1. A method for providing a context-based service to a terminal of a communication network comprising, at a context server cooperating with said communication network: a) receiving a query from a service application capable of implementing said context based service, said query indicating that said context server should perform an action when a query condition is fulfilled, said query condition referring to one or more attributes of derived context information indicative of a context of said terminal; b) generating a query evaluation trigger indicating that said query condition should be evaluated when said derived context information is updated; c) identifying raw context information allowing derivation of said derived context information; d) generating a calculation trigger indicating that said derived context information should be calculated when an update of said raw context information is received from said terminal; e) receiving from said terminal an update of said raw context information and, according to said calculation trigger, calculating a new value of said derived context information according to said update; and f) according to said query evaluation trigger, evaluating said query condition by using said new value and, if said query condition is fulfilled, performing said action.
1. A method for providing a context-based service to a terminal of a communication network comprising, at a context server cooperating with said communication network: a) receiving a query from a service application capable of implementing said context based service, said query indicating that said context server should perform an action when a query condition is fulfilled, said query condition referring to one or more attributes of derived context information indicative of a context of said terminal; b) generating a query evaluation trigger indicating that said query condition should be evaluated when said derived context information is updated; c) identifying raw context information allowing derivation of said derived context information; d) generating a calculation trigger indicating that said derived context information should be calculated when an update of said raw context information is received from said terminal; e) receiving from said terminal an update of said raw context information and, according to said calculation trigger, calculating a new value of said derived context information according to said update; and f) according to said query evaluation trigger, evaluating said query condition by using said new value and, if said query condition is fulfilled, performing said action. 4. The method according to claim 1 , wherein e) receiving from said terminal, comprises, after calculating said new value of said derived context information, storing said new value in a context database cooperating with said context server, said context database also storing a previously stored value of said derived context information.