Serializer/Deserializer are used during marshalling/unmarshalling process.
When your web service send a response back to the consumer, the server needs a serializer. Once the response is received on the client side, you client now need a deserializer to be able to understand the response.
With Axis, the method registerTypeMapping() of the call object allows you to declare deserializers on the client side.
Check Axis Api
doc for further information
If your complex object is a bean (according to Sun spec JavaBean), then you will be able to us the default bean deserializer Axis is bundled with : org.apache.axis.encoding.ser.BeanDeserializerFactory.class
But you also need to double check that all the datatypes you are using in your bean are supported by the default Axis deserializer
Otherwise, you'll have to declare and create your own deserializer
HTH,
[ November 21, 2003: Message edited by: Jean-Louis Marechaux ]