Reliable broadcast protocol for selectively partially ordering PDUs (SPO protocol)

Methods to provide reliable broadcast communication for multiple entities in distributed systems by using unreliable broadcast communication services are discussed. In real distributed applications, each entity sends every PDU (protocol data unit) to only the subset, rather than all the entities, and each entity receives only PDUs destined to it from some entity in the same order as they were sent. Such a broadcast service is named an SPO service (service for selectively partially ordering PDUs). How to design a protocol which provides the SPO service for entities by using unreliable broadcast networks in the presence of lost PDUs is discussed. The SPO service can be a useful facility in designing and implementing distributed systems like distributed database systems