You must understand
SOAP structure (part, envelope, header, body)
faults: server, client, versionMismatch, mustUnderstand
when these faults are throw.
WSDL
types, portType, message, binding, service,
you must know how each these items correspond in
java code
Anderson Fonseca :: Brazil<br />SCJA 1.0, SCJP 1.4, SCWCD 1.4, SCBCD 1.3, SCDJWS, SCEA(I), SCEA 5 (I,II,III)