Protocol for exchanging user model data objects among ubiquitous devices

A system comprising:

• at least one hardware processor;
• and
• a non-transitory computer-readable storage medium having stored thereon program code, the program code executable by the at least one hardware processor to:
• automatically provide, by a client device to a server, information regarding the identity of data components comprising a user model stored at the client device, wherein each of said data components is associated with an attribute of a user of the client device;
• automatically identify, by said server, data components that are missing in said user model, based, at least in part, on a reference model stored at said server;
• automatically send, by said server, to said client device, said identified missing data components;
• automatically update, by said client device, said user model to include said identified missing data components;
• and
• automatically send, by said client device, data contained in one or more of said data components in said updated user model, to enable a service provided by said server.