A method is disclosed for performing message payload processing functions in a network element on behalf of an application. According to one aspect, a network element receives user-specified input that indicates a particular message classification. The network element also receives one or more data packets. Based on the data packets, the network element determines that an application layer message, which is collectively contained in payload portions of the data packets, matches the particular message classification. The network element processes at least a portion of the message by performing, on behalf of the application to which the message is directed, and relative to at least the portion of the message, one or more actions that are (a) specified in the user-specified input and (b) associated with the particular message classification.