SAP HCI is made as Integration System-as-a-Services (PAAS) which helps you to combine many unbiased systems/applications for a business method. HCI can do Cloud to Cloud, Cloud to On-premise, On-premise to On-premise and Hybrid model. HCI provides Adapters (Connectivity alternatives) for example: Cleaning soap Adapter, IDoc, HTTP, Mail, SFTP,Ariba, oData. https://sap-s-4hana-cloud29517.ambien-blog.com/34322918/hana-cloud-integration