DOM Basics 
Purpose
DOM is a standard designed to provide the developer with an easy-to-manipulate tree structure representation of an XML document. This structure is appropriate for applications that need to access and manipulate the XML document directly. Since the whole tree is maintained in the memory, DOM-based applications can deteriorate server performance. Thus, it is not recommended that you use it for parsing large XML documents, especially when you are interested in some part of it and not the whole document.
DOM can be used either to traverse an existing DOM Tree, and extract specific information, or to build a DOM Document in memory, and then either forward it to some application, which will process it, or to serialize it, thus creating an XML file.
Later, the most important methods and interfaces will be outlined. The whole definition and description of these methods can be found either in the JavaDoc documentation of the SAP XML Toolkit for Java, or on the following site:
http://xml.apache.org/
Note that the above address is related to the DOM, SAX and JAXP 1.2 Specification standard APIs.