The State of the Game
The list of possible uses for XML is almost endless, and new applications are being added all the time. The current roll call of XML applications includes, in no particular order of importance, the following items. This list is by no means complete, but it does include the most important or the most promising applications:
- • The Open Software Description (OSD) format software distribution and update-Microsoft has a vision of zero install software; software that can be downloaded from the Internet, used, and then discarded.
Have you ever thought about the fact that when your Web browser downloads a Java applet or executes a piece of JavaScript code, you have in essence downloaded a piece of software, used it and, when you close the browser, thrown it away? By extending CSS (and you will see an example of this later in this chapter), Microsoft and Marimba would like to distribute software, even binary code, via the Internet. - • The Internet Open Trading Protocol (OTP)-An XML protocol for the exchange of financial transaction information, electronic payment, credit card information, and bank account details.
- • The Java Speech Markup Language (JSML)-Adds structural information to synthesized speech so that it can sound more natural.
- • The Health Level 7 (HL7) initiative for formatting electronic patient records-This doesn't just mean medical records, it means insurance information and treatment and billing details. This is probably one of the least publicized applications, but it is probably the one with the most far-reaching consequences. It comes at a time when most of the Western countries are struggling to gain control of their medical care costs: an area where administration costs seem to threaten dominance over actual medical costs.
- • The Open Financial Exchange Specification (OFE)-This is another candidate format and protocol for e-commerce.
- • The Handheld Device Markup Language (HDML)-This is a sort of mini-HTML that would allow hand-held devices (PDAs like the PalmPilot, mobile telephones, and palm computers) to browse the Web and communicate over the Internet.
- • The Channel Definition Format (CDF)-Though once trumpeted as the breakthrough in a new model for Web publishing called Push Media, CDF has become a useful way of subscribing through Internet Explorer to Web sites that provided regularly updated information (news, stock price quotations, and so on).
- • Visual XML (VXML)-A way of describing Web sites and publishing them in the Virtual Reality Modeling Language (VRML). This gives the browser a virtual 3D navigation experience (similar to what has already been done for some years by the Hyperwave people).
- • The Signed Document Markup Language (SDML)-A means to electronically sign and verify electronic documents (a little similar to public key encryption mechanisms like those that form the heart of PGP (Pretty Good Privacy)).
- • The Translation Memory Exchange (TMX)-A way to exchange vocabulary databases between (high-end) translation and localization software packages.
- • OpenTag-A method for inserting XML tags in text to allow the extraction, translation, and re-insertion of translated material.
- • The Platform for Privacy Preferences (P3P)-A method for Web sites to use RDF and XML to identify the nature of their content (such as adults only material).
- • WebBroker-A means for distributed software components to communicate over the Internet with each other.
- • The Development Markup Language (DML)-A means for development organizations (such as the WHO, UNESCO, the OECD, the Rockefeller Foundation and the World Bank) to exchange information.
- • The XML Query Language (XML-QL)-An implementation of SQL in XML.
- • The Bioinformatic Sequence Markup Language (BSML)-Represents and displays genetic sequence information.
- • The Chemical Markup Language (CML)-Represents and displays chemical molecule information.
- • The Synchronized Multimedia Integration Language (SMIL)-Integrates independent multimedia objects (video, graphics, audio, and so on) into a synchronized multimedia presentation.
This is just a small sample of the many applications that people have thought up for XML. Some of them have the backing of the largest companies (Visa, Microsoft, Oracle, to name just a few), others are personal interest involving just a few people.
I don't have the space here to go into the details of all of these applications. I have therefore picked one of the most interesting, the Mathematics Markup Language (MathML). I will also focus on two application areas (graphics and behaviors) where XML will most probably have the greatest impact on non-specialist audiences.