Horsham
Reed Technology and Information Services
USA 
| Bos, Lisa Horsham Reed Technology and Information Services USA | Lisa W Bos |
| Director, Content Management |
| Reed Technology and Information Services |
| 1 Progress Drive
Horsham
(Pennsylvania)
USA
(19044)
Email: lisa.bos@reedtech.com |
| Biography |
I've been to the W3C site and now I'm more confused than ever! |
| So, to clear up the confusion, let's step back a little. |
| First, you might be coming from any number of backgrounds. You could be: |
| Content Creators |
| Software Developers |
| For some really good reasons that will ultimately benefit all of us, XML and related specifications address each of these tasks and more. No wonder the XML world can be confusing-it would be unreasonable to expect most people to understand the technical details of specifications related to each of these tasks. |
| Categorizing the specifications can help to avoid some of the confusion. This in itself is a challenge, since most specifications can be classified in multiple ways. But, the following category list is a useful start. |
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| You probably noticed that content creators don't show up in this table very often. While content creators will always need a high-level understanding of the pros and cons of various technical options, there is little reason they should be required to understand the technical "guts" of a particular solution in order to be able to do their jobs. For example, a graphic artist should not be concerned with the XML tags used to create an image. However, he will be interested in whether a particular graphic file format is lightweight, can be sized without a reduction in quality, and is useful to both Web and print products. Similarly, an author should be excited about XML because it is portable among all the applications she wants to use or because it faciliates repurposing of her data—not because she thinks those angle brackets are really cool. |
| Today, of course, many content creators are forced to worry about these things—to do the job of a software developer. This is because XML, related specifications, and the applications that support them are still evolving, and because conversations about technical nuts and bolts are regularly mixed up with conversations about grammars for specific kinds of content. If the software developers do their jobs right, then in the future more and more of the nuts and bolts will live invisibly under the hood of XML applications, and content creators won't have to think about them unless they really want to. |
Who manages the development of XML-related standards? |
| The development of XML and many other XML-based specifications is managed by the World Wide Web Consortium or W3C. However, individuals, businesses, and other organizations are developing additional specifications you might be interested in. This is especially true of grammars (DTDs) that are appropriate for specific kinds of content. |
| This presentation sticks to the list of specifications being developed by the W3C. A complete list of these can be found at http://www.w3c.org/tr . Most W3C specifications have abstracts and introductions that provide an easy to understand overview of the specification objectives and contents. Many also include a history section and links to useful tutorials on other sites. |
| If you are interested in additional specifications and XML generally, Robin Cover's site (on the OASIS site) is a great place to start. See http://www.oasis-open.org/cover/xml.html . |
W3C process |
| Before we get started, you should be aware that the W3C doesn't produce "standards", it produces technical reports or specifications. These have a life cycle of the following stages, and "Recommendation" is as high as a specification ever gets. These descriptions are from the W3C web site. |
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Common principles in W3C specifications |
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The related specifications |
| The first thing you'll notice about the W3C specifications is that there are a lot of them, and that many interdependent specifications are at very different places in the W3C life cycle. |
| Only a small number of the current W3C Notes are listed here. |
Markup and Markup Construction |
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Data Interfaces and Models |
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Stylesheets |
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Grammars |
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Details about some of the specifications |
Markup and Markup Construction |
HTML, XML, and XHTML | ||||||
| HTML and XML are stable but still evolving. XHTML is the next step in that evolution. To quote the W3C: "XHTML 1.0 is the first major change to HTML since HTML 4.0 was released in 1997. It brings the rigor of XML to Web pages and is the keystone in W3C's work to create standards that provide richer Web pages on an ever increasing range of browser platforms including cell phones, televisions, cars, wallet sized wireless communicators, kiosks, and desktops." |
Namespaces | ||||||
| The XML Namespace specification provides mechanisms for multiple tag sets to be used together without collisions from duplicate names (if, for example, both sets of tags you want to combine contain a "name" element, but the two elements have very different meanings and content models). Namespaces also provide a means to identify (point to) the definition for each tag set that's used. |
XPath, XPointer, and XLink | ||||||
| XPath describes a way to address parts of an XML document. It uses a non-XML syntax that can be embedded within URIs and XML attribute values. XPath has a subset that can be used for pattern matching tests in XSLT. |
| XPointer specifies a language for pointing into the structures (e.g. elements, strings) of XML documents. It makes use of the XPath specification. |
| XLink defines constructs for explicitly linking from XML documents to other XML documents and Internet resources. Think of this as a very evolved version of the HTML <A> tag. In that analogy, XPointer would describe how to build the HREF attribute value. |
Data Interfaces and Models |
DOM | ||||||
| The Document Object Model is an API. It describes HTML or XML documents as trees and how those trees can be accessed and manipulated by software. This allows the dynamic processing of documents—for example, on the fly changes to the document layout as displayed in a browser. |
| For the geeks, here's a quote from the W3C: "The Document Object Model, despite its name, is not an object model in the same way as the Component Object Model (COM). The COM, like CORBA, is a language-independent way to specify interfaces and objects; the Document Object Model is a set of interfaces and objects designed for managing HTML and XML documents. The DOM may be implemented using language-independent systems like COM or CORBA; it may also be implemented using language-specific bindings like the Java or ECMAScript bindings that we define." |
RDF | ||||||
| RDF is the Resource Description Framework, a means of representing metadata about a resource (e.g. a document or a user) in the form of properties and property values. RDF is not necessarily encoded with XML; however, it is reliant on certain other technologies related to XML, such as those for dealing with internationalization. When using RDF, you create your own set of properties and values—RDF itself does not contain a list of such sets, it just explains how they should be created. |
XML Schema | ||||||
| The XML Schema activity has been divided into two areas: Structures and Datatypes. |
| The easiest way to describe XML Schema Part 1: Structures is to say that it defines a replacement for DTDs, and that it uses an XML syntax rather than the markup defined in XML 1.0 document type definitions (DTDs). To be more accurate, Structures defines a superset of what's possible with DTDs. |
| XML Schema Part 2: Datatypes describes a way to use datatypes in XML Schemas. This will enable applications to validate the content of XML elements and attributes in ways that are critical to data management and that are not possible with DTDs. |
Stylesheets |
| Both CSS and XSL allow style definitions to be captured separately from the documents they are associated with. This provides a number of benefits, including easier maintenance, greater consistency, greater flexibility (the ability to switch among stylesheet dynamically), and easier document authoring. |
CSS | ||||||
| Cascading Stylesheets Level 1 was first approved as a recommendation in 1996. Since then, it has been evolving to support more complex rendering rules, including print and voice styling. CSS Level 2 was made a recommendation in 1998. |
| CSS can be used with both HTML and XML, although neither Netscape and Internet Explorer fully support all its capabilities. |
XSL and XSLT | ||||||
| The Extensible Stylesheet Language is an XML vocabulary for creating stylesheets that can format and transform XML documents. XSL is an extremely powerful means to manipulate documents, and is therefore complex and has been difficult to finalize. While the complete specifications is still a working draft, XSLT (XSL Transformations), a subset of XSL, is now a proposed recommendation with a number of implementations. At first glance, transformations might appear more complicated than formatting, and so it could seem odd to finalize the transformation specification first. However, since XSLT can be used to dynamically produce other document formats (including HTML) from XML, it is actually of more practical short term benefit than the formatting language would be. |
Grammars |
Graphics | ||||||
| There are two types of graphics formats being discussed by the W3C right now. The first, Scalable Vector Graphics (SVG), is a vector format with an XML syntax. Vector images are small in file size, making SVG well-suited for the Web. Because it is an XML-based format, DOM-aware software will be able to build and manipulate SVG graphics on the fly. SVG has gotten support from a number of industry groups and companies. Corel is currently offering a beta export filter to SVG from CorelDRAW. |
| The second format is a Web "profile" of CGM. CGM is a complex ISO standard commonly used in engineering disciplines. CGM images can be a composite of vector and raster images. |
Math | ||||||
| MathML is an XML syntax for describing mathematical content. While current browsers do not support MathML or stylesheets for rendering it, plugins are becoming available. |
Multimedia | ||||||
| The Synchronized Multimedia Integration Language (SMIL) describes a syntax for timing and synchronization information. This kind of information is necessary for describing multimedia content such as training programs and animation. SMIL Boston is an XML equivalent to SMIL. |
| The timing and synchronization components of SMIL Boston are expected to be useful in other XML applications like XHTML. |
| Note: This information is up-to-date as of mid-October, 1999. |
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