What Is COBOL?
COBOL (Common Business-Oriented Language) is an old but reliable programming language developed in the late 1950s. It was created for business, finance, and administrative systems used by companies and governments. Despite its age, COBOL remains widespread due to its ability to handle large volumes of data processing with accuracy.
The language’s simplicity allows it to be readable and understandable to users with modest programming skills. COBOL is thus still used across many legacy mainframe systems operating under major financial institutions, government agencies, and large enterprises.
This is part of a series of articles about legacy code.
Key Components of a Mainframe System
A COBOL mainframe system includes the following components.
Central Processing Unit (CPU)
The CPU is responsible for performing complex calculations and data processing tasks. Mainframe CPUs use techniques such as parallel processing, pipelining, and dynamic partitioning to maximize their efficiency. They allow multiple tasks to be processed simultaneously, speeding up data handling and transaction processing.
Memory and Storage
Mainframes are often equipped with large quantities of RAM to enable fast data retrieval and processing speeds, which is useful for operations needing real-time data access. For long-term data storage, mainframes use high-capacity disks and tape drives. These storage solutions ensure data integrity while supporting large-scale backup and recovery operations.
Input/Output Devices
Input/output (I/O) devices are critical to mainframe operations, enabling interaction with peripheral devices and external systems. Mainframes support a variety of I/O devices, including high-speed printers, disk drives, and network interfaces. Advanced I/O subsystems manage the data traffic between the mainframe and peripheral devices, reducing bottlenecks.
Networking Components
Networking components include hardware and software elements that allow large systems to communicate with other computers and networks. Mainframes use dedicated network interfaces and high-speed connections to ensure reliable data transmission. Networking protocols and security measures protect the data and maintain connectivity. This infrastructure supports the large-scale transactions and data exchanges typical of enterprises.
| Tips from the expert→ Omer Rosenbaum, CTO & Co-founder at Swimm In my experience, here are tips that can help you better understand and leverage COBOL and mainframe systems: 1. Leverage COBOL-IT for cross-platform development: COBOL-IT is an open-source COBOL compiler that supports multiple platforms. It allows you to develop and test COBOL applications on modern operating systems before deploying them on mainframes, enhancing portability and flexibility. 2. Utilize source code analyzers for legacy systems: Tools like IBM’s Application Discovery and Delivery Intelligence (ADDI) can help analyze and understand legacy COBOL codebases. They provide insights into code dependencies and structure, which is crucial for refactoring and modernization efforts. 3. Explore hybrid cloud integration: Mainframes can be integrated with cloud services to create a hybrid environment. This approach allows you to extend the capabilities of COBOL applications with cloud-native features like AI, big data analytics, and IoT. IBM Cloud and AWS Mainframe Modernization are viable platforms for such integration. 4. Implement database modernization techniques: Modernizing the data layer, such as migrating from VSAM to modern relational databases (e.g., DB2, Oracle), can improve data management, querying capabilities, and integration with other systems, providing better performance and scalability. 5. Foster cross-generational knowledge transfer: Encourage collaboration between seasoned COBOL developers and newer programmers. Creating mentorship programs and documenting best practices can ensure that valuable knowledge is preserved and transferred, mitigating the risks associated with the retiring workforce. |
COBOL Programming in Mainframe Systems
Here are some of the main aspects of programming a COBOL mainframe system.
Development Environment and Tools
The development environment includes tools to support coding, compiling, and debugging. Integrated development environments (IDEs) like IBM’s Rational Developer for z Systems provide a solution for COBOL development, offering features like syntax highlighting, code completion, and real-time error checking. Code management and version control systems are often used to ensure consistency and track changes across the development lifecycle.
Coding Standards and Best Practices
Adhering to COBOL programming standards ensures code quality and maintainability. Standards often focus on aspects like structured programming, meaningful naming conventions, and commenting to make the code more readable and easier to manage. Best practices emphasize modularity and reuse of code, which can reduce complexity and improve efficiency.
Common Development Tasks
Common development tasks in COBOL include writing new programs, updating existing ones, and migrating code from older systems. These tasks often involve interacting with databases, managing file input/output operations, and ensuring compatibility with legacy systems. Developers routinely write and optimize algorithms to handle large-scale data processing.
Debugging and Testing
Debugging involves identifying and fixing errors in the code. Tools like IBM’s Debug Tool for z/OS offer features to trace program execution and analyze variable values dynamically. Testing ensures that the COBOL programs meet the specified requirements and perform reliably in production environments. Common testing strategies include unit tests, integration tests, and system tests, which are often automated.
Beyond COBOL: Future of Mainframe Applications
While many organizations still rely on COBOL mainframes, there is often a need to modernize COBOL applications to support new features or work processes. Here are some of the ways that organizations can prepare their mainframe systems for new and future demands.
Refactoring Legacy Code
Refactoring involves restructuring existing code without altering its external behavior. This process aims to improve code readability, reduce complexity, and enhance maintainability. It helps extend the lifespan of COBOL applications, making them more adaptable to modern needs.
Increasing modularity and removing redundant code are common refactoring techniques. The objective is to make the codebase cleaner and simplify integration with newer technologies and systems, enabling a smoother transition to modernized environments.
APIs: Bridging Old and the New
APIs (application programming interfaces) serve as bridges between old mainframe applications and new technologies. By developing APIs, organizations can expose functionalities of legacy COBOL programs to modern applications, enabling interaction between disparate systems.
APIs enable integration with web services, mobile apps, and other modern interfaces, allowing legacy systems to access new digital capabilities without extensive overhauls of the existing infrastructure. This strategy also ensures scalability and aids in future-proofing mainframe investments.
Containerization and Microservices
Containerization involves packaging applications and their dependencies into containers, ensuring consistency across different environments. This makes it easier to develop applications across multiple systems, with each component remaining portable.
Microservices architecture breaks down applications into smaller, independent services that can be developed, deployed, and scaled separately. This approach often goes hand-in-hand with containerization, allowing organizations to make their mainframe applications more agile. It also enables quicker updates and more efficient resource utilization.
Enhancing Security
Enhancing security in mainframe systems involves multiple layers of defense. Mainframes are inherently secure due to their architecture, but additional measures like encryption, multi-factor authentication, and regular security audits are important to protect sensitive data.
Implementing stringent access controls and monitoring network traffic for unusual activities are critical components of a security strategy. These measures ensure the integrity and confidentiality of data, protecting it from potential cyber threats.
Migration to Modern Platforms
Migrating from a mainframe system to a modern platform can be a complex task, but it is often essential for organizations seeking to modernize their IT infrastructure. This process involves moving applications, data, and business processes to more flexible, scalable environments like cloud platforms.
Migration strategies often include rehosting, refactoring, and rearchitecting, with varying levels of complexity and control. It’s important to consider the advantages and challenges of each migration strategy before committing. Careful planning and execution, along with rigorous testing, help ensure a smooth transition and minimize disruptions to business operations.
Related content: Read our guide to COBOL migration
Documenting legacy code with Swimm
Legacy code represents a significant challenge as well as an opportunity for software organizations. Managing legacy code entails more than just dealing with untidy or outdated code; it involves transforming it into a reliable and efficient foundation that supports future development initiatives. Handling legacy code effectively can lead to considerable long-term savings and heightened productivity, marking it as a strategic priority for any R&D organization.
Swimm is a devtool that will help you and your team document legacy code in an easy, manageable, and effective way. Utilize AI to create docs about legacy code and then discover those docs directly in your IDE. Those docs then stay up to date with ongoing code changes, boosting your team’s productivity and enhancing the quality of your codebase.
