Throw node

Use the Throw node to throw an exception in a message flow.

The Throw node is available in the following operation modes:
  • Developer
  • Application Integration Suite
  • Standard
  • Advanced
  • Express
  • Scale
For more information, see Operation modes.

This topic contains the following sections:

Purpose

An exception can be caught and processed by:

  • A preceding TryCatch node
  • The message flow input node (the built-in nodes, for example HTTPInput and MQInput, have Catch terminals)
  • A preceding AggregateReply node

Include a Throw node to force an error path through the message flow if the content of the message contains unexpected data. For example, to back out a message that does not contain a particular field, you can check (using a Filter node) that the field exists; if the field does not exist, the message can be passed to a Throw node that records details about the exception in the exception list subtree in the message.

The Throw node is contained in the Construction drawer of the palette, and is represented in the IBM® Integration Toolkit by the following icon:

Throw node icon

Using this node in a message flow

Include a Throw node with a TryCatch node in your message flow to alert the systems administrator of a potential error situation; for example, if you have a Compute node that calculates a number, test the result of this calculation and throw an exception if the result exceeds a certain amount. The TryCatch node catches this exception and propagates the message to a sequence of nodes that process the error.

Terminals and properties

When you have put an instance of the Throw 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.

The Throw node terminal is 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 Throw node Description properties are described in the following table.

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

Property M C Default Description
Message Catalog No No   The name of the message catalog from which the error text for the error number of the exception is extracted. Enter the fully-qualified path and file name of the message catalog that contains the message source. This file can be your own message catalog, or the default message catalog that is supplied with IBM Integration Bus. To use the default supplied catalog, leave this property blank.
Message Number No No 3001 The error number of the exception that is being thrown.
  • If you have created your own message catalog, enter the number for the message in the catalog that you want to use when this exception is thrown.
  • If you are using the default message catalog, specify a number between 3001 (the default) and 3049. These numbers are reserved in the default catalog for your use. The text of each of these messages in the default message catalog is identical, but you can use a different number in this range for each situation in which you throw an exception; use the number to identify the exact cause of the error.
Message Text No No   Additional text that explains the cause of the error. Enter any additional free format text that contains information that you want to include with the message when it is written to the local error log; for example, if you have checked for the existence of a particular field in a message and thrown an exception when that field is not found, you might include the text: 
The message did not contain the required field: Branch number
If you are using the default message catalog, this text is inserted as &1 in the message text.
The Monitoring properties of the node are described in the following table.
Property M C Default Description
Events No No None Events that you have defined for the node are displayed on this tab. By default, no monitoring events are defined on any node in a message flow. Use Add, Edit, and Delete to create, change or delete monitoring events for the node; see Configuring monitoring event sources by using monitoring properties for details.

You can enable and disable events that are shown here by selecting or clearing the Enabled check box.