A mechanism for visualizing TCP-socket interactions

TCP sockets are an important and ubiquitous construct. In order to better understand the behaviour of programs using TCP sockets, we have developed instrumentation that transparently collects information about each socket and graphically displays it as a single, unified view. This paper will describe the instrumentation which leverages an existing tool, POET (Partial-Order Event Tracer), to display the partial order derived from the socket operations. Several challenges in constructing this instrumentation will be discussed in detail. These challenges include accounting for relative delays in receiving information from the processes at two ends of the TCP stream, collating information from the two ends such that events can be sent to POET in a coherent form, and determining a useful and accurate visual representation of the communication sequences.