Text that describes the purpose of the node in the message flow.

The Publication node Basic properties are described in the following table.

Property M C Default Description
Implicit Stream Naming Yes No Cleared If you select this check box, the name of the WebSphere MQ queue on which the input message was received is taken as the stream name.
Subscription Point No No   The subscription point value for the node.
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This build: July 31, 2007 21:17:24

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