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Oracle Workflow can call the selector/callback function with the following commands:

• RUN--to select the appropriate process to start when either of the following two conditions occur:

• A process is not explicitly passed to WF_ENGINE.CreateProcess.

• A process is implicitly started by WF_ENGINE.CompleteActivity with no prior call to WF_ENGINE.CreateProcess.

• SET_CTX--to establish any context information that a function activity in an item type will need to execute, just before it executes a function activity in a new database session.

• TEST_CTX--to determine if a form can be launched with the current context information just before the Oracle Applications Notification Viewer form launches a reference form. If the context is incorrect, the form cannot be launched and a message is displayed to that effect. See: Reviewing Notifications in the Notification Viewer Form.

1->	procedure <procedure name> (			item_type	in varchar2,
				item_key	in varchar2,
				activity_id	in number,
				command	in varchar2,
				result	in out varchar2) is
2->	<local declarations>
3->	begin
	if ( command = 'RUN' ) then
	<your RUN executable statements>
	resultout := '<Name of process to run>';
	return;
	endif;
4->	if ( command = 'SET_CTX' ) then
	<your executable statements for establishing context information>
	return;
	end if;
5->	if ( command = 'TEST_CTX' ) then
	<your executable statements for testing the validity of the current context information>
	resultout := '<TRUE or FALSE> ';
	return;
	endif;
6->	if ( command = '<other command>' ) then
	resultout := ' ';
	return;
	endif;
7->	exception
	when others then
	WF_CORE.CONTEXT ('<package name>', '<procedure name>', <itemtype>, <itemkey>,
	to_char(<actid>), <command>);
	raise;
8->	end <procedure name>;

1-> When the Workflow Engine calls the selector/callback function, it passes four parameters to the procedure and may expect a result when the procedure completes. The parameters are defined here:

	itemtypeThe internal name for the item type. Item types are defined in the Oracle Workflow Builder.
itemkey	A string that represents a primary key generated by the workflow-enabled application for the item type. The string uniquely identifies the item within an item type.
actid	The ID number of the activity that this procedure is called from. Note that this parameter is always null if the procedure is called with the 'RUN' command to execute the selector functionality.
command	The command that determines how to execute the selector/callback function. Either 'RUN', 'SET_CTX', or 'TEST_CTX'. Other commands may be added in the future.
result	A result may be returned depending on the command that is used to call the selector/callback function.
	If the function is called with 'RUN', the name of the process to run must be returned through the result parameter. If the function is called with 'SET_CTX', then no return value is expected. If the function is called with 'TEST_CTX', then the code must return 'TRUE' if the context is correct or 'FALSE' if the context is incorrect. If any other value is returned, Oracle Workflow assumes that this command is not implemented by the callback.

2-> This section declares any local arguments that are used within the procedure.

3-> The procedure body begins in this section with an IF statement. This section contains one or more executable statements that make up your selector function. It executes if the value of command is 'RUN'. One of the executable statements should return a result for the procedure that reflects the process to run. For example, a result can be 'REQUISITION_APPROVAL', which is the name of a process activity.

4-> .This section contains one or more executable statements that set item type context information if the value of command is 'SET_CTX'. The Workflow Engine calls the selector/callback function with this command just before it begins to execute a function activity in a new database session. This command is useful when you need to set item type context in a database session before the activities in that session can execute as intended. For example, you might need to set up the responsibility and organization context for function activities that are sensitive to multi-organization data.

5-> .This section contains one or more executable statements that validate item type context information if the value of command is 'TEST_CTX'. The Workflow Engine calls the selector/callback function with this command to validate that the current database session context is acceptable before the Workflow Engine executes an activity. For example, this callback functionality executes when the Oracle Applications Notification Viewer form is just about to launch a reference form. The code in this section should return 'TRUE' if the context is correct, and 'FALSE' if the context is incorrect. If the context is incorrect, you can raise an exception and place a message in the WF_CORE error system to indicate the reason the context is invalid. The raised exception is also printed in an error message in the form.

5->This section handles execution modes other than 'RUN', 'SET_CTX' or 'TEST_CTX' as others may be added in the future. Since your function does not need to implement any of these other possible commands, it should simply return null.

6->This section calls WF_CORE.CONTEXT( ) if an exception occurs, so that you can include context information in the error stack to help you locate the source of an error. See: CONTEXT.