Concepts
Legacy systems integrally associated with successfully running business operations are often perceived as a bone of contention when it comes to software transformation. They are perceived as hard-to-change, monolithic systems that pose a challenge to migrate towards more modern or agile designs. That said, there are several agile design approaches that can be utilized to overcome typical challenges associated with legacy systems. Below, we shall dive into three of such approaches in detail.
1. Strangler Fig Application
The Strangler Fig Application is an agile design strategy named after the strangler fig tree, which grows by gradually enveloping a host tree to eventually replace it completely. Similarly, this approach involves building a new system around the edges of the old one, gradually replacing the functionalities of the old system until it’s completely “strangled” and can safely be removed without disrupting the business process. This approach can be useful for large business-critical systems that cannot be replaced all at once due to their size and complexity.
For instance, a large banking system may have multiple functionalities such as user accounts, transactions, loans, etc., each of which may be gradually migrated to a new system using the Strangler Fig approach.
2. Microservices Architecture
Microservices Architecture is an agile design approach that structures an application as a collection of small autonomous services, each centered around a specific business capability. This segregation allows for each microservice to be maintained, upgraded, scaled, and deployed independently.
Consider a large e-commerce platform that may have several functionalities including user management, product management, and order management. The Microservices architecture would involve segregating these functionalities into separate services that can be worked on independently of one another. This structure makes dealing with legacy systems easier as each functionality or microservice can be individually maintained or upgraded, thereby reducing the complexities involved with full-system upgrades or maintenance.
3. Continuous Refactoring
Continuous Refactoring is an agile approach aimed at making small, incremental improvements to code, redesigning it to make it more efficient and maintainable without affecting its behavior. It involves regularly examining and improving the system’s codebase. This approach allows organizations to maintain the quality of their code, keeping it clean and efficient, while continually improving their legacy systems in line with modern coding practices.
In the context of a well-established software firm with a diverse coding-base, continuous refactoring can prove to be a boon. Older pieces of code can be incrementally improved, ensuring their efficiency and performance without the need for a major overhaul.
Comparison of the Agile Approaches:
| Strangler Fig | Microservices | Continuous Refactoring | |
|---|---|---|---|
| Start of implementation: | Gradual | Direct split | Anytime |
| Level of Investment: | High | Moderate | Low |
| Impact on Business: | Low | High | Medium |
| Ease of Migration: | Moderate | Low | High |
In Conclusion
In conclusion, redesigning legacy systems is a strategic decision that must be tailored to each unique organizational context. An agile design can pave the way for smooth transition and continuous improvement. Choosing the right approach will depend on factors such as the current system’s structure, business impact of potential disruptions, available resources, and the ideal final state of the system. Whichever course is chosen, it helps to bring the organization closer towards a more adaptable, resilient and scalable future.
Answer the Questions in Comment Section
1) True/False: Agile design approaches do not address the challenges with legacy systems.
- Answer: False
Explanation: Agile design approaches are especially helpful in addressing the challenges that accompany legacy systems, such as lack of technical documentation, insufficient tests, and tight coupling.
2) Multiple Select: Which of the following are common legacy system challenges that can be addressed by agile design approaches?
- A. Old and obsolete technology
- B. Insufficient testing
- C. Tight coupling
- D. All of the above
Answer: D. All of the above
Explanation: Agile design approaches address many legacy system challenges including obsolete technologies, inadequate testing, and tight coupling that makes it difficult to make isolated changes.
3) Single Select: Which agile design approach emphasizes iterative development, frequent communication with stakeholders, and flexible response to changes?
- A. Waterfall Method
- B. Scrum
- C. Spiral Model
- D. V-Model
Answer: B. Scrum
Explanation: Scrum is an Agile methodology that focuses on iterative development, frequent communication with stakeholders, and ability to respond quickly to changes.
4) True/False: An agile design approach includes long cycles of development without any feedback or communication with stakeholders.
- Answer: False
Explanation: In contrast to traditional methods, agile design promotes frequent feedback and communication with stakeholders, ensuring that the development meets their needs and expectations.
5) Multiple Select: Which of the following three are Agile design approaches?
- A. Waterfall
- B. Scrum
- C. Lean
- D. Kanban
Answer: B. Scrum, C. Lean, D. Kanban
Explanation: Scrum, Lean and Kanban are all considered agile methodologies as they promote iterative development, collaboration and flexibility.
6) Single Select: Which agile system design approach uses a continuous flow method to improve efficiency?
- A. Scrum
- B. Lean
- C. Kanban
- D. Extreme Programming
Answer: C. Kanban
Explanation: Kanban is an agile design approach that uses a continuous flow method to manage work and improve efficiency.
7) True/False: Agile design approaches can help address legacy system issues through continuous integration and continuous deployment.
- Answer: True
Explanation: Through continuous integration and deployment, agile design approaches promote frequent testing and releasing of the software to address the issues faced by legacy systems.
8) Multiple Select: Agile design approaches can improve legacy system issues by:
- A. Encouraging frequent testing
- B. Incorporating customer feedback faster
- C. Reusing outdated technologies
- D. Breaking the project into smaller, manageable chunks
Answer: A. Encouraging frequent testing, B. Incorporating customer feedback faster, D. Breaking the project into smaller, manageable chunks
Explanation: Agile design approaches address legacy system issues by providing frequent testing, incorporating customer feedback promptly, and breaking down the project into smaller tasks for better management.
9) Single Select: What method is associated with pairing programmers for legacy system issue resolutions?
- A. Extreme Programming
- B. Waterfall Model
- C. Scrum
- D. Kanban
Answer: A. Extreme Programming
Explanation: Extreme Programming (XP) is an agile design approach that pairs programmers to work together, encouraging continuous communication and immediate feedback to address issues with legacy systems.
10) True/False: Using agile will cause your legacy system to be upgraded overnight.
- Answer: False
Explanation: Transitioning from a legacy system using an agile design approach will be a gradual process, involving iterative developments and constant stakeholder feedback.
Great post! I’m particularly interested in how Incremental Refactoring can help with a legacy system.
Incremental Refactoring seems more feasible than Big Bang refactoring for our monolithic app. Has anyone successfully applied this?
Can someone explain more about the Strangler Fig Pattern?
Thanks for the blog post! Very helpful information.
How is the Branch by Abstraction approach different from the Strangler Fig Pattern?
We’ve tried the Strangler Fig Pattern and found it effective but challenging with tightly coupled systems.
The concept of Feature Toggles has been a game-changer for our team. Anyone else utilizing it?
Not all legacy systems are suitable for these approaches. Some might just need a complete overhaul.