Chapter 25. How .NET and Web Services Work


Chapter 25. How .NET and Web Services Work

Web services, and its cousin, .NET, are little known technologies that use the Internet to dramatically increase businesses' and individuals' productivity. They allow programs and services to be run remotely across the Internet, and also allow services to be delivered automatically to people's desktops. The technologies are extremely malleable and can be used for a wide variety of purposes. For example, web services can be used to automatically deliver up-to-the-minute weather and stock information to someone's computer, and they can also be used to automatically tie together the computer systems of business partners, so that they can easily exchange goods, services, and information.

The two technologies are much talked about, much hyped, and frequently misunderstood. But throw away all the hype, and they're simply modular software components wrapped inside a specific set of Internet communications protocols, which can be run across the Internet. They're quietly revolutionary technologies, because they in essence can do away with the need for an operating system to run software. Specific Internet protocols and web browsers, instead, work much like an operating system and let people run applications and use services inside their web browsers.

While the term web services is often used broadly, in fact, the only true web services are those that use a number of specific protocols and technologies. At the heart of web services is the Extensible Markup Language (XML), which is used to describe a web service, and then help find and run a specific web service. (For more information about XML, turn to Chapter 19, "How Markup Languages Work.") Simple Object Access Protocol (SOAP) is the web services communication standard. Other important technologies, explained in the following spread, include the Web Services Description Language (WSDL) and Universal Description, Discovery and Integration (UDDI). The web service itself is a piece of software written in a language such as Java, and that can be found and run over the Internet using these protocols and technologies.

Web services and .NET share a very similar architecture. Both require that applications be written and then run using XML, SOAP, WSDL, UDDI, and related technologies. The difference is in how the actual applications are written and run. Web services are typically written in Java, and can be run in any browser that has Java capabilities.


Understanding .NET and Web Services

Web services and .NET allow programs or services to be run remotely across the Internet, using a web browser. First the program, service, or applet that will be run in .NET or as a web service needs to be created. (Throughout the rest of this illustration, we'll refer to the program, service, or applet generically as a "service.") For a web service, the service is frequently written in Java. For .NET, it is generally written using a development platform called Visual Studio .NET, which allows developers to use a variety of languages, including Microsoft's Visual Basic .NET, C++ .NET, and Visual C# .NET. After it is written, it is posted to an application server, which will deliver it when requested. The site hosting the service is commonly called a service provider.



 


Chapter 26. How Grid Computing Works

The world's biggest supercomputer is not an individual machine with massive processing power. Instead, it's a collection of tens of thousands of normal-sized individual computers like the one sitting on your desk, whose power can be combined into one giant system.

That's the promise of grid computing. And it's not just a promise. It's already working.

The theory behind grid computing is fairly straightforward. It combines the computational power of many computers, servers, databases, and other computing resources in a network or across the Internet. A main server or servers breaks up large computational tasks, such as solving complex problems relating to biochemistry, into smaller subtasks and sends those subtasks to computers that are part of the grid. When those computers have idle time and resources, they perform the subtask, and send the results back to the server or servers, which collates all the subtasks and solves the computational problem.

There have been many grid implementations, but the largest and best-known so far is the Search for Extraterrestrial Intelligence project (SETI@home), overseen by the University of California, Berkeley. In it, four million people in 226 countries downloaded a screensaver that kicked in when their computer was idle, and analyzed radio signals for signs of extraterrestrial intelligence. SETI@home scientists claim that the combined resources of its computing grid were more powerful than all the supercomputers on the planet combined. Similar grids have been used for mapping genomes and analyzing proteins.

Similar grids, however, will be increasingly used by corporations to apply their own computing resources to large problems. In this kind of architecture, all the computers in a corporation would register themselves with the corporate grid, and when idle time was detected in computers, they could be applied to other tasks. For example, if a server is normally used only a few times a month to process a corporate payroll, it could be used for other computing tasks when it would be otherwise idle if used as part of a grid.

Companies such as IBM and Sun are increasingly using grid computing as well. For example, IBM has launched a multibillion dollar "on-demand computing" program in which businesses can outsource computing tasks to IBM, and IBM in turn uses a grid to do that processing.

To date, most grid projects use their own individual architectures. However, there is an attempt to create a set of standards that can be used when building grids and grid projects. The standards are being established under the aegis of the Globus Project, which already has a set of proposed standards out, and has released toolkits that developers can use to help build grids.

It's likely that in the long term, grid computing will become a standard part of the way that businesses and the Internet work. It will have moved from the search for extraterrestrial life to the center of corporate life.