Messaging Passing Communication AOS Dan Huang Why Need Message • RPC and ROI hiding communication for transparency. • Hiding communication is not an appropriate mechanism • Messaging is needed for communication Message Oriented Communication • Many distributed system and application are built on message-oriented model on the transport layer. • Socket is a communication end point to which an application can write data that are to be sent out over the underlying network, and from which incoming data can be read Socket Primitive Interface Message Passing Interface • MPI is designed for parallel applications and as such is tailored to transient communication. • MPI assumes communication takes place within a known group of processes. Each group is assigned an identifier • Each process within a group is also assigned a (local) identifier. Message Passing Interface • Some of the most intuitive message-passing primitives of MPI. Message-queuing Systems • The essence is that they offer intermediateterm storage capacity for messages, without requiring either the sender or receiver to be active during message transmission. • The systems are targeted to support message transfers that are allowed to take minutes instead of seconds or milliseconds. Messaging Queue Model • The basic idea is that applications communicate by inserting messages in specific queues. • These messages are forwarded over a series of communication servers and are eventually delivered to the destination. • Sender only guarantees that its message will be inserted in the recipient‘s queue. Messaging Queue Model • the execution mode of the sender and receiver Messaging Queue Model • Basic interface to a queue in a messagequeuing system General Architecture of a MessageQueuing System General Architecture of a MessageQueuing System Message Broker of a Message-Queuing System • Message broker acts as an application-level gateway in a message-queuing system • Main purpose is to convert incoming messages so that they can be understood by the destination application Message Broker of a Message-Queuing System • The general organization of a message broker