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How to Refactor legacy applications

How to Refactor Legacy Applications

12th May, 2022

Every business owner would at some point in running their business, and managing their applications would need to decide one thing – whether to refactor or rewrite their applications. These are the two options that IT decision makers have to consider when they tackle legacy software.  In this article, we will be discussing all the intricate details about refactoring and rewriting, followed by how to refactor legacy applications. 

Refactor – the process of improving the old code’s structure without changing its structure. The main purpose is to clean up lines of complex codes, reduce redundancies and make the codes manageable and readable. Once the refactoring process is complete, the software will function normally, because the external structure of the system remains intact, only better. There are no foundational changes to the code.

Rewriting – The process of making major changes to the non-functional nature of the application. It is easy for a three-tier legacy application to be crippled due to technical debt, and in order to make it functional, you might need to build a new base with new and added features to improve the extensibility and maintainability of the application. 

Introduction to Refactoring

Refactoring legacy applications is one of the natural incidents in application development. As an application is developed, eventually, it will go through a number of code changes, and sometimes, it will go through the hands of different developer teams. This could cause the application to cease functioning, behave abnormally or freeze, especially if the code base isn’t neatly structured. 

It is a situation that can happen at any time, but the clever move would be to prepare for it, and make the best move based on your business goals. 

With Refactoring, the alteration is done in its internal structuring, and without changing the external behavior of the application. The process consists of a series of preserving transformations, and it is these transformations that are called refactoring, done not as a separate task, but as a part of day to day programming. The procedure is not easy because when a new feature is done to the source code, it will have to be analyzed to see if it works in a structured, straightforward manner. 

You can refactor an application several times during its lifecycle, adding new features and functionalities. The main purpose of refactoring is thus, not to remove existing functionalities or to add new ones, but to remove complex lines of code to ensure that codes are easier to maintain, and confusing codes are changed into simpler ones. 

When do you need to refactor?

Obviously, when the codes get too complicated and unwieldy to manage. But you can also refactor when you need to do a peer review or when you need to fix a bug. 

Why Refactoring is Important?

There will definitely be some point in your time when refactoring is the answer to chunky, messy and outdated code. But it is also important to know that developers suggest another option – rewrite the codes. Rewriting is easy, but it is pricey, and time consuming too. Refactoring might be the cheaper answer, but it is a very difficult procedure. 

Refactoring helps rectify another error – code smell. Code smell is a situation that happens when a lot of bad practices lead to bad code. As your application progresses, your developer will keep adding codes to it, and sometimes more codes to fix the bugs, and over time, more codes will be added, and in many cases, there will be repetitive codes, duplicate codes and so on. Or the developer might have written long methods/functions, too many parameters, code placement, non-intuitive variable names, etc.

Eventually, code smell can cause a stink, leading to poor readability, poor project maintainability and so on. The bad practices are often not intentional, the developer might be running out of time, or they might put off improving upon the code, thinking they would do it some other time, and eventually forget it.

Benefits of Code Refactoring

Advantages of Refactoring

1. Helps Keep The Codes Clean, Reusable

With refactoring, you can eliminate the code smell once and for all. It is almost akin to cleaning your used dishes in the kitchen, and not leaving them to rot in the sink for the next day. When cleaned correctly, the dishes will look as good as new, and can be used again and again. But when left as it, you will not be able to use it. Similarly, clean codes are easier to handle, update and improve. 

2. Can Be Done on Any Kind of Architecture

It is possible to refactor different types of software, depending on what the developer thinks is the best for the legacy code architecture. It could be tightly monolithic or massively distributed. 

3. Improve Quality of Code Without any Hindering in the Functioning

Developers refactor anytime they think it is good, and deploy the app at the same time. They don’t need to maintain two different codebases like in the rewrite mode. 

4. Excellent Flexibility

Developers can refactor selected segments, especially if the problem is only on that selected part of the program. 

Rewrite Vs Refactor – The Debate.

The biggest confusion is whether you have to rewrite or refactor. If the goal is to start over and replace the functionalities of the application, you can rewrite the codes, and create a new application. The rewrite option will not be an easy one because you might have to manage two different development teams – one for managing the old applications, and making updates, and the other team for creating the new one from scratch. The advantage of rewriting is that you no longer have to endure the headache of retrofitting the old codes, and cater to the new technologies and trends. The developer team will have the freedom to create a complete masterpiece and make their mark with their creation. 

Hence, rewriting is much costlier than refactoring because you don’t have to maintain two code bases. But when you consider the time factor, refactoring finishes quickly because you don’t have to create a new system from scratch.

Common Challenges Faced When Rewriting Code.

Refactoring does come with challenges.  For one, you could confuse it with the requirement of Rewrite. Refactoring isn’t always the answer if the problem is functional, you might have to hire a developer to do the rewrite.

Another challenge is to find the right software developer team. This is a task that requires a lot of expertise and knowledge because at any step, they might have to face ambiguities and complex patterns. 

Neglecting to have a stable unit test suite is a challenge because the process of refactoring can soon become overwhelming. So make sure to have the test unit ready.

 

The Steps For Refactoring Code.

Refactoring Steps -HD


Developers usually have their own methods and techniques to refactor legacy codes. Nevertheless, there are some basic steps that they follow to complete the process. Let’s check out what they are:

1. Checking For The Flaws

Legacy codes usually have more than one flaw. The internal structuring can be changed only when you identify the root problem. To do this, you need a comprehensive application audit, and when done correctly, it is easy to gain visibility into the faults. But to do this, you also need to understand how scalable, operational and well-documented the application is. 

2. Splitting Monolith Codes

Breaking monolith codes is a very important step in refactoring because it helps in code readability. The developer will split each monolith code, separate them into classes, modify the code, test and release. This allows the developer to study each specific module, and understand the codebase deeply. This would guide them to move into the next steps.

3. Extract The Logic Code

This is the next stage in refactoring. In this, the developer extracts each flow’s set of principles and refactor it, making a straightforward approach. Through the extract methods, the developer can take the code fragment capable of being grouped, pushed to a separate method, with the old code replaced. 

4. Choosing The Right Architecture

Choosing the right architecture entails a lot of careful consideration and extensive analysis. Since the application’s behavior cannot change, the architecture selection must be based on three major drivers : risks involved, quality attributes and business vision/mission. Quality attributes are all about the maintainability, resilience, agility, performance, security and accessibility of the software. The quality attributes must be analyzed carefully because adjusting one shouldn’t be detrimental to another. 

The risks involved include financial risks, competition products and delay in time to market. 

There are architecture options that you can choose from – layered, event-driven, space-based, micro services, etc. If mixing the architectures is the best option for you, so be it. 

Final Thoughts.

There aren’t any absolute choices, you cannot say you have to choose code refactoring, or that code rewriting is better. It depends on the project, the developer team, the type of application, the long term and short term applications.

However, if you feel that the codes need to be updated to reduce technical debt, and that you need to add new features for better functionality, then refactoring is the most feasible answer. Especially, if you have to deal with only minor issues from time to time. 

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