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Make room for JavaSpaces, Part 2

Build a compute server with JavaSpaces

By Eric Freeman, JavaWorld.com, 01/21/00

I've just returned from the second Jini Community Summit, where Ken Arnold and I led a birds-of-a-feather session on JavaSpaces. This encouraging meeting highlighted a number of interesting JavaSpaces applications, including Bill Olivier's JavaSpaces-based email system at the University of Wales. Also featured was the Department of Defense's explorations of battlefield management software, in which battlefield resources, such as tanks, are represented in a space.

TEXTBOX: TEXTBOX_HEAD: Make room for JavaSpaces: Read the whole series!

• Part 1. Ease the development of distributed apps with JavaSpaces
  
  
• Part 2. Build a compute server with JavaSpaces
  
  
• Part 3. Coordinate your Jini apps with JavaSpaces
  
  
• Part 4. Explore Jini transactions with JavaSpaces
  
  
• Part 5. Make your compute server robust and scalable

:END_TEXTBOX

In addition, there was significant interest in continuing to advance the JavaSpaces technology, and a number of areas were suggested for its improvement. One problem that the conference attendees wanted to confront was the painful process of setting up and running JavaSpaces (as well as Jini) for the first time -- probably the greatest barrier to using the technology. This problem is now being addressed in a new working group started by Ken Arnold, called Out of the Box (for more information, see the Resources section at the end of the article). Another area of community effort involves the development of helper or utility interfaces and classes that provide a valuable set of tools for new JavaSpaces developers. This article is based around one of those tools in particular: the compute server.

Basically, a compute server is an implementation of a powerful, all-purpose computing engine using a JavaSpace. Tasks are dropped into the space, picked up by processes, and then computed; the result is written back into the space and, at some point, retrieved. Beginning JavaSpaces programmers often ask how to implement such a system; in fact, the JavaSpaces Technology Kit ships with two sample compute servers, which perform computations for ray tracing and cryptography.

Compute servers are quite useful even for advanced programming. At the Jini Summit, it was decided that a common set of interfaces should be created to standardize JavaSpaces-based compute servers so that programmers could avoid reinventing the wheel every time they wanted to implement one. As a result, the community has created a working group whose goal is to build a specification and reference implementation of a compute-server architecture. One aim of this article is to kick off that work.

The compute server explained

A compute server provides a service that accepts tasks, computes them, and returns results. The server itself is responsible for computing the results and managing the resources that complete the job. Behind the scenes, the service might use multiple CPUs or special-purpose hardware to compute the tasks more quickly than a single-CPU machine could.

Historically, compute servers have been used to take advantage of the resources of large farms of processors in order to tackle computationally intensive problems -- ray tracing, weather modeling, cryptography, and so-called "grand challenge" computational problems. More recently, compute servers have begun to move into the mainstream, and have been put to work in a variety of environments, from the creation of financial models for Wall Street to the construction of large-scale order-entry and fulfillment centers that service the Web. All of these applications use the compute server to break a large computational problem into smaller problems, and then allow a distributed set of processors to solve these smaller problems in parallel.

 

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