Web Services-Common Pitfalls and Troubleshooting
NullPointerException calling WebService with Axis
If you get an exception like the following:
Caused by: java.lang.NullPointerException
at java.util.Hashtable.put(Hashtable.java:396)
at com.sun.org.apache.xerces.internal.jaxp.SAXParserImpl.setProperty(SAXParserImpl.java:395)
at org.apache.axis.encoding.DeserializationContextImpl.parse(DeserializationContextImpl.java:246)
at org.apache.axis.SOAPPart.getAsSOAPEnvelope(SOAPPart.java:538)
at org.apache.axis.Message.getSOAPEnvelope(Message.java:376)
at org.apache.axis.client.Call.invokeEngine(Call.java:2583)
at org.apache.axis.client.Call.invoke(Call.java:2553)
at org.apache.axis.client.Call.invoke(Call.java:2248)
... 5 more
It's most likely because you are using Java 1.5 with Axis 1.1. If you want your client to run on Java 1.5, you will need to upgrade to Axis 1.2RC2.
Losing Session with Axis Client
For more information about cookie-based sessions with Axis clients, read the Consuming with Axis in Java section.