If you need ERP backend access for push content (such as SAP Business Workflow), wire the SAP Gateway Hub and its ERP backend.
Note: as the FLIGHT OData services are installed with SAP Gateway installation, your ERP box might not have the FLIGHT services. In that case please use your OData services (such as the one from SAP Business Workflow) in the configuration example below.
Steps to Implement
Configure the OData so that the service execution goes to ERP backend from SAP Gateway Hub.
On the Gateway Hub, Run the transaction code /IWFND/MAINT_SERVICE. Find the FLIGHT services.
In the Service Catalog for "RMTSAMPLEFLIGHT", find the System Alias and Add System Alias so that the service execution goes to the remote Backend system by checking in the "Default System" box.
In this way, the OData service access to the Gateway Hub goes to the Backend system.
Let's configure the bgRFC on the backend box. This queue will go to Gateway Hub.
On the ERP Backend box, Run the transaction code SBGRFCCONF. The steps are pretty much similar with what you had done at the Gateway Hub.
Run the transaction code SM59. Create a new RFC Destination in Connection Type 3. Supply Target Host = <the remote SAP Gateway Hub server name> and its System Number.
Click on the Special Options tab, and scroll down to select Transfer Protocol = Classic with bgRFC. Save the config.
Run the transaction code SBGRFCCONF. Select the Define Inbound Dest. tab. Click on the create icon.
Here you enter the RFC Destination value you had created. This is going to be the name of the queue. Make sure to choose Logon/server group value too.
Click on the Scheduler: Destination tab.
Create the bgRFC Configuration as "Inbound".
Now you had configured the bgRFC setting to create a push queue from the Backend.
Now the landscape should be complete - if you subscribe the service, a new subscription entry will be created in the subscription table /IWBEP/D_MGW_SUB in the Backend system. You can use the same troubleshooting tips learned in the SAP Gateway Hub configuration steps.
The entire landscape is ready for subscribe & notify.
What's next? - Let's learn tips & tricks of Subscribable OData and Notification API in ABAP.