The reason is simple. The IT industry needs standards like never before. The complexity of distributed, heterogeneous, multi-drop, transactional systems is so enormous that the industry can no longer afford to do an SQL (i.e. say "yes, yes" to standards but "nudge, nudge, wink, wink NO what I mean" in actual implementation). Likewise interoperability has become so important that some major players have painted themselves into a corner. For example, having rejected CORBA, most RPC mechanisms, J2EE, and even its own DCOM in favor of .NET, Microsoft now desperately needs for XML and Web Services to work and be the gateway/bridge into their otherwise proprietary islands of servers and systems. And with Linux emerging as a major server side player, the Unix bunch (Dell, HP, IBM, Sun, etc) also can ill afford to have Linux and its systems split into fractiously mutually exclusive editions _ XML and web Services can help prevent this.
So quite a number of major players have to have XML and a broad range of other standards succeed simply because as IT reaches the distributed processing innovation plateau, no vendor can afford, as in the past, to be caught out on the wrong gauge track (interoperability or the 7 A's are truly IT's marching orders). Thus the broad set of XML, Web Services, communication/messaging/transaction standards carry much more weight than ever before - IT and software vendors risk being cutoff from significant segments/markets in the IT world.
Enter XML-eXtensible Markup Language a generalized document markup language.
Given that SGML, XML's predecessor. is conceded to be more expressive and
powerful, how could a system of data tags (see XML Sample File below)have
so powerful an influence on IT systems ? First, as previously mentioned,
timing is of the essence and the industry is looking for standards. Second,
although the tagging system of XML is deceptively simple (a big improvement
So XML paradoxically, is very programming friendly at the cost of being somewhat direct user manipulation unfriendly.One can see from the example above how verbose XML can be in comparison to comma delimited files for example. Also one of the reasons XHTML is taking so long to adopt on the web (its the XML form of HTML) - is because XHTML is much less forgiving of simple syntax errors than HTML.
So the first success of XML has been in the programming community. XML is being widely adopted as the preferred method to store a programs setup and customization/preferences information. Remember the old .ini files from Windows 3.x days - those are very much likely to be in XML format today. For the customization and usability this opens up - here is XML's first silver bullet award.
Next, XML is also being used much more broadly as the storage format for
documents and workspaces used by major commercial programs. Open Office stores
its word processing, spreadsheet , presentation and other documents in XML
format. Microsoft in Office 2003 will follow suit. This has 3 payoffs:
And following on the theme of document interuse and exchange, XML along with its transformation tool, XSLT-XML Stylesheet Language Transformations, is starting to become a favored method for document translation and interchange betwen systems. This again has potentially widespread repurcussions - because small,adhoc or short-term document interchange absorbs the brunt of maintenance programming efforts in many organizations. For large volume or specialized transactions and messaging, other tools can and are being used. But XML+XSLT has a strong role to play - especially in transforming essentially the same message for many output targets: a file, a web page, a mobile phone, a pager, etc.
Finally, the whole edifice of Web Services, the distributed calling of programming services in an absolutely standard way, is built primarily on 4-5 XML extensions: SOAP_Simple Object Access Protocol, WSDL-Web Services Definition Language, XML Signature and Encryption, SAML-Security Assertion Markup Language and UDDI-Universal Description, Discovery, and Integration. Web Services is a Big Thing because it represents the possibility of having asingl, universal method for calling on distributed services instead of the growing proliferation of specialized and often proprietary service calls. Yes, Web Services have been overhyped for the past two years because of the many key standards like SAML and XML Signature, XML Encryption which are just now being ratified. But the promise is real - and most of the kay players are still sticking to open, free, and uniform standards. But this one has the potential to get proprietary or patented paths -so stay tuned.
So XML already has some serious silver bullets in its belt and with Web
Services may have one of the most important. Just as SQL is required for
any coder working with databases, understanding some of the key XML services
will be required of developers working with unstructured documents - which
is just about every programmer.
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