Besides the conclusion of agreements about quality of service (QoS), one of the major prerequisites for a global service market are means to monitor the fulfillment of those agreements. From a user's perspective, the time needed to complete a service transaction represents one of the most critical QoS parameters. As most electronic services are usually based on distributed applications, obviously the same techniques can be used to measure the performance of electronic services as well as the underlying applications. In recent years several techniques evolved to monitor the application performance. However, the new aspect of service orientation adds relevant new requirements that are to be posed on such solutions. This paper evaluates the various techniques from a service oriented point of view and presents open research questions.