Legacy code is a common challenge for software developers who want to adopt Scrum, an agile framework for delivering valuable products in short iterations. How can you use Scrum with legacy code without compromising quality, speed, or customer satisfaction? In this article, you will learn some practical tips and best practices for applying Scrum principles and practices to legacy code.
Legacy code is any code that is difficult to change, test, or understand. It may be written in outdated languages, lack documentation, or depend on obsolete technologies. Legacy code can slow down development, increase maintenance costs, and introduce bugs and security risks. However, legacy code may also contain valuable features, business logic, or user data that cannot be easily replaced or migrated.
Legacy code is both a blessing and a curse. It often can hold the secret sauce for the product while at the same time be wrapped up in a ball of band-aids and bailing wire. This often makes it where it is frozen in time. So, you either have a small set of people who know it well enough to make changes, or worst case, no one is left who knows it and "we just don't touch it, we code around it." Either way, you have a problem. The best solution for getting out of the problem as well as avoiding it is sound architecture that is adhered to strictly. This includes code reviews where others learn the code, contribute to the unraveling, and enforce long-term best paths. Also, carefully manage "emergency changes" or "it's just a prototype".
Since legacy code comes up naturally during development you have to be aware that you cannot prevent working with it. Over time any code, even the one a team creates themselves, can turn into legacy code. A team needs to invest in technical excellence and continuous refactoring to establish a framework for handling legacy code and technical debt.
Use Scrum with legacy code by incorporating incremental changes and refactoring into the sprint cycles. Begin by creating a solid test suite to ensure existing functionalities remain intact. Prioritize user stories that involve updates or improvements to the legacy code. Allocate time for refactoring during sprints to gradually enhance code quality. Encourage collaborative efforts and knowledge sharing within the team to address challenges related to the legacy codebase. By integrating legacy code improvements into the regular Scrum process, you can progressively modernize and maintain the codebase while delivering value to the end-users.
Every code that is not in current development scope will turn into legacy code. Due to the fact that no one works at this code, the knowledge about decreases and developers might fear to change it. If legacy code is well structured and tested, it is more easy to change later.
If you have legacy code and you don't have a SME on the legacy code, 1. Create automated black box tests for the legacy code to confirm that it remains stable. 2. Reverse engineer the legacy code so you can create design documentation, add comments, and update the coding standards (if the legacy code is lacking in any of these) 3. Once you understand how the legacy code behaves and its architecture, if the decision is made that changes are needed, then do incremental refactoring while running your nightly build + tests. Prioritize test failures from your nightly builds and technical debt from the legacy code.
Scrum is a popular agile methodology that helps teams deliver working software in short cycles, usually lasting two to four weeks. This methodology emphasizes collaboration, feedback, and adaptation, as well as quality, value, and customer satisfaction. In order to deal with legacy code, Scrum can be used to break down complex problems into manageable tasks and prioritize the most important and urgent features or fixes. Moreover, it can help teams deliver incremental improvements and updates while testing and reviewing the code frequently and thoroughly. Refactoring and improving the code as needed is also possible with Scrum, as well as communicating and aligning with stakeholders and users.
Using Scrum with legacy code is a good idea. Incremental refactorings, changes and the increase of automatic tests reduce the risk of breaking changes and reduce the fear to change the code.
The perfect usage scenario for scrum is a greenfield project from scratch. Nevertheless, I believe every kind of project could be done with scrum. This is especially the case when a complete team for a longer time period is working on it. Having legacy code make the start a little harder to get into the project but nothing else. Why? I just give you an example: estimating tasks without knowing the legacy code well is impossible.
Over the years have heard as organizations that adopt Scrum proclaim 'it really only works for new product development development.' I have always felt that is not correct. True that it is easier to adopt on new products, because there is no previous development method. Apart from this dynamic, the use of Scrum with Legacy code can work very well. The tenants of Scrum can truly help in: - Breaking down the herculean effort of updating Legacy code and removing Tech Debt - Defining dependencies and prioritizing work - Planning work and executing the plan - Daily standups where the team can share what is going well and where there are complications. This is key as Tech Debt often is complicated to resolve. Scrum helps work it as a team.
Scrum has in-built ceremonies for inspection (review and retrospective) which can help identify why a code base is difficult to change or adapt to the requirements. Doing this as a team helps educate those not directly involved in changing the code, which helps the Product Owner to add items to the Product Backlog. Sustainable pace is key to Scrum and so the team can help the Product Owner prioritise improvements against other backlog items, to get the balance right for the future of the product.
More than how you can use scrum in a legacy code environment focus should be on WHY to use scrum ? Scrum is a light weight framework that could be applied for any complex work. Scrum is all about empiricism so the experiential knowledge team possesses can be best. Further the events and artifacts of scrum can bring transparency about refactoring, maintenance issues etc...which would best benefit the business to take decision on whether it is wiser to continue investing in the product.
Before you start using Scrum with legacy code, it is essential to do some preparation work to ensure a seamless transition and avoid any potential issues. You should assess the existing state of the code and recognize the main opportunities and challenges. Additionally, you should define the scope and vision of the project, as well as the expected outcomes. It is also important to form a cross-functional and self-organizing team that can manage both the technical and business aspects of the project. Furthermore, you should set up a reliable and automated build, test, and deployment environment. Moreover, you should create a product backlog that lists all features, bugs, and improvements that need to be done. Additionally, you should estimate the effort and complexity of each backlog item and assign a priority. Finally, you should plan the first sprint and agree on the sprint goal and definition of done.
There are no economies of scale in software development so Scrum is at its best when there is one autonomous team only. If this will not achieve the results and more than one team is needed, think about the "fracture lines" on how to split the code base to allow each team to work independently.
1. Under the architecture of legacy code(as much as possible) 2. Break the whole Piece into bigger chuncks. 3. Slice down into even more smaller pieces . 4. Plan each small refactoring activity in sprint keeping in mind that basic functionality should not break. ** The secret to work with legacy code is planning and deep analysis.
Once you have prepared for Scrum with legacy code, you can start executing the sprints and delivering value to your customers. To do this, you should follow the Scrum roles, events, and artifacts as defined in the Scrum Guide. Start each sprint with a sprint planning meeting to select the backlog items for the sprint and break them down into tasks. Work on the tasks in small batches and use version control, code reviews, and pair programming to ensure quality and consistency. Additionally, write unit tests, integration tests, and acceptance tests for the new or modified code and run them regularly. Refactor the code to improve its readability, maintainability, and performance. Use code analysis tools and metrics to monitor the code quality and identify technical debt. At the end of each sprint, conduct a sprint review meeting to demonstrate the working software to stakeholders and users and collect feedback. Finally, conduct a sprint retrospective meeting to reflect on the sprint and identify what went well and what can be improved.
Scrum within a legacy software is no different than Scrum in a greenfield project. When dealing with legacy code it is important to, for the team to engage in disciplined and rigorous engineering practices, like TDD, continuous refactoring and a planned rework of difficult or overly complex pieces of code. Setting up static code analysis and continuous integration as a strong focus on test automation is vital in order to prevent new technical debt from creeping into the code base. Keep in mind that, even and especially with legacy software, it is important to keep it working at all times. So setting up rigorous testing before changing code is advised so that there is immediate feedback whether code changes break existing functionality.
Ideally the team will own the code base in its entirety, from requirement, through development, assurance testing, into production and ownership of reported bugs and incidents. If there are factors or teams performing any functions outside the team think about these dependencies and how collaboration can be achieved. This inspection can be done through product review and retrospectives.
Scrum is not a fixed or rigid process, but a flexible and adaptive one. To improve your Scrum practices and outcomes, you should continuously seek feedback from customers, users, and stakeholders and incorporate it into your product backlog and sprint planning. Experimenting with different techniques, tools, and approaches to solve legacy code challenges is also important. Additionally, learning from other teams and communities that have used Scrum with legacy code can be beneficial. Celebrating achievements and recognizing team efforts helps keep the team motivated, engaged, and empowered to make decisions and solve problems.
Using Scrum is not the aim here, delivering value for the organisation should be the aim. Learn how to measure the impacts over time as a feedback into the planning process. This will breed trust and help the team work even closer with the stakeholders through the Product Owner over time.
Scrum is adaptive process. In case of legacy code, changes are hard to implement due to its old outdated architecture. Implementing small refactoring to legacy code will lead to more manageable agile code in future to work with. Understanding the architecture and taking small steps each sprint will benefit the the product in long run .