XML Software Guide: XML APIs

Last Modified:     March 2, 2009

A number of application programming interfaces exist to make dealing with common XML tasks such as parsing easier. Most are written in Java, although Python and perl APIs are also quite popular.

SAX

The Simple API for XML; an extremely popular event-based interface for any XML parser, which differs dramatically from the mempory-intensive, tree-based DOM approach to parsing. SAX is somewhat of a grass-roots effort, spearheaded by David Megginson, developed collaboratively by the members of the XML-DEV mailing list. As you can tell from the rest of this page, SAX is the basis for quite a few Java APIs. The May 1998 version of SAX, now called SAX1, is supported by nearly every XML parser. The current version, SAX2, released in May 2000, is supported by many but not all major parsers. Megginson sees SAX addressing a need much like JDBC fills for SQL. The idea behind SAX is to provide an interface by which any Java application can access any XML parser, provided the parser has a SAX driver. Virtually every major XML parser either supports the SAX1 and/or SAX2 interface directly or indirectly via third-party drivers. SAX comes with sample drivers (e.g., Lark and MSXML). [freeware for all Java platforms]

JAXP: Java API for XML Parsing

[For potentially more current information about Sun's XML efforts, see the Java Technology and XML page.] Sun's JAXP, the Java API for XML Parsing, originally released in April 2000, provides a standard (but optional) interface to XML for Java applications. It does not require use of Sun's Java Project X parser (below), although this is the default. Download the JAXP code and specification. According to the JAXP README,

"The Java API for XML Parsing (JAXP) Optional Package enables basic functionality for reading, manipulating, and generating XML documents through pure Java APIs. The API provides a standard way for any XML-conformant parser to be accessed by an application. The reference implementation uses the high performance Java Project X as its default XML parser. However, the software's pluggable architecture allows any XML conformant parser to be used. This release is addressed to Java developers who want access to Sun's fast and fully-conformant XML software for development. The library includes fast XML parsers (both validating and non-validating) and supports an optional in-memory object model tree for manipulating and writing XML structured data. Using this software, application and tool developers can build fully-functional XML-enabled Java applications for e-commerce, application integration, and web publishing. This release offers 100% conformance to the XML 1.0 Specification, SAX 1.0, DOM Level 1 Core, and XML namespaces."

[freeware for all Java platforms]

Java Project X

[For potentially more current information about Sun's XML efforts, see the Java Technology and XML page.] JavaSoft renamed its former XML Library to Java Project X. Early Access release 2 became available Dec. 1, 1998. Technology Release 1 became available in late February 1999 with Technology Release 2 following in May 1999. Java Project X provides "full XML processing capabilities, including a fast XML parser with optional validation, an in-memory object model tree that supports the W3C DOM Level 1 recommendation, and basic support for JavaBeans integration with XML." See the FAQ and our WDVL entry with a code example. In a Q and A interview, Dave Brownell said:

"Java Project X is the codename for a set of core XML-enabling services, using Java^TM technology."

Note that JavaSoft has submitted a proposal for a Java Standard Extension for XML. [freeware for all Java platforms]

DOM Level 1: Java XML API definitions

Java XML API definitions are part of the W3C effort to define the Document Object Model (DOM), Level 1. The DOM defines "a platform- and language-neutral interface that will allow programs and scripts to dynamically access and update the content, structure and style of documents. The Document Object Model provides a standard set of objects for representing HTML and XML documents, a standard model of how these objects can be combined, and a standard interface for accessing and manipulating them." Note: DOM Level 2 is a W3C Candidate Recommendation as of May 2000. DOM2 has its own Java Language Binding page. [freeware for all Java platforms]

SAXON

"The SAXON package is a collection of tools for processing XML documents. The main components are:

• An XSLT processor, which implements the Version 1.0 XSLT and XPath Recommendations.... with a number of powerful extensions
• A Java library, which supports a similar processing model to XSL, but allows full programming capability, which you need if you want to perform complex processing of the data or to access external services such as a relational database
• A slightly improved version of the Ælfred parser from Microstar. (But you can use SAXON with any SAX-compliant XML parser if you prefer).

So you can use SAXON by writing XSL stylesheets, by writing Java applications, or by any combination of the two. If you are only interested in running the XSLT interpreter, on a Windows platform, try Instant SAXON". SAXON also includes a useful example application called DTD Generator that creates a DTD from an XML instance. [freeware for all Java platforms]

Coins

"Tightly Coupled JavaBeans and XML Elements". Bill la Forge of JXML is the major person behind Coins, although he receives considerable input from the java-xml-interest emailing list. A Coin consists of two "faces": an XML element is the persistent form, and the JavaBean instance is the runtime form. Coins is an alternative to Java Serialization in which each JavaBean property is exposed as an XML element attributes. [freeware for all Java platforms]

Quick

A more recent JXML effort (February 2000) is Quick, an API for converting XML files into a structure of objects, using the classes of your choice. Quick uses a schema language, QJML, to define markup languages and their relationship to Java classes. Quick replaces the former JXML effort called MDSAX (Multi-Document Simple API for XML). [freeware for all Java platforms]

Docuverse DOM SDK

(Previously known as FREE-DOM and SAXDOM.) Don Park's DOM SDK is layered on top of SAX; provides a DOM (Document Object Model) interface in Java. Can be used with Swing to support custom node implementations. Extensive javadoc documentation. Supports both XML and HTML DOMs. Third party software with which DOM SDK is compatible: SAX1, JAXP 1.0, COINS, DOM Parser, Koala XSL Engine, and many others. [free product from Docuverse for all Java platforms]

4Suite: 4DOM, 4XPath, 4XSLT

4Suite is FourThought's proven, standards-based suite of Python software for Web application development. 4Suite consists of five major components, all of which are open-source (although two are not yet publicly available). The three available components are:

• 4DOM is an implementation of the W3C's standard DOM API for HTML and XML content manipulation. 4DOM has full distributed-object support based on the IDL used in the formal DOM spec.
• 4XSLT is a powerful XSLT processor based on the latest draft of the W3C's XSLT specification. One of its many uses is to render XML documents as customized and stylized HTML for current Web browsers. 4XSLT also provides a powerful programming API for applications to use for low-level, customized transformations of XML documents.
• 4XPath is a library implementating of the W3C's XPath language for indicating and selecting portions of an XML document.

[freeware for all Python platforms]

DDML/XSchema

According to author/developer Simon St.Laurent, "The XSchema project [now called DDML: Document Definition Markup Language] is a cooperative effort, based on the xml-dev mailing list. The XSchema specification, when complete, will provide a means for XML developers to describe their XML document structures using XML document syntax." The main goal of XSchema is to eliminate the need for XML language creators to use a DTD to define their new language; they would use XML syntax instead. The advantages of XSchema are many. Note:Since XSchema first appeared, a W3C Note, Document Content Description (DCD) for XML appeared from IBM, Microsoft, and Textuality to provide an RDF vocabulary that expresses data (i.e., a subset of the XML-Data proposal) and datatypes without a DTD. [freeware for all Java platforms]

LT XML

According to LTG, "LT XML is an integrated set of XML tools and a developers' tool-kit, including a C-based API. The release now available will run on UNIX and WIN32. The LT XML tool-kit includes stand-alone tools for a wide range of processing of well-formed XML documents, including searching and extracting, down-translation (e.g. report generation, formatting), tokenising and sorting. Sequences of tool applications can be pipelined together to achieve complex results. For special purposes beyond what the pre-constructed tools can achieve, extending their functionality and/or creating new tools is easy using the LT XML API. Minimal applications require less than one-half page of C code to express. LT XML provides two views of an XML file; one as a flat stream of markup elements and text; a second as a sequence of tree-structured XML elements. The two views can be mixed, allowing great flexibility in the manipulation of XML documents. It also includes a powerful, yet simple, querying language, which allows the user to quickly and easily select those parts of an XML edocument which are of interest." [C language freeware for UNIX and WIN32 platforms]

IBM's XML Productivity Kit for Java

[Note: This technology has been retired.] XPK4J is another IBM alphaWorks technology. "XML Productivity Kit is a companion technology to the XML Parser for Java which provides the next level of programming resources needed to quickly build and deploy robust XML applications using the Java language....Both DOM and SAX have been encapsulated in a set of basic JavaBeans that can be used to build other XML JavaBeans and interconnect between these two standards. The important XPK4J JavaBeans in the set are DOM and SAX filter classes suitable for extending for specific needs." [freeware for all Java platforms]

XAF: XML Architectural Forms

[This effort orginally by David Megginson has been taken over by JXML as part of MDSAX.] "The Java XAF package allows you to process architectural forms with any Java-based, SAX-conformant XML parser. The core of the package is a SAX driver, com.megginson.xml.xaf.SAXDriver, which sits between a regular SAX parser and the client's document handler, translating the SAX events according for the specified base architecture. XAF lets an XML document masquerade as many different documents, by associating the document with one or more base architectures. For example, by specifying the right architectural forms, you can embed RDF or MathML in an XML document without actually using the RDF or MathML element type names." [freeware for all Java platforms]

XML Testbed

Steve Withall's XML Testbed provides "its own supporting XML infrastructure, including an XML parser and grove. A key feature of the infrastructure is a 'node type registry', which allows dynamic control over which classes are used for particular types of elements - the element class to represent them, the parser class to parse them, the customizer class to edit them and the view class to display them (using a Swing text editor kit). The XML Testbed provides means to edit and then parse an XML source.... The software has been designed to be as modular as possible, to be divided into a suite of relatively small packages, each with a clear role.... [XML testbed includes a] nascent XSL engine, XML-based user interface configuration, and a database analyser for generating an XML file of the schema of a database." The overall structure includes a diagram that shows the relationship among the many packages. This software does not presently support DOM compliance. [freeware for all Java platforms]

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XML Software Guide: Specialized XML Software