1. A method for maintaining service correlation within a network service access gateway, said method comprising: receiving a first service invocation into the service access gateway, said first service invocation having a service correlation identifier associated therewith; persisting the service correlation identifier within the service access gateway; forwarding the first service invocation to a recipient; receiving a second service invocation to the service access gateway, said second service invocation being related to the first service invocation; and associating the first service invocation with the second service invocation in the service access gateway according to the service correlation identifier.