Direct Connection in PI 7.3

Hi Experts,

I am working on SOAP(web service) to Proxy scenario.

It is a sync interface and no mapping.

Now I have a requirement: Source system should connect to SAP ECC directly without PI. It mean source system will calling the proxy directly.

In PI 7.1, we can achieve it with connect connection, But in PI 7.3, there is no direct connection in ID.

Any body knows how to achieve it in PI 7.3?

Thanks,

Sep