Monitoring

Logging can be very helpful in analyzing the (faulty) behavior of a server application in response to client requests. HypertextLogger is a simple component that produces HTML in response to logging instructions. Its main purpose it to provide a better readable log file. By choosing you favorite CSS, you can highlight what is important and leave other information unfocused (timestamps).

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Upon creation of the logger, it produces a new .html file to which logging events are written. Because most Browsers can deal with open-ended (i.e. not properly closed by tags) HTML files, a single page can be used to collect lots of events. And if you let e.g. Apache serve these log files, you can monitor server applications remotely.

How can I provide programs with self diagnostic behavior? How can I implement this in a way that has low impact on the way I write programs (or Java classes to be more specific). If programs could run such a self diagnose then perhaps it takes less time to find the cause of an observed problem.

These thoughts are sprung when I found an error in an application that went into production just a few days earlier. The problem itself was easily fixed (just a typo in some properties file) but I was a bit surprised that obviously my tests did not cover this particular execution path. Sure, I should have written more tests to have a higher coverage (JCoverage can tell me what percentage), but what if I had programmed this behavior differently(how?) such that a self diagnose run would have detected it?