Hi,
For TCP Virtualization to work successfully, you need to first get a good idea of the following:
1. How are the data packets delimited ?
2. What kind of data is being sent ? Is it Text ? If text, is it JSON, XML ?
Devtest product has wide range of options when it comes to dealing with the data delimiters and handing of your data protocol, but you need to be clear about how your backend TCP service deals with the data.
Once you have found out the rudimentary details, you would go about recording and if necessary use one or more data protocols to interpret the request and response.
I have a working example with TCP Virtualization documented here: Cascading Data Protocol Handlers - Working Example with TCP Virtualization.pdf
IN this example, the backend treats the data as XML text. You would also find the necessary java programs that simulate a TCP Server and Client in the documents section of this community.
PLease try it out and let me know if you have any further questions.
-Sankar