QoS-based synchronous/asynchronous data transmission model in group communication

A large-scale network like the Internet is composed of various types of communication channels. Here, each communication channel supports quality of service (QoS) which may be different from others. In group communication, each process sends a message to multiple processes while receiving messages from multiple processes. In addition, messages are required to be causally delivered. In order to realize the atomic and ordered delivery of messages, even if a process with enough QoS channel receives messages, the process has to wait to deliver the messages until another process with lower QoS channel receives the messages. Thus, multimedia data cannot be delivered to processes so as to satisfy the real-time constraint if a slower process is included in a group. In this paper, we discuss group communication protocols by which multimedia messages can be delivered to a process with same time constraint properties which satisfy QoS requirements of multimedia messages.