With the rapid growth of cloud computing, developing business applications on Platform-as-a-Service (PaaS) systems is increasingly popular among industry companies. Various services are developed to support different business requirements on PaaS systems. However, to the best of our knowledge, currently there is no service that provides mobile social messaging services to enable users of their apps to share messages in their social networks (e.g., We Chat, Whats App, Kaka Talk). Lack of such mobile social messaging services prevents industry companies from succeeding in drastic market competitions (e.g., Capture high customer satisfactory). In this paper, we propose a service-based framework to enable the mobile social messaging in PaaS systems (e.g., IBM Blue mix). Using this framework, developers can focus on the service encapsulation of existing applications, and define their business process flows via the conversation management in our platform (no coding work is needed). As such, our framework can effectively reduce the development workload for mobile social messaging in PaaS systems.