Sun lets Jini Starter Kit 1.1 out of the bottle

JavaWorld author Frank Sommers talks with Jini architect Jim

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As for large-scale networks, right now the lookup service is built around the idea of a workgroup: you register everything in a lookup service, and you find things in that lookup service. That's fine for a workgroup. But it doesn't scale up to larger and larger groups. In larger and larger groups, you want to filter somehow.

If I had a lookup service for all of Sun, I wouldn't want all the printers to be included. I would only want to know about the local printers. But there might be Sun-wide services that I'd want to use, like the HR database information, which provides someone's phone number when given their name. Those are things that I'd like to find anywhere within the corporation. However, I don't want this information available outside the corporation.

One of the things we're thinking about now is how you identify services that should be registered in a hierarchy of lookup services, rather than just your local lookup service. What kind of gradations do you want? How do these gradations work? Are the gradations based on locality of service? Are they based on who uses the service?

One of the ideas I'm playing around with is the notion of a Person object that could register in various places. The idea is to find what printer, for example, or what lookup service is associated with me or some other person. You would register this Person object in many different lookup services. If I were doing this for Sun, a top-level lookup service might contain Person objects for everybody in Sun. And so I would go to that lookup service to find the Person object for somebody else in Sun, say Ken Arnold. And based on that object, I could ask it what current lookup service is associated with this person. And from that, I could find the printer, or the scanner, or other services that were local to him, not me.

JavaWorld: In that case, the lookup service would belong to a person. A person might have several lookup services that he or she prefers to use.

Jim Waldo: Yes. Or, it might be a lookup service that associates with the location of a person. When Ken is visiting California, I find the lookup service that he uses in California.

JavaWorld: Would all the services he uses register in the California lookup service?

Jim Waldo: Yes.

JavaWorld: And that would take place automatically; the user would not have to be aware of that. So, if someone moves about, he would carry those services with him?

Jim Waldo: That's what I'm playing with right now. There is this notion of your home lookup service, and your current lookup service.

You know, we're having a great time. I hope other people in the Jini community are having as much fun as we are. And the people who are using it are the ones who are making it so much fun.

Frank Sommers is the founder and CEO of Autospaces, a startup focused on bringing Jini technology to the automotive software market. He has been programming in Java since 1995, after attending the first public demonstration of the language on the Sun Microsystems campus in November of that year. His interests include parallel and distributed computing, the discovery and representation of knowledge in databases, and the philosophical foundations of computing. When not thinking about computers, he composes and plays piano, studies the symphonies of Gustav Mahler, and explores the writings of Aristotle and Ayn Rand.

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