Message-level security
SOA brings changes in the requirements for data confidentiality and data integrity. When a message sent to party 1 (brokerage) contains parts intended for party 2 (bank), we need the ability to differently encrypt and/or sign the part that is intended for use only by party 2. Clearly, traditional transport layer security mechanisms such as SSL/TLS are not good enough here, as they cannot stop party 1 from reading and/or tampering with the message part intended for party 2.
Message-level security (as opposed to transport-level security) is a new approach to solve this problem. With this approach, different parts of a message can be protected differently, to make them usable only by intended parties in the message path.