Legacy Application Modernization - Cloud Migration Strategies

Legacy Application
Modernization - Cloud Migration Strategies

It is crucial to modernize your legacy systems as technology innovations offer new business solutions and cost-cutting opportunities. Upgrades and replacements are required when existing applications fail to fulfil the complex requirements of evolving business needs and/or maintenance is cumbersome, expensive, and outside the core competency of your organization.

Today modernizing legacy systems is often achieved through cloud migration process, which can be of several different types, each meant to address specific business needs in the context of cost and pace. Planning and executing the right strategy is vital to preventing service disruptions and facilitating business continuity.                    

For a fruitful cloud migration with minimal flaws and at an appropriate speed for your organization, the following options should be considered:

Cloud Migration Strategies:


Re-hosting in the cloud, also known as “Lift-&-Shift,” is today’s most common approach to refreshing applications while simultaneously leveraging the operational benefits the cloud offers. In this approach, application infrastructure, and the connectivities therein, are migrated to the cloud while the codebase remains the same.

Cloud infrastructure as a service (IaaS) enables you to immediately reduce operational costs as well as eliminate capital investments. Enterprises looking for an expedient migration without disturbing the existing application workflow generally choose this rehost approach as a first step in their cloud migration.


“Refactoring” refers to re-organizing your application so that it operates better within the cloud environment. Refactoring often includes modifying the application code base to utilize Cloud-native functions. Essentially, you’re switching to a PaaS model.

Refactoring is a more labor- intensive process than rehosting, but you’ll gain much bigger benefits for your organization.  For example, if your application is resource intensive, an immediate refactoring benefit and cost reduction would be on-demand consumption of resources. 


Some of your organization’s applications may not be compatible with the Cloud due to architectural decisions made while building the app. In this case, it could be wise to consider “re-architecting.”

Re-architecting allows you to divide an application into several functional components that can be individually adapted and further developed. The individual components, or “microservices,” can even be incrementally transferred to the cloud.

Re-architecting applications for the cloud leads to major code adjustments and will cost considerably more time and money. However, it provides more flexibility, scalability, reusability, and ultimately more control over your architecture.  For example, microservices updates can be made faster with less risk to related components.  Further, your developers will now be able to re-use languages, containers, and the framework in which they’ve already invested.


Sometimes, re-architecting an application is not enough to fully leverage the benefits of the cloud, and a total rebuild is required.  With a rebuild, you will completely redevelop an application on a PaaS infrastructure, unlike a refactor, where you only modify application parts, or a re-architecture., where you modify the design of the application but the functions are largely the same.

Rebuilding is the redesign of applications in the cloud through the retirement of existing code, and the new use of innovative features on your cloud provider’s platform. A cloud-native application is inexpensive to use and highly scalable.


An alternative to rebuilding an application is to replace it with Software-as-a-Service (SaaS). When existing SaaS applications can provide you with all the functionalities your business needs, at a lower cost. This approach is logical and again, enables you to focus on the core competencies of your organization.

Modernize your Legacy Systems with Nallas

At Nallas, we offer a wide range of cloud and product engineering services while making use of modern tools and technologies.

Our team of dedicated technology specialists guide you throughout your entire cloud journey. Also, we can assist you in choosing the right strategy that sequences your work according to business priority and benefit.

Talk to our experts to modernize your legacy environment now.

Read more about our Cloud Engineering services here.  
Read more about our Product Engineering services here.