Home / Blog / Consider These Things Before Legacy Application Re-architecting

Consider These Things Before Legacy Application Re-architecting

There is always a time in a company’s life when change is inevitable to survive in the market. We’ve already outlined a bunch of software modernization strategies in our guide, but in this article, we will concentrate on the re-architecting approach. Re-architecting of outdated applications is the perfect choice for businesses willing to upgrade their app functionality and make their system extensible for future growth.  

What you will see in this guide is what legacy software re-architecting is, the benefits and drawbacks of this invasive approach, and useful tips for a successful migration.

What Is Legacy Software Re-architecting?

Legacy application re-architecting refers to redesigning the existing architecture with new advanced computing concepts. Using declarative models and parts of the original code, engineers can preserve a good deal of the business logic and avoid building a new application from scratch. In other words, you can migrate code-independent business processes to a new system while utilizing modern technologies. 

Re-architecting strives to improve performance, stability, and other non-functional aspects of the app. The process is lengthy and expensive; however, it can bring many benefits if done correctly. 

What Problems Software Re-architecting Solves

How can your legacy application benefit from re-architecting? Which problems will disappear after you re-architect your system to fit in the modern IT environment?

Elevated costs 

Businesses that operate with legacy software often suffer from increased costs caused by the inflexibility of the traditional IT infrastructure. A modern IT ecosystem allows for the scale-out elasticity that hardware-based infrastructure fails to provide. For example, cloud storage can save you a significant portion of the budget, which explains the ever-growing popularity of cloud platforms like Azure and AWS that offer serverless architecture.

Serverless architecture gives access to the pay-per-use pricing model that eliminates overspending on unused or duplicated services. At the same time, this structure ensures auto-scaling and relieves developers of the duty to constantly monitor the system, thus allowing them to concentrate on improving the system. 

Failures of monolithic architecture 

Legacy software solutions are often monolithic apps created as a large system with a single code base and are known for brutally failing after experiencing a minor issue. Unlike the microservice approach that provides fault tolerance with decoupled services, monolithic architecture is prone to jeopardizing the entire application. The microservice architecture ensures that other services continue functioning when one service fails, which prevents the app from a complete shutdown. 

Lack of scalability

Legacy systems are notorious for the lack of scalability that resurfaces when the company grows bigger. Small companies might not take this feature seriously at first, but once they expand and get closer to the sizes of Facebook or Amazon, the need for becoming scalable becomes apparent. 

When you re-architect legacy systems for the cloud, your applications or parts of them automatically scale up or down, depending on the demand. When you experience a sudden spike in traffic, your system will expand to meet the demand, while when the user traffic goes down, the application will shrink to reduce unnecessary costs. 

Inability to comply with all technical and business requirements

As mentioned before, re-architecting enables companies to preserve the business processes, functionalities, and differentiators. Re-architecting involves redeveloping the legacy application to suit a more advanced platform while keeping the business processing intact.

In other words, you can modernize the system to enjoy the complete set of modern IT environment characteristics without the need to create new business logic. Moreover, you can even optimize business logic and data workflow while benefiting from more advanced architecture. This modernization approach enables companies to use the new technology paradigm to change their interactions with customers and transform the business.

3 Signs It’s Time to Re-architect the Legacy System

When does change become irrefutable? Let’s talk about the most important signs that show that it is definitely time to re-architect outdated software.

Reasons to re-architect legacy software - ModLogix

#1 You are dependent on hardware that is expensive to maintain

Legacy software makes you dependent on high maintenance hardware with skyrocketing expenses and increasing vulnerabilities. A great example of such a system is the Department of Homeland Security in the United States that has 168 highly critical vulnerabilities that expose the department to significant security breaches. Besides, your legacy platform will not keep up with the newest technologies and innovations, you will end up overspending on costly maintenance and eventually may lose your competitive edge. 

#2 You have cloud compatibility issues 

Re-architecting code becomes an essential step when you start having problems with the integrations with cloud components. If you decide to migrate to the cloud and discover that your monolithic system is not compatible with the cloud, consider re-architecting. This method allows you to break down your stale app into functional components, also known as microservices, that can be individually adapted and moved to the cloud environment. 

#3 Your business outgrew the application

You may want to consider re-architecting software if your business requirements outgrew the application potential. For example, your business has acquired another firm or decided to build a custom solution without starting from zero. Basically, you have new tasks that your current system is unable to solve and thus require a dramatic update. In this case, rearchitecting your solution and making it more adaptable to the changes will allow you to gain scalability and keep up with changing requirements smoothly.

How Is Legacy Application Re-architecting Different from Other Modernization Approaches?

Re-architecting is not the only modernization strategy out there. Although modernization experts identify many types, we will focus on the most prominent ones: rehost, replatform, and re-architect. 

Legacy software modernization approaches - ModLogix

Rehosting or Lift and Shift

Rehosting is the simplest and least invasive modernization method and entails shifting the application to the new IT environment without making any changes to the code or architecture. 

The benefits of rehosting:

  • No effort as you simply move the app without making any changes. 
  • No disruptions to business processes.
  • No compliance and policy changes are required. 

The drawbacks of rehosting:

  • High rate of migration failures with rehosting.
  • In the absence of pre-migration changes to accommodate the new ecosystem, performance issues might occur.
  • Moving apps without working on the existing problems might result in bigger issues after the migration. 


Replatforming goes a dash further and introduces some minor changes to the application to take advantage of the new IT paradigm. For example, you may change how the app interacts with your legacy database first to benefit from automation in the cloud environment. 

The benefits of replatforming:

  • No major changes are required, which makes this approach affordable. 
  • Apps can take advantage of scalability. 
  • Leveraging cloud features like storage services, infrastructure as code, etc.

The drawbacks of replatforming:

  • Hard to navigate and keep low-effort as scope tends to grow. 
  • Limited services, as specialized ones, require significant changes to the application. 


Legacy system re-architecting requires an in-depth understanding of both the modern IT environment and the application. This approach is the most invasive of the three and takes the longest to complete. However, it is also the approach that gives you the ability to build custom solutions. Rearchitecting allows you to plan ahead and evaluate the load according to future needs, thus avoiding scalability issues. 

The benefits of re-architecting:

  • You can preserve business logic while redeveloping the app with more modern technology. 
  • The re-architected app will be built on the microservice architecture that allows for greater agility, innovation, and scalability. 

The drawbacks of re-architecting:

  • This approach is the most time-consuming type of migration.
  • You will need the best data engineers on your team or an experienced modernization vendor to see the migration through. 
  • The increased amount of time and human resources makes this approach quite expensive.

Possible Risks of Re-architecting a Legacy System

Incomplete or missing documentation

In most cases, companies decide to re-architect outdated applications that have been around for at least 10 to 15 years and are missing detailed documentation. Back then, there were no strong coding standards and practices that resulted in messy and undocumented code. Now, these codebases are hard to read, maintain, and streamline, which complicates the re-architecting process. Besides having difficulties with smooth system expansion, you will probably face a lack of engineers who developed these systems and know them well enough. If the documentation or essential parts of it are missing, teams are forced to begin projects with a black box full of business processes, technology, and other essential data. 

Solution: To organize this chaos, start documenting requirements and leave more time for planning and analyzing to establish an order. 

Get Free Code assessment

Start re-architecting your legacy software with a FREE source code assessment

Learn more

Decrease in customer experience

Long-term customers get used to small details in your app, and even a tiny change in UI might lead to user disappointment as they have to relearn how to interact with your program. 

Solution: Make customers an integral part of the innovation process and take their opinions into account. 

Team effort coordination

If you decide to re-architect code, you will still need to keep the old product afloat as well as work on the modernization. You will need to either split your team in half and assign one task or the other or have your entire team switch from one task to another. Both options are not very viable. 

Solution: First, analyze your human resources to establish how many employees could devote their time to maintaining and updating. If you discover the lack of personnel who can fill this gap, hire a reliable legacy modernization partner. Without a professional team, your re-architecting project is bound to drain your time and resources.

Tricks and Best Practices from ModLogix — Your Reliable Legacy System Modernization Partner

Here is a short list of the things to consider before starting the re-architecture process for an application: 

1. Invest into documentation

To avoid challenges of legacy system upgrading, proper documentation is the number one requirement for successful projects. If your documentation is poor, partial, outdated, and unstructured, start with writing application logic, current architecture, business logic, environment, planned upgrade actions, etc.  

To make this process more efficient, use an online tool such as Atlassian Confluence which will provide rich functionality for team collaboration. 

2. Try to keep the data layer untouched for as long as possible

Most of the projects have data storage (like SQL server) on the backend that’s outdated and usually requires refactoring as well. But if you can create new data models which connect to existing entities in the database, you will be able to run new and old versions side by side. This will make testing easier and will allow for a gradual transition. 

3. Plan your project deliveries in phases

It’s common that the rearchitecting process drags on with the companies barely seeing any changes or improvements in their software. So, in order to avoid any stakeholder or customer frustration, plan to deliver the new version in phases. Plus, you also can adjust the product on the go according to customer feedback.  

Optimally, a working version must be deployed at the end of each phase. For example: 

Phase #1 – Proof of concept: a phase where you test new approaches, validate the planned implementation. 

Phase #2 – Core functionality: migration of the most critical features. 

Phase #3 – Alpha testing as soon as all functionality fixes are finished. 

Phase #4 – Bug fixing, preparing for production. 

4. Do a prototype development

Since app re-architecting implies the use of new tools and technologies, including new programming languages, frameworks, and platforms, make sure your team has enough experience with the new toolset. Otherwise, incorrect assumptions and estimates can possibly be made that lead to wasting the set budget. 

If your organization lacks technical expertise, consult with qualified vendors to validate your estimates

5. Retire unnecessary components

Almost all old software products have had now-obsolete functionality added to the product over the years. That’s why when rebuilding legacy software, it’s crucial to review the current functionality, documentation, business goals and retire the parts that are no longer important or not widely used.  

It is an excellent opportunity to create an optimized system.  

6. Add new functionality 

If you have any product improvements in mind, the re-architecting phase is usually the best time to consider planning and implementing the new functionality. Conduct deep research before adding any features; they should encourage business growth and ensure high ROI in the end. 

Upgrading AngularJS to Angular 11

Learn how to upgrade the system and add new functionality simultaneously.

Upgrading AngularJS to Angular 11

System rearchitecting helped us add the new functionality to the app and improve the software in general when eliminating performance issues in AngularJS.

Final Thoughts

In the plethora of various software modernization services, it might be challenging to make the right choice. In case you are still unsure when to re-architect code or when to simply lift and shift the system, contact ModLogix. We are a team of application migration experts that are always ready to share about different kinds of modernization, their benefits, and risks. Contact us to learn about software modernization services and estimate your project.

Latest Blog Posts

Ask Us Any Question

* Please enter your name
* Please leave a message

    How to protect your business from getting obsolete?

    Download the white paper to discover hands-on approaches to aging software and mainframes.

    Get Your FREE Template!

    Please, provide the email address so that we can send the whitepaper to you.

    * Please enter your name

      We use cookies to ensure that we give you the best experience on our website. By continuing to browse this site you accept the use of cookies.

      Get Your FREE Template!

      Please, provide the email address so that we can send the whitepaper to you.

      * Please enter your name

        Get Your FREE Template!

        Please, provide the email address so that we can send the checklist to you.

        * Please enter your name