• Useful Resources
  • Selected Reading

Posts about Extreme Programming written by swengineer. Timing is Everything. Product Management delivering complete specifications in a timely fashion greatly improves the productivity of the Engineering team (Complete being relative the type of specifications – as we discussed in the previous blog). What is “eXtreme Programming”? EXtreme Programming (XP) is a software development process as well as a methodology. A (software development) process defines who is doing what when and how. This means, it provides principles, techniques and practices for the efficient, predictable and repeatable production of software systems. Extreme Programming (XP) is an agile software development framework that aims to produce higher quality software, and higher quality of life for the development team. XP is the most specific of the agile frameworks regarding appropriate engineering practices for software development.

  • Extreme Programming (XP) is an intense, disciplined and agile software development methodology focusing on coding within each software development life cycle (SDLC) stage. These stages are: Continuous integration to discover and repair problems early in the development process Customer involvement and rapid feedback These XP methodology.
  • Extreme programming (XP) is a software development methodology which is intended to improve software quality and responsiveness to changing customer requirements. As a type of agile software development, it advocates frequent 'releases' in short development cycles, which is intended to improve productivity and introduce checkpoints at which new customer requirements can be adopted.

This chapter gives an overview of Extreme Programming.

What is Agile?

The word ‘agile’ means −

  • Able to move your body quickly and easily.

  • Able to think quickly and clearly.

In business, ‘agile’ is used for describing ways of planning and doing work wherein it is understood that making changes as needed is an important part of the job. Business‘agililty’ means that a company is always in a position to take account of the market changes.

Ref: Cambridge Dictionaries online.

In software development, the term ‘agile’ is adapted to mean ‘the ability to respond to changes − changes from Requirements, Technology and People.’

Agile Manifesto

A team of software developers published the Agile Manifesto in 2001, highlighting the importance of the development team, accommodating changing requirements and customer involvement.

The Agile Manifesto states that −

We are uncovering better ways of developing software by doing it and helping others do it. Through this work, we have come to value −

  • Individuals and interactions over processes and tools.

  • Working software over comprehensive documentation.

  • Customer collaboration over contract negotiation.

  • Responding to change over following a plan.

That is, while there is value in the items on the right, we value the items on the left more.

Characteristics of Agility

Following are the characteristics of Agility −

  • Agility in Agile Software Development focuses on the culture of the whole team with multi-discipline, cross-functional teams that are empowered and selforganizing.

  • It fosters shared responsibility and accountability.

  • Facilitates effective communication and continuous collaboration.

  • The whole-team approach avoids delays and wait times.

  • Frequent and continuous deliveries ensure quick feedback that in in turn enable the team align to the requirements.

  • Collaboration facilitates combining different perspectives timely in implementation, defect fixes and accommodating changes.

  • Progress is constant, sustainable, and predictable emphasizing transparency.

Software Engineering Trends

The following trends are observed in software engineering −

  • Gather requirements before development starts. However, if the requirements are to be changed later, then following is usually noticed −

    • Resistance to the changes at a later stage of development.

    • There is a requirement of a rigorous change process that involves a change control board that may even push the changes to later releases.

    • The delivery of a product with obsolete requirements, not meeting the customer’s expectations.

      The Windows Phone SDK Update for Windows Phone 7.8 adds two new emulator images to your existing Windows Phone SDK installation. This update supports both the Windows Phone SDK 7.1 and the Windows Phone SDK 8.0. Using this update, you can provide the Windows Phone 8 Start screen experience in your Windows Phone 7.5 apps. Windows phone 7 apps download.

    • Inability to accommodate the inevitable domain changes and technology changes within the budget.

  • Find and eliminate defects early in the development life cycle in order to cut the defect-fix costs.

    • Testing starts only after coding is complete and testing is considered as a tester’s responsibility though the tester is not involved in development.

    • Measure and track the process itself. This becomes expensive because of −

    • Monitoring and tracking at the task level and at the resource level.

    • Defining measurements to guide the development and measuring every activity in the development.

    • Management intervention.

  • Elaborate, analyze, and verify the models before development.

    • A model is supposed to be used as a framework. However, focus on the model and not on the development that is crucial will not yield the expected results.

  • Coding, which is the heart of development is not given enough emphasis. The reasons being −

    • Developers, who are responsible for the production, are usually not in constant communication with the customers.

    • Coding is viewed as a translation of design and the effective implementation in code is hardly ever looped back into the design.

  • Testing is considered to be the gateway to check for defects before delivery.

    • Schedule overruns of the earlier stages of development are compensated by overlooking the test requirements to ensure timely deliveries.

    • This results in cost overruns fixing defects after delivery.

    • Testers are made responsible and accountable for the product quality though they were not involved during the entire course of development.

  • Limiting resources (mainly team) to accommodate budget leads to −

    • Resource over allocation

    • Team burnout.

    • Loss in effective utilization of team competencies.

    • Attrition.

Extreme Programming − A way to handle the common shortcomings

Software Engineering involves −

  • Creativity

  • Learning and improving through trials and errors

  • Iterations

Extreme Programming builds on these activities and coding. It is the detailed (not the only) design activity with multiple tight feedback loops through effective implementation, testing and refactoring continuously.

Extreme Programming is based on the following values −

  • Communication

  • Simplicity

  • Feedback

  • Courage

  • Respect

What is Extreme Programming?

XP is a lightweight, efficient, low-risk, flexible, predictable, scientific, and fun way to develop a software.

eXtreme Programming (XP) was conceived and developed to address the specific needs of software development by small teams in the face of vague and changing requirements.

ICC profiles provide a way to ensure consistent color across all your devices. Paper texture and brightness also affect—and change—a printed image. Printed images don't have the same range, saturation, and contrast as a monitor, which makes the colors typically darker and less vibrant than on screen. Hp printer monitor software.

Extreme Programming is one of the Agile software development methodologies. It provides values and principles to guide the team behavior. The team is expected to self-organize. Extreme Programming provides specific core practices where −

  • Each practice is simple and self-complete.

    Selenium ide tutorial pdf. Aug 20, 2019  Selenium is a free (open source) automated testing suite for web applications across different browsers and platforms. Key Highlights of Selenium Tutorial PDF are 1000+ pages. Selenium Tutorial in PDF - This wonderful tutorial and its PDF is available free of cost. However you can help us serve more readers by making a small contribution. Selenium IDE Selenium Integrated Development Environment (IDE) is a Firefox plugin that lets testers to record their actions as they follow the workflow that they need to test. Selenium RC Selenium Remote Control (RC) was the flagship testing framework that allowed. Selenium IDE The root of web application you want to test The list of actions in the actual test case to execute The log of the events that were executed, including any errors or warning that may have occurred. Sep 21, 2019  Selenium is a free open source testing tool which caters different testing needs. This tutorial cover Selenium webdriver, IDE, TesNG. Following course will make you Selenium pro. Tutorials are designed for beginners with little or no automation experience.

  • Combination of practices produces more complex and emergent behavior.

Embrace Change

A key assumption of Extreme Programming is that the cost of changing a program can be held mostly constant over time.

This can be achieved with −

  • Emphasis on continuous feedback from the customer

  • Short iterations

  • Design and redesign

  • Coding and testing frequently

  • Eliminating defects early, thus reducing costs

  • Keeping the customer involved throughout the development

  • Delivering working product to the customer

Extreme Programming in a Nutshell

Extreme Programming involves −

  • Writing unit tests before programming and keeping all of the tests running at all times. The unit tests are automated and eliminates defects early, thus reducing the costs.

  • Starting with a simple design just enough to code the features at hand and redesigning when required.

  • Programming in pairs (called pair programming), with two programmers at one screen, taking turns to use the keyboard. While one of them is at the keyboard, the other constantly reviews and provides inputs.

  • Integrating and testing the whole system several times a day.

  • Putting a minimal working system into the production quickly and upgrading it whenever required.

  • Keeping the customer involved all the time and obtaining constant feedback.

Iterating facilitates the accommodating changes as the software evolves with the changing requirements.

Why is it called “Extreme?”

Extreme Programming takes the effective principles and practices to extreme levels.

  • Code reviews are effective as the code is reviewed all the time.

  • Testing is effective as there is continuous regression and testing.

  • Design is effective as everybody needs to do refactoring daily.

  • Integration testing is important as integrate and test several times a day.

  • Short iterations are effective as the planning game for release planning and iteration planning.

History of Extreme Programming

Kent Beck, Ward Cunningham and Ron Jeffries formulated extreme Programming in 1999. The other contributors are Robert Martin and Martin Fowler.

In Mid-80s, Kent Beck and Ward Cunningham initiated Pair Programming at Tektronix. In the 80s and 90s, Smalltalk Culture produced Refactoring, Continuous Integration, constant testing, and close customer involvement. This culture was later generalized to the other environments.

In the Early 90s, Core Values were developed within the Patterns Community, Hillside Group. In 1995, Kent summarized these in Smalltalk Best Practices, and in 1996, Ward summarized it in episodes.

In 1996, Kent added unit testing and metaphor at Hewitt. In 1996, Kent had taken the Chrysler C3 project, to which Ron Jeffries was added as a coach. The practices were refined on C3 and published on Wiki.

Scrum practices were incorporated and adapted as the planning game. In 1999, Kent published his book, ‘Extreme Programming Explained’. In the same year, Fowler published his book, Refactoring.

Extreme Programming has been evolving since then, and the evolution continues through today.

Success in Industry

The success of projects, which follow Extreme Programming practices, is due to −

  • Rapid development.

  • Immediate responsiveness to the customer’s changing requirements.

  • Focus on low defect rates.

  • System returning constant and consistent value to the customer.

  • High customer satisfaction.

  • Reduced costs.

  • Team cohesion and employee satisfaction.

Extreme Programming Advantages

Extreme Programming solves the following problems often faced in the software development projects −

  • Slipped schedules − and achievable development cycles ensure timely deliveries.

  • Cancelled projects − Focus on continuous customer involvement ensures transparency with the customer and immediate resolution of any issues.

  • Costs incurred in changes − Extensive and ongoing testing makes sure the changes do not break the existing functionality. Is playon free. A running working system always ensures sufficient time for accommodating changes such that the current operations are not affected.

  • Production and post-delivery defects: Emphasis is on − the unit tests to detect and fix the defects early.

  • Misunderstanding the business and/or domain − Making the customer a part of the team ensures constant communication and clarifications.

  • Business changes − Changes are considered to be inevitable and are accommodated at any point of time.

  • Staff turnover − Intensive team collaboration ensures enthusiasm and good will. Cohesion of multi-disciplines fosters the team spirit.

(Redirected from Extreme Programming)
Planning and feedback loops in extreme programming
Software development
Core activities
Paradigms and models
Methodologies and frameworks
Supporting disciplines
Practices
Tools
Standards and Bodies of Knowledge
Glossaries

Extreme programming (XP) is a software development methodology which is intended to improve software quality and responsiveness to changing customer requirements. As a type of agile software development,[1][2][3] it advocates frequent 'releases' in short development cycles, which is intended to improve productivity and introduce checkpoints at which new customer requirements can be adopted.

Other elements of extreme programming include: programming in pairs or doing extensive code review, unit testing of all code, avoiding programming of features until they are actually needed, a flat management structure, code simplicity and clarity, expecting changes in the customer's requirements as time passes and the problem is better understood, and frequent communication with the customer and among programmers.[2][3][4] The methodology takes its name from the idea that the beneficial elements of traditional software engineering practices are taken to 'extreme' levels. As an example, code reviews are considered a beneficial practice; taken to the extreme, code can be reviewed continuously, i.e. the practice of pair programming.

  • 1History
  • 2Concept
    • 2.2Activities
    • 2.3Values
    • 2.5Principles
  • 3Practices
  • 4Controversial aspects

History[edit]

Kent Beck developed extreme programming during his work on the Chrysler Comprehensive Compensation System (C3) payroll project.[5] Beck became the C3 project leader in March 1996. He began to refine the development methodology used in the project and wrote a book on the methodology (Extreme Programming Explained, published in October 1999).[5]Chrysler cancelled the C3 project in February 2000, after seven years, when Daimler-Benz acquired the company.[6]

Many extreme-programming practices have been around for some time; the methodology takes 'best practices' to extreme levels. For example, the 'practice of test-first development, planning and writing tests before each micro-increment' was used as early as NASA's Project Mercury, in the early 1960s.[7] To shorten the total development time, some formal test documents (such as for acceptance testing) have been developed in parallel with (or shortly before) the software being ready for testing. A NASA independent test group can write the test procedures, based on formal requirements and logical limits, before programmers write the software and integrate it with the hardware. XP takes this concept to the extreme level, writing automated tests (sometimes inside software modules) which validate the operation of even small sections of software coding, rather than only testing the larger features.

Origins[edit]

Two major influences shaped software development in the 1990s:

  • Internally, object-oriented programming replaced procedural programming as the programming paradigm favored by some developers.
  • Externally, the rise of the Internet and the dot-com boom emphasized speed-to-market and company growth as competitive business factors.

Rapidly changing requirements demanded shorter product life-cycles, and often clashed with traditional methods of software development.

The Chrysler Comprehensive Compensation System (C3) started in order to determine the best way to use object technologies, using the payroll systems at Chrysler as the object of research, with Smalltalk as the language and GemStone as the data access layer. Chrysler brought in Kent Beck,[5] a prominent Smalltalk practitioner, to do performance tuning on the system, but his role expanded as he noted several problems with the development process. He took this opportunity to propose and implement some changes in development practices - based on his work with his frequent collaborator, Ward Cunningham. Beck describes the early conception of the methods:[8]

The first time I was asked to lead a team, I asked them to do a little bit of the things I thought were sensible, like testing and reviews. The second time there was a lot more on the line. I thought, 'Damn the torpedoes, at least this will make a good article,' [and] asked the team to crank up all the knobs to 10 on the things I thought were essential and leave out everything else.

Beck invited Ron Jeffries to the project to help develop and refine these methods. Jeffries thereafter acted as a coach to instill the practices as habits in the C3 team.

Information about the principles and practices behind XP disseminated to the wider world through discussions on the original wiki, Cunningham's WikiWikiWeb. Various contributors discussed and expanded upon the ideas, and some spin-off methodologies resulted (see agile software development). Also, XP concepts have been explained[by whom?], for several years, using a hypertext system map on the XP website at http://www.extremeprogramming.org circa 1999.

Beck edited a series of books on XP, beginning with his own Extreme Programming Explained (1999, ISBN0-201-61641-6), spreading his ideas to a much larger audience. Authors in the series went through various aspects attending XP and its practices. The series included a book critical of the practices.

Current state[edit]

XP generated significant interest among software communities in the late 1990s and early 2000s, seeing adoption in a number of environments radically different from its origins.

The high discipline required by the original practices often went by the wayside, causing some of these practices, such as those thought too rigid, to be deprecated or reduced, or even left unfinished, on individual sites. For example, the practice of end-of-day integration tests for a particular project could be changed to an end-of-week schedule, or simply reduced to testing on mutually agreed dates. Such a more relaxed schedule could avoid people feeling rushed to generate artificial stubs just to pass the end-of-day testing. A less-rigid schedule allows, instead, the development of complex features over a period of several days.

Meanwhile, other agile-development practices have not stood still, and as of 2019 XP continues to evolve, assimilating more lessons from experiences in the field, to use other practices. In the second edition of Extreme Programming Explained (November 2004), five years after the first edition, Beck added more values and practices and differentiated between primary and corollary practices.

The Theory of Sustainable Software Development explains why extreme programming teams can thrive in spite of team disruptions.[9][non-primary source needed]

Concept[edit]

Goals[edit]

Extreme Programming Explained describes extreme programming as a software-development discipline that organizes people to produce higher-quality software more productively.

XP attempts to reduce the cost of changes in requirements by having multiple short development cycles, rather than a long one.In this doctrine, changes are a natural, inescapable and desirable aspect of software-development projects, and should be planned for, instead of attempting to define a stable set of requirements.

Extreme programming also introduces a number of basic values, principles and practices on top of the agile programming framework.

Activities[edit]

XP describes four basic activities that are performed within the software development process: coding, testing, listening, and designing. Each of those activities is described below.

Coding[edit]

The advocates of XP argue that the only truly important product of the system development process is code – software instructions that a computer can interpret. Without code, there is no working product.

Coding can be used to figure out the most suitable solution. Coding can also help to communicate thoughts about programming problems. A programmer dealing with a complex programming problem, or finding it hard to explain the solution to fellow programmers, might code it in a simplified manner and use the code to demonstrate what he or she means. Code, say the proponents of this position, is always clear and concise and cannot be interpreted in more than one way. Other programmers can give feedback on this code by also coding their thoughts.

Testing[edit]

Testing is central to extreme programming.[10] Extreme programming's approach is that if a little testing can eliminate a few flaws, a lot of testing can eliminate many more flaws.

  • Unit tests determine whether a given feature works as intended. Programmers write as many automated tests as they can think of that might 'break' the code; if all tests run successfully, then the coding is complete. Every piece of code that is written is tested before moving on to the next feature.
  • Acceptance tests verify that the requirements as understood by the programmers satisfy the customer's actual requirements.

System-wide integration testing was encouraged, initially, as a daily end-of-day activity, for early detection of incompatible interfaces, to reconnect before the separate sections diverged widely from coherent functionality. However, system-wide integration testing has been reduced, to weekly, or less often, depending on the stability of the overall interfaces in the system.[citation needed]

Listening[edit]

Programmers must listen to what the customers need the system to do, what 'business logic' is needed. They must understand these needs well enough to give the customer feedback about the technical aspects of how the problem might be solved, or cannot be solved. Communication between the customer and programmer is further addressed in the planning game.

Designing[edit]

Extreme Programming And Agile Processes In Software Engineering

From the point of view of simplicity, of course one could say that system development doesn't need more than coding, testing and listening. If those activities are performed well, the result should always be a system that works. In practice, this will not work. One can come a long way without designing but at a given time one will get stuck. The system becomes too complex and the dependencies within the system cease to be clear. One can avoid this by creating a design structure that organizes the logic in the system. Good design will avoid lots of dependencies within a system; this means that changing one part of the system will not affect other parts of the system.[citation needed]

Values[edit]

Extreme programming initially recognized four values in 1999: communication, simplicity, feedback, and courage. A new value, respect, was added in the second edition of Extreme Programming Explained. Those five values are described below.

Communication[edit]

Building software systems requires communicating system requirements to the developers of the system. In formal software development methodologies, this task is accomplished through documentation. Extreme programming techniques can be viewed as methods for rapidly building and disseminating institutional knowledge among members of a development team. The goal is to give all developers a shared view of the system which matches the view held by the users of the system. To this end, extreme programming favors simple designs, common metaphors, collaboration of users and programmers, frequent verbal communication, and feedback.

Simplicity[edit]

Software

Extreme programming encourages starting with the simplest solution. Extra functionality can then be added later. The difference between this approach and more conventional system development methods is the focus on designing and coding for the needs of today instead of those of tomorrow, next week, or next month. This is sometimes summed up as the 'You aren't gonna need it' (YAGNI) approach.[11] Proponents of XP acknowledge the disadvantage that this can sometimes entail more effort tomorrow to change the system; their claim is that this is more than compensated for by the advantage of not investing in possible future requirements that might change before they become relevant. Coding and designing for uncertain future requirements implies the risk of spending resources on something that might not be needed, while perhaps delaying crucial features. Related to the 'communication' value, simplicity in design and coding should improve the quality of communication. A simple design with very simple code could be easily understood by most programmers in the team. Sims 4.

Feedback[edit]

Within extreme programming, feedback relates to different dimensions of the system development:

  • Feedback from the system: by writing unit tests,[5] or running periodic integration tests, the programmers have direct feedback from the state of the system after implementing changes.
  • Feedback from the customer: The functional tests (aka acceptance tests) are written by the customer and the testers. They will get concrete feedback about the current state of their system. This review is planned once in every two or three weeks so the customer can easily steer the development.
  • Feedback from the team: When customers come up with new requirements in the planning game the team directly gives an estimation of the time that it will take to implement.

Feedback is closely related to communication and simplicity. Flaws in the system are easily communicated by writing a unit test that proves a certain piece of code will break. The direct feedback from the system tells programmers to recode this part. A customer is able to test the system periodically according to the functional requirements, known as user stories.[5] To quote Kent Beck, 'Optimism is an occupational hazard of programming. Feedback is the treatment.'[12]

Courage[edit]

Several practices embody courage. One is the commandment to always design and code for today and not for tomorrow. This is an effort to avoid getting bogged down in design and requiring a lot of effort to implement anything else. Courage enables developers to feel comfortable with refactoring their code when necessary.[5] This means reviewing the existing system and modifying it so that future changes can be implemented more easily. Another example of courage is knowing when to throw code away: courage to remove source code that is obsolete, no matter how much effort was used to create that source code. Also, courage means persistence: a programmer might be stuck on a complex problem for an entire day, then solve the problem quickly the next day, but only if they are persistent.

Respect[edit]

The respect value includes respect for others as well as self-respect. Programmers should never commit changes that break compilation, that make existing unit-tests fail, or that otherwise delay the work of their peers. Members respect their own work by always striving for high quality and seeking for the best design for the solution at hand through refactoring.

Adopting the four earlier values leads to respect gained from others in the team. Nobody on the team should feel unappreciated or ignored. This ensures a high level of motivation and encourages loyalty toward the team and toward the goal of the project. This value is dependent upon the other values, and is oriented toward teamwork.

Rules[edit]

The first version of rules for XP was published in 1999 by Don Wells[13] at the XP website. 29 rules are given in the categories of planning, managing, designing, coding, and testing. Planning, managing and designing are called out explicitly to counter claims that XP doesn't support those activities.

Another version of XP rules was proposed by Ken Auer[14] in XP/Agile Universe 2003. He felt XP was defined by its rules, not its practices (which are subject to more variation and ambiguity). He defined two categories: 'Rules of Engagement' which dictate the environment in which software development can take place effectively, and 'Rules of Play' which define the minute-by-minute activities and rules within the framework of the Rules of Engagement.

Here are some of the rules (incomplete):

Coding

  • The customer is always available
  • Code the unit test first
  • Only one pair integrates code at a time
  • Leave optimization until last
  • No overtime

Testing

  • All code must have unit tests
  • All code must pass all unit tests before it can be released.
  • When a bug is found, tests are created before the bug is addressed (a bug is not an error in logic; it is a test that was not written)
  • Acceptance tests are run often and the results are published

Extreme Programming In Software Engineering In Hindi

Principles[edit]

The principles that form the basis of XP are based on the values just described and are intended to foster decisions in a system development project. The principles are intended to be more concrete than the values and more easily translated to guidance in a practical situation.

Feedback[edit]

Extreme programming sees feedback as most useful if it is done frequently and promptly. It stresses that minimal delay between an action and its feedback is critical to learning and making changes. Unlike traditional system development methods, contact with the customer occurs in more frequent iterations. The customer has clear insight into the system that is being developed, and can give feedback and steer the development as needed. With frequent feedback from the customer, a mistaken design decision made by the developer will be noticed and corrected quickly, before the developer spends much time implementing it.

Unit tests contribute to the rapid feedback principle. When writing code, running the unit test provides direct feedback as to how the system reacts to the changes made. This includes running not only the unit tests that test the developer's code, but running in addition all unit tests against all the software, using an automated process that can be initiated by a single command. That way, if the developer's changes cause a failure in some other portion of the system that the developer knows little or nothing about, the automated all-unit-test suite will reveal the failure immediately, alerting the developer of the incompatibility of their change with other parts of the system, and the necessity of removing or modifying their change. Under traditional development practices, the absence of an automated, comprehensive unit-test suite meant that such a code change, assumed harmless by the developer, would have been left in place, appearing only during integration testing – or worse, only in production; and determining which code change caused the problem, among all the changes made by all the developers during the weeks or even months previous to integration testing, was a formidable task.

Assuming simplicity[edit]

This is about treating every problem as if its solution were 'extremely simple'. Traditional system development methods say to plan for the future and to code for reusability. Extreme programming rejects these ideas.

The advocates of extreme programming say that making big changes all at once does not work. Extreme programming applies incremental changes: for example, a system might have small releases every three weeks. When many little steps are made, the customer has more control over the development process and the system that is being developed.

Embracing change[edit]

The principle of embracing change is about not working against changes but embracing them. For instance, if at one of the iterative meetings it appears that the customer's requirements have changed dramatically, programmers are to embrace this and plan the new requirements for the next iteration.

Practices[edit]

Extreme programming has been described as having 12 practices, grouped into four areas:

Fine-scale feedback[edit]

  • Pair programming[5]
  • Whole team

Continuous process[edit]

  • Refactoring or design improvement[5]

Shared understanding[edit]

  • Collective code ownership[5]
  • Simple design[5]

Programmer welfare[edit]

Controversial aspects[edit]

The practices in XP have been heavily debated.[5] Proponents of extreme programming claim that by having the on-site customer[5] request changes informally, the process becomes flexible, and saves the cost of formal overhead. Critics of XP claim this can lead to costly rework and project scope creep beyond what was previously agreed or funded.

Change-control boards are a sign that there are potential conflicts in project objectives and constraints between multiple users. XP's expedited methods are somewhat dependent on programmers being able to assume a unified client viewpoint so the programmer can concentrate on coding, rather than documentation of compromise objectives and constraints.[15] This also applies when multiple programming organizations are involved, particularly organizations which compete for shares of projects.[citation needed]

Other potentially controversial aspects of extreme programming include:

  • Requirements are expressed as automated acceptance tests rather than specification documents.
  • Requirements are defined incrementally, rather than trying to get them all in advance.
  • Software developers are usually required to work in pairs.
  • There is no Big Design Up Front. Most of the design activity takes place on the fly and incrementally, starting with 'the simplest thing that could possibly work' and adding complexity only when it's required by failing tests. Critics compare this to 'debugging a system into appearance' and fear this will result in more re-design effort than only re-designing when requirements change.
  • A customer representative is attached to the project. This role can become a single-point-of-failure for the project, and some people have found it to be a source of stress. Also, there is the danger of micro-management by a non-technical representative trying to dictate the use of technical software features and architecture.
  • Dependence upon all other aspects of XP: 'XP is like a ring of poisonous snakes, daisy-chained together. All it takes is for one of them to wriggle loose, and you've got a very angry, poisonous snake heading your way.'[16]

Critics have noted several potential drawbacks,[5] including problems with unstable requirements, no documented compromises of user conflicts, and a lack of an overall design specification or document.

Scalability[edit]

ThoughtWorks has claimed reasonable success on distributed XP projects with up to sixty people.[citation needed]

Engineering

In 2004, industrial extreme programming (IXP)[17] was introduced as an evolution of XP. It is intended to bring the ability to work in large and distributed teams. It now has 23 practices and flexible values.

Severability and responses[edit]

In 2003, Matt Stephens and Doug Rosenberg published Extreme Programming Refactored: The Case Against XP, which questioned the value of the XP process and suggested ways in which it could be improved.[6] This triggered a lengthy debate in articles, Internet newsgroups, and web-site chat areas. The core argument of the book is that XP's practices are interdependent but that few practical organizations are willing/able to adopt all the practices; therefore the entire process fails. The book also makes other criticisms, and it draws a likeness of XP's 'collective ownership' model to socialism in a negative manner.

Certain aspects of XP have changed since the publication of Extreme Programming Refactored; in particular, XP now accommodates modifications to the practices as long as the required objectives are still met. XP also uses increasingly generic terms for processes. Some argue that these changes invalidate previous criticisms; others claim that this is simply watering the process down.

Other authors have tried to reconcile XP with the older methodologies in order to form a unified methodology. Some of these XP sought to replace, such as the waterfall methodology; example: Project Lifecycles: Waterfall, Rapid Application Development (RAD), and All That. JPMorgan Chase & Co. tried combining XP with the computer programming methods of capability maturity model integration (CMMI), and Six Sigma. They found that the three systems reinforced each other well, leading to better development, and did not mutually contradict.[18]

Criticism[edit]

Extreme programming's initial buzz and controversial tenets, such as pair programming and continuous design, have attracted particular criticisms, such as the ones coming from McBreen[19] and Boehm and Turner,[20] Matt Stephens and Doug Rosenberg.[21] Many of the criticisms, however, are believed by Agile practitioners to be misunderstandings of agile development.[22]

In particular, extreme programming has been reviewed and critiqued by Matt Stephens's and Doug Rosenberg's Extreme Programming Refactored.[6]

Criticisms include:

  • a methodology is only as effective as the people involved, Agile does not solve this[citation needed]
  • often used as a means to bleed money from customers through lack of defining a deliverable product[citation needed]
  • lack of structure and necessary documentation[citation needed]
  • only works with senior-level developers[citation needed]
  • incorporates insufficient software design[citation needed]
  • requires meetings at frequent intervals at enormous expense to customers[citation needed]
  • requires too much cultural change to adopt[citation needed]
  • can lead to more difficult contractual negotiations[citation needed]
  • can be very inefficient; if the requirements for one area of code change through various iterations, the same programming may need to be done several times over. Whereas if a plan were there to be followed, a single area of code is expected to be written once.[citation needed]
  • impossible to develop realistic estimates of work effort needed to provide a quote, because at the beginning of the project no one knows the entire scope/requirements[citation needed]
  • can increase the risk of scope creep due to the lack of detailed requirements documentation[citation needed]
  • Agile is feature-driven; non-functional quality attributes are hard to represent as user stories.[citation needed]

See also[edit]

References[edit]

  1. ^'Human Centred Technology Workshop 2005', 2005, PDF, Informatics-UK-report-cdrp585[permanent dead link]
  2. ^ abUPenn-Lectures-design-patterns 'Design Patterns and Refactoring', University of Pennsylvania, 2003.
  3. ^ abUSFCA-edu-601-lecture Extreme Programming.
  4. ^'Manifesto for Agile Software Development'. Agilemanifesto.org. 2001. Retrieved March 26, 2019.
  5. ^ abcdefghijklmComputerworld-appdev-92 'Extreme Programming', Computerworld (online), December 2001.
  6. ^ abcRosenberg, Doug; Stephens, Matt (2003). Extreme Programming Refactored: The Case Against XP. Apress. ISBN978-1-59059-096-6.
  7. ^Larman 2003.
  8. ^Interview with Kent Beck and Martin Fowler. informit.com. March 23, 2001.
  9. ^Sedano, Todd; Ralph, Paul; Péraire, Cécile (2016). Proceedings of the 10th ACM/IEEE International Symposium on Empirical Software Engineering and Measurement - ESEM '16. pp. 1–10. doi:10.1145/2961111.2962590. ISBN9781450344272.
  10. ^Lisa Crispin; Tip House (2003). Testing Extreme Programming. ISBN9780321113559.
  11. ^'Everyone's a Programmer' by Clair Tristram. Technology Review, November 2003. p. 39.
  12. ^Beck, K. (1999). Extreme Programming Explained: Embrace Change. Addison-Wesley. ISBN978-0-321-27865-4.
  13. ^'Extreme Programming Rules'. extremeprogramming.org.
  14. ^Ken AuerArchived September 20, 2008, at the Wayback Machine
  15. ^John Carroll; David Morris (July 29, 2015). Agile Project Management in easy steps, 2nd edition. In Easy Steps. p. 162. ISBN978-1-84078-703-0.
  16. ^'Extreme Programming explained: What we really think of XP'. softwarereality.com.
  17. ^Cutter Consortium. 'Industrial XP: Making XP Work in Large Organizations - Cutter Consortium'. cutter.com.
  18. ^Extreme Programming (XP) Six Sigma CMMI.
  19. ^McBreen, P. (2003). Questioning Extreme Programming. Boston, MA: Addison-Wesley. ISBN978-0-201-84457-3.
  20. ^Boehm, B.; R. Turner (2004). Balancing Agility and Discipline: A Guide for the Perplexed. Boston, MA: Addison-Wesley. ISBN978-0-321-18612-6.
  21. ^Stephens, Matt; Doug Rosenberg (2004). The irony of extreme programming. , MA: Dr Dobbs journal.
  22. ^sdmagazineArchived March 16, 2006, at the Wayback Machine

Further reading[edit]

  • Ken Auer and Roy Miller. Extreme Programming Applied: Playing To Win, Addison–Wesley.
  • Ken Auer; Ron Jeffries; Jeff Canna; Glen B. Alleman; Lisa Crispin; Janet Gregory (2002). 'Are Testers eXtinct? How Can Testers Contribute to XP Teams?'. Springer-Verlag. doi:10.1007/3-540-45672-4_50.Cite journal requires |journal= (help)
  • Kent Beck: Extreme Programming Explained: Embrace Change, Addison–Wesley.
  • Kent Beck and Martin Fowler: Planning Extreme Programming, Addison–Wesley.
  • Kent Beck and Cynthia Andres. Extreme Programming Explained: Embrace Change, Second Edition, Addison–Wesley.
  • Alistair Cockburn: Agile Software Development, Addison–Wesley.
  • Martin Fowler: Refactoring: Improving the Design of Existing Code, Addison–Wesley.
  • Harvey Herela (2005). Case Study: The Chrysler Comprehensive Compensation System. Galen Lab, U.C. Irvine.
  • Jim Highsmith. Agile Software Development Ecosystems, Addison–Wesley.
  • Ron Jeffries, Ann Anderson and Chet Hendrickson (2000), Extreme Programming Installed, Addison–Wesley.
  • Craig Larman & V. Basili (2003). 'Iterative and Incremental Development: A Brief History', Computer (IEEE Computer Society) 36 (6): 47–56.
  • Matt Stephens and Doug Rosenberg (2003). Extreme Programming Refactored: The Case Against XP, Apress.
  • Waldner, JB. (2008). 'Nanocomputers and Swarm Intelligence'. In: ISTE, 225–256.

External links[edit]

Wikimedia Commons has media related to Extreme programming.
Wikiquote has quotations related to: Extreme programming
  • Using an Agile Software Process with Offshore Development – ThoughtWorks' experiences with implementing XP in large distributed projects

Extreme Programming In Software Engineering Ppt

Retrieved from 'https://en.wikipedia.org/w/index.php?title=Extreme_programming&oldid=914475764'

⇐ ⇐ Game Of Thrones Books Free
⇒ ⇒ Logitech Bluetooth Keyboard Driver