>Can any one tell me how I can develop middle tier in vfp using vb as the front end?

In addition to the other replies, I'd suggest the use of MTS for hosting your VFP DLL's (if your three-tier app will be distributed among more than one machine). See this MSDN article: http://msdn.microsoft.com/library/default.asp?URL=/library/techart/MTSVFP.htm