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What, exactly, is the Grid?
  Here's a description of the Grid for those still uncertain as to what it really is.

A computational infrastructure. Cyberspace on steroids. A virtual machine. Imagine taking apart various desktop computers and souping up each of the components -- memory, CPU, graphics devices -- so that they are thousands of times faster and orders of magnitude more sophisticated than they are now. When you connect them via a network that shoots data across the country at speeds approaching that of light, what you end up with is no longer a computer but a portal to a flexible and powerful computing environment. That's the Grid.

Or, at least, that is the Alliance's vision of the Grid.

What exists now are the pieces. The Alliance is building the system of software that will integrate this ensemble so that its many and varied pieces will operate as if they were one. We know this type of distributed computing can work on individual heroic projects -- the challenge is to make it work seamlessly, efficiently, and routinely so that it becomes as ubiquitous and encompassing as is the electrical power grid today.


Layers of the Grid

When you compose a letter on a computer, hundreds of software components are, in some way, involved in this simple task. There are components that change the size of type, check grammar, format the layout. Others recognize the printer you are using and attach the bits and bytes that instruct your printer what to do. Still others -- the operating system and print scheduler -- make sure these bits reach their destination. If you diagrammed the relationship among these components, you'd wind up with a pyramid that, in many respects, resembles a corporate organizational structure. At the top, in the CEO's office, is the word processing program as it appears on your screen. Underlying it are the divisions, or group of programs, that encapsulate still more groups that perform related but distinct functions. The further down you drill into any of these groups, the more specific become the tasks each software module executes.

The software schema for the Alliance's National Technology Grid is a similar cascade of hierarchical layers. The base is the hardware -- computing resources, networks, and vast distributed sets of data. But overlying it are three interdependent layers of software in which specific functions are being bundled to perform progressively more complicated tasks.

These divisions are, of course, artificial because unlike conventional software architectures, the Grid's system is flexible. Researchers will assemble functions in whatever way best fits their needs. The system must also accommodate the dynamic nature of the Grid. Bandwidth will fluctuate, computers will be upgraded or unavailable, software will be modified. The software system, however assembled, must deliver reliable, high performance without the user needing to be aware of these continual changes to the underlying system.

  • Applications answer the question: Why do we need a Grid? Most of them now stem from science and engineering, but eventually they will cross all areas of society. The Alliance is focusing on six data- and compute-intensive areas: chemical engineering, cosmology, environmental hydrology, molecular biology, nanotechnology, and scientific instrumentation. Other applications such as collaboration, knowledge management (or data mining), and visualization are also helping define the performance requirements of the Grid.
  • Programming Tools make it easier to develop programs for the Grid by masking some of the complexities of the underlying structure. Some of these tools, such as application toolkits, provide flexible frameworks for assembling applications from software modules, some of which may be located on computing systems at other institutions. Newer parallel programming languages, libraries, and compilers map applications onto distributed resources in ways that compensate for what are often dramatic differences in power, architecture, and data representation. Object-oriented techniques and commodity technologies, too, can simplify programming for the Grid.
  • Services, or middleware, are similar to the operating system on a conventional computer. They are the intermediaries to the hardware and provide such basic services as security, authentication, resource scheduling, and assurances as to the quality of service. The software encapsulating these services will be designed in such a way that the programming tools and applications dependent upon them can assess and dynamically respond to changes in the Grid.
  • Physical Resources are the computers, visualization environments, mass storage devices, and networks associated with high-performance computing. The specialized software associated with each resource can be made more Grid compatible.

Not to be left out of this description of the Grid are people. Scientists, engineers, computer programmers, teachers, business leaders, people from all walks of life are working together in creating this infrastructure. This interdisciplinary approach is essential because eventually everyone will be able to take advantage of its capabilities. Just as the Internet has touched the lives of kindergartners as well as researchers, the Grid will lead to new ways of working, living, and learning in the coming century.


For a detailed description of computational grids, read The Grid: Blueprint for a New Computing Infrastructure, Ian Foster and Carl Kesselman, eds. (San Francisco: Morgan Kaufmann, 1999).


Access Online | Posted 1-8-1999