Connectivity 
The following graphic provides an overview of all the components that can communicate with each other with the Integration Server:
All the systems either send messages to, or receive messages from the Integration Server. It is the task of the Integration Server to distribute the messages received according to the rules that are configured in the Integration Directory. In this way, messages can be exchanged between all systems in a heterogeneous system landscape, regardless of whether a message was sent to the Integration Server using an adapter or the proxy runtime.
Note
Communication using the Integration Server is oriented towards asynchronous communication. Synchronous communication is supported.
As soon as all communication parties in a scenario can exchange messages with the Integration Server, the communication parties can all communicate with each other using the Integration Server as the mediator. The following sections describe the various communication parties of the Integration Server:
Communication Using Web Services Runtime
Web service runtime makes direct communication between service consumer and service provider or a mediated communication using the Integration Server possible.
Communication Using Adapter Runtime
The Advanced Adapter Engine can also process message locally and it is possible to configure communication without including the Integration Engine.
For more information, see Local Message Processing with the Advanced Adapter Engine
Communication Using Industry Standards (RosettaNet, CIDX)
Sender systems that can only process asynchronous messages can communicate with systems using sync/async communication.
For more information, see Sync/Async Communication
The various options available for letting systems communicate using the Integration Server are summarized under the term Connectivity.