Which framework would require the implementation of custom correlation?

Custom correlation is needed when the default detection mechanisms of AppDynamics are not capable of auto-correlating transactions across tiers or across parent-child threads in complex multithreaded applications. Custom correlation enables the user to configure AppDynamics to propagate a unique correlation key by using the extension points of the distributed protocol or by decorating the payload. Among the four options, a custom TCP concurrent server is the most likely to require the implementation of custom correlation, as it is an unsupported framework and protocol that may not have easily-defined method calls or payload objects to configure as exit points or entry points. The other options, such as SOAP, JMS, and WCF, are supported by AppDynamics and can be automatically correlated by the agents without the need for custom configuration. References: Custom Correlation for Java Applications and Configure Custom Correlation for .NET Applications in the AppDynamics community.