Extreme programming (XP) is defined as a software engineering paradigm that uses an Agile-based software development framework to optimize the software development process by creating good quality programs while considering constantly shifting end-user demands. This article explains the fundamentals of extreme programming, its working, and the key values and principles that lay its foundation.
Extreme programming (XP) refers to a software engineering paradigm that uses an Agile-based software development framework to optimize the software development process by creating good quality programs while considering frequently shifting end-user demands. The process focuses on shorter development cycles to enhance overall software productivity and establishes crucial checkpoints while adapting to new customer requirements.
Today’s fast-paced environment uses strong software engineering principles. Traditional software development and project management practices have largely been linear and are no longer viable. This implies that IT professionals need to figure out alternate ways to manage constantly changing development tasks.
Considering these drawbacks of traditional systems, a team of 17 IT specialists proposed Agile project management strategies in 2001 based on incremental development techniques. The principles and values of such a philosophy are summarized in the Agile Manifesto, which emphasizes flexible, fast-paced, and collaborative software development practices. XP is one of the several Agile frameworks used by companies such as Ford Motor Company, Chrysler, and IBM to streamline their software development processes.
The emergence of extreme programming
Software engineer Kent Beck first introduced extreme programming in the 1990s. The XP concept was outlined back then to enable developers to write high-quality software quickly and efficiently by adapting to the changing needs of end users. The methodology reveals engineering practices that allow developers to perform routine tasks beyond their capabilities. That is why the framework is titled ‘extreme’ programming.
Extreme programming seeks the involvement of customers in the development process. Such a practice allows companies to zero in on users’ essential features and minimizes risks by channeling resources in the desired direction. Under extreme programming, customers provide regular feedback on the system. XP also promotes collaborative work, allowing team members to work jointly on one activity or a software project to make it a success and boost productivity.
Extreme programming follows the incremental approach to building products by using continual testing and revision methods. It simplifies development tasks and speeds up the launch of a new product in the market. It makes the coding process efficient and effective, giving customers’ demands importance and value. In short, XP delivers software as and when needed rather than delivering everything simultaneously.
XP shares key Agile principles such as end-user involvement in development tasks, good communication between team members, and iterative development cycles.
Difference between XP and traditional development processes
- XP gives customers, interactions, and user experience more importance than processes and tools
- XP focuses on the significance of working software rather than just documenting everything
- Extreme programming leans toward collaborative work more than traditionally followed policies of contract negotiation
- XP is known for responding to change rather than following a defined plan
All this happens when the entire team comes together to fine-tune their practices to situations at hand based on the constant feedback that enables them to visualize where they stand and what needs to be done to achieve the goal.
Extreme programming was the first Agile software development framework that could overhaul the conventional waterfall model. With XP, there was a significant change in the traditional requirements-gathering process. Also, testing was given the utmost importance when it came to the delivery of the software product. Moreover, XP brought the focus back onto core software engineering practices such as pair programming (the practice of pair programming), test-driven development (reiterative software development technique), refactoring (changing the design of the code without changing the functionality), continuous integration (integrate program code into a shared repository multiple times per day), automated testing, and so on.
The extreme programming framework follows a workflow that involves five iterative development stages. Let’s understand each stage in detail.
Stage I: Planning
Planning defines the first phase of the XP lifecycle. In this stage, customers meet the team of developers and outline their requirements through user stories that reveal the desired result. The team then uses these client requirements to create multiple iterations necessary to achieve the desired functionality on a part-by-part basis. In situations where user stories are challenging to estimate and develop iterations, ‘spikes’ are introduced, which signify the necessity for further research.
Stage II: Designing
Designing is a subpart of the planning phase. It covers one of the principle XP values:’ simplicity’. This implies that a good quality design gives definitive logic and structure to system implementation and reduces unnecessary complexities and redundancies.
Stage III: Coding
Coding is the most critical phase of all the lifecycle stages. Here, code is written by following coding standards that fall under specific XP practices such as pair programming, metaphor, regular integration, refactoring, code review with collective code ownership, and so on.
Stage IV: Testing
The testing phase comes after the coding stage. The development process routinely involves two tests: unit tests and acceptance tests. Unit tests refer to automated testing practices that confirm whether the developed features work as intended. Acceptance tests relate to customer testing, which determines whether the overall system is developed by keeping initial user requirements in mind. The testing phase validates the performance of codes and gives insights into bugs that may arise in specific scenarios.
Stage V: Listening
The listening phase applies to every development stage. It implies maintaining constant communication and feedback with the clients to ensure that their expectations and requirements are always met. Besides listening to client requirements, developers can also input the technical aspects of refining the overall system by altering certain software features.
Frequent communication involves the active participation of customers and project managers, who are vital to defining the business logic and value expected from the software. Thus, listening typically lays the foundation of a new software design.
The development process encompasses the cooperation of several members with specific roles and responsibilities. The following people are actively involved in XP:
- Customers: The XP framework engages customers in the development process. Customers provide user stories and continuous feedback and are vital to making business decisions related to the software project.
- Developers: Developers are a group of individuals that work together to write codes and create a software product. They implement user stories and conduct testing regularly. XP allows collaboration of cross-functional teams; hence, developers’ skill sets can differ based on client requirements.
- Managers: Managers act as a bridge between the end users and developers. They organize meetings, regulate discussions, and check on the product’s progressive KPIs.
- Coaches: Coaches refer to team mentors who draw team members’ attention to top XP practices. They help avoid mistakes in the development process and are generally external assistants or consultants.
Extreme programming uses its own set of principles, values, and practices that have a significant impact on the software development process. Values cover the underlying purpose of the development tasks, while principles entail the abstract behavior that guides participants through the software engineering process. Let’s take a look at the fundamental values and principles that direct XP practices:
XP is based on five fundamental values: communication, simplicity, feedback, courage, and respect. Let’s understand each one in detail:
- Communication: Communication plays an essential role in the development process. Without communication, there’s no flow of information and knowledge. For example, consider a case where the development team encounters a bug or problem while coding. Generally, there’s at least one individual in the group who is aware of how to solve that problem or bug. However, without communication, the team does not learn about the issue and prevents the knowledgeable individual from offering a solution to it. As a result, the problem persists in the development process.
- Simplicity: Simplicity refers to accomplishing tasks in simplistic ways that actually work. Although simplicity is a subjective parameter, the team must not ignore that the most straightforward thing should really ‘work’. Moreover, at the team level, what’s simple for one group may be complex for the other. It all depends on different teams’ knowledge, skills, and experience.
- Feedback: Feedback goes back to the traditional waterfall model. However, XP is more about adapting to change based on early and constant feedback. If the need arises, the team can course-correct the development process quickly.
Feedback falls under various types. For example, feedback from your peers while you code can be vital in pair programming. Similarly, the opinions of other team members, including end users, are also crucial.
Tests can also provide the necessary feedback about the system being developed. For example, the system design is probably complex if the tests are difficult to write. One can thereby simplify the design considering the test results. Sometimes, the finished code for a deployed product also acts as a good source of feedback.
One must also bear in mind that too much feedback can derail development tasks. For example, suppose the team receives more feedback than it can handle. In that case, it can be detrimental to the entire development process as it can take the unit off track from accomplishing the overall objective. Hence, it is necessary to ensure that there are limited feedback sources and one can eliminate a few of them, so that excess feedback is avoided.
- Courage: Courage is more about taking action while tackling fearful situations. It is essential to be courageous while being a part of the XP’s development team. Giving and receiving honest feedback is necessary. Also, accepting that the solution provided to a problem or bug that received substantial investments is a failure is equally required. Thus, with courage, the development process becomes easier as you take the current issues head-on and tackle them as needed, simplifying the overall situation.
- Respect: Respecting peers, customers, the project, and future users is the fundamental premise of XP. Without mutual respect, even above-par technical expertise cannot save the development project from failing. Everyone gains in the XP cycle with care and respect for each other.
Principles guide individuals in specific ways that make the values more transparent and less ambiguous. They throw light onto values that are a ticket to success. For example, the value of courage may say it is better to tackle big problems in a program at once. However, the principle of ‘Baby Steps’ says that more significant changes can be risky, so handling problems in tiny steps is a feasible option. Here, the principle of baby steps illuminates the value of courage but makes it less complex and easier to understand. Let’s understand some of the vital XP principles in detail:
- Humanity: Software products are created for humans. Hence, it is essential to design products considering human needs, strengths, and weaknesses so that the products are put to use. Extreme programming has this principle in hindsight while developing any software.
- Economics: Development teams following XP practices are always mindful of the economic realities of software development. They tend to analyze current situations to determine the financial risks and needs of the project, so that system implementation is undertaken based on business value rather than technical know-how.
- Mutual benefit: XP uses the principle of mutual benefit that dwells on the fact that all activities you do should benefit all team members, i.e., current and future team members. For example, writing automated acceptance tests does not just help present design features to existing team members but also enables new members to understand the system.
- Self-similarity: The self-similarity principle says that sometimes copying a solution from a similar problem is feasible as it saves the developer’s time and effort. However, the problem’s context should be considered as the solution for a different contextual problem may not work for the current situation.
- Diversity: The XP environment can benefit from a diverse workforce. With people and coworkers having different mindsets, perspectives, attitudes, and skills, there’s an opportunity for better ideas to surface that help the development cause. Values of courage and respect can help this diverse culture thrive, and the team can perform well with effective communication.
- Reflection: The principle of reflection is more about analyzing your work and determining how to improve it. XP provides weekly and quarterly cycles to optimize development tasks by considering the results of previous cycles.
- Flow: Traditional software development practices had discrete stages, which had fewer feedback sources and course-correction opportunities, and took a long time to progress. However, under the XP framework, software development unfolds in activities and there is a consistent ‘flow’ between consecutive events.
- Opportunity: Software development is all about tackling more and more problems. However, each situation allows you to improve and explore. This way, you can look for more solutions that are intimately aligned with your goals, and at the same time, are creative. It can also help in creating solutions that prevent the problems from reoccurring.
- Redundancy: According to the redundancy principle, when encountering a critical problem, it is better to employ multiple tactics to fight it. For example, if we consider the defects aspect, there is not one wholesome tactic that can guarantee that the end products will be free of all defects. With XP, you can use quality measures such as pair programming, continuous integration, tests, and so on to create a line of defense that can handle any severe problem throughout various development phases.
- Failure: Failure is part and parcel of any human activity. It results in substantial knowledge gain. Hence, it is vital to learn and act quickly from failure to decide what works and doesn’t work for your tasks.
- Quality: This principle aims at ‘quality improvements’ to enhance the overall speed of the development product. For example, refactoring refers to altering the code structure without impacting its functionality. This implies that the code is modified in a way that makes it easier to understand and update, resulting in fewer code defects. As such, you can deliver more value faster as the need to fix bugs is eliminated considerably.
- Baby steps: As observed in traditional development cycles, significant changes can be risky. However, changes are introduced in tiny steps at different levels under XP. For example, developers write code in steps using test-driven development (TDD) and integrate it with the mainline multiple times in a day rather than in weeks or months. Thus, XP allows for short development cycles rather than long phases.
- Accepted responsibility: Under the XP framework, responsibility is accepted and not assigned. Responsibility gives you the authority to make vital decisions for matters associated with your role.
Extreme programming is a controlled software development process that is based on the principles of courage, respect, communication, and simplicity. XP is a popular Agile-based development methodology that is lightweight and relies on constant consumer feedback. As the XP framework has shorter development cycles, developers write and rewrite the code of XP projects, allowing clients to witness the system evolve and see subsequent growth in their business value.
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