To obtain good performance in messaging over mobile networks, we have developed a Gateway. Gateway is a message hub that transmits information using store-and-forward messaging and provides powerful optimization and data transformation. The SmartCaching component provides generic caching in an N-tier architecture, an essential function of Gateway. Gateway can be integrated into Pronto, a middleware system for mobile applications with messaging as a basis [15]. Pronto then offers: 1) a lightweight client of Message Oriented Middleware (MOM) based on Java Message Service(JMS), 2) Gateway for reliable and efficient transmission between mobile devices and a server, and 3) Serverless JMS based on IP multicast. Integration of Gateway within Pronto provides a solution for mobile application-specific problems such as resource constraints, network characteristics, and data optimization.