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Realigning IT to the business with app modernization


Your on-premises applications were great at one time. That’s why you chose or built them, after all. But as digital business continues to take hold, your on-premises apps and infrastructure are likely no longer aligned to your organization’s requirements.

In the digital world, your applications need to be cloud-ready, enabling you to optimize operations and transform to innovate faster, respond more quickly to customer needs, and leverage breakthrough technologies. But requiring modern capabilities running on flexible infrastructures doesn’t necessarily mean starting from scratch.

Application modernization is the process of aligning legacy software to your current business needs, whether that means refactoring, rearchitecting, or replacing. It helps you minimize the in-house server footprint and the costs that come with it. Even more importantly, it allows for greater agility, speed, scalability, reliability, and security.

But what’s the difference between the various application modernization approaches? And what’s the right approach for your needs? Read on for our primer on app modernization.


Before we get into the various approaches to app modernization, we should discuss rehosting. While it doesn’t technically fall into the category of app modernization, rehosting is the first step many companies take towards modernizing their application portfolios.

What is it? Rehosting is simply moving an application from its on-premises environment to a modern cloud infrastructure. It is the most straightforward of the four options and generally delivers dramatic boosts in performance.

Why rehost? Companies choose to rehost an application when they are pleased with its performance and functionality but need the benefits of an agile cloud infrastructure. They retain the familiarity and functionality of the original application while reducing their data-center footprint and networking, compute, and storage costs. They also reduce their capital investment and maintain business continuity.

Now, let’s focus on application modernization.

Approach 1: Refactoring

What is it? Refactoring is restructuring code to improve performance without changing its intended function. Companies will opt to refactor applications when, as in the case of rehosting, they are basically satisfied with the functionality but the code needs to run on a more modern foundation, such as a current operating system.

Why refactor? Refactoring applications reduces technical debt, improves performance and efficiency, cuts costs, and creates code portability where none existed before. As importantly, refactored applications can receive all vendor software updates, ensuring security standards and performance are maintained.

Many organizations, for example, have machines running Windows Server 2008. Microsoft support for those operating systems is about to expire. With minimal changes to the underlying structure but no alternation of the software’s functionality, these applications can run on modern foundations and move to flexible cloud systems. Once refactored, applications can be containerized or leveraged with PaaS services.

Approach 2: Rearchitecting

What is it? Rearchitecting transforms single-tier architectures into multi-tier systems in which functions and processes are divided in a modern cloud implementation. This is far more efficient and delivers immediate reliability gains. When rearchitecting, applications transform from monolithic to microservices-based architectures.

Why rearchitect? Many companies built their systems when their organizations were much smaller and simpler, but with growth, existing architectures are often too simplistic to meet current demands. In fact, we regularly see companies relying on single-tier architectures, in which the operating system, application, and database all exist on the same server. However, single-tier systems have only limited scalability and poor uptime and reliability. For example, if one component comes under a heavier load, the entire system slows. Similarly, if a component fails, the business will simply grind to a halt. Rearchitecting these to multi-tier cloud instances eliminates these concerns.

Rearchitected applications can be containerized or moved to PaaS or serverless environments to deliver easy portability, more efficient software development and deployment, and a level of future-proofing that would not otherwise be available.

Approach 3: Replacing

What is it? There are two choices when it comes to replacing aging, on-premises systems: redeveloping with new code built for modern cloud infrastructures using current development tools or shifting to SaaS. Replacing is the most labor-intensive option of all three app modernization approaches and may involve some level of business disruption.

Why replace? The replace option is for companies that are in need of a specific function, such as payroll or inventory but know that the legacy system is so out of date that starting from scratch in the cloud or moving to SaaS would be the most efficient option. Companies that rebuild have an unprecedented opportunity to create functionality that exactly matches current needs and future requirements.

When choosing between rebuilding yourself or going with a SaaS solution, it makes sense to build functions that are highly proprietary, confidential, or critical to your organization from a competitive standpoint but go with SaaS solutions when there’s a best-of-breed option available. For example, organizations likely wouldn’t build their own CRM system, given the availability of powerful existing SaaS solutions. On the other hand, telecom providers may build back-end inventory management tools or digital billing solutions, given the importance of both to retaining a competitive edge.

Whatever approach you take, at its core, application modernization is about realigning your technology to your business needs and doing so in an efficient and cost-effective manner. All application modernization options deliver the same fundamental advantages: shrinking the in-house server footprint to reduce the associated costs, including networking, compute, storage, and backup; improving agility, speed, scalability, security, and reliability; and reducing costs and making expenditures more predictable.

Rishi Kulkarni heads up the cloud-native practice at Capgemini North America and Jigar Pathak is a member of the application and cloud technologies solution team. For more information about how to harness the power of cloud and application technologies to make digital business a reality, access The digital CIO’s handbook here.


Jigar Pathak

Jigar is a multi-cloud solution architect, responsible for designing architectures. He also deploys and manages client infrastructures.