The SAAJ APIs extend their counterparts in the org.w3c.dom package:
The Node interface extends the org.w3c.dom.Node interface.
The SOAPElement interface extends both the Node interface and the org.w3c.dom.Element interface.
The SOAPPart class implements the org.w3c.dom.Document interface.
The Text interface extends the org.w3c.dom.Text interface.
Moreover, the SOAPPart of a SOAPMessage is also a DOM Level 2 Document and can be manipulated as such by applications, tools, and libraries that use DOM. For details on how to use DOM documents with the SAAJ API, see Adding Content to the SOAPPart Object and Adding a Document to the SOAP Body.