When you include a node in your message flow that requires ESQL to customize its function (the Compute, Database, and Filter nodes), you must code the ESQL statements that provide the customization in an ESQL module within an ESQL file. You can use the same ESQL file for more than one module, if you choose.
Before you start
To complete this task, you must have completed the following task:
ESQL files are stored in a file system or in a shared repository. If you are using a file system, this can be the local file system or a shared drive. If you store files in a repository, you can use any of the available repositories that are supported by Eclipse, for example CVS.
To create an ESQL file:
You can also press Ctrl+N. This displays a dialog that allows you to select the wizard to create a new object. Click Message Brokers in the left view; the right view displays a list of objects that you can create for WebSphere Business Integration Message Broker. Click Message Flow ESQL File in the right view, then click Next.
The New Message Flow ESQL File wizard is displayed.If you type in the name of a project that does not exist, the error message The specified project does not exist is displayed in the dialog and you cannot continue until you specify a valid project name.
When
creating ESQL files, the overall file path length must not exceed 256 characters,
due to a Windows file system limitation. If you try to add a message flow
to a broker archive file with ESQL or mapping files with a path length that
exceeds 256 characters, the compiled message flow will not be generated and
cannot be deployed. Therefore, make sure that the names of your ESQL files,
mapping files, projects, and broker schema are as short as possible.
An ESQL file can also be created automatically for you. If you select Open ESQL from the menu displayed when you right-click a Compute, Database, or Filter node, and the module identified by the appropriate property does not already exist within the broker schema, a module is automatically created for you. This is created in the file <message_flow_name>.esql in the same broker schema within the same project as the <message_flow_name>.msgflow file. If that ESQL file does not already exist, that is also created for you.
The contents of a single ESQL file do not have any specific relationship with message flows and nodes. It is your decision which modules are created in which files (unless the specified module, identified by the appropriate property, is created by default in the file <message_flow_name>.esql as described above). Monitor the size and complexity of the ESQL within each file, and split the file if it becomes difficult to view or manage.
If you create reusable subroutines (at broker schema level) within an ESQL file, you might want to refer to these routines from ESQL modules in another project. To do this, specify that the project that wants to invoke the subroutines depends on the project in which the ESQL file containing them is defined. You can specify this when you create the second project, or you can update project dependencies by selecting the project, clicking Properties, and updating the dependencies in the Project Reference page of the properties dialog.
Related concepts
Project references
Development repository
Message flows
Mappings
Broker schema
ESQL modules
Related tasks
Developing message flow applications
Related reference
Built-in nodes
ESQL
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