I know that while configuring the HTTP and IDOC scenarios, there is no need to configure the sender communication channel and sender agreement, but why?
In Netweaver application platform there are two engines i.e. J2EE Engine and ABAP Engine, Sender Agreements need to be configured only for the adapters those resides on J2EE Engine. The adapters like HTTP and IDOC, which resides on ABAP Engine can directly interact with Integration Engine of XI, hence there is no need to configure the sender communication channel and sender agreement for HTTP and IDOC adapter.
