What,Web,Service,amp,#63,Repri DIY What is a Web Service?
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Reprintable Article: Permission is granted for thefollowing article to forward, reprint, distribute, use forezine, newsletter, website, offer as free bonus or part ofa product for sale as long as no changes are made and thebyline, copyright, and resource box is included. ----------------------------------------------------------What is a Web Service?By Stephen BucaroTry to find an article on the Web that explains, in plainEnglish, what a "Web Service" is and you'll be going aroundin rhetorical circles with no simple explanation, and noexamples. Most articles start out with some ambiguousexplanation like: "Web services identified with WSDL andUDDI protocols make functionality available over theInternet using SOAP encapsulated in XML envelopes" andthen the articles start spewing out programming code.Examples of programming code don't help if you don't havean overview of what a Web Service is.David Berlind in his article "What are Web servicesanyway?" for ZDNet.com says, "At last fall's GartnerSymposium I asked several attendees -- presumably C-leveltechnology executives -- if they could give me adefinition of Web services ... No one knew. Before thesession's end, over half the attendees had left becausethey were expecting a discussion about something else."When you do find examples of Web Services, they areapplications like; retrieving a stock quote, finding thebest price for a product, saving an appointment to acalendar, or validating a credit card number. These areall things that we have been doing on the Web for years.So, what's the big deal about Web Services?Web services can be thought of as an evolution of thesoftware components concept. For example, say you haveseveral different word processors on your computer, or onyour network. In the early days of software, eachapplication needed to contain it's own separate spellchecking code. With components, the spell checkingfunction is programmed into a separate module that can beshared by several different word processor programs. Everyprogrammer doesn't have to write their own spell checkingcode, they can license the use of a spell checking modulefrom a components vender.The same thing is possible over the internet using DCOM,CORBA, JavaBeans, etc. But these technologies were allcreated by different organizations. The components find itdifficult to communicate with each other. It requires alot of information sharing and pre-planning to make thesecomponents work together. "Web Services" is a set ofvendor-neutral specifications and protocols developed bystandards organizations such as OASIS and the W3C.Using these standard protocols, Web sites can share Webapplications in a manner similar to how a spell checkingcomponent can be shared between word processor programs.Every Web site does not have to write it's own programcode to retrieve a stock quote, find a best price, savingan appointment to a calendar, or validate a credit cardnumber. They can license the use of these functions fromWeb Service providers.From the human Web users point of view, the Web stillappears to work the same. There is nothing new. That iswhy it's so difficult to find a simple explanation of"Web Services". The new technology of Web Services is whatgoes on under the hood. That's why most articles about thesubject jump right into the programming code. Many "WebService" articles are just articles about XML.The html code used by the Web today is inadequate for theWeb services task. Html is great for formatting Web pages,but it tells you nothing about the data contained in theWeb page. XML (eXtensible Markup Language) allowsprogrammers to define their own tags to describe the dataon a Web page, and communicate those definitions to thereceiving system. XML is not binary computer code, similarto html, XML is just ASCII text.When a Web site wants to use a Web Service, it makes arequest in a standard format called SOAP (Simple ObjectAccess Protocol). SOAP messages are written in XML. SOAPmessages are sent back and forth between the serviceprovider and service consumer. How does a programmer knowwhat services are provided and what messages to use inaccessing them? Web services use a standard message formatcalled WSDL (Web Services Description Language) todescribe themselves. WSDL is written in XML.How does a developer find available Web Services? They canbe found by using a protocol called UDDI (UniversalDescription, Discovery and Integration) to search adirectory of services available. Web Service providersregister their services in the directory. Developers canlocate and select a provider for the service that meettheir requirements. Similar to the licensing fees paid bythe developer of the word processor for the spell checkingcomponent, web developers will have to pay for the use ofWeb Services.Developers don't have to use Web Services developed byother people. Microsoft's .NET and Sun Microsystems'sJ2EE are frameworks that contain resources and classlibraries for developing Web Services. There are also anumber of open source framework's available, for examplethe Mono project hosted by the open Source softwarecompany Ximian. www.ximian.com/devzone/projects/mono.htmlWhen you use a Web Service or a Web site that uses a WebService, either licensed or directly, you will be requiredto pay, and you WILL use Web Services, because desktopapplications will no longer be available. The formerpractice of paying one-time to use a software applicationas much as you want does not generate a continuous streamof revenue for software companies. Web Services allow thesoftware companies to milk a continuous stream of moneyfrom you. Maybe that is the simple explanation of Webservices that we can't seem to find.----------------------------------------------------------Resource Box:Copyright(C)2002 Bucaro TecHelp. To learn how to maintainyour computer and use it more effectively to design a Website and make money on the Web visithttp://bucarotechelp.comTo subscribe to Bucaro TecHelp Newsletter Send a blankemail to [email protected] Article Tags: Simple Explanation, Word Processor