Hi Gayatri,
We have SAP PI 7.3 as well, and we are facing probably exact the same situation, so your solution could work for us. I am just wondering did the solution below, just pure java mapping, without using Soap Axis, work for you in your SAP PI 7.30 landscape?
ECC--->proxy--->PI--->java
or ABAP mapping---->request--->REST webservice--->response---->same java or ABAP
mapping---->proxy---->ECC.
It would be very helpful to hear your feedback.
Blue