com.netscape.pm.model
Interface ISimpleWorkPerformer

public interface ISimpleWorkPerformer

This interface defines a custom activity that gets data field values, performs a task, and finishes up by setting data field values in a process instance. Apart from accessing data field values as input, and setting values when it finishes, the ISimpleWorkPerformer class does not have any other access to information on the work item or the process instance. The perform method is where you define the main body of work that the activity accomplishes.

Method Summary

void	destroy() This method does any cleaning up that is needed when the application that uses the custom activity is unloaded.
void	init(java.util.Hashtable env) This method performs initialization tasks required by the custom activity when the application starts.
void	perform(java.util.Hashtable in, java.util.Hashtable out) This method performs whatever tasks the activity needs to do.

Method Detail

init

public void init(java.util.Hashtable env)
          throws java.lang.Exception

This method performs initialization tasks required by the custom activity when the application starts. The init method is not executed each time a custom activity is created in a process instance -- it is invoked only once when the application starts. You would use the init method to do things like set up database connections that are shared by all instances of the activity, or to define variables that are constant across all instances of the activity.

It takes a hashtable of environment variables as its input argument. This hashtable is automatically passed to it when it is invoked. The parameters in the hashtable are defined in an XML description file.

The values of the parameters in the hashtable are determined by the process designer when creating the process map. For example, if the environment hash table includes a parameter Language, then when the process designer opens the properties editor for the custom activity in the Builder, they see a property called Language. Note that Language is not a data field -- it is a property of the custom activity.

Define the init method to perform whatever initialization tasks are desired. To get the value of a parameter in the environment hashtable, call the get method on the environment hashtable. The get method returns the value of the parameter, or null if there is no such parameter. For example:

public void init( Hashtable environment ) throws Exception { String lang = (String) environment.get( "Language" );

Note: because of the lack of types in XML, all the values of the hashtable are strings.

Parameters:

env - a hashtable that contains an element for each ENVIRONMENT entry of the XML file

Throws:

java.lang.Exception - any exception will prevent the application from loading itself.

Since:

PAE 4.0

perform

public void perform(java.util.Hashtable in,
                    java.util.Hashtable out)
             throws java.lang.Exception

This method performs whatever tasks the activity needs to do. This method is invoked each time a process instance reaches this activity. The implementation of this method has to be multi-threaded.

The input hashtable contains values taken from data fields, and the output hashtable contains values to put into data fields.

To get the value of a parameter in the input hashtable, call the get method on the input hashtable. This method returns the value of the parameter, or null if there is no such parameter.

To set data field values, call put on the output hashtable. When the perform method has finished executing, the values in the output hashtable are automatically inserted into the appropriate data fields according to the mapping information in the XML description file.

Example of perform()

This example gets the name of the user from a data field in the process instance (exactly which data field is determined by the XML description file) and puts a value in the WelcomeMsg parameter of the output hashtable. This greeting is inserted automatically into a data field, whose exact identity is again determined by the XML description file. public void perform( Hashtable input, Hashtable output ) throws Exception { // Get the value of the UserName parameter of the input hashtable. // String userName = (String) input.get( "UserName" ); // Throw an exception if no user name is available. // if( userName == null ) { throw new Exception( "UserName has not been initialized!" ); } // Generate a greeting. // String msg = "Hello " + userName; // Put the greeting into the WelcomeMsg parameter of // the output hashtable. // output.put( "WelcomeMsg", msg ); }

The XML description file specifies the parameters in the input hashtable, and indicates which data field provides the value for each parameter. The same file also specifies the parameters in the output hashtable, and indicates how the values of the output parameters are mapped back into data fields in the process instance.

Parameters:

in - a hashtable of input parameters that usually contain values of data fields in the process instance

out - a hashtable of output parameters that the work performer generates

Throws:

java.lang.Exception - all exceptions will be mapped to the exception nodes based on the exception mapping defined in the XML file.

Since:

PAE 4.0

destroy

public void destroy()

This method does any cleaning up that is needed when the application that uses the custom activity is unloaded. Typically this method would clean up resources that were allocated by the init method.

Since:

PAE 4.0