Method for switching protocols transparently in multi-user applications

Abstract

An application programming interface implements a method for transparently switching from one communication protocol to another and for restoring the state of a previous connection. The application programming interface executes on a local, client computer, as well as remote computers. It includes functions that multi-user application programs can call to communicate in a device independent manner with other applications executing on remote computers. To support communication on a variety of different computer communication protocols, the application programming interface accesses programs called service providers that implement the communication protocols and support the message passing model of the interface. The application programming interface can transparently switch the protocol on a remote computer by sending a system message to a compatible version of the interface on the remote computer that includes an identifier of the service provider for the new protocol. In response to the message, the application programming interface loads the new service provider and takes steps to set-up a new connection. The application programming interface can also restore the state of previous connection on a remote computer by sending a system message. In response to this message, the application programming interface on the remote computer retrieves the previous connection state from an MRU stack and loads the service provider for the previous connection.