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Java Global Instance

Shared Configuration

The Java Global Instance shared configuration resource allows you to specify a Java object that can be shared across all process instances in a Java Virtual Machine (JVM). When the process engine is started, an instance of the specified Java class is constructed. When the process engine is shut down, if specified, a cleanup method is invoked on the object and the object is released before the engine shuts down. Any Java Method activity can be configured to access the shared Java Global Instance when the process engine runs. Any Java Code activity can access the shared Java Global Instance by invoking the static methods of the configured Java class.

If multiple process instances access the shared Java Global Instance, you may want to ensure that only one process instance can access the object at a time. You can accomplish this by either declaring the methods of the configured class as synchronous or by using a critical section group. See TIBCO ActiveMatrix BusinessWorks Process Design for more information about using critical section groups.

Java class files or archives referenced by this resource must be available to the Java VM in which TIBCO Designer and the TIBCO ActiveMatrix BusinessWorks process engine are running. This is done either by adding the correct path to the classpath in the designer.tra and bwengine.tra files (see the comments in the .tra files for more information about modifying the classpath) or by using an Alias Library resource. If you add the path to the classpath, the system class loader loads the class into the Java VM. If you use an Alias Library resource, the TIBCO ActiveMatrix BusinessWorks application class loader loads the class into the Java VM. If both techniques are used, the class loaded by the system class loader takes precedence. Objects created from classes loaded by different class loaders are not able to interact. For example, an Alias Library resource points to the location of Java ClassA and a Java Method activity references ClassA. Java class ClassB is placed in the classpath and referenced by a Java Code activity. The Java Method activity can pass the ClassA object to the Java Code activity, but the ClassB object in the Java Code activity may not be able to interact with the ClassA object. If you want objects to interact correctly, ensure that the activities use the same class loader.

Configuration

The Configuration tab has the following fields.

Field	Global Var?	Description
Name	No	The name to appear as the label for the shared configuration resource.
Description	No	Short description of the resource.
Java	No	This field contains the Library, Class, and Method fields that specify the Java object to create.
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	Use the Show Class Browser button to locate the class you want to use.
Method	No	Select a constructor from the drop down list of constructors available for this class. This will be used to construct the class when the engine is started. This field displays only the default constructor (that is, the constructor with no parameters) or constructors that have only parameters of Java primitive types. You cannot create an object using a constructor that requires an object, array, or non-primitive type for a parameter.
Parameters Input	No	The input parameters for the constructor selected in the Method field. Each input parameter has three fields: • Parameter — Name of the parameter. • Type — Datatype of the parameter. • Value — Supply a value for the parameter in this field. Note: When string is the datatype for the parameter, do not use quotes around the string when entering the value.

Advanced

The Advanced tab has the following fields:.

Field	Global Var?	Description
Invoke Cleanup Method	No	When checked, this specifies that you want to invoke a method on the object before the object is released from memory when the process engine terminates. This allows you to perform cleanup activities, such as closing connections, releasing resources, 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 object in memory is released. The method selected cannot contain any parameters, therefore only methods without parameters are listed in this field. Any values returned by the selected method are ignored, but exceptions raised by the selected method are sent to the log.

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