XML can be considered as a representation of hierarchical data, and the XML-related standards - as methods of processing such data. We describe benefits of XML view on legacy data and its processing, and suggest a method to develop XML tools and make them reusable for different tree-like structures in different programming languages.
Our approach is to use virtual machine technology, in particular, the Scheme programming language. We're taking the unusual step of using the Scheme syntax itself as a native virtual machine language. Together with the
Abstract
Mapping XML Schemas to class definitions and relational schemas allows for seamless marshaling and unmarshaling of an object's state to and from XML documents. W3C XML Schemas provide a rich set of datatypes and validity rules, both built-in, and user definable. It is possible to map data structures defined in a Schema document to data structures in object oriented languages and relational databases. This paper presents approaches to automating such mapping.
In simple cases, a Schema document can be generated based on a class definition,
Web Services can make your applications Web applications.
Web Services are published, found and used through the Web.
What You Should Already Know
Before you continue you should have a basic understanding of the following:
* HTML
* XML
If you want to study these subjects first, find the tutorials on our Home page.
What are Web Services?
* Web services are application components
* Web services communicate using open protocols
* Web services are self-contained and self-describing
* Web services can be discovered using UDDI
* Web
The XML Namespaces Recommendation seems to be causing a great deal of confusion. This note attempts an alternative explanation of the mechanism described in the Recommendation which I hope will be less confusing.
In the data model implied by XML, an XML document contains a tree of elements. Each element has an element type name (sometimes called the tag name) and a set of attributes; each attribute consists of a name and a value. Applications typically make use of the element type name and attributes of an element in determining how to process the
History:
In its appendix of references, XML Schema acknowledges the influence of DTD and other early XML schema efforts such as DDML, SOX, XML-Data, and XDR. It appears to have picked pieces from each of these proposals, but is also a compromise among them. Of those languages, XDR and SOX continued to be used and supported for a while after XML Schema was published. A number of Microsoft products supported XDR until the release of MSXML 4.0 (which dropped XDR in favor of XML Schema) in October 2001. Commerce One, Inc. supported its SOX schema
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