Installation and User Guide for the tool  “EJB Wizard For Code Generation”

Introduction to the tool

                           This tool is meant for generation of Enterprise Java Bean Source code files with a minimum effort of coding. Generally most of the industries leading IDEs offer such a wizard, but not many free IDEs like JBuilder Foundation, Forte For Java etc. give such features,  because they offer such features in their Enterprise versions. But the EJB programmers who are learning EJB or using EJB for their personal use, they are in need of such a tool through which they can generate EJBs without much coding. This tool can be used with free EJB servers like the one that comes with Sun’s J2EE SDK. Even it can be used with many open source EJB servers are available for free on the internet.

Why a Wizard is needed for EJB code generation?

                           EJB is such a framework where a lot of mappings between the classes are to be done at the source code level. For example every create method of Home interface should have a corresponding ejbCreate method in the Bean Class with a related signature. It is nothing but a coding complexity to create such related  methods with a proper matching. Another reason is that many EJB classes will have the same code for the EJB framework methods which  should follow some rules to qualify as a valid EJB. Next come the case of Entity beans where a huge volume of code should be written for accomplishing the database tasks. And there are many more complexities in the coding of EJB classes.

                           Each of the above mentioned complexities can be handled by a tool if it can intelligently generate the code by taking a fewer inputs from the user. With such a tool, EJB developer can concentrate on what fields and business logic methods the Bean should have rather than coding the same repetitive code again and again for each bean.  Once such code is ready , he/she can concentrate on the business logic rather than meddling with the code to follow EJB framework rules.

What features can this tool offer?

• This tool can generate the following types of EJBs following the EJB 1. 1 specification.
• • Statefull Session Beans
  • Stateless Session Beans
  • Entity Beans with Bean Managed Persistence (uses Database code)
  • Entity Beans with Container Managed Persistence

• This tool can generate the EJBs that are to be coded from the scratch. It can generate only the new EJBs and it wont offer the maintenance or modification of existing beans.
• This tool offers the validations required for EJBs and generic Java classes like duplication of methods in a class, mandatory primary key for entity beans etc. But it doesn’t do the validations following the Java Language Specification to 100%. In near future such validations will be done.
• Code for all the methods common to EJB framework like ejbCreate, finders etc will be completely written by this tool. Since this tool is generating the code for generic implementation of EJBs, neither the user’s requirements not the business logic can be obtained as an input in an intuitive manner. Hence this tool generates only that code related to EJB framework and the code common to any application. User has to write the application specific code using some IDE or text editor.
• Depending upon the specification of the bean that is going to be generated, unto 70% of the bean’s code can be generated through the wizard if used cautiously.
• Some restrictions are imposed in usage of the tool while following EJB specification to achieve a balance between the effort user has to put for using the tool and the efficiency of the code generation.

A Few Words from the Author

In future this tool may support creation of the Entity beans from the existing database.Since this tool is in the pre matured stage, it may have bugs or areas of improvement. This is “the tool for you” and it is going to evolve from your requirements and suggestions. Please keep sending the bugs so that I can fix them as soon as possible , to make the tool bug free. Please feel free to send your suggestions and comments so that I can improve the tool.  I am available at nphanindrakumar@yahoo.com.

Installation and Startup of the tool

1.     Copy the EjbGenerator.zip file into the local machine

2.     Extract the contents into some folder.

3.     Check your classpath so that Java 1.2.*/1.3 SDK and J2EE SDK libraries are available for execution of the tool. Even the alternate SDKs for Java and EJB can be used.

4.     On Windows Operating system, double click the batch file RunEjbGenerator.bat for execution of the tool.  

5.     On other Platforms you can run the tool by directly invoking the java interpreter with  the command “java ejbgen.gui.Driver”. This can be used on Windows also.

6.     Then start using the tool to Generate EJBs

How to use the tool

Startup Screen

This tool starts with a screen shown as below.

Click “Create Session Bean” button for creating the Session Bean.

Click “Create Entity Bean” button for creating the Entity Bean.

Click “EXIT” button to Quit.

Creating Session Bean

On Clicking Click “Create Session Bean” button in the Startup screen the “Basic Info” screen appears as below,  where the session bean specification should be given.

In the “Basic Info” screen enter the primary information for the session bean.

• For “Bean Package Name” enter the package to which the generated bean classes should belong to.
• For “Bean Class Name” enter the name of the Session Bean class. While entering it, both home interface and remote interface names will be generated automatically. If needed those class names can be modified.
• Select the “Session Bean Type” from the radio button. The next coming screens, validations and bean code generation will be done according to the bean type selected.
• “JNDI Name for Database” and “Name of the Table” fields don’t need any input while generating Session Beans.
• Enter the directory or path where the Session Bean Files are to be created. “Browse” button can be used for selecting the directory using GUI.
• Enter the description for the class, which will be used as the JavaDoc comment for the class. Each line of text entered into it will become a line of JavaDoc comment for the class description.
• Selecting the check box “Create Console Messages For Every Method Entry & Exit” will result in generation of Log code into the methods created by the tool. Log will be generated with System.out.println statements at the beginning and ending of each method’s code generated. Unselecting it won’t generate the log statements.
• Click next to add the fields and methods required for the session bean. Refer to the sections “Adding Bean Methods” and “Adding Bean Fields” for information on how to add fields and methods for a session bean.
• Here is the example screen with data entered into it for creation of a session bean.

Creating Entity Bean

On Clicking “Create Entity Bean” button in the Startup screen the “Basic Info” screen appears as below,  where the entity bean specification should be given.

In the “Basic Info” screen enter the primary information for the entity bean.

• For “Bean Package Name” enter the package to which the generated bean classes should belong to.
• For “Bean Class Name” enter the name of the Entity Bean class. While entering it, both home interface and remote interface names will be generated automatically. If needed those class names can be modified.
• Select the “Persistence Type” of the bean from the radio button. The next coming screens, validations and bean code generation will be done according to the persistence type selected.
• If the persistence type is selected as Bean Managed, enter “JNDI Name for Database” and “Name of the Table” fields. This data will be used with an assumption that the Entity Bean data will be store in the specified Table, which belongs to the Database mentioned.
• If the persistence type is selected as Container Managed, the EJB container will provide persistence and database mapping code and its specification will be provided at the time of bean deployment. So no need to input the Database and Table names.
• Enter the directory or path where the Entity Bean Files are to be created. “Browse” button can be used for selecting the directory using GUI.
• Enter the description for the class, which will be used as the JavaDoc comment for the class. Each line of text entered into it will become a line of JavaDoc comment for the class description.
• Selecting the check box “Create Console Messages For Every Method Entry & Exit” will result in generation of Log code into the methods created by the tool. Log will be generated with System.out.println statements at the beginning and ending of each method’s code generated. Unselecting it, wont generate the log statements.
• Click next to add the fields and methods required for the session bean. Refer to the sections “Adding Bean Methods” and “Adding Bean Fields” for information on how to add fields and methods for an entity bean.
• Here is the example screen with data entered into it for creation of an entity bean.

Adding Bean Fields

“Field Editor” screen will appear by clicking “Next” button in the “Basic Info” Screen. The screen looks as follows for Container managed persistent entity bean.

Here the fields or the bean class data members can be added and the fields can be marked for their related methods or additional behavior. The screen when used for different beans, it appears a little different according to type of the bean. Here is the description for using the “Field Editor”.

• Upper portion of the screen has the widgets to be used for inputting the field details. Lower portion of it has the Table that shows the important details of the fields added to the bean.
• For adding a new field, enter data into the input fields and then click “Add New Field” button.
• For editing/modifying an existing field, select the field from the table by clicking the field (it shows the field details in the widgets), then modify that data and finally click “Edit Selected Field” button.
• For deleting an existing field, select the field from the table by clicking the field and then click “Delete Selected Field” button.
• Data for “Field Name”, “Datatype” and “Scope” is used for creating the field/data member for the bean class. This data is mandatory for any field’s definition. “Description” is used for making the JavaDoc comments for a field and it is optional.
• “Create Set Method” and  “Create Get Method” checkboxes are to be used for creating get and set methods(relating to the field) in the bean and the required methods to the remote interface.
• “Persistent” checkbox is to be used to tell that the field is persistent, and tool will generate the code appropriately.
• “Primary Key” checkbox is to tell that the field will be the primary key of the database table corresponding to the bean.
• “Create Find Method” and “Create Find-In-Range Method” checkboxes are to tell the tool to generate the methods to search/query the beans based upon the value or range of values that matches the bean’s field value.
• Among the field input widgets, some may not be available depending on the bean types and accordingly, the table may contain reduced number of columns. Here are the details on it.
• • Stateless Session Bean won’t have any of the check boxes as the bean will have neither state nor the persistence.
  • Statefull session beans will have the “Create Set Method” and  “Create Get Method” checkboxes for setting/getting the state of the session bean. Rest of the check boxes wont be available as Statefull session beans don’t need persistence.
  • Container Managed Persistent Entity beans will have the all the checkboxes except the “Persistent” checkbox. It is so because, for such beans Container should know the persistence policy through deployment descriptor and not from the bean code. For such bean there should be exactly one primary key.
  • Bean Managed Persistent Entity beans will have the all the checkboxes including the “Persistent” checkbox. It is so because for such beans, the code will have the persistence policy. If a particular bean is not selected to be “Persistent”, then it can’t be designated as primary key and it cant have finder methods. For such bean there should be exactly one primary key.

After giving the proper inputs for the fields, click next to enter the “Method Editor” Screen where the methods can be provided for the bean. 

Adding Bean Methods

“Method Editor” screen will appear by clicking “Next” button in the “Field Editor” Screen. The screen looks as follows for Container managed persistent entity bean.

Here the methods for the bean class(and in turn to the home and remote interfaces) can be added. The screen when used for different beans, it appears a little different according to type of the bean. Here is the description for using the “Method Editor”.

• Upper portion of the screen has the table showing the methods required by EJB framework to qualify the bean to be a valid EJB. Lower portion of it has the Table that shows Business Logic methods that are required for the actual functionality of the bean.
• Framework methods come with standard definitions and can’t be modified/deleted.  But for some kinds of beans additional ejbCreate methods can be added but with only different method parameters. For that use “Add Create” button.
• For viewing or modifying any method select the method from appropriate table and then click “View/Modify” button of that table. It will show “Method Maker” screen as below.

If the method is a Framework one, then some/all of the widgets may not be editable. But if it is a framework one, the existing content can be changed. Then click “OK” button to confirm the changes or else click “Cancel” button to discard the changes. This closes the “Method Maker” screen and reflects the changes in “Method Editor” screen.

• To delete a particular method, select the method from appropriate table and then click “Delete” button of that table.
• To add a new overloaded “ejbCreate” method, click “Add Create Method” which will show “Method Maker” screen. There enter the parameters for the new “ejbCreate” method. Clicking OK will add a new “ejbCreate” method.
• To add a new Business Logic method, click “New Method” which will show “Method Maker” screen. There enter the method specification along with the “Description”(which becomes method’s JavaDoc comments). Clicking OK will add a new Business Logic method.

Creating the EJB Code

Necessary changes in any screen can be made by navigating to different screens using “Next” and “Prev” buttons.

After completion of defining the methods in the “Method Editor” screen, click “Finish” button which will show the following message.

This message confirms that the EJB classes’ source code is generated in the path specified.  Clicking “Yes” shows the opening screen of the tool, where the next bean can be generated. Clicking “No” will terminate your session with this tool and the tool execution ends there.