In computing, the Java API for XML Processing, or JAXP ( ), one of the Java XML Application programming interfaces, provides the capability of validating and parsing XML documents. It has three basic parsing interfaces:
the Document Object Model parsing interface or DOM interface
the Simple API for XML parsing interface or SAX interface
the Streaming API for XML or StAX interface (part of JDK 6; separate jar available for JDK 5)
In addition to the parsing interfaces, the API provides an XSLT interface to provide data and structural transformations on an XML document.
JAXP was developed under the Java Community Process as JSR 5 (JAXP 1.0), JSR 63 (JAXP 1.1 and 1.2), and JSR 206 (JAXP 1.3).
JAXP version 1.4.4 was released on September 3, 2010. JAXP 1.3 was declared end-of-life on February 12, 2008.
DOM interface
The DOM interface parses an entire XML document and constructs a complete in-memory representation of the document using the classes and modeling the concepts found in the Document Object Model Level 2 Core Specification.
The DOM parser is called a , as it builds an in-memory Document representation. The is created by the . The creates an instance - a tree structure containing nodes in the XML Document. Each tree node in the structure implements the interface. Among the many different types of tree nodes, each representing the type of data found in an XML document, the most important include:
element nodes that may have attributes
text nodes representing the text found between the start and end tags of a document element.
SAX interface
The creates the SAX parser, called the . Unlike the DOM parser, the SAX parser does not create an in-memory representation of the XML document and so runs faster and uses less memory. Instead, the SAX parser informs clients of the XML document structure by invoking callbacks, that is, by invoking methods on an instance provided to the parser. This way of accessing document is called Streaming XML.
The DefaultHandler class implements the , the , the , and the interfaces. Most clients will be interested in methods defined in the ContentHandler interface that are called when the SAX parser encounters the corresponding elements in the XML document. The most important methods in this interface are:
and methods that are called at the start and end of a XML document. startElement() and endElement() methods that are called at the start and end of a document element. characters() method that is called with the text data contents contained between the start and end tags of an XML document element.
Clients provide a subclass of the DefaultHandler that overrides these methods and processes the data. This may involve storing the data into a database or writing it out to a stream.
During parsing, the parser may need to access external documents. It is possible to store a local cache for frequently used documents using an XML Catalog.
This was introduced with Java 1.3 in May 2000.
StAX interface
StAX was designed as a median between the DOM and SAX interface. In its metaphor, the programmatic entry point is a cursor that represents a point within the document. The application moves the cursor forward - 'pulling' the information from the parser as it needs. This is different from an event based API - such as SAX - which 'pushes' data to the application - requiring the application to maintain state between events as necessary to keep track of location within the document.
XSLT interface
The XML Stylesheet Language for Transformations, or XSLT, allows for conversion of an XML document into other forms of data. JAXP provides interfaces in package allowing applications to invoke an XSLT transformation. This interface was originally called TrAX (Transformation API for XML), and was developed by an informal collaboration between the developers of a number of Java XSLT processors.