You can't and you don't. XML itself is not a programming language, so XML files don't ‘run’ or ‘execute’. XML is a markup specification language and XML files are just data: they sit there until you run a program which displays them (like a browser) or does some work with them (like a converter which writes the data in another format, or a database which reads the data), or modifies them (like an editor).
If you want to view or display an XML file, open it with an XML editor or an XML browser.
The water is muddied by XSL (both XSLT and XSL:FO) which use XML syntax to implement a declarative programming language. In these cases it is arguable that you can ‘execute’ XML code, by running a processing application like Saxon, which compiles the directives specified in XSLT files into Java bytecode to process XML.
www.referjava.com
Thursday, February 15, 2007
Can I use JavaScript, ActiveX, etc in XML files?
This will depend on what facilities the browser makers implement. XML is about describing information; scripting languages and languages for embedded functionality are software which enables the information to be manipulated at the user's end, so these languages do not normally have any place in an XML file itself, but in stylesheets like XSL and CSS.
XML itself provides a way to define the markup needed to implement scripting languages: as a neutral standard it neither encourages not discourages their use, and does not favour one language over another, so it is possible to use XML markup to store the program code, from where it can be retrieved by (for example) XSLT and re-expressed in a HTML script element.
Server-side script embedding, like PHP or ASP, can be used with the relevant server to modify the XML code on the fly, as the document is served, just as they can with HTML. Authors should be aware, however, that embedding server-side scripting may mean the file as stored is not valid XML: it only becomes valid when processed and served, so care must be taken when using validating editors or other software to handle or manage such files. A better solution may be to use an XML serving solution like Cocoon, AxKit, or PropelX.
www.referjava.com
XML itself provides a way to define the markup needed to implement scripting languages: as a neutral standard it neither encourages not discourages their use, and does not favour one language over another, so it is possible to use XML markup to store the program code, from where it can be retrieved by (for example) XSLT and re-expressed in a HTML script element.
Server-side script embedding, like PHP or ASP, can be used with the relevant server to modify the XML code on the fly, as the document is served, just as they can with HTML. Authors should be aware, however, that embedding server-side scripting may mean the file as stored is not valid XML: it only becomes valid when processed and served, so care must be taken when using validating editors or other software to handle or manage such files. A better solution may be to use an XML serving solution like Cocoon, AxKit, or PropelX.
www.referjava.com
Can I do mathematics using XML?
Yes, if the document type you use provides for math, and your users' browsers are capable of rendering it. The mathematics-using community has developed the MathML Recommendation at the W3C, which is a native XML application suitable for embedding in other DTDs and Schemas.
It is also possible to make XML fragments from other DTDs, such as ISO 12083 Math, or OpenMath, or one of your own making. Browsers which display math embedded in SGML have existed for many years (eg DynaText, Panorama, Multidoc Pro), and mainstream browsers are now rendering MathML (eg Mozilla, Netscape). David Carlisle has produced a set of stylesheets for rendering MathML in browsers. It is also possible to use XSLT to convert XML math markup to for print (PDF) rendering, or to use XSL:FO.
www.referjava.com
It is also possible to make XML fragments from other DTDs, such as ISO 12083 Math, or OpenMath, or one of your own making. Browsers which display math embedded in SGML have existed for many years (eg DynaText, Panorama, Multidoc Pro), and mainstream browsers are now rendering MathML (eg Mozilla, Netscape). David Carlisle has produced a set of stylesheets for rendering MathML in browsers. It is also possible to use XSLT to convert XML math markup to for print (PDF) rendering, or to use XSL:FO.
www.referjava.com
How do I create my own document type?
Document types usually need a formal description, either a DTD or a Schema. Whilst it is possible to process well-formed XML documents without any such description, trying to create them without one is asking for trouble. A DTD or Schema is used with an XML editor or API interface to guide and control the construction of the document, making sure the right elements go in the right places.
Creating your own document type therefore begins with an analysis of the class of documents you want to describe: reports, invoices, letters, configuration files, credit-card verification requests, or whatever. Once you have the structure correct, you write code to express this formally, using DTD or Schema syntax.
www.referjava.com
Creating your own document type therefore begins with an analysis of the class of documents you want to describe: reports, invoices, letters, configuration files, credit-card verification requests, or whatever. Once you have the structure correct, you write code to express this formally, using DTD or Schema syntax.
www.referjava.com
Is there an XML version of HTML?
Yes, the W3C recommends using XHTML which is ‘a reformulation of HTML 4 in XML 1.0’. This specification defines HTML as an XML application, and provides three DTDs corresponding to the ones defined by HTML 4.* (Strict, Transitional, and Frameset).
The semantics of the elements and their attributes are as defined in the W3C Recommendation for HTML 4. These semantics provide the foundation for future extensibility of XHTML. Compatibility with existing HTML browsers is possible by following a small set of guidelines (see the W3C site).
www.referjava.com
The semantics of the elements and their attributes are as defined in the W3C Recommendation for HTML 4. These semantics provide the foundation for future extensibility of XHTML. Compatibility with existing HTML browsers is possible by following a small set of guidelines (see the W3C site).
www.referjava.com
If XML is just a subset of SGML, can I use XML files directly with existing SGML tools?
Yes, provided you use up-to-date SGML software which knows about the WebSGML Adaptations TC to ISO 8879 (the features needed to support XML, such as the variant form for EMPTY elements; some aspects of the SGML Declaration such as NAMECASE GENERAL NO; multiple attribute token list declarations, etc).
An alternative is to use an SGML DTD to let you create a fully-normalised SGML file, but one which does not use empty elements; and then remove the DocType Declaration so it becomes a well-formed DTDless XML file. Most SGML tools now handle XML files well, and provide an option switch between the two standards
www.referjava.com
An alternative is to use an SGML DTD to let you create a fully-normalised SGML file, but one which does not use empty elements; and then remove the DocType Declaration so it becomes a well-formed DTDless XML file. Most SGML tools now handle XML files well, and provide an option switch between the two standards
www.referjava.com
Should I use XML instead of HTML?
Yes, if you need robustness, accuracy, and persistence. XML allows authors and providers to design their own document markup instead of being limited by HTML. Document types can be explicitly tailored to an application, so the cumbersome fudging and poodlefaking that has to take place with HTML becomes a thing of the past: your markup can always say what it means (trivial example: next Monday ).
Information content can be richer and easier to use, because the descriptive and hypertext linking abilities of XML are much greater than those available in HTML.
XML can provide more and better facilities for browser presentation and performance, using XSLT and CSS stylesheets;
It removes many of the underlying complexities of SGML-format HTML (which led to them being ignored and broken) in favor of a more flexible model, so writing programs to handle XML is much easier than doing the same for all the old broken HTML.
Information becomes more accessible and reusable, because the more flexible markup of XML can be used by any XML software instead of being restricted to specific manufacturers as has become the case with HTML.
XML files can be used outside the Web as well, in existing document-handling environments (eg publishing).
If your information is transient, or completely static and unreferenced, or very short and simple, and unlikely to need updating, HTML may be all you need.
www.referjava.com
Information content can be richer and easier to use, because the descriptive and hypertext linking abilities of XML are much greater than those available in HTML.
XML can provide more and better facilities for browser presentation and performance, using XSLT and CSS stylesheets;
It removes many of the underlying complexities of SGML-format HTML (which led to them being ignored and broken) in favor of a more flexible model, so writing programs to handle XML is much easier than doing the same for all the old broken HTML.
Information becomes more accessible and reusable, because the more flexible markup of XML can be used by any XML software instead of being restricted to specific manufacturers as has become the case with HTML.
XML files can be used outside the Web as well, in existing document-handling environments (eg publishing).
If your information is transient, or completely static and unreferenced, or very short and simple, and unlikely to need updating, HTML may be all you need.
www.referjava.com
Who is responsible for XML?
XML is a project of the World Wide Web Consortium (W3C), and the development of the specification is supervised by an XML Working Group. A Special Interest Group of co-opted contributors and experts from various fields contributed comments and reviews by email.
XML is a public format: it is not a proprietary development of any company, although the membership of the WG and the SIG represented companies as well as industrial research and academic institutions. The v1.0 specification was accepted by the W3C as a Recommendation on Feb 10, 1998.
www.referjava.com
XML is a public format: it is not a proprietary development of any company, although the membership of the WG and the SIG represented companies as well as industrial research and academic institutions. The v1.0 specification was accepted by the W3C as a Recommendation on Feb 10, 1998.
www.referjava.com
Why is XML such an important development?
It removes two constraints which were holding back Web developments:
dependence on a single, inflexible document type (HTML) which was being much abused for tasks it was never designed for;
the complexity of full SGML, whose syntax allows many powerful but hard-to-program options.
XML allows the flexible development of user-defined document types. It provides a robust, non-proprietary, persistent, and verifiable file format for the storage and transmission of text and data both on and off the Web; and it removes the more complex options of SGML, making it easier to program for.
www.referjava.com
dependence on a single, inflexible document type (HTML) which was being much abused for tasks it was never designed for;
the complexity of full SGML, whose syntax allows many powerful but hard-to-program options.
XML allows the flexible development of user-defined document types. It provides a robust, non-proprietary, persistent, and verifiable file format for the storage and transmission of text and data both on and off the Web; and it removes the more complex options of SGML, making it easier to program for.
www.referjava.com
Aren't XML, SGML, and HTML all the same thing?
Not quite; SGML is the mother tongue, and has been used for describing thousands of different document types in many fields of human activity, from transcriptions of ancient Irish manuscripts to the technical documentation for stealth bombers, and from patients' clinical records to musical notation. SGML is very large and complex, however, and probably overkill for most common office desktop applications.
XML is an abbreviated version of SGML, to make it easier to use over the Web, to make it easier for you to define your own document types, and to make it easier for programmers to write programs to handle them. It omits all the complex and less-used options of SGML in return for the benefits of being easier to write applications for, easier to understand, and more suited to delivery and interoperability over the Web. But it is still SGML, and XML files may still be processed in the same way as any other SGML file (see the question on XML software).
HTML is just one of many SGML or XML applications—the one most frequently used on the Web.
Technical readers may find it more useful to think of XML as being SGML−− rather than HTML++.
SOURCE : www.referjava.com
XML is an abbreviated version of SGML, to make it easier to use over the Web, to make it easier for you to define your own document types, and to make it easier for programmers to write programs to handle them. It omits all the complex and less-used options of SGML in return for the benefits of being easier to write applications for, easier to understand, and more suited to delivery and interoperability over the Web. But it is still SGML, and XML files may still be processed in the same way as any other SGML file (see the question on XML software).
HTML is just one of many SGML or XML applications—the one most frequently used on the Web.
Technical readers may find it more useful to think of XML as being SGML−− rather than HTML++.
SOURCE : www.referjava.com
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