In addition to end users, every system needs to integrate with other IT systems. Those systems may be a part of different departments, clients, partners, or suppliers. The various systems need to exchange data in a standard format that evolves over time. Almost every few years, files and data format standards get changed to increase data exchange efficiency, and most systems require changes to adopt these. Hard-to-change legacy systems that stick to using an old format could result in system incompatibility and a system that your supplier and partner may not want to use. The inability to accommodate standard needs adds greater risk to businesses due to complex workarounds and lost productivity.
Adding a workaround for simple business needs may make a system more complex. Modern systems are built on a service-oriented architecture, which makes it easier to accommodate any new requirement by adding a new service independently. Old systems are often built on a monolithic architecture, and adding any new feature means you need to rebuild and test the entire system.
Modern architectures are API-oriented and can be easily integrated with another system to offload heavy lifting. For example, a taxi-booking app uses Google Maps for Global Positioning System (GPS) navigation or Facebook and Twitter for user authentication. A lack of APIs makes these integrations harder in a legacy system, resulting in complex custom code.
As more load increases from another dependent upstream system, a legacy application can face a scalability issue. Often, legacy applications are built on a monolithic architecture and are hardware-dependent. Scalability is a big challenge with a monolithic system, as it cannot scale horizontally due to hardware dependency and vertical scaling being limited to the maximum system capacity. Breaking monolithic applications into microservices can solve scaling challenges and help keep up with demand.
In addition to software maintenance, legacy applications are also costly for hardware infrastructure as they run on a particular version. They spread across multiple databases with duplicate data and similar functionality. Due to their monolithic nature, it's hard to perform consolidation and use the flexibility of cloud-based infrastructure to save costs. Let's look at the approach to the modernization of legacy systems.