Flexible and reliable messaging using runtime monitoring

The asynchronous nature of communications in message-based systems like service-oriented architectures introduces two major issues: inability to detect lost and out-of-sequence messages, and unrealizability of some messaging protocols. We show that these problems are actually different manifestations of the same phenomenon: communicating peers ending up with divergent views of the message exchange in which they are involved. We introduce the concept of monitor-based messenger (MBM), which processes messages locally through a runtime monitor enforcing a specific protocol of interaction, and stamps them with a monitoring token. We demonstrate that: 1) some unrealizable protocols become realizable using MBMs; 2) MBMs offer protection against unreliable messaging, and can decrease delivery time and required queue size compared to strict messaging solutions.