Sun Microsystems Inc. last week used its JavaOne conference to highlight Project JXTA, a new peer-to-peer computing effort that faces skeptics who say they have heard it all before.

First announced in April and promoted at last week's gathering as the "next wave of distributed computing," JXTA is a set of protocols, demonstration applications and implementation source code that is freely available to developers. The software creates a way for all kinds of computers, including laptops and handhelds, to interact directly, without having to rely on a central server as a go-between.

At least on the surface, JXTA (pronounced "juxta," short for "juxtapose") seems similar to Sun's Jini project, announced with fanfare two years ago.

Jini, designed to let computers interact directly with each other, has gone almost nowhere. A predicted flood of Jini devices and applications failed to materialize.

"Jini assumed that there would be a Java node somewhere on the net," says Juan Carlos Soto, Sun's group product marketing manager for JXTA. "JXTA does not make that assumption."

There are other differences, Soto says. Jini focused more on APIs and the Java language. JXTA focuses on protocols and doesn't care what language developers use to write code.

"The Jini programming model is foreign to most application developers," says Frank Greco, CEO of Crossroads Technologies, a New York software engineering company that focuses on mobile applications. "JXTA is a very nice interim step to pull them into a more distributed environment. It will show them what can be done with a flexible and secure peer-to-peer framework."

The peer-to-peer JXTA protocols will let programs interact with each other over the 'Net, as HTTP and HTML let Web browsers work with any Web server. "HTTP and HTML let you distribute a client/server model over the Internet," Sun's Soto says. But client and other devices on the edge of the network have become more powerful and more capable than ever.

Details of the JXTA project, conceived in Sun's research group under Sun Chief Scientist Bill Joy, are at www.jxta.org.

JXTA consists of a basic set of protocols that let computer nodes find each other, organize into peer groups, exchange messages within groups and manage the nodes forming the group.

The JXTA core is a set of programs, dubbed building blocks, that use the protocols for these purposes. One program is "peer monitoring," used to manage the nodes in a group. This program can detect if one node is using too much bandwidth or capacity, then pass this alert to a management console so an administrator can reconfigure the faulty node. The core also includes security features.

Running above these core services are generic programs that make use of the underlying protocols. One example is JXTA Search, a service introduced at JavaOne, which consists of source code that performs a distributed search among JXTA nodes. Above the services run applications, such as instant messaging and a groupware program, that would use the lower levels of JXTA to let peers have these functions.

"These layers are not software API layers," says Steve Waterhouse, director of engineering for JXTA applications and services. "Instead, it's like the protocol layers of TCP/IP, with HTTP running above that. In JXTA, nodes can have JXTA code written in Java or C or even Perl. But the underlying protocols are common to them all."

Last week, besides introducing JXTA Search, Sun demonstrated an application for encrypted chat between JXTA nodes.

"Current instant messaging programs rely on servers for security, to find users and so on," Waterhouse says. "JXTA doesn't. We can do a secure chat between any two JXTA nodes."

Also announced at the conference was a project to port JXTA to handheld devices. A project to write JXTA in C, as well as in Java, was announced at the April 25 JXTA unveiling.

Network World (US)

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