You do not have to interrogate the distribution model, it is optional.

There are two function modules that can interrogate the ALE distribution model: ale_model_determine_if_to_send and ale_model_info_get. ale_model_determine_if_to_send is called with the message type and possibly with the logical receiving system if it is already known in the application. A check is made in the ALE distribution model that a message flow has been maintained for the input parameters. If this is not so, the export parameter idoc_must_be_send is set to initial; otherwise, an "X" is returned. If there are filter objects in the distribution model that control this message flow, they are not evaluated. An IDoc must only be created if ale_determine_if_to_send returns an "X".

Module ale_model_info_get is used for more complex queries made to the ALE distribution model. It is called with the message type to be dispatched. In return, you get a table containing all the potential recipients of this message type, as well as the associated filter objects. Note that there may be several entries for one receiver in the table returned. If there are no entries in the distribution model, the exception no_model_info_found is issued. If an exception is issued, an IDoc does not have to be created. Otherwise an IDoc does have to be created. You will find the receiving logical system in the rcvsystem field in a table entry.

The end result, that is, whether the receivers receives an IDoc and what the IDoc looks like, is only determined after all the filter objects for a message flow in the distribution model have been evaluated. This is carried out in the ALE layer.