Software Tracing

Software Tracing

In the December 2010 Embedded Systems Design “parity bit” column, Mira Samek of  state-machine.com writes “Instead of re-inventing all this for every project at hand, you can combine them into a generic, reusable state machine *framework*. A framework like this allows you to take software tracing to the entirely new level, because a framework funnels all important interactions within the system. … This sort of software tracing is not just a theoretical possibility.  For example, the open source QP state machine frameworks that I’ve described in my book Practical UML Statecharts in C/C++, 2nd Ed contain software tracing instrumentation called Q-SPY.”  [Where UML stands for Unified Modeling Language.]

So the QP state machine framework is another framework that treats all the events that cause particular routines to execute.

I expect that the code for the state machine states of the open source QP state machine frameworks must be one routine for each state in order that the framework can execute the correct state for a given event – just as in the Exploratory Project Message Controller (mC) framework.  That is, that the state machine selection mechanism can’t be promoted to the framework without making the code for each state into a separately callable method.

As Mira Samek points out, having the selection done within the framework allows instrumentation for software tracing to take place automatically in the framework without the need to add it to the code for the various states.  Therefore, I propose to add such tracing via logging to a disk file to the Exploratory Project mC.  Since various applications of the interconnected network can reside on separate computers, a disk file will be necessary for each application.  Or, perhaps, a logging application can be implemented to receive and store the trace output of each of the networked applications.  This would depend upon the sequencing of the communication mechanism to indicate the relative occurrences of the events in the various applications.