Is it possible to use session variable in SoapUI Mock service

I have implemented a mock service.it mock a async soap web service with call back result.When a request arrive with a unique id, mock service provide a response ("Prossesing") and store the requestid in a context like this (within Script):

context.put("requestid",mockerequest.requestid)

A call back is fired (from AfterScript) with stored requestid after few millisecond to show async behavior, using ThreadSleep .

From context, requestid is extracted like this,which is passed with callback result :

context.get("requestid")

It works fine with a single call. But when repeated requests are performed during load test, requestid
in the context is changed(next request is changing current requestid ) and a callback is fired with a wrong request id.It now problem to test multiple request in one go.

Do SoapUI support any kind of session variable, where value will be preserved for each session to avoid this problem ?