This topic contains sections marked as revised for this release

WebSphere Message Brokers
File: ac04800_
Writer: Terry Cowling

Reference topic

This build: July 31, 2007 21:17:39

Label node

The Label node receives a message that is propagated by a RouteToLabel node to dynamically determine the route that the message takes through the message flow.

This topic contains the following sections:

Purpose

Use the Label node in combination with a RouteToLabel node to route that a message through the message flow based on message content. The RouteToLabel node interrogates the LocalEnvironment of the message to determine the identifier of the Label node to which the message must be routed next. You can propagate the message by coding ESQL in a Compute node, or by coding Java™ in a JavaCompute or user-defined node.

Precede the RouteToLabel node in the message flow with a Compute node or JavaCompute node and populate the LocalEnvironment of the message with the identifiers of one or more Label nodes that introduce the next sequence of processing for the message.

Design your message flow so that a Label node logically follows a RouteToLabel node within a message flow, but do not connect it physically to the RouteToLabel node. The connection is made by the broker, when required, according to the contents of LocalEnvironment.

The Label node provides a target for a routing decision, and does not process the message that it handles in any way. Typically, a Label node connects to a subflow that processes each message in a specific way, and either ends in an output node or in another RouteToLabel node.

The Label node can also be used as the target of a PROPAGATE statement, which is specified in a Compute or Database node.

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

Label node icon

Using this node in a message flow

Look at the following sample 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.

Configuring the Label node

When you have put an instance of the Label 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 Label node as follows:

  1. Optional: 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, there is a single mandatory property for the Label node, Label Name, which identifies a target for a RouteToLabel node. Label Name must not be the same as the name of the instance of the node itself, and it must be unique within the message flow in which it appears. The name of the instance can be modified by the workbench if the subflow, of which this Label node is a part, is embedded into another message flow.

Terminals and properties

The Label node terminals are described in the following table.

Terminal Description
Out The output terminal to which the message is routed.

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 Label node Description properties are described in the following table.

Property M C Default Description
Node name No No The node type 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 Label node Basic properties are described in the following table.

Property M C Default Description
Label Name Yes No   An identifier for the node. It is used as a target for a message routed by a RouteToLabel node.
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This build: July 31, 2007 21:17:39

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