A survey on context aware system & intelligent Middleware’s

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Context aware system or Sentient system is the most profound concept in the ubiquitous computing. In the cloud system or in distributed computing building a context aware system is difficult task and programmer should use more generic programming framework. On the basis of layered conceptual design, we introduce Context aware systems with Context aware middleware's. On the basis of presented system we will analyze different approaches of context aware computing. There are many components in the distributed system and these components should interact with each other because it is the need of many applications. Plenty Context middleware's have been made but they are giving partial solutions. In this paper we are giving analysis of different middleware's and comprehensive application of it in context caching. The Context aware or Sentient systems are comes under pervasive computing. Weiser (1991) introduced pervasive which refers to the integration of mobile devices such as notebook, PDAs, smartphones etc into the humans everyday life. It is expected that the services should react specifically to their time, places and current locations. Context can be refer as location, identities of nearby people and object, and changes to those objects. The situation of entity can be characterized by context. Users profile, device status, networking information or sensors are the ways to retrieve context information. The first context aware application is developed by Want et. al. (1992) which is based on Active badge Location System. According to the users current location, location-aware tour guide applications developed in middle 1990s. (Abowd et. al., 1997; Sumi et. al., 1998; Cheverest et. al., 2000) Person's emotional state, focus of attention, place, time and date, people in the user's environment can be defined as the sentient defined by Dey (1998). Hull et al. (1997) describe context as the aspects of the current situation. Brown defines context to be the elements of the user's environment which the computer knows about. Most context aware systems make use of external sentient factors as they provide useful data, such as place information. Furthermore, external attributes are easy to sense by using off-the-shelf sensing technologies. Watson Project used logical data (Budzik and Hammond, 2000) and the IntelliZap Project (Finkelstein et al., 2001) which support the user by giving useful information due to information read out of web pages, records etc. When dealing with sentient, three entities can be differentiated (Dey and Abowd, 2001): places (rooms, buildings etc.), people (individuals or groups) and things (physical objects, Mobile Component, computer components etc.). These entities may be given by various attributes which can be classified into four categories: identity (each entity has a unique identifier), location (an entity's position, co-location etc.), status (or activity, meaning the properties of an entity, e.g., heat and lightning for a room, processes running currently on a mobile etc.) and time (used for timestamps to define events etc.). II. APPROACHES