referred to in this product as builders) so that it could carry out its main mission: to help programmers build distributed Java applications.
This is an area where I have to be careful. In the Java world, the word
application
has a special meaning. It identifies a Java program that can run stand-alone (in other words, it's not an applet and doesn't need to execute in a Java-enabled browser). More precisely, then: The main purpose of VAJ is to help programmers build distributed Java packages, where a package can include one or more Java applets. The distributed nature of the package comes into play when one or more beans in a Java applet are executing remotely on a Java server.
The Power of Remote Beans
The
Java version
of Visual Age is built on beans. IBM would probably prefer the previous sentence to read that it's "built on parts." In this case, however, a bean and a part are the same thing. Becaus
e Java beans are components providing both design-time and execution-time behaviors, they have all the ingredients needed to reincarnate a part -- in the Visual Age sense -- in the Java world.
From within the program's integrated development environment (IDE), you can drag and drop parts taken from a parts palette into the visual composer window. These parts are simply Java beans; in fact, you can import a Java bean into the VAJ environment, and it immediately becomes a usable part. VAJ reads the bean's interface, locating methods and events, and automatically incorporates them into the IDE.
Another important technology is Java's remote method invocation (RMI). RMI lets a Java application or applet invoke an object's method across the wire. In other words, a Java application on one machine can execute a method within a Java object on another machine. More important, the calling application has no idea that the invoked method is remote. RMI provides the communications plumbing needed to distribute
an application.
The beta version of VAJ that I tested comprised two programs, the IDE and the enterprise application builder (EAB). IBM officials say that the commercial release of the program, which will run on Windows 95 or NT, will merge the two programs to create a single package.
The IDE includes the editor, compiler, browsers, and other modules. It masks the fact that a project is a collection of files. Instead, you move smoothly from project to class to source code. The IDE's incremental compile capability speeds up the applications-development cycle. VAJ is also team-aware -- its repository-based source control mechanism lets multiple developers work on a project simultaneously. Additionally, VAJ retains the Visual Age program-by-wiring paradigm. You populate a form with parts (in this case, they are called beans) and define the behavior of the application by wiring a source part to a destination part and specifying the nature of that connection.
The EAB is a collection of four wizar
ds: data access builder, C++ access builder, Customer Information Control System (CICS) access builder, and RMI access builder. The EAB allows existing data applications to deliver content over the Web. Each builder guides you through a remarkably small number of steps for building wrapper Java code.
For example, if you point the data access builder at an ODBC database, it automatically builds a collection of classes that -- via Java Database Connectivity (JDBC) -- can read, add, delete, or update the contents of the database. You have to identify which columns you want to access, but beyond those simple specifications, data access builder does the rest. Similarly, C++ access builder provides Java wrapper code for accessing C++ applications, CICS access builder links your Java code to CICS transactions, and RMI access builder constructs the necessary stub and proxy code for calling Java methods remotely.
At the time of this writing, Visual Age for Java was due for release at the end of June. IBM h
ad not yet set pricing. If the final version is anything like the beta version, VAJ will join the likes of Delphi and Optima as a robust client/server development system.
Product Information
Visual Age for Java
Internet:
http://www.software.ibm.com/ad/vajava
Visual Age for Java
