Can I connect to an on-premise database if my application server is on cloud?

Question

#Process Modeling: We have below scenario in my project, Intiall we developed whole application on premise, Create entity based recordsand, Used smart services to connect to the Database.. Now we are planning Appian application servers will be in the cloud, but the database servers will be on-premise. Therefore, we will need to connect to the database by using REST services on the ESB proxy. Please can you suggest me Can I re use the existing entity based functionalities or do i need to create all service based functionalities? Does any one had past experience, Please suggest me your thoughts. 
 OriginalPostID-224488 
 OriginalPostID-224488

Stefan Helzle · Accepted Answer

The Appian cloud team will set up a VPN connection to your corporate network. This way Appian cloud can directly access any resource inside your corporate network. Off course depending on firewall rules and other security related things. But be aware that a network connection over the internet is always slower than a local one. So make sure that your type of application matches the resulting performance of DB requests.

forum.appian.com/.../Cloud_VPN_Integration.html