NEW STRAITS TIMES-MANAGEMENT TIMES

Chee Han Wen

CORBA, which stands for common object request broker architecture, has been around for a while but yet to gain popularity, probably because of its complexity.

Locally, there have been projects and research conducted using Corba but mainly in labs and institutions of higher learning. Worldwide, the architecture is making inroads in industries such as banking, automation and communications mainly because of the Internet boom and the need for platform-independent systems.

So what is Corba? It is a set of specifications developed by the Object Management Group (OMG) which was founded in 1989 by Unisys, Hewlett- Packard, Sun Microsystems, 3Com, Data General, Canon and Philips.

The Internet, or specifically the World Wide Web, was previously considered as a two-level direct interaction between a client and a server. The client, via the Web browser, obtained information or data from the server. This kind of request for information by the client was on a "as is" basis. This means that the client will obtain pre-configured information.

With the introduction of the common gateway interface (CGI), a dynamic request from the client to a specific server can be made. The CGI is able to function as a medium for carrying and processing the request from the client.

However, the CGI has several weaknesses. Data flow under the CGI medium is slow in the sense that the request for certain data by client is continuously repeated as a whole whenever the client requests for information from the server. Such a processing method quickly exhausts the server's resources when receiving multiple requests from many clients simultaneously.

Using applications that run partially under the client's resource instead of the server's could solve this problem. This was made possible with the introduction of the Java programming language. By using Java applets, part of the application can be executed under the client's computer through the Java virtual machine (JVM) built into the Web browser.

Take note that Java is not confined to developing Web applications as it can also be used to develop standalone and networked applications as well.

Consider the following situation: if the server is used for controlling a physical devices running under C or C++ language, how will the client interact with the server if it were to be Web-based? The answer is through the integration of Corba which is aplatform, operating system and programming language-independent architecture.

This means a client could be running Windows 98 while the server is under Linux and yet the client and the server could interact through Corba. Through Corba, distributed systems were made possible.

Corba defines standard interfaces in order for a distributed system to work effectively without any geographical barrier.

For example, if a client wants to request for information on a company, the financial background can be retrieved from one server and the list of employees from another server.

It's even possible for these servers to be located at different places.

At the same time, Corba also allows for both the client and server to exist in the same machine. With Corba, the terms "client" and "server" are further blurred because a client can behave as server and vice versa. If a client requests information from the server and the server responds to the request, Corba integration will allow the server to request information from the client. This will be useful in situations such as verifications.

When a client passes parameters to the server, the server will respond in accordance to the parameters. After completing its task, the server can send further parameters back to the client to inform of success or failure in executing the request.

Corba uses its own interface language known as interface definition language (IDL) which has commands and syntax similar to C and C++ languages. Developing commercial applications with Corba is not easy. To integrate Corba into existing applications, oneshould have a good understanding of advanced programming and preferably more than one programming language.

Those who are up to the challenge can first obtain an object request broker package which is available from various companies such as Sun and Visigenic.

Corba now faces competition from other architectures such as distributed component architecture model (DCOM) from Microsoft and remote method invocation (RMI) from Sun. DCOM is still considered young and until now works only under the Windows platform while for RMI, both the client and server have to be developed under the Java, and so it is not language- independent.

OMG now has more than 700 members and is still growing. In view of the trend, we can expect more applications integrated with the technology in the near future.

The writer can be contacted at rchee@pc.jaring.my.

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