Round Trip Engineering

Code generation

After the completion of design stage, complete class diagrams or sometimes known as the design class diagrams would be generated within a particular model. The general prerequisite for code generation to be done would require at least a design class diagram. Rational Rose is a very powerful CASE tool that capable of generating codes from a particular language based on the predefined semantics. Typically, they are six steps by steps guidelines would be followed during code generation.

1.0 Assign Java Classes to Java Components in Your Model

2.0 Check Syntax (optional)

3.0 Check the Classpath

4.0 Set the Project Properties that affect Code Generation (optional)

5.0 Backup Your Source

6.0 Generate Java Source Code from Your Model 6.1 Generating Java source from a Class Diagram 6.2 Generating Java source from a Component Diagram

7.0 View (browse) and extend the Generated Source

1.0 Assign Java Classes to Java Components

A component may be anything perhaps the generated codes as well. Rational Rose Java models .java files as components. Every .java file in Rose will be treated as a component as well. Therefore, upon completion of code generation, the .java file would be seen in the component view as a physical component.

1) Rose can automatically generate the .java physical components for you when multiple classes are being code generated

2) To do this, the menu option from Tools > Option > Notation > Default Language must be JAVA enabled

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Most of the time, Rose would not be able to produce a single .java file that consists of multiple classes. If you would like to have multiple classes to reside in a single .java file, a component must be created and all the related classes should be placed inside (assign) and upon code generation, all the classes would appear in the physical .java file. (Note, too, that if you place any Java classes in your newly created package, Rose would create a mirror image in Component view. It is then used to create directory or Java packages.)

2.0 Check Syntax (optional)

You can choose to check the syntax of your model components before you try generating code. Note, though, that syntax checking is done automatically for you when you generate code. Rose Java’s Syntax checking is based on Java code semantics

3.0 Check the Classpath

Classpath is the address pointing to the directory of JAVA compiler. Before code generation, the classpath must be properly set. Rose Java uses this classpath when you generate code or reverse engineer existing Java source. All you have to do for checking the classpath is to navigate to Tools > Java/J2EE > Project Specification and by clicking the New / Insert button which looks

something like and a button like will appear. Again, click on the dotted button and an option dialog box would appear

Select Directory and most of the time, the JDK API library would reside in the following address.

Click on OK and followed by checking the two option below and you are done for checking the classpath.

When declaring Classpaths, consider:

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Round Trip Engineering

Where are your files? Specifically, what are the fully qualified path names?

What are the package or import statements in the source? You must have a Classpath entry for the leftmost directory in a package/import statement.

During reverse engineering, Rose converts each package/import statement in your source generated by Rose into a path in your file system, then makes certain a fully qualified path to the class file exists on the Classpath tab (creating it if necessary).

For reverse engineering, Rose Java requires a Classpath to the JDK class library. For example, depending on the version of the JDK you’re using, you’ll need a CLASSPATH setting to classes.zip, rt.jar, or other appropriate library file. (Check your JDK documentation for current names and locations.). A sample path to the rt.jar file in JDK 1.4.1 would be x:\jdk1.2.1\bin\jre\rt.jar. For the picture above, the author has placed the JDK in Program Files folder under C:\ drive. Therefore, if your JDK is placed in your Program Files folder, the CLASSPATH would be C:\jdk1.4.1\bin\jre\rt.jar

4.0 set the Project Properties that affect Code Generation (optional)

The following properties affect code generation. You set the values for these settings via the Code Generation tab of the Rose Java Project Specification.

· IDE – Determines which Java environment or IDE you are working in. The default is Internal Editor and indicates you’re working in a standard JDK environment. The other options are: IBM VisualAge for Java, Visual Café, Forte for Java, and JBuilder.

· Stop on Error – When enabled, Rose stops generating Java code at the first error it encounters. By default, this property is not set, thus allowing code generation to proceed even when there may be errors. Errors recognized by Rose are written to the Log.

· Create Missing Directories – When the Create Missing Directories setting is enabled (the default), Rose creates any undefined directories that are referenced as packages in a Rose model when you generate Java code.

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· Automatic Synchronization Mode – When this feature is enabled, Rose automatically initiates code generation any time you create, delete, rename, or modify a Java element in your library. By default, this feature is off.

In addition, you can determine the format for the code you generate and control how comments are created with these properties:

· Indentation – You can specify whether to use spaces or tabs and the number of spaces or tabs to use when formatting code. The default is three spaces.

· Opening Braces – By default, opening braces start on a new line for both classes and method declarations.

· Comment Style – Rose generates comment text from your model documentation fields according to the style you select: The Rose default, standard Java comments, or Javadoc. If you select Javadoc, Rose Java generates the Javadoc tags you select. You can use the Javadoc compiler to generate HTML documentation. For more details, see Comments and Javadoc.

You can set the values for all of these settings via the Style tab of the Java Project Specification.

5.0 Backup your source

When you generate code to an existing .java file, Rose creates a backup of your current source using the file extension .~jav. However, if you intend to round-trip engineer your Java source, be sure to back it up before you begin. If you generate code from a model more than once before looking for a backup, the .~jav file that Rose creates will not contain your original code.

6.0 Generate Java Source Code from Your Model

Code generation can be done with two approaches such as generating JAVA source code from class diagram or from component diagram. You can select one or more classes or one or more components (logical or physical) then click Tools > Java/J2EE > Generate Java

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If this is the first time you’ve generated code for a model element, a mapping dialog appears enabling you to map packages and components to your Rose Java classpath settings. If there are errors or warnings, a message will alert you and you can view the messages in the Rose Log window (click View > Log). Once code generation is complete, the .java files and related directory structure are in place. You can also view the newly generated java source from within Rose.

Note: You can enable Automatic Synchronization Mode to automatically initiate code generation any time you create or modify a Java element in your model. This is set on the Style tab on the Java Project Specification (Tools > Java > Project Specification).

6.1 Generating Java Source from a Class Diagram

From a class diagram, you can generate Java source from classes or from logical packages. Before you begin, be sure you understand how Rose Java generates code for classes based on how they’re assigned to components. (For details, see Code Generation in Rose Java.) Follow these steps to generate Java source from classes in a class diagram in Rose:

1. Open your model and display the class diagram that contains the classes and packages for which you want to generate Java source.

2. Select one or more classes or packages in the diagram.

3. Optionally, use the syntax checker before generating your Java source. Although Rose checks syntax as part of code generation, checking your model before generating could save you time.

4. Click Tools > Java/J2EE > Generate Code.

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5. If you have not mapped a package or component to an entry in your classpath settings (for example, this is the first time you’ve generated code for a component or package), the Component Mapping dialog appears allowing you to set up the appropriate associations.

6. Check the Rose Log window to view the results of the Java generation, including any errors that occurred.

7. Correct any errors and repeat step 4 until no errors are returned.

8. View and edit the generated code using the Internal Editor.

6.2 Generating Java source from a Component Diagram

1. Open your model and display the component diagram that contains the packages and components for which you want to generate Java source.

2. Select one or more packages and components in the diagram.

3. Optionally, use the syntax checker before generating your Java source.. Although Rose checks syntax as part of code generation, checking your model before generating could save you time.

4. Click Tools > Java/J2EE > Generate Code.

5. If you have not mapped a package or component to a directory in your classpath to receive the generated source files (for example, this is the first time you have generated code for a component or package), the Component Mapping dialog box appears allowing you to set up the appropriate associations.

6. Check the Rose Log window to view the results of the Java generation, including any errors that occurred.

7. Correct any errors and then repeat step 4 until no errors are returned.

8. View and edit the generated code using the Internal Editor.

7.0 View (browse) and Extend the Generated Source

After generating Java, you may want to view (browse) the generated source (right-click on a class and click Java/J2EE > Edit Code) and create the actual functionality for your application or applet. Rose provides an Internal Editor for viewing and editing your .java files. You can modify the generated source from within the editor. To update your model with the changes, you need to reverse engineer the .java file back into your model.

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