SAAJ API Overview:
The SOAP with Attachments API for JavaTM (SAAJ) 1.2.1 provides the API for creating and sending SOAP messages by means of the javax.xml.soap package. It is used for the SOAP messaging that goes on behind the scenes in JAX-RPC and JAXR implementations. Developers can also use it to write SOAP messaging applications directly instead of using JAX-RPC.
Axis uses SAX (event-based) parsing to acheive significantly greater speed than earlier versions of Apache SOAP.
Axis is compiled in the JAR file axis.jar; it implements the JAX-RPC API declared in the JAR files jaxrpc.jar and saaj.jar. It needs various helper libraries, for logging, WSDL WebServices - Axis
Axis needs to be able to find an XML parser. If application server or Java runtime does not make one visible to web applications, download and add it.
Java 1.4 includes the Crimson parser, so you can omit this stage, though the Axis team prefer Xerces.
Yet to add....