Before we go on, it’s worth noting that the cloud provides an opportunity to consider the IT ecosystem as a whole and how it can be modernized. As you shall see, cloud migration at scale involves looking at each application and determining how it should be thought of in this new environment called the cloud. Is further investment in certain applications justified? Should they be retired?
Many enterprises have held their applications for far too long without assigning to them a maintenance or retirement schedule. Therefore, for fear of complexity, lack of documentation, resources, source code, or other reasons, applications remain untouched.
Even for applications that remain on-premises, modernization can save time and money. An internal Microsoft IT study in 2010 demonstrated that the number of problem reports (“tickets”) and the time to resolve them increased with the age of the application and system software. (This analysis led to a focused effort to ensure that all applications were on the latest version of the operating system and other systems software such as database.)
Moreover, and more important, migration to the cloud provides an opportunity to evaluate and modernize applications and, in particular, their business logic. This activity can provide great returns on investment and impact to the top-line revenue.
There are many motions that one can take to modernize application and services portfolios, such as the following:
Rehost Move a VM or an operating environment from the on-premises datacenter to a hoster
or a cloud. This model is also known as co-location.
Replatform A legacy environment becomes unsustainable based on cost or operational requirements; a solution is to “retain and wrap” the application without making changes to the code, possibly compromising the integrity and security of the operation.
Retire and Rewrite (or Reenvision) When there are sufficient new requirements that cannot be met by the older environment, the best way to proceed is to rewrite the application in a newer, better-suited environment. Often this occurs when examining the portfolio of applications and
consolidating several that have similar function.
Burst out With all of the new compute, data, and service models that are being provided in cloud environments, each providing capabilities and capacities that where never before accessible to an IT environment, many applications are bursting out to the cloud. These applications are doing innovative types of analytics, reporting, high-performance computing, visualization, and so on. Keeping frequently used (“hot”) data locally while aging-out infrequently accessed (“cold”) data to far cheaper cloud storage is another common pattern.
Expand Enterprises are now exploring how to expand their older applications and how to add functionality to provide to mobile devices and web front ends the same capabilities that previously were limited to a computer screen. They are even moving to enhance the applications with search or video services, as an example.
Cloud-Native Applications As companies begin their investigation of the cloud, they frequently realize that there are new forms of applications like Big Data, new types of analytics, entirely new capabilities such as machine learning, and applications for the Internet of Things (IoT) that are uniquely fitted to live in the cloud.
Source of Information : Microsoft Enterprise Cloud Strategy