20. A computer readable medium containing software instructions embodied therein for causing a computer system to perform a method for updating data within a peer-to-peer system comprising, the method comprising: publishing a data change of a first data type over a broadcast channel; in response to said data change, a join engine peer accessing a global attribute object model to identify a second data type and additional attributes of said second data type, wherein said global attribute object model defines a first dependency between at least one attribute of said first data type and at least one attribute of a third data type and a second dependency between said additional attributes and attributes of said third data type, wherein said first dependency requires synchronization of said third data type with said data change; using said global attribute object model to generate a query for retrieving said additional attributes from a first source system; transmitting said query to said first source system; responsive to a reply from the first source system, generating a modified attribute set and publishing said modified attribute set to a third source system associated with said third data type, wherein said modified attribute set comprises said additional attributes and said data change, and wherein said third data type is synchronized, as specified in said first dependency, with said data change in said modified attribute set.
24. The computer readable medium of claim 20 , wherein said global attribute object model maps dependencies between attributes of said third data type and attributes of said first data type.