1. A method of identifying underlying services of transactions in a service-oriented architecture (“SOA”)-based computer network, the method comprising: characterizing messages communicating among services by applying a function to each message to transform each message into a characterization value having a fixed length indicative of the contents of each message, thereby forming characterization values, each service receiving and/or transmitting messages associated with a plurality of transactions that are unspecified by the associated messages, each transaction being supported by a subset of said services; determining if the messages are inbound messages or outbound messages; based on the messages being an inbound message or an outbound message, associating each of the messages with one of the said services; based on the association of two or more messages with the same service, linking the two or more messages to form a context for the two or more messages; enhancing the characterization values for each of the two or more messages by incorporating the context with the characterization values; storing said enhanced characterization values external to said messages without altering said messages; comparing enhanced characterization values to determine dependencies within a subset of said services; and determining at least one of the plurality of transactions as supported by the subset of said services according to the determined dependencies.