Refactoring Monolithic Applications into Microservices: A Cheat Sheet for COBOL and RPG Applications on IBM i

If you maintain a COBOL or RPG application on IBM i, your modernization options are likely top of mind. Thankfully, you have viable options to consider that are gaining traction by the day, paving the way for your own modernization efforts.

Refactoring is one of those options. Specifically, transforming your monolithic application into microservices.

Remember to abide by common standards and best practices in your refactoring project.

You may be sold on microservices or knee-deep in the technology already, but before we dive into the process, let's first quickly review why we should consider the transition:

1. Increased Agility: Microservices allow for more efficient development cycles, as each service can be developed, tested, and deployed independently.?
2. Scalability: Individual microservices can be scaled as needed, allowing for better resource management.?
3. Maintainability: Microservices are easier to manage and debug because they are small, self-contained units.?

A Step-by-Step Plan for Refactoring the Application

Before you commit to a refactoring project, lay out a proper plan as your first step. These are steps to consider:

1. Identification of the Application's Logic Domains: Start by breaking down the existing monolithic application into smaller, logical units or domains. These domains will form the basis of your microservices.?
2. Setting Up API Gateways: An API gateway acts as a single entry point for clients to access the various microservices. This simplifies the client-side interactions and provides a level of abstraction between the client and the services.?
3. Containerization: Containerization involves packaging an application, along with its libraries, dependencies, and configuration files required to run it, into a single unit or 'container.' Docker is a popular platform for containerization.?
4. Orchestration: Orchestration is the automated configuration, management, and coordination of computer systems, applications, and services. Tools like Kubernetes are used for orchestration in a microservices environment.?

Challenges and Solutions

As part of your plan, factor in the challenges you expect to face and prepare to address them. These are just some of the likely challenges you'll face:

1. Complexity: Microservices introduce complexity due to their distributed nature. Using well-defined APIs and robust service orchestration tools can help manage this complexity.?
2. Data Management: All services share a common database in a monolithic architecture. But in a microservices environment, each service has its own database. This can lead to data consistency issues. Implementing strategies like eventual consistency and transactional outbox can help overcome these challenges.?
3. Inter-Service Communication: Microservices need to communicate with each other, which can be a challenge. Using protocols like HTTP/REST or gRPC can simplify inter-service communication.?

Tools and Technologies

Implementing best practices and strategies will ensure maximum project success, but be sure you have the proper tools and technologies in place to get the job done:

1. IBM Rational Developer for i (RDi): This is an integrated development environment (IDE) that can help in refactoring COBOL and RPG applications.?
2. Docker and Kubernetes: These are essential tools for containerization and orchestration, respectively.?
3. Spring Boot and Netflix OSS: These can be used to create and manage microservices, handling aspects like load balancing, service discovery, and fault tolerance.?
4. CM evolveIT: For static code analysis and quality checks.?

Standards and Best Practices

Remember to abide by common standards and best practices in your refactoring project. Here is a quick list of what you'll want to consider for your plan:

1. Single Responsibility Principle: Each microservice should have only one responsibility.?
2. API Versioning: This allows for changes in the microservices without affecting the clients.?
3. Health Checks: Regular health checks should be performed to ensure that all services are running as expected.?
4. Log Centralization: Logs from all microservices should be centralized to simplify monitoring and debugging.

Final Thoughts

Remember that refactoring a monolithic application into microservices is not a trivial task. It requires careful planning and execution. However, the benefits of increased agility, scalability, and maintainability make it a worthwhile endeavor.

CM First Group Can Help

Our deep experience with legacy enterprise systems puts us uniquely positioned to help reinvent your modernization efforts and set the stage for COBOL refactoring that can transform your organization.

Please contact us for more information or to schedule a demonstration of our CM evolveIT software and how its impact analysis capabilities can set your COBOL refactoring project up for long-term success.

You can also call us at 888-866-6179 or email us at [email protected].