The Doppler Quarterly Spring 2019 - Page 62

Public Internet User Premise Data Center Figure 1: On-premises- only application environment Users connect to the organization’s web servers over the public Internet. During their sessions, both web requests and the resulting return of data happen with little regard for the cost of data entering (ingress) or leaving (egress) the organization. In fact, orga-nizations with all their deployments on-premises rarely have to account for the variable costs of ingress or egress. Initial Application Migration At some point, people in the organization encounter a compelling reason to move their application to the public cloud. Perhaps they discover attractive cloud eatures, or find they need the geographic reach the public cloud can provide. Regardless of the impetus for migrating, they decide to move the application front end and business logic into a single public cloud provider, while leaving the data back end on premises. They decide to leave the data in the back end because there is simply too much of it to move conve- niently, and because some of their back-end data systems are incompatible with the selected public cloud provider (think IBM Db2 running on AIX or an AS/400 industry vertical application). High- Speed Connection Public Internet Premise Data Center User Public Cloud Figure 2: Hybrid environment with public cloud application and on-premises data Typically, the connection between on-premises and public cloud is handled through a high-speed connection such as Azure ExpressRoute or AWS Direct Connect. The user still connects to the application front end through the public Internet, and the front end and business logic operate mostly unchanged (depending on the application stack tech- nology in use). 60 | THE DOPPLER | SPRING 2019