The recently published HTTP and Memcache structures provide detailed information on the performance of applications using these protocols, including information such as URLs, keys, response times, status codes etc.
http://sflow.org/sflow_memcache.txt
However, rather than attempt to develop application specific metrics for every application layer protocol, it is worthwhile generalizing the core measurements and defining metrics that can be applied to any networked application. The following draft specification identifies common transaction attributes and counters that can be exported by an sFlow agent embedded within the application: