Data Transport Subsystem: The SFOC Glue

Abstract

The Data Transport Subsystem (DTS) is a core subsystem of SFOC which holds together the GIFs, TISes, DMDs, DTVs and other SFOC application subsystems allowing them to operate in a distributed LAN based workstation environment. DTS does this by providing two primary features. The first feature is transparent local and remote interprocess communication. The communications interface is identical between two application subsystem processes whether they're running in the same machine or different machines. The second feature is the Logical Name Server, which makes connections on a name basis without regard to location or network topology. With these two features SFOC becomes a distributed system. Processes within a subsystem can even be distributed to perform load leveling and enhance system performance. Distribution fosters the use of redundancy and hot backups by allowing nodes to serve multiple purposes. Distribution allows isolation of mission telemetry while providing shared use of a common database. It supports the SFOC goal of off-the-shelf hardware expansion and upgrade. DTS provides an open-close-send-receive model of interprocess communication. It offers three types of service: virtual circuit, datagram and broadcast. The virtual circuit service supplies a full duplex path between communication endpoints and guarantees data integrity. The datagram service allows many communications endpoints to send to one endpoint. This is useful for sending status to a central process. The broadcast service allows a process to send to many receiver endpoints. This can be used for continuous monitoring of telemetry streams by multiple processes.