US Patent 7231439 Dynamically swapping modules for determining a computer user's context

Techniques for providing information about a current state modeled with multiple attributes is described. The providing of information can include receiving from a first source an indication of an ability to supply values for one of the state attributes of the modeled current state, and supplying to a client a value for the one attribute received from the first source. After the supplying of the value, the providing can include receiving from a second source a value supplying ability for the one attribute and supplying of a value for the one attribute based on values received for the one attribute from the first and second sources. After the supplying of that value, the providing can include receiving from the first source an indication of a value supplying inability for the one attribute and supplying a value for the one attribute received from the second source.