Before you start:
To work with mappings, use the Message Brokers Toolkit for WebSphere Studio and create a message flow project as described in Creating a message flow project.
This topic area describes the tasks that are involved in creating and maintaining mappings.
The name of the mapping files created is of the form flowname_nodename. For example, if you launch the Message Flow Mapping editor from a new Mapping node called Mapping in a flow called topflow, the mapping file's name is topflow_Mapping.mfmap. If there is another Mapping node in the same flow called Mapping1, launching the editor from this node opens the file topflow_Mapping1.mfmap, because the root file topflow_Mapping1 is distinct from topflow_Mapping.
The Message Flow Mapping editor is populated using information from schema files, and shows message or database structures in the form of a tree. Nesting levels of message structures with possibly recursive data types can be infinite. Mapping information is stored in a resource that is separate from the resource containing the message flow information, and mapping resources are visible in the Resource Navigator view.
Fields that have been mapped are highlighted with a small arrow to the left of the field name. If a previously-mapped input or output no longer exists in a message or database definition, it is described as unresolvable in the task list.
The namespace prefixes are needed when mapping something that involves a target namespace. You can also add or modify broker schema paths so that a mapping statement can refer to an ESQL subroutine in another broker schema without having to use the fully-qualified path. The Organize Schema References option is used to automatically generate schema paths. You can also use the Outline view to rename the mapping routine. Each Mapping node is associated with a named mapping routine and, although they share the same name initially, the mapping routine and mapping file are independent.
This is useful when a mapping routine involves multiple messages, because it allows you to specify the message to be set as the output message body. However, if the mapping routine contains one output message only, you still need to set the message to be the output message body if the output message is different from the input message.
The order of mapping statements in the resulting mapping ESQL routine (and consequently, their execution order) is determined by the order of mapping targets (message elements and database table columns). In cases where there are multiple message mapping routines on the target side, one of them can be declared as the resulting message body in the mapping editor. This means that the other message mapping routines represent the resulting message headers and ESQL statements corresponding to these message mapping routines are generated first in the resulting mapping ESQL procedure (see Mapping and ESQL).
If there are multiple mappings with the same target, an ESQL statement is generated for each mapping. The order of generated statements in this case is undefined; the target item value might be overridden and the resulting value will be the one corresponding to the last mapping.
In mapping objects, mapping editors, and mapping expression composers, the notation "I#" (including double quotes) is used as the index for a repeating structure. This index is displayed as I# (without double quotes) in the debugger variable view and in error or warning messages. To avoid unexpected results, do not use double quotes in the name of a message element, message attribute, or a database table.
Related concepts
Mappings
Mapping types
Message mapping
Namespaces
Correlation names
Related tasks
Creating a mapping file
Configuring a mapping
Mapping and ESQL
Defining mappings
Related reference
Mappings
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