we have a Manufacturing Execution System (MES) based on Java technology. The MES make request to equipments (equipments are separate machine in factory) based on the DCP protocol. It is clear that Dynatrace can't detect the purepath entry from equipment to MES and other way around. For this reason, we want to instrument the DCP methods in Java to see the incoming and outgoing transactions (requests) in Dynatrace. Does this help?
@matthias_scholz the approach I usually take when instrumenting "unknown" application is to look at method hotspots and determine your points of interest. Be sure to have a "wide" time range. Also - don't forget to use the CPU profiler and look also at method hotspots from there. Sometimes the requests are in separate threads running on some pre-initialized thread pools and you won't have any Dynatrace services detected.
Then look at the stackframes and download and decompile interesting classes and then put your custom services where it makes sense.
It's time-consuming, however still much faster than finding someone who has the code, understands it and is willing to cooperate. Especially true for closed systems and 3rd party vendors.