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ArticlesJava's RAD Route to Data Access


Visual Café Pro lets you develop distrbuted data access applications using Java.

Rick Grehan

With its Visual Café Pro (VCP) package, Symantec brings rapid application development for Java into areas often associated with traditional client/server development. The professional version of Visual Café adds wizards (software assistants) and database middleware technology to help developers create Java programs that access information from databases on the back end. This data is then presented to the end user in any Java-compliant Web browser.

VCP consists of Visual Café and the dbAnywhere middleware, lashed together by a set of wizards. The program illustrates an emerging breed of development tools that let users leverage the Web to access data stored in a wide variety of databases. VCP represents a logical progression for Symantec's Café, which I used when I converted the BYTE benchmarks from C to Java. (Back then, Café wasn't a visual development environment, but it was a solid Java development system whose integrated debugger was a blessed relief from the command-line debugger that's included in the Sun Java Development Kit.)

Symantec has constructed upon this foundation the kind of form-based application-building environment that's becoming the mainstay of Windows development. When you start a new project, VCP lets you select from among three templates: a completely empty project, a basic application, or a basic applet. The first template is an empty workspace that's a throwback to life before Café went visual. The latter two templates jump-start your application with empty forms ready for filling with buttons and text fields and such. In fact, the application template prebuilds "about" and "quit" dialog boxes.

Visual Café comes with a basic set of predefined components. You'll find buttons, scroll bars, and text fields, as well as a collection of dialog boxes. When you click and drag a component from the tool palette, VCP pours the necessary Java source code into your project to instantiate the component.

New in the Visual Café environment is its interaction wizard, which is a button to the left of the component speedbar. The interaction wizard lets you mouse-click your way through the process of associating an action to a component-received event. For example, you could use the interaction wizard to connect a mouse-click event on an "about" button to the opening of an "about" dialog box; Visual Café Pro will then write the code for you.

The database middleware component is supplied by dbAnywhere, which supports the Sun/JavaSoft Java Database Connectivity (JDBC) API; dbAnywhere is able to handle a variety of back-end databases, ranging from lowly dBase II all the way up to Oracle Server, either through direct drivers or ODBC drivers. Applets that are created by the Café side of Visual Café Pro communicate with a dbAnywhere server, thus providing what is formally a three-tier architecture: Applet as the GUI, dbAnywhere in the middle, and database drivers on the back end. Notice what this means: A client can download an applet from an Internet server on one machine, but that applet can connect to a dbAnywhere server running on a completely different machine on the Internet, anywhere in the world.

Practically speaking, though, at this stage dbAnywhere functions as merely a connection and translation service by connecting the applet to the database and translating between the database driver and the JDBC API. I suspect that Symantec has another edition of Visual Café in the works, perhaps an enterprise version, that will allow developers to extend dbAnywhere, adding business logic programming into the middle tier.

Doing programming with Java components is not a pretty thing. Because Java has no notion of a resource file (at least not yet, anyway), every detail of a component -- for example, a button's size, color, or font -- must be hardwired into the source code. Also, programming to JDBC amounts to working with SQL, which has never been pretty. Visual Café Pro, therefore, handles a great deal of ugliness for you. Symantec's RAD kit is no Delphi for the Internet yet -- but it's pretty close.


Product Information

Visual Café Pro...............$499.95
Symantec
Cupertino, CA
Phone:    (408) 253-9600
Internet: http://cafe.symantec.com

Rick Grehan is a senior technical editor for BYTE reviews and the coauthor of The Client/Server Toolkit for C/C++ Programmers (NobleNet, 1996). You can reach him at rick_g@bix.com.

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