Messages which are provided to an application are monitored. Similarities between the messages are determined based on a distance algorithm, in one approach, and messages which are similar are assigned to a common group. For example, the messages may be HTTP messages which include a URL, HTTP header parameters and/or HTTP post parameters. The messages are parsed to derive a string which is used in the distance calculations. Additionally, application runtime data such as response times is obtained and aggregated for the group. Further, a representative message can be determined for each group for comparison to subsequent messages. Results can be reported which include a group identifier, representative message, count and aggregated runtime data.