WebSphere Message Brokers
File: ac04720_
Writer: Terry Cowling

Reference topic

This build: July 31, 2007 21:17:34

Mapping node

This topic describes the Mapping node.

This topic contains the following sections:

Purpose

Use the Mapping node to construct one or more new messages and populate them with the following types of information:
  • New information
  • Modified information from the input message
  • Information taken from a database
You can modify elements of the message body data, its associated environment, and its exception list.

When you first open or create a message map for the node, if you select This map is called from a message flow node and maps properties and message body, the headers in the input message are always copied to the output message without modification. To modify the message headers in a Mapping node, select This map is called from a message flow node and maps properties, headers, and message body. When you select this property, the map that is created allows additional elements, including MQ, HTTP, and JMS headers, to be mapped.

These components of the output message can be defined using mappings that are based on elements of both the input message and data from an external database. You create the mappings that are associated with this node, in the mapping file that is associated with this node, by mapping inputs (message or database) to outputs. You can modify the assignments made by these mappings using supplied or user-defined functions and procedures; for example, you can convert a string value to uppercase when you assign it to the message output field.

Use the Mapping node to:

  • Build a new message
  • Copy messages between parsers
  • Transform a message from one format to another

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

Mapping 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 Mapping node

When you have put an instance of the Mapping 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 Mapping 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:
    1. Specify in Data Source the name by which the appropriate database is known on the system on which this message flow is to execute. The broker connects to this database with user ID and password information that you have specified on the mqsicreatebroker, mqsichangebroker, or mqsisetdbparms command.

      z/OS platform On z/OS systems, the broker uses the broker started task ID, or the user ID and password that were specified on the mqsisetdbparms command JCL, BIPSDBP in the customization data set <hlq>.SBIPPROC.

    2. Select the Transaction setting from the drop-down menu. The values are:
      • Automatic (the default). The message flow, of which the Mapping node is a part, is committed if it is successful; that is, the actions that you define in the mappings are performed and the message continues through the message flow. If the message flow fails, it is rolled back. If you choose Automatic, the ability to commit or rollback the action of the Mapping node on the database depends on the success or failure of the entire message flow.
      • Commit. To commit any uncommitted actions that are performed in this message flow on the database that is connected to this node, irrespective of the success or failure of the message flow as a whole, select Commit. The changes to the database are committed even if the message flow fails.
    3. In Mapping Routine, identify the mapping routine that is to be run in this node. By default, the name that is assigned to the mapping routine is identical to the name of the mappings file in which the routine is defined. The default name for the file is the name of the message flow concatenated with the name of the node when you include it in the message flow (for example, MFlow1_Mapping.mfmap for the first Mapping node in message flow MFlow1). You cannot specify a value that includes spaces.

      If you click Browse next to this entry field, a dialog box is displayed that lists all available mapping routines that can be accessed by this node. Select the routine that you want and click OK; the routine name is set in Mapping Module.

      To work with the mapping routine that is associated with this node, double-click the node, or right-click the node and click Open Mappings. If the mapping routine does not exist, it is created for you with the default name in the default file. If the file exists already, you can also open file <flow_name>_<node_name>.mfmap in the Broker Development view.

      A mapping routine is specific to the type of node with which it is associated; you cannot use a mapping routine that you have developed for a Mapping node with any other node that uses mappings (for example, a DataInsert node). If you create a mapping routine, you cannot call it from any other mapping routine, although you can call it from an ESQL routine.

      For more information about working with mapping files, and defining their content, see Developing message mappings.

    4. In Mapping Mode, specify the mode to use to process information that is being passed through the Mapping node. You can choose any combination of Message, LocalEnvironment, and Exception components to be generated and modified by the Mapping node.

      You must set this property to reflect accurately the output message format that you need. If you select an option (or accept the default value) that does not include a particular component of the message, that component is not included in any output message that is constructed.

      LocalEnvironment was known as DestinationList in some previous versions; it is retained for compatibility.

      The Environment component of the message tree is not affected by the mode setting. Its contents, if any, are passed on from this node.

      The options are explained in the table below.
      Mode Description
      Message (the default) The message is generated or passed through by the Mapping node, as modified within the node.
      LocalEnvironment The LocalEnvironment tree structure is generated or passed through by the Mapping node, as modified within the node.
      LocalEnvironment And Message The LocalEnvironment tree structure and message are generated or passed through by the Mapping node, as modified by the node.
      Exception The Exception List is generated or passed through by the Mapping node, as modified by the node.
      Exception And Message The Exception List and message are generated or passed through by the Mapping node, as modified by the node.
      Exception and LocalEnvironment The Exception List and LocalEnvironment tree structure are generated or passed through by the Mapping node, as modified by the node.
      All The message, Exception List, and LocalEnvironment are generated or passed through by the Mapping node, as modified by the node.
    5. For database warning messages to be treated as errors, and the node to propagate the output message to the failure terminal, select Treat Warnings as Errors. The check box is cleared initially.

      When you select the check box, the node handles all positive return codes from the database as errors and generates exceptions in the same way as it does for the negative, or more serious, errors. If you do not select the check box, the node treats warnings as normal return codes, and does not raise any exceptions. The most significant warning raised is not found, which can be handled safely as a normal return code in most circumstances.

    6. For the broker to generate an exception when a database error is detected, select Throw Exception on Database Error. The check box is selected initially. If you clear the check box, you must handle the error in the message flow to ensure the integrity of the broker and the database. The error is ignored if you do not handle it through your own processing, because you have chosen not to invoke the default error handling by the broker. For example, you could connect the Failure terminal to an error processing subroutine.
  3. On the Parser Options tab:
    1. Parse Timing is, by default, set to On Demand. This setting causes validation to be delayed until it is parsed by partial parsing. If you change this value to Immediate, partial parsing is overridden and everything in the message is parsed and validated, except those complex types with a composition of Choice or Message that cannot be resolved at the time. If you change this value to Complete, partial parsing is overridden and everything in the message is parsed and validated; complex types with a composition of Choice or Message that cannot be resolved at the time cause a validation failure.
    2. Select Use XMLNSC Compact Parser for XMLNS Domain and set the XMLNSCparser options to use the XMLNSC parser for messages in the XMLNS Domain.
  4. On the Validation tab, set the properties as described in Validation properties. Note that if a message is propagated to the Failure terminal of the node, it is not validated.

    For more details, see Validating messages.

Terminals and properties

The Mapping node terminals are described in the following table.

Terminal Description
In The input terminal that accepts a message for processing by the node.
Failure The output terminal to which the input message is propagated if a failure is detected during the computation. If you have selected Treat Warnings as Errors, the node propagates the message to this terminal if database warning messages are returned, even though the processing might have completed successfully.
Out The output terminal that outputs the message following the execution of the mappings.

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 Mapping 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 Mapping node Basic properties are described in the following table.

Property M C Default Description
Data Source No Yes   The ODBC data source name of the database in which reside the tables to which you refer in the mappings that are associated with this node (identified by the Mapping Module property).
Transaction Yes No Automatic The transaction mode for the node. Valid values are Automatic or Commit.
Mapping Routine Yes No Mapping The name of the mapping routine that contains the statements to execute against the database or the message tree. The routine is unique to this type of node.
Mapping Mode Yes No Message The mode used to process information that is passed through the Mapping node. Valid values are:
  • Message
  • LocalEnvironment
  • LocalEnvironment And Message
  • Exception
  • Exception And Message
  • Exception And LocalEnvironment
  • All
To construct a map that propagates multiple target messages, set this property to LocalEnvironment And Message to ensure that the node executes correctly.
Treat Warnings as Errors Yes No Cleared If you select the check box, database SQL warnings are treated as errors.
Throw Exception on Database Error Yes No Selected If you select the check box, database errors cause the broker to throw an exception.

The parser options for the Mapping node are described in the following table.

Property M C Default Description
Parse Timing Yes No On Demand This property controls when an input message is parsed. Valid values are On Demand, Immediate, and Complete.

For a full description of this property, see Parsing on demand.

Use XMLNSC Compact Parser for XMLNS Domain Yes No Cleared Setting this property causes the outgoing MQRFH2 to specify the XMLNS instead of XMLNSC parser, allowing an external application to remain unchanged. If outgoing messages do not contain MQRFH2 headers, this property has no effect.
Retain Mixed Content Yes No Cleared This property controls whether the XMLNSC parser creates elements in the message tree when it encounters mixed text in an input message. If you select the check box, elements are created for mixed text. If you clear the check box, mixed text is ignored and no elements are created.
Retain Comments Yes No Cleared This property controls whether the XMLNSC parser creates elements in the message tree when it encounters comments in an input message. If you select the check box, elements are created for comments. If you clear the check box, comments are ignored and no elements are created.
Retain Processing Instructions Yes No Cleared This property controls whether the XMLNSC parser creates elements in the message tree when it encounters processing instructions in an input message. If you select the check box, elements are created for processing instructions. If you clear the check box, processing instructions are ignored and no elements are created.

The Validation properties of Mapping node are described in the following table.

Property M C Default Description
Validate Yes Yes None This property controls whether validation takes place. Valid values are None, Content and Value, Content, and Inherit.
Failure Action Yes No Exception This property controls what happens if a validation failure occurs. You can set this property only if Validate is set to Content or Content and Value. Valid values are User Trace, Local Error Log, Exception, and Exception List.
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This build: July 31, 2007 21:17:34

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