758Part IVConnectionsthe Associate so much so that (Cedant web hosting) it s a
758Part IVConnectionsthe Associate so much so that it s a good way to get banned from Amazon altogether. Slamming the door on requests from a particular IP block is almost the only way to controlaccess to a public Web server. Even if an organization wants to give you large amounts of information in a data feed, themechanics right now are not very elegant. We are aware of many large and well-respecteddata-related businesses that move data around in text files (or spreadsheets) that are down- loaded via some mechanism such as FTP (or e-mail) and parsed on both ends by custom Perlcode (or by hand). Often, there is no way to send only data that has changed the feeds aredumped out and processed in a dumb way every so often, rather than updating only if andwhen changes occur. Obviously, these are all batch processes, which have no possibility ofworking in real-time. XML-based Web services promise to offer a common language, a com- mon transport mechanism, a common authentication and authorization method, and poten- tially common code for organizations to access each other s data. If Web services were just about moving data around, the idea would be extremely useful butnot at all sexy. What excites everyone about Web services is the promise that it can helpsolve the hardest problems of distributed computing once and for all. Brutal simplicityThink back, if you can, to the bad old days before the Web. If you can go back far enough, think back to the days when the Internet itself was a rarity and networking something limitedto high-end universities (it may help to remember that for a long time one of Apple s sellingpoints in college computer labs was AppleTalk). Back in those dark days, my children, things such as operating systems and programming lan- guages were major barriers to integration they were little islands in the sea of incompatibil- ity. If you were going to write an application, you were specifically writing it for a particularplatform and language sometimes even for a particular version of a compiler. It was very, very hard to make one program talk to another program. If you wrote a COBOL program onaVAX, that was where it was going to stay. With a great deal of effort you could get one pro- gram to send something simple, such as ASCII data, to another but any little thing couldmess up your interapp communication. If you changed anything on one side, it might meanthat you had to change a bunch of stuff on the other side, too. These programs were said tobe tightly coupled. This meant a lot of duplication of effort. Porting was technically difficult, and the marketwasfragmented. So a team that wrote an application say, an accounting program forMinicomputer X was not necessarily going to have the resources to do the same forMicrocomputer Y. Lots of teams wrote lots of accounting programs, and all the formats wereproprietary. None of them could exchange data with each other, much less share tasks easily. Slowly, mankind groped toward a way to make programs talk to each other. The blanket termfor this activity was distributed computing. It took until the mid-1990s for these methods toreach the common programmer, in the form of standards such as DCOM, CORBA, and JavaRMI. These standards enabled all programs that shared a common architecture to call eachother s methods and send data back and forth. When you are able to embed a spreadsheetinside a word processor document, it s via the magic of DCOM. These common object models, however, had three major problems. They were still more orless tied to particular platforms or programming languages; they were considered difficult tolearn, and they reached general usability at the same moment that the Web arrived to tanta- lize us with the possibility of Internet-scale loosely coupled, distributed computing based onopen standards.
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