In this talk, I will present a generative approach to gateway construction, z2z, based on a domain-specific language for describing protocol behaviors, message structures, and the gateway logic. Z2z includes a compiler that checks essential correctness properties and produces efficient code. We have used z2z to develop a number of gateways, including SIP to RTSP, SLP to UPnP, and SMTP to SMTP via HTTP, involving a range of issues common to protocols used in the home. Our evaluation of these gateways shows that z2z enables communication between incompatible devices without increasing the overall resource usage or response time.