In our opinion application instrumentation is the only reasonable way to overcome the problems of today's application performance management. However, due to the enormous efforts posed on the developer nowadays it is hardly ever used. This immediately leads to a number of research questions that have to be tackled in the future. The following enumeration provides an overview of the most important open research questions concerning application instrumentation:
Instrumentation methodology: A methodology for the developer must be provided in order to alleviate the task of identifying relevant measurement points. Current application techniques simply offer APIs to be called from an application but give no hint about where to actually place the calls in the code. The instrumentation definitely has to take place during application development and thus the instrumentation methodology must be integrated into the software development process.
Automation and tool support: To further alleviate a developer's task a great amount of automation and tool support must be achieved. Therefore, means to facilitate or even automate the instrumentation process must be developed. E.g., in the area of component based application development the code required to measure response time of an individual component might entirely be generated by a development tool.
Correlation of subtransactions: Means to avoid the cumbersome correlation of subtransactions to their parent transactions are desperately needed. The idea of transporting unique transaction identifiers through the application as parameters is awkward to say the least. In some cases (e.g., component bases development, third party instrumentation) this approach even makes an instrumentation nearly impossible. By correlating transactions, e.g., using the identifiers of the underlying control flows, this could be simplified by far.
Integration with remaining existing techniques: Finally, a tighter integration of application instrumentation with the existing techniques is required in order to deliver an exhaustive overview of the status of the application to be monitored.