Legacy systems

What is a legacy system?

Legacy system is an outdated piece of software, tool, or technology that’s still in use, even though there are many modern alternatives available. In simpler terms legacy system definition means old computer or hardware programs built with old and obsolete tech stack. These systems are still used by many because it’s deeply embedded into organizational operations and may take too much time, effort, and investment to replace. According to the manufacturers, legacy systems are still prevalent in 74% of manufacturing and engineering organizations. The main drawback with legacy systems is its limited scalability, which might be a concern for a growing organization, when they demand their systems to handle increased workloads. 

Characteristics of legacy system

Built with old tech, frameworks, and methodology: legacy systems in software engineering are mostly built with languages like Mainframe, COBOL, MS-DOS, and other old technologies. 

Prone to security vulnerabilities: weak and old-aged security measures often make these systems vulnerable to threats and security attacks. 

Incompatibilities with modern platforms: organizations relying on legacy platforms have limitations integrating them with other systems like cloud, SaaS, etc. 

Scalability problems: modern data requirements are so vast that legacy systems may not be able to scale up and support. 

Expensive to maintain: legacy systems are both inefficient and expensive to maintain. 

Legacy systems examples could be anything that relies on technology older than 90s or earlier than that. Some legacy system examples are an inventory management system that runs on 90s SQL or an on-premises manufacturing ERP systems that’s difficult to connect. Speaking of ERP being legacy systems, not all ERP falls under legacy system and out-dated category — only when the ERP lacks cloud integration, mobile access, comes with performance limitations, and high maintenance costs.  

Difference between legacy and cloud systems

Difference between legacy and cloud systems is that legacy systems are on-premises systems that are outdated, but cloud systems are modernistic & hosted on cloud. Other differences are listed below on the table, along with factors. 

How to integrate legacy systems?

Legacy systems integration is the process of connecting outdated legacy systems with modern applications for reasons like extending functionality, seamless data transfer, or leveraging the best of both technologies. 

But it’s easier said than done as there are many challenges in legacy systems integration. Like incompatibility, data siloes, security risks, and process complexities. 

You could follow the following approaches to integrate legacy systems with modern tools. 

1. Through Middleware: middleware can act as a bridge between the two systems, enabling communication. The middleware could be enterprise service buses or tools like IBM WebSphere. 

2. Data integration platforms: using third-party integration tools like Talend or Informatica to extract data, transform, and load them into the destination system. 

3. Database integration: using connectors or custom scripts to integrate databases of legacy systems with that of modern tools.  

4. Event-driven systems: setting up event-based architectures where a certain event in the legacy system would trigger the change in modern systems, updating/syncing changes in real time. 

While you are integrating legacy systems with modern tools, it’s important to check compatibility between both and check for potential security issues. 

Legacy systems modernization

Legacy systems modernization is updating or upgrading old legacy tools to something new, that meets current or future business needs and comes with modern features. The shift from old to new-age tools is what modernization mean here.  

People may prefer legacy system modernization for many reasons. 1. high performance needs, 2. wants to scale, 3. wants to innovate, improve, and invest in modern architectures. Or simply help employees get user-friendly experience.  

Some legacy systems modernization approaches to follow: 

1. Rehosting: it’s like lift-and-shift. Moving the current data, workflows, and functions to the new system, but core functions remain the same, while the back-end hosting vary. 

2. Refactoring: making the legacy system better, so it could function better, scale, and accommodate more than it could before. 

3. Re-platforming: system architecture will remain the same; but moving things (databases) to a modern platform. 

4. Re-architecting: getting the new architecture designed to suit current/future needs, like transferring from a mono-lithic to a serverless architecture. 

5. Replacement: sending off the old legacy system with a goodbye and completely replacing it with a similar-functioning SaaS. It’s like migrating from legacy to SAP, where you transfer the entire ecosystem from legacy to SAP for advanced functions, analytics, and integration capabilities. 

6. Retirement: phasing out old systems, while transferring its functions into the new ones.