The Mobile Collaboration Architecture is a middleware architecture for developing and deploying context-aware collaborative applications for mobile users. MoCA comprises client and server APIs, a set of core services for registering applications, the ability to monitor and infer the execution context of mobile devices, and an object-oriented framework for instantiating and customizing server proxies according to applications? specific adaptation and context-processing requirements. MoCA facilitates the development of distributed programs that require access to individual and group context to define application-specific and dynamic adaptations. MoCA?s design focuses on simplicity, extensibility, scalability, protocol heterogeneity, and application customization.