Database Reference
In-Depth Information
INTRODUCTION
EXtreme Programming (XP) and other Agile Methodologies (AMs) have started to
gain considerable interest in the IT community during the last several years. They have been
proposed as a way to build quality software systems fast and be able to easily adapt to rapidly
and frequently changing requirements in the environment. Agile processes are focused on
early, fast and frequent production of working code through the fast iterations and small
increments. The processes are characterized by intensive communication between partici-
pants, rapid feedback, simple design and frequent testing. By their proponents, the software
code is the main deliverable, while the role of system analysis, design and documentation in
software development and maintenance is de-emphasized and to some extent ignored.
A number of processes claiming to be “agile” have been proposed so far. The best
examples are eXtreme Programming (XP) (Beck, 2000), Scrum (Schwaber & Beedle,
2002), Feature-Driven Development (FDD) (Palmer & Felsing, 2002), Adaptive Software
Development (ASD) (Highsmith, 2000), Crystal methods family (Cockburn, 2002) and
DSDM (Stapleton, 2003). There have been attempts in applying agile values, principles
and practices in earlier phases of the software life cycle, such as analysis and design, under
the initiatives called Agile Modeling (Ambler, 2002) and eXtreme Modeling (Extreme,
2003). Efforts have been made to investigate how the Unifi ed Modeling Language (UML)
can be used in an agile process, as well as how to use the Rational Unifi ed Process (RUP)
(Jacobson, Booch & Rumbaugh, 1999) in an agile manner (Larman, 2001; Ambler, 2002).
The authors of the listed agile approaches have formed the Agile Alliance and published
the Agile Manifesto that represents a condensed defi nition of principles and goals of agile
software development (Agile Alliance, 2001). These principles are:
Individuals and interactions over processes and tools,
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Working software over comprehensive documentation,
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Customer collaboration over contract negotiation, and
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Responding to change over following a plan.
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Agile Development (AD) paradigm challenges many of the common assumptions in
software development. One of the most controversial is its rejection of signifi cant efforts in
up-front design in favor of a more evolutionary approach. According to its critics this is very
similar to the so-called code-and-fi x hacking strategy in software development. XP and other
AMs minimize the role of common design techniques in traditional software development
such as frameworks, design patterns, modeling tool support, modeling languages, model
repositories and reusability. On the other hand, AD supporters claim that their methodolo-
gies include just enough design efforts for the project to be successful, and AD design is
actually done in a different way than in traditional software processes. For example, in XP
simple metaphor-like design, refactoring, architecture prototypes, and test-based design are
used in an evolutionary way for software design purposes. These characteristics of XP and
other AMs are opposite to the current initiatives and paradigms in software development,
such as Model-Driven Development (MDD) (OMG, 2003). While both AD and MDD claim
to address the challenges of high change rates, short time-to-market, increased return-on-
investment and high quality software, their proposed solutions are actually very dissimilar.
The question is whether principles and practices of both development paradigms can be
combined in order to take the benefi ts of both approaches.
