Legacy Software – The Big Rebuild
In a recent post, we discussed legacy software, why it exists, the risks of using it, and an overview of the available options. This article will examine one option in greater depth: a complete rebuild of legacy software systems. Legacy technology often involves outdated hardware and software that can be difficult to maintain and integrate with modern solutions.
Research confirms that legacy systems often present significant hurdles, including “limited scalability, poor interoperability, and heightened security risks,” making integration with modern solutions difficult.
What is Legacy Software?
Legacy software refers to outdated technology systems, applications, or platforms still in use within an organisation. These systems may no longer be actively supported or updated by their vendors, making them difficult and costly to maintain. Legacy software can pose a significant challenge for businesses, hindering their ability to innovate and adapt to changing market conditions. Often, these systems were built using older programming languages and frameworks that are no longer widely used, complicating efforts to integrate them with modern technologies or mobile devices. As a result, organisations may rely on an outdated solution that no longer aligns with their business needs or technological advancements.
Ready to modernise your legacy systems but unsure where to start? Download our Legacy Software checklist today!
Challenges of Legacy Systems
Legacy systems present several challenges to organisations, including:
- Technical Debt – Legacy systems often require a substantial investment in technical support, including maintenance fees, labour costs, and hosting expenses. This ongoing expenditure can drain resources that could otherwise be used for innovation and growth.
- Security Vulnerabilities – Outdated software exposes organisations to cyber-attacks and data breaches. Without regular updates and patches, legacy systems may have unaddressed security flaws that malicious actors can exploit.
- Performance Issues – Legacy systems can be slow, inefficient, and prone to errors, reducing productivity and user satisfaction. These performance issues can disrupt daily operations and frustrate users.
- Integration Challenges – Legacy systems may not be compatible with modern technologies, making integration with other systems and applications difficult. This lack of compatibility can create data silos and hinder information flow across the organisation.
- Lack of Vendor Support – Vendors may no longer provide support or updates for legacy systems, leaving organisations to manage them independently. This makes it challenging to resolve issues or implement necessary changes.
When Should You Consider Rebuilding Legacy Software?
When assessing whether to rebuild, it is crucial to consider the state of your existing software.
- When you do not have access to the underlying code base – This is a common problem, particularly when businesses assume they will work with the same developer indefinitely. If the developer has sole possession of the source code, it may be lost if they go out of business or the relationship breaks down. This issue is especially problematic for compiled languages.
- When the original language is obsolete – Just as software can become outdated, so can its programming language. While some languages evolve into newer versions, many become obsolete. Of the estimated 9,000 programming languages historically used, only 500–1,000 are still in active use today, leaving many as dead ends.
- If only a tiny percentage of the software is being used – Maintaining overly complex software when only a tiny portion of its functionality is in use can be unnecessarily expensive. In such cases, starting afresh is often more cost-effective.
If the software is relatively simple, and only a few key functions are needed, there is little point in incrementally modernising the system when a complete redevelopment could take just a few weeks.
If the software is critically broken and cannot be fixed, sometimes it fails, and either the necessary resources to fix it are unavailable, or the repair cost is prohibitive.
Why Rebuild Legacy Software?
Rebuilding legacy software presents an opportunity to start anew and implement modern technologies and best practices. Key reasons to rebuild include:
- Enhancing Security – A rebuild allows organisations to address security vulnerabilities and ensure compliance with regulatory requirements. Modern development practices prioritise security, making it easier to safeguard sensitive data and prevent breaches.
- Improving Performance – Modern software improves system performance, reduces errors, and enhances user satisfaction. Leveraging the latest technologies and methodologies results in more efficient and reliable systems.
- Reducing Costs – Rebuilding legacy software can lower maintenance costs and improve efficiency. A well-designed new system that considers scalability and maintainability can reduce long-term expenses and free up resources for other initiatives.
- Boosting Integration Capabilities – Modern software can be designed for seamless integration with other systems and applications, enhancing overall functionality. This improved integration streamlines workflows, facilitates data sharing, and supports better decision-making.
The Big Plan for a Software Development Project
All software development requires a plan, but with legacy software, many moving parts must be considered. The best approach varies between businesses, but a full system audit is almost always necessary. A thorough plan should also assess whether custom software solutions are needed to meet specific business requirements. We recommend starting with:
- User Audit – Identifying users and their software requirements.
- Software Audit – Conduct a full review (including code-level analysis if possible) of all features in the current system. Assessing code quality is crucial to determining areas that need refactoring or redevelopment.
- Comparison – Evaluating which components need redevelopment, which can be archived, and which should be removed.
- Critical Issues – Identifying features that can be improved, fixed, or added to enhance software functionality.
Data Management involves determining which data needs to be migrated to the new system and which can be archived. Sometimes, small software tools may be required to access archived data, but these should remain separate.
This process defines version 1 of the rebuilt software. It is the foundation for the Software Requirement Specification (SRS), which should outline stakeholders, budgets, and timeframes like any new development project.
While a rebuild’s development and testing phase is similar to those of any other project, transitioning from the old system to the new one presents a unique challenge.
There are three primary deployment strategies:
- Complete cutover involves ceasing the legacy software and immediately switching to the new system. This method is effective if rigorous testing has been conducted, users have been trained, and developers can resolve any immediate issues.
- Phased rollout – Releasing the new system to a subset of users and gradually expanding access as the software proves its stability.
- Parallel operation – Running the legacy and new systems side by side for a transition period.
Each approach has advantages and disadvantages, but an experienced developer will recommend the most suitable option.
Best Practices for a Successful Rebuild
To maximise the success of a legacy software rebuild, organisations should adhere to best practices, including:
- Conducting a Thorough System Audit – Understanding the existing system, identifying areas for improvement, and defining the scope of the rebuild project.
- Writing a Software Requirement Specification (SRS) – Outlining functional and non-functional requirements to ensure alignment among all stakeholders.
- Considering Stakeholders, Budgets, and Timeframes – Ensuring effective communication and collaboration to manage expectations and secure necessary resources.
- Following a Structured Development and Testing Process – Using a structured approach, including agile methodologies, to adapt to changes and ensure high-quality software.
- Releasing the New Software in a Controlled Manner – Phasing the release to a subset of users or running it in parallel with the legacy system to identify and resolve issues before full deployment.
By adhering to these best practices, organisations can successfully navigate the complexities of rebuilding legacy software and achieve a modern, efficient, and secure system that meets current and future needs.
Summary of Code Quality
Starting anew is often the best—or only—option when transitioning from legacy software to modern best practices. One key advantage of a rebuild is leveraging cloud computing, which offers greater flexibility, scalability, and cost savings.
The advantage is that you are not starting from scratch—you already have an existing system and a clear understanding of what works, what could be improved, and what should be discarded. The challenge, however, lies in the additional planning required.
In another post, we will explore an alternative approach: incremental improvement, which can help mitigate some of these challenges.
If you need assistance with legacy software, please get in touch.
More of our post on legacy software can be found here : Legacy Software Modernisation Posts
Download our Legacy Software Modernisation checklist here.
