SAP HCI is developed as Integration System-as-a-Service (PAAS) which helps to integrate several independent devices/apps for a company course of action. HCI can do Cloud to Cloud, Cloud to On-premise, On-premise to On-premise and Hybrid model. HCI gives Adapters (Connectivity possibilities) for example: SOAP Adapter, IDoc, HTTP, Mail, SFTP,Ariba, oData. https://s4hanacloudfaq36802.howeweb.com/28715842/hana-cloud-integration