Mobile data services become increasingly important in the age of wireless broadband data access. We propose a service platform that can provide context-aware and localized/personalized data services. We involve the data broadcasting and publish/subscribe techniques into our system. A prototyping system for a mobile guiding application is implemented. This guiding system is different from most modern navigation systems with some distinctive features. We allow mobile users to know the current status of the surrounding area such as the temperature, traffic conditions, and the vacancy information in a hotel or a parking place. We provide video sharing and playing on the fly with the support of quality-of-service control and seamless handoff.