Copyright © Cloud Software Group, Inc. All Rights Reserved

Java Method

Activity

The Java Method activity allows you to invoke a method contained in a Java class. You can construct an instance of the specified Java class, if you choose to invoke the constructor for the class.

The Java class file must be located in the classpath for TIBCO Designer and the TIBCO ActiveMatrix BusinessWorks process engine. Update the designer.tra and bwengine.tra file to contain the directory where your Java class files are located.

See Common Features of Java Code and Java Method for more information about features available in the Java Code activity.

Configuration

The Configuration tab has the following fields:

Field	Global Var?	Description
Name	No	The name to appear as the label for the activity in the process definition.
Description	No	Short description of the activity.
Java Global Instance	No	You can execute methods on shared Java objects created by Java Global Instance resources by specifying the resource in this field. See Java Global Instance for more information about the shared Java objects created by Java Global Instance resources. When a resource is specified in this field, the Library and the Class fields are automatically populated with the correct values from the Java Global Instance resource, and the fields on the Advanced tab become unavailable. You can select the method to execute in the drop down list in the Method field. Note: If the configuration of the Java Global Instance resource changes, you must select and view any Java Method activities in your process definitions that reference the Java Global Instance to automatically propagate the changes. An exception is raised if you attempt to test your process definitions before refreshing the reference to the Java Global Instance. You may need to manually update the mappings of any input or output if you select a new method with a different signature in the Java Global Instance resource.
Java	No	This field contains the Library, Class, and Method fields that allow you to specify which class and method to execute.
Library	No	Use this field to specify an AliasLibrary resource that is used to locate the Java class files. See TIBCO Designer Palette Reference for more information about AliasLibrary resources.
Class	No	The declared Java class whose method you want to execute. Use the Show Class Browser button to select the class and method, or use the Java Global Instance field to specify a shared Java object.
Method	No	The method in the selected Java class you want to execute. This field is automatically populated when you use the Show Class Browser button. You can use the drop down list to select a different method in the selected Java class, if desired. Note: You can hover the cursor over this field to display the signature of the selected method.

Advanced

The Advanced tab has the following fields:.

Field	Global Var?	Description
Construct Declared Class	No	This field controls whether the declaring class must be constructed when the activity is executed or whether an object reference must be supplied in the activity’s input schema. When this field is checked, the declaring class is constructed using the default constructor when the activity executes. In this case, the declaring class is not included in the activity’s input schema. When this field is unchecked, you must supply an object reference for the Java class specified on the Configuration tab. The object must be created and contained in the output schema of a previously executed activity, such as a Java Code activity, another Java Method activity, a RMI Server process starter, or an XML To Java activity. In this case, the declaring class is included in the activity’s input schema. This field is not available when a static method is selected.
Cache Constructed Class	No	This field is only available when the Construct Declared Class is checked. When checked, this specifies that all instances of this Java Method activity will share the instance of the constructed declaring class. If the constructed object is cached, it is kept in memory until the process engine terminates. If this field is unchecked, each instance of this Java Method activity creates its own copy of the declaring class. See Caching the Java Class for more information about caching the declared class.
Invoke Cleanup Method	No	This field is only available when the Cache Constructed Class field is checked. When checked, this specifies that you want to invoke a method on the cached object before the object is released from memory when the process engine terminates. This allows you to perform cleanup activities, such as closing connections, updating database tables, and so on. When this field is checked, the Cleanup Method field appears.
Cleanup Method	No	This field is only available when the Invoke Cleanup Method field is checked. This field allows you to specify the name of the method to invoke before the cached class in memory is released. The selected method cannot contain any parameters, therefore only methods with no parameters are listed in this field. Any values returned by the selected method are ignored, but any exceptions raised are sent to the log.

Caching the Java Class

When the Cache Constructed Class check box is selected on the Advanced tab, all instances of the same Java method activity share the same Java object. For example, each process instance that executes this Java Method activity will share the same instance of the class.

Also, if this activity is executed multiple times in a loop, each execution of this activity uses the same cached instance of the object. Figure 16 illustrates multiple processes and Java Methods in a group all sharing the same Java class.

If you choose to cache the constructed instance of the class, the same Java object is shared by Java Method activities that invoke methods on the class. Therefore, be aware of potential concurrency issues, if your class or its methods are not threadsafe.

Figure 16 Sharing a cached class

However, different instances of a Java Method activity that invoke methods on the same class do not share the instance of the object. For example, Figure 17 illustrates two Java Method activities in the same process definition, each executing different methods on the same Java object. However, each of these Java Method activities operate on their own instances of the inv class, if they both select the Cache Constructed Class check box.

Figure 17 Different Java Method activities in the same process do not share the class

In the process definition illustrated in Figure 17, for each process instance that is created, each time the inv.CheckInventory activity executes, it shares one instance of the inv object that has been cached. Similarly, each time the inv.DecreaseInv activity executes, it shares the instance of the inv object that the activity has cached. However, the inv.CheckInventory and inv.DecreaseInv activities do not share their cached Java objects with each other.

Input

See TIBCO ActiveMatrix BusinessWorks Process Design for more information about mapping and transforming input data.

The input for the activity is the following.

Input Item	Datatype	Description
<declaringClass>	Java Object	An object reference to the Java Class specified on the Configuration tab. This element is not shown when the method you want to invoke it static. Also, this element is only available when the Construct Declared Class field on the Advanced tab is unchecked.
MethodParameters	varies	This element contains a list of input parameters that are required for the Java method selected on the Configuration tab. This element is not available when the selected method has no parameters.

Output

The output for the activity is the following.

Output Item	Datatype	Description
MethodReturnValue	varies	The Output tab will have the return value specified for the Java method selected on the Configuration tab. This element is not available for methods that return void.

Error Output

The Error Output tab lists the exceptions that can be thrown by the invoked method. Once a method to invoke is selected, the exceptions that the method can throw are listed on the Error Output tab. Because a method can return any Java exception, the potential exceptions cannot be listed here.

While all potential errors cannot be known, the error schema for all errors is the same. The following describes the schema for exceptions returned by the Java Method activity.

Error Schema Element	Datatype	Description
<exceptionName>	complex	The fully-qualified name of the exception, including the Java package name. This is a container for the other elements.
<exceptionName>	Java Object	The Java exception object.
exceptionClassName	string	The exception class name. The value of this element is obtained by calling the <exception>.getClass().getName() method.
exceptionMessage	string	The exception message. The value of this element is obtained by calling the <exception>.getMessage() method.

 

Copyright © Cloud Software Group, Inc. All Rights Reserved