Making sure business-critical applications are equipped to support today’s business needs is an essential task for enterprise IT leaders. The process of transforming, reformulating, or relocating legacy software is known as Application Modernization - whether that means migrating to the cloud, adopting microservices, making use of modern development methods like DevOps, or simply automating more processes.

In this article we’ll consider the five core approaches that can be used for application modernization, from simply buying a replacement to redesigning an entire system.

Why is application modernization so important?

In today’s digital-first environment, end users expect services to be accessible anytime, anywhere, and at lightning speed – so enterprise applications need to change quickly as customer demands evolve. But many ‘legacy’ enterprise applications are far from new or nimble, and often have not been able to keep up with recent technological changes. In the long run, businesses can save time and money by modernizing applications rather than maintaining existing code; IT leaders must consider how best to balance the cost (and benefits), risk and impact of change.

Among the enterprise applications most often in need of modernization are those written in Java – a language widely used in software development for nearly thirty years. Many Java apps power business-critical systems, processes and operations, but they often have a complex monolithic architecture that makes it difficult for developers to apply changes with confidence. This brake on agility can directly impact competitiveness and business success.

What is Application Modernization?

Application modernization has become an umbrella term for a variety of things, which are generally intended to improve the performance, robustness, responsiveness of legacy software. Common definitions include:

  • Cloud migration: Modernizing applications frequently involves migrating legacy systems to cloud environments. Though public cloud is an increasingly popular choice for many enterprises, private and hybrid cloud (an integrated combination of public and private clouds, and on-premises infrastructure) options remain relatively common.
  • Microservices: More than a technology, microservices are an architectural choice. Rather than creating a monolithic structure with a single code base, microservices break components into smaller pieces so that they can be updated and operate independently. This approach is designed to make individual changes faster and simpler, but can massively increase the complexity of an overall system.
  • Containerization: Containers are a way of packaging, deploying, and running software relatively quickly and easily in a way that allows it to operate consistently across different hardware, environments and platforms. Containerization offers great scalability and portability, which is often optimal for cloud infrastructures. Kubernetes has become the most popular orchestration system used to automate processes in containerized applications.
  • Orchestration and automation: Automation is necessary to ensure that development, operations, and security teams can sustainably manage the modernization of their applications at scale. In fact, many organizations view automation as the goal of modernization in and of itself, since it is the necessary enabler of modern CI/CD pipelines which allow greater agility and faster code changes. Orchestration is the coordination of the automated operational tasks associated with software development, such as configuring environments, building, testing and deployment.

5 Key Application Modernization Strategies

Once you decide to modernize a legacy application five key strategic approaches are available, though it’s important to note that no one size fits all. Different strategies are available – it depends on the application and what you want to achieve. The core options are:

  1. Rehost: Transfers the application component to a different infrastructure (physical, virtual, or cloud) to take advantage of some related benefit like the elasticity of cloud compute resources. Often implemented as a classic ‘lift and shift’, without materially changing its code, functions, or features.
  2. Replatform: Migrate to a new runtime platform, without modifying the code structure, functions, or features. This requires minimal modifications to the code.
  3. Rearchitect: Materially alter the design and structure of existing code to improve performance and maintainability, and reduce technical debt, without changing application behavior. Shifting to microservices or cloud-native architectures are common examples.
  4. Rebuild: Rewrite or redesign the application component from scratch while keeping its scope and specifications. Typically, an extremely difficult and costly option, undertaken only when there is little other choice.
  5. Replace: Dispose of the legacy application component entirely and replace with a new solution that better meets current needs. Switching tooling developed in-house for modern SaaS alternatives might be an example of where Replace makes sense.

How to choose the right Application Modernization approach

When deciding between these options, IT leaders must consider many factors, including workload, architecture, cost, risk, and security. Rehost, Replatform and Rearchitect are more common choices for Java modernization than Rebuild and Repurchase, which are not practical options for large, complex legacy apps where operational continuity is essential. That’s no doubt why respondents to Diffblue’s Java Application Modernization Survey said they plan to modernize over 80% of existing Java systems.

Rehost, Replatform and Rearchitect have one other important R in common: Refactor. Some level of code change is almost always required – from relatively small adjustments in a cloud migration to an extensive amount in a full-blown codebase redesign.

Even the smallest such change to existing code comes with some risk, but when it needs to happen at scale to transform applications in daily use, things become really challenging. That’s why comprehensive unit testing is such a key element in application modernization: 97% of IT leaders, asked in a Diffblue survey, said it’s very or extremely important. But many legacy applications have few unit tests, and getting to the coverage level required can seem like a mountain to climb. Fortunately, Generative AI for code can help you do it faster, better, and at scale.

Be ready for change

Businesses need to be well prepared to adapt to change, especially in a digital landscape where greater agility is becoming essential. Applications that have been modernized are more likely to meet future business needs.

AI for code can play an essential role in accelerating application modernization and reducing the risk of change. Learn more by downloading our ebook – or take a look at what Diffblue Cover can do.