SAP HCI is built as Integration System-as-a-Service (PAAS) which helps to combine multiple unbiased units/purposes for a company course of action. HCI can perform Cloud to Cloud, Cloud to On-premise, On-premise to On-premise and Hybrid design. HCI gives Adapters (Connectivity alternatives) for example: SOAP Adapter, IDoc, HTTP, Mail, SFTP,Ariba, oData. https://s4-hana-cloud-trial71481.blogunteer.com/27756586/hana-cloud-integration