EMS

• A producer sends a MESSAGE to the central server. The server stores the message until it has DELIVERED it to each consumer
• Producer to server; server to consumers.
• Store and forward queue PROTOCOL.
• The central server stores all messages and delivery state for all its clients; it requires disk resources in PROPORTION to total throughput volume.
• Disk failure on a server host computer can be catastrophic, affecting all messages from every client. Many installations protect against disk failure USING safeguards such as disk mirroring.
• The central server is the master of overall delivery state.

RV

• A producer sends a message to consumers. The producer stores the message until each consumer has acknowledged receipt
• Peer-to-peer.
• Stream-oriented protocol.
• Each producer stores its outbound messages and some delivery state; it requires disk resources in proportion to its outbound volume.
• Disk failure on a peer host computer affects only the messages that its programs produce or consume. However, disk mirroring for each individual peer is often impractical.

EMS

RV