It is astonishing that a tool for trace performance statistics could be implemented almost independently of the semantics of the trace data, because the word performance does not suggest this. The tool only has to know which record field contains the time stamp (for SIMPLE tools this is the time record field named ACQUISITION). In our numerous analyses which we performed with SIMPLE, we found that 95%of the values needed for performance statistics can be assigned to one of the following cases:
When a certain performance value could not be computed with these functions, this was usually due to the fact that the events needed for this computation were not (or only partly) recorded. For the specification of the event records which have to be used for the computations, the modules of the filtering layer can be used. This has the additional advantage that the same syntax for expressions can be used for specifying filter rules and performance statistics commands. With the help of the graphics module of the tool support layer, the computed values should be displayed visually, e.g. as scatter plots, bar graphs or box plots.
The user often needs a short summary only. This could be the number of values, the minimum, maximum, and mean value, the sum, and the variance or standard deviation of the values. All these values can be computed within one run through the event trace. This is a big advantage especially for large event traces. There is even an algorithm which allows an almost exact estimation of the median and other quantiles without storing single values .
It would be an useful addition to the command language to not only allow the computation of frequency and time values in total for the whole event trace, but also separately for each value of a particular token record field. This enables the user to display the values e.g. for each process or node, if the appropriate information is stored in the event record.
The ideas presented in this subsection are implemented in the SIMPLE tool trcstat (TRaCe STATistics). As the main topic of this article is object-independence of trace monitoring and analysis systems, we do not describe other tools of SIMPLE here. The curious reader is referred to . Examples can be found in  and in the detailed SIMPLE User's Guide .