A Fault-Tolerant Session Layer with Reliable One-Way Messaging and Server Migration Facility

Despite being extremely successful, TCP has a number of shortcomings when network disruptions occur, or when peers do not follow a request-reply interaction: it does not handle connection crashes, event-driven communication or application migration. In many cases, programmers must engineer their own solutions to write reliable distributed applications. To overcome these limitations, we propose FTSL, a Fault-Tolerant Session Layer that works on top of TCP. Besides offering a full-duplex connection, FTSL owns a number of distinctive features: it tolerates TCP connection crashes, it provides highly decoupled reliable patterns for one-way communication, and it enables server-side migration. While the first two greatly simplify distributed systems programming for a wide range of applications, the latter enables cloud systems managers to move a server application for load balance or maintenance, without moving the entire virtual machine. We present the FTSL protocol, its implementation, and resort to performance to show that FTSL imposes a reasonable overhead for the guarantees it provides.