Copyright © Cloud Software Group, Inc. All Rights Reserved

Java Event Source

Process Starter

The Java Event Source allows you to create a custom process starter written in Java. For example, you may want to start a TIBCO ActiveMatrix BusinessWorks process when an application inserts a row into a database table. Your custom process starter would observe the database for insert events, then call the onEvent() method with the desired data as input when an insert occurs. The Java Event Source process starter creates a process when the onEvent() method is invoked and the object passed to the method is passed to the process definition.

This process starter uses an abstract class to define the interface. You can either write and compile your custom Java code in your own code editor and upload the class to TIBCO ActiveMatrix BusinessWorks, or you can use the Code tab to add your implementation code to the appropriate methods. See JavaProcessStarter Abstract Class for more information about the methods required by this class.

If you want to use the Edit Class button on the Code tab, select Edit>Preferences>Other to specify the Java editor you want to use to edit source code. If you do not specify an editor, a simple popup editing window is provided.

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.
Use External Class	No	When this field is checked, the Code tab is disabled, and you must load the class using the Class Library and Class fields. When this field is unchecked, you must add your code to the appropriate methods on the Code tab.
Java	No	This field contains the Class Library, Class, and Init Method fields that allow you to specify which class and method to use.
Class 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 compiled Java class that implements the JavaProcessStarter abstract class. Use the Show Class Browser button to select the class from the specified Class Library.
Init Method	No	The init() method for the class. This field is automatically populated when you use the Show Class Browser button. See JavaProcessStarter Abstract Class for more information about the init() method. 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.
Init Method Parameters	No	This table allows you to specify default values for the input parameters of the init() method. Each input parameter has three fields: • Parameter Name — Name of the parameter. • Parameter Type — Datatype of the parameter. • Parameter Value — Specify a default value for the parameter.

JavaProcessStarter Abstract Class

The JavaProcessStarter abstract class defines the interface of your Java Process Starter with the TIBCO ActiveMatrix BusinessWorks process engine. You must define an implementation for the following methods:

•

init() — this method is called when the process engine starts up. This method should initialize any resource connections. You could also specify a Java Global Instance on the Advanced tab that initializes resource connections. Java Global Instances are also loaded and initalized during process engine start up. You can call this.getJavaGlobalInstance() to obtain the Java Global Instance resource in your process starter code.

•	onStart() — this method is called by the process engine to activate the process starter. This method should activate any event notifier or resource observer code. The notifier or observer code can then call the onEvent() method to start a process instance.

•	onStop() — this method is called by the process engine to deactivate the process starter. This method should deactivate any event notifier or resource observer code.

•	onShutdown() — this method is called by the process engine when the engine shuts down. This method should release any resources and resource connections and perform any required clean up operations.

The following methods are already implemented and can be used in your code:

•	onEvent(Object object) — this method is called when a listener or resource observer catches a new event. The input to this method is a Java object containing the event data.

•

getGlobalInstance() — this method returns an object reference to the Java Global Resource specified on the Advanced tab of the process starter. This is useful if you want to place initialization code or other shared information in a Java Global Resource instead of in the init() method of this class.

•	onError() — this method throws the exception specified in the input parameter. Use this method to propagate an error to the TIBCO ActiveMatrix BusinessWorks process instance when a listener or resource observer fails to generate an event.

Code

This tab is only enabled if the Use External Class field is unchecked. This tab allows you to add implementation code to the appropriate methods of the JavaProcessStarter class. You can choose to display the full Java class or display a particular method by selecting the appropriate value in the Show field at the top right of the Code tab.

The code tab has the following fields/buttons.

Field/Button	Description
Source Code	The source code of the JavaProcessStarter implementation class.
Show	Displays the selected method or the entire class. The following are valid options to select: • init • onStart • onStop • onShutdown • Entire Class
Compile Button	Compiles the current source code. When the code in the activity needs compilation (for example, the code changes), a yellow warning icon appears on this button. The code will either compile successfully or the View Errors dialog will appear to display any errors in the code. After compilation, the source and compiled java code are placed into the lib/palettes/javaCode directory in the TIBCO ActiveMatrix BusinessWorks installation directory.
View Errors Button	Displays the errors encountered when the code was compiled.
Edit Class Button	Displays the source code in the editor specified with the TIBCO Designer preferences. If no editor is specified, a simple popup editing window is used. Use Edit>Preferences>Other to specify the Java editor you want to use to edit source code. Note: On MS Windows platforms, a temporary file is created to hold the Java code when you edit your code with this button. This file is located in either C:\temp or C:\tmp or your working directory. If your working directory contains a space (for example C:\Documents and Settings\...), there may be problems opening the temporary file. Make certain either the C:\temp or C:\tmp directory exists to avoid this issue.

Compiling Java Code

You can compile each Java Code activity and Java Process Starter resource individually with the Compile button on the Code tab, or you can compile all Java Code and Java Process Starter resources in your project at once with the Tools > Java Code > Compile All Code menu item.

When you use the Compile All Code menu item, the Compile All Code dialog appears. Figure 13 illustrates this dialog.

Figure 15 Compile All Code dialog

 

 

All process definitions containing Java Code activities and Java Process Staters that do not compile successfully are listed in the Activities area. Each Java Code activity or Java Process Starter is listed under the process definition in which it is located. You can select any Java Code activity or Java Process Starter in the Activities area to display the compilation errors for that activity.

The dialog has the following buttons:

•	Start/Cancel Compile — Click Start Compile to begin compiling all Java Code activities and Java Process Starters in your project. When the code is compiling, this button is renamed Cancel Compile to allow you to cancel the compile all operation.

•	Go To Resource —You can select any process definition, Java Process Starter, or Java Code activity, then click the Go To Resource button to display that resource in the design and configuration panels.

•	Close — Closes the Compile All Code dialog.

Advanced

The Advanced tab has the following fields:.

Field	Global Var?	Description
Java Global Instance	No	A Java Global Instance resource. Specify a value in this field if you want to reference a Java Global Instance resource in your JavaProcessStarter implementation class. You can use the getGlobalInstance() method to obtain a reference to the Java Global Instance resource. See Java Global Instance for more information about Java Global Instance resources.
Convert Output Object To XML	No	When this field is unchecked, the object passed to the onEvent() method is output by this process starter as a Java object reference. You can use the Java To XML activity to render the Java object as an XML tree, if desired. Check this field if you want the data of the input object to the onEvent() method to be converted to an XML tree in this process starter’s output. For the output to be returned as an XML tree, the output object type must be specified. To achieve this, you must add the getOutputObjectType() class to your implemenntation class. For example, the output can be a string:   public Class getOutputObjectType() {    return String.class; } Then, the object you pass into the input parameter of the onEvent() method must be a String.

Misc

The Misc tab contains the following fields:

Field	Description
Sequencing Key	This field can contain an XPath expression that specifies which processes should run in order. Process instances with sequencing keys that evaluate to the same value will be executed sequentially in the order the process instance was created. See TIBCO ActiveMatrix BusinessWorks Process Design for more information about controlling the execution order of process instances and about XPath expressions.
Custom Id	This field can contain an XPath expression that specifies a custom ID for the process instance. This ID is displayed in the View Service dialog of TIBCO Administrator, and it is also available in the $_processContext process variable.

Output

The output for the activity is the following.

Output Item	Datatype	Description
javaObject or Object	varies	The Java object that was passed to the onEvent() method. By default, this element is a Java object reference. If the Convert Output Object to XML field is checked on the Advanced tab and the output class is specified in your implementation class, the output is represented as an XML tree.

Error Output

The Error Output tab lists the exceptions that can be thrown by the Java Event Source resource. Because the resource can return any Java exception, all potential exceptions cannot be listed here. However, the error schema for all errors is the same. The following describes the schema for exceptions returned by the Java Event Source resource.

Error Schema Element	Datatype	Description
msg	string	The TIBCO ActiveMatrix BusinessWorks error message. See TIBCO ActiveMatrix BusinessWorks Error Codes for more information.
msgCode	string	The TIBCO ActiveMatrix BusinessWorks error code. See TIBCO ActiveMatrix BusinessWorks Error Codes for more information.

Copyright © Cloud Software Group, Inc. All Rights Reserved