With the ubiquity and pervasiveness of mobile com- puting, together with the increasing number of social networks, end-users have learned to live and share all kinds of information about themselves. As an example, Facebook reports that it has currently 500 million active users, 200 million of which access its services on mobile systems; moreover, users that access Facebook through mobile applications are twice as active as non-mobile users, and it is used by 200 mobile operators in 60 countries . More specific mobile platforms such as Foursquare, which unlike Facebook only collects location information, reports 6.5 million users worldwide, and also has a mobile presence (both with a web application and iPhone / Android applications) . Context- aware architectures intend to explore this increasing number of context information sources and provide richer, targeted services to end-users, while also taking into account arising privacy issues.
While multiple context management platform architectures have been devised , this paper focuses primarily on Context- Broker-based architectures, such as the ones proposed in the projects Mobilife  and C-Cast . More specifically, it focuses on the context management platform XCoA . This platform uses XMPP for its main communication protocol, and publishes context information in a Context-Broker. This context informa- tion is provided by Context-Agents, such as mobile terminals, sensor networks and social networks. Due to the nature of the XMPP protocol, the context information is provided in XML form.
This paper proposes the usage of a NoSQL storage system for the purpose of context information storage and retrieval in an XMPP broker-based context platform such as XCoA, together with a full-text searching engine. Through a comparison made through prototypes, the paper clearly demonstrates the advantages of NoSQL storage systems applied to the area of Context Management.
Conference: 2011 Conferência sobre Redes de Computadores in Coimbra, Portugal