how to code that performs like server as well as client?

Question

I want to know Is it possible to create a application which acts as a server for multiple clients as well as acts as a client for host server?

In my scenario I want to receive request from multiple clients and send this request to another host server machine which has database access and this machine sends respose to my server machine and this server finally send response to client.

Please give me any suggesstions for this?

thanks.