Adding business logic

Business logic is any Java code invoked as an action in an event, such as a screen customization. Business logic is specific to the application and is not provided as part of HATS.

You can add business logic to your project using the Create Business Logic wizard. To invoke this wizard, right-click in the HATS Project View tab of the HATS Studio, and select New HATS > Business Logic. You can also right-click in the Navigator tab of the HATS Studio, and select New > Other > Host Access Transformation Server > HATS Business Logic, and then click Next.

In the Create Business Logic wizard, specify the project to which you want to add the business logic and supply the fully-qualified Java class name. Optionally, you can supply a package name, or select an existing Java package by clicking Browse. If you want your business logic to have access to the project global variables, check the Get global variable checkbox. Click Finish when you have provided the required information.

You can see the business logic files in the project by expanding the Source folder on the HATS Project View tab of the HATS Studio. Each package name or class name appears in the Source folder. Expand the package name folder to see the Java class name. Double-click on the class name to edit the class.

If you use the Create Business Logic wizard to create business logic, the method is named "execute" by default. If you write your own class, the method must meet specific requirements:

• Marked public and static
• Have a return type of void
• Take a com.ibm.hats.common.BusinessLogicInfo object as the only parameter

The method must follow the form:

public static void myMethod (BusinessLogicInfo businesslogic)

followed by your own business logic code.

The BusinessLogicInfo object passed to your custom Java code enables you to access and use or modify various objects and settings of your HATS project. These include:

• The javax.servlet.http.HttpServletRequest class
• The javax.servlet.http.HttpServletResponse class
• The connection hashtable, which contains the settings for the connection information you provided for the application
• Class properties, which provide default settings for objects such as components and widgets
• The com.ibm.hats.common.GlobalVariable objects in the application
• The com.ibm.hats.common.HostScreen object, which contains "greenscreen" information
• The java.util.Locale class of the client
• The com.ibm.hats.common.TextReplacementList values and settings
• The client session identifier string
• The current screen orientation of bi-directional sessions
• The existence of the Screen Reverse button in the browser for bi-directional sessions.

For more information about the classes made available to you, see the Java documentation at the product Web site (http://www.ibm.com/software/webservers/hats) for the BusinessLogicInfo class.

Incorporating Java code from other applications

You can incorporate Java code from other existing applications into your HATS projects in a variety of ways.

If you want to incorporate the source code (.java files) from your existing business logic so you can modify the code, you can import the .java files into the Source folder in your existing project. Select File > Import > File System to open the Import wizard. In the Import wizard, select the location of your source files in the Directory field. Select the Source folder of your project in the destination Folder entry field. When your source .java files are imported, they are automatically compiled and packaged into your HATS project. You can also edit, set breakpoints, and debug your source files in the WebSphere Studio workbench.

You can also incorporate a Java archive (.jar) file with compiled Java business logic. This method imports the Java archive file into the .ear project. There will only be a single copy of the Java file in the .ear file, but it is available to all of the HATS projects contained in that .ear project. There are three steps to this method.

1. Import the .jar file into the HATS .ear project. Select File > Import > File System to open the Import wizard. Select the Java archive (.jar) you want to import in the Directory field. Select your HATS .ear project as the destination Folder. When your .jar file is imported, click the Navigator tab of the HATS Studio and expand your HATS ear project. You will see the imported java archive file.
2. In the Navigator tab of the HATS Studio, select the project in which you want to invoke your business logic. Right-click on the high level HATS project and select Properties. In the Properties dialog, select Java Build Path in the left table and select the Libraries tab on the right. Click Add JARs to display the JAR Selection dialog. Expand the HATS .ear project, and select the newly import Java archive file. Click OK in the JAR Selection dialog, and click OK in the Properties dialog. Repeat this process for all HATS projects for which you want to use the business logic.
3. In the Navigator tab of the HATS Studio, select the project in which you want to invoke your business logic. Expand the project, the webApplication folder, and the META-INF folder. Double-click on the MANIFEST.MF file. Type in the name of your newly imported jar at the end of the Class-Path: line.

There are other ways to import Java archives into the HATS project. HATS projects are extensions of Web projects in the WebSphere Studio workbench. For more information about importing Web projects, open the Help perspective in the WebSphere Studio workbench and select Application Developer Documentation. Expand the sections as follows to find information on Web projects: Concepts > Projects > Web projects.