Specifying and detecting spatio-temporal event in location based collaborative environment

In the location based collaboration, the change of the spatio-temporal relationship of the people-people or people-place is the key context for collaboration. So, the location based collaborative environment should support the spatio-temporal event sub/pub service. The key problem in spatio-temporal event subscription is how to specify the different spatio-temporal events. At first, we analyzed the spatial predicate, temporal predicate, comparison predicate and connecting predicate, and then gave the schema of spatio-temporal event. In spatio-temporal event publishing, we put forward a two-steps event detecting mechanism. Lastly we verify the higher efficiency than other event detecting algorithms.