How did most mainframe applications become monoliths?
- Mainframes have been around for 50+ years and can still run applications developed 50+ years ago
- Common programming languages such as Common Business Oriented Language (COBOL) and Programming Language/I (PL/I) allowed for procedural code to be easily developed
- Mainframe tools such as Customer Information Control System (CICS) and Information Management System (IMS) allowed procedural code to be developed in an environment that could scale up easily
- Mainframe hardware has become more powerful over time to keep pace with the performance demands of monolithic applications
With these factors in mind, it is easy for monolithic systems to grow to over 10 million lines of interdependent source code, making the task of modernizing look very daunting and costly.