Extreme Programming vs. Scrum

Attribute	Extreme Programming	Scrum
Development Methodology	Agile	Agile
Primary Focus	Software Engineering Practices	Project Management
Team Size	Small to Medium	Small to Large
Roles	Programmer, Customer, Tester, Tracker, Coach	Product Owner, Scrum Master, Development Team
Iterations	Short iterations (1-2 weeks)	Sprints (2-4 weeks)
Planning	Continuous Planning	Sprint Planning
Requirements	Flexible and Embrace Change	Fixed for the Sprint
Documentation	Minimal Documentation	Documentation as needed
Testing	Test-Driven Development (TDD)	Testing throughout the Sprint
Meetings	Stand-up Meetings, Planning Meetings, Retrospectives	Daily Scrum, Sprint Planning, Sprint Review, Sprint Retrospective

Introduction

When it comes to agile software development methodologies, Extreme Programming (XP) and Scrum are two popular choices. Both methodologies aim to improve the efficiency and effectiveness of software development teams, but they have different approaches and emphasize different aspects of the development process. In this article, we will compare the attributes of Extreme Programming and Scrum, highlighting their similarities and differences.

Team Structure

In Extreme Programming, the team is typically small and cross-functional, consisting of developers, testers, and customers. The team works closely together, with constant communication and collaboration. The team is self-organizing and responsible for making decisions collectively. On the other hand, Scrum teams are also cross-functional but are usually larger than XP teams. Scrum teams have defined roles, including a Scrum Master, Product Owner, and Development Team. The Scrum Master facilitates the process, while the Product Owner represents the customer and sets the priorities. The Development Team is responsible for delivering the product increment.

Iterative and Incremental Development

Both Extreme Programming and Scrum follow an iterative and incremental development approach. In Extreme Programming, the development is divided into short iterations called "sprints," typically lasting one to two weeks. Each sprint delivers a potentially shippable product increment. The team continuously integrates and tests the code, ensuring high-quality deliverables. Similarly, Scrum also follows the iterative approach with sprints, but the duration is usually longer, ranging from two to four weeks. Each sprint in Scrum aims to deliver a potentially releasable product increment, and the team conducts a sprint review at the end of each iteration to gather feedback.

Requirements and Planning

Extreme Programming focuses on frequent and continuous customer involvement. The customer is an integral part of the team and provides feedback throughout the development process. Requirements are captured as user stories and are prioritized by the customer. The team estimates the effort required for each user story and plans the iterations accordingly. In contrast, Scrum relies on a Product Owner to define and prioritize the product backlog. The Product Owner collaborates with the team to refine and estimate the user stories. The team then plans the sprint backlog based on the prioritized items from the product backlog.

Emphasis on Testing

Both Extreme Programming and Scrum emphasize the importance of testing in the development process. In Extreme Programming, testing is an integral part of the development cycle, and the team follows Test-Driven Development (TDD) practices. Developers write tests before writing the actual code, ensuring that the code meets the specified requirements. The team also conducts frequent and automated tests to catch any regressions. Similarly, Scrum teams also focus on testing, but the approach may vary. Some Scrum teams adopt TDD practices, while others emphasize manual and exploratory testing. The goal is to ensure the quality of the product increment and identify any defects early in the development process.

Communication and Collaboration

Both methodologies emphasize the importance of communication and collaboration within the team. In Extreme Programming, the team practices pair programming, where two developers work together on the same code. This promotes knowledge sharing, code review, and reduces the chances of errors. The team also holds daily stand-up meetings to discuss progress, challenges, and plan the day. Similarly, Scrum teams also have daily stand-up meetings, where each team member provides updates on their work. Scrum teams also conduct sprint planning meetings, sprint reviews, and retrospectives to ensure effective communication and collaboration.

Flexibility and Adaptability

Extreme Programming and Scrum both embrace flexibility and adaptability in the development process. Extreme Programming encourages embracing change and welcomes new requirements even late in the development cycle. The team continuously refactors the code to accommodate changes and ensures that the software remains flexible and maintainable. Scrum also allows for changes, but they are typically managed through the product backlog. The Product Owner can reprioritize the backlog based on changing requirements, and the team adapts the sprint backlog accordingly. Both methodologies aim to deliver value to the customer by responding to changes effectively.

Conclusion

Extreme Programming and Scrum are both popular agile methodologies that offer different approaches to software development. Extreme Programming focuses on close collaboration, continuous customer involvement, and emphasizes practices like TDD and pair programming. On the other hand, Scrum provides a structured framework with defined roles and ceremonies, allowing for effective planning and prioritization. Both methodologies promote iterative and incremental development, testing, and emphasize the importance of communication and collaboration within the team. The choice between Extreme Programming and Scrum depends on the specific needs and preferences of the development team and the project at hand.