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«ABSTRACT The purpose of this research study is to perform a comparison and contrast analysis on three F. Davis Cardwell published longitudinal case ...»

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While this method breaks development up into more manageable “chunks,” it still relies upon the ability to analyze and design the entire system at the beginning of the project and, therefore, has the same problems with incorporating change as the Waterfall method. (Dillman, 2003, p.

3)

THE PERFORMANCE OF AGILE METHODS:

COMPARISON TO TRADITIONAL DEVELOPMENT METHODS

Figure 3. The Incremental Method (Dillman, 2003, p. 3) The “Evolutionary/Iterative” method is another attempt to modify the Waterfall method to make it more practical. Like the incremental approach, the Evolutionary/Iterative method develops only a subset of the solution to the problem. Unlike the Incremental approach, an iteration of the solution begins with the requirement analysis for that particular subset, and continues with the subset of the requirements throughout the iteration. The set of phases from requirements analysis through implementation is repeated until the complete solution is in place. (Dillman, 2003, p. 4)

Figure 4. The Evolutionary/Iterative Method (Dillman, 2003, p. 4)

The final traditional development method is the “Spiral” method. With the Spiral method, iterations are performed in both the requirements analysis and design phases to more completely understand the problem that the software is intended to solve. Once the problem and its intended solution are completely understood, the rest of the development processes continue sequentially, as with the other traditional methods. The Spiral method is considered to be the most flexible of the traditional software development methods. (Dillman, 2003, p.

4)

THE PERFORMANCE OF AGILE METHODS:

COMPARISON TO TRADITIONAL DEVELOPMENT METHODS

Figure 5. The Spiral Method (Dillman, 2003, p. 4) While all of these methods can be used to develop complex software, they all share a fundamental

assumption that limits their usefulness in developing complex software to solve practical problems:

namely, that software can be developed using methods that were initially derived from engineering methods. Fowler (2005, pp. 4 – 7) argues that software development is fundamentally a different activity from engineering activity, and therefore requires a different type of methodology to be effective.

ORIGINS AND HISTORY OF AGILE DEVELOPMENT

In response to a common dissatisfaction with traditional software development methods, the authors of the agile manifesto recorded and presented to the world a new approach to software development.

At the core, just as traditional software development methods are an attempt to impose discipline onto the development process, agile methods are an attempt to impose ethical values onto the development process. Agile methods recognize that the purpose of software is to solve a problem, and that the desired solution is often dynamic rather than static. Agile methods try to provide an optimal level of process for the intended solution, balancing between not enough process and the tendency of the software to devolve into a big ball of mud, and too much process and the tendency of the process to become rigid and resistant to change. (Fowler, 2005, p. 3) No one was more surprised at the success of the meeting than the authors of the manifesto.

According to Alistair Cockburn, many of the participants did not expect anything substantially useful to come out of the meeting; “I personally didn’t expect that this particular group of agilites to ever agree on anything substantive.” (Beck, et al., 2001.) His initial skepticism was replaced by a belief in the importance of the manifesto, a belief that was apparently shared among the authors: “Speaking for myself, I am delighted by the final phrasing [of the manifesto]. I was surprised that the others appeared equally delighted by the final phrasing. So we did agree on something substantive.” (Beck, et al., 2001.) The principles underlying agile methods are not new. There is evidence that some of the ways in which agility is imposed on software development were being used as early as 1957. (Abbas, et al., 2008, p. 2) Many of the methods that are now considered agile have been suggested throughout the history of software development as improvements over the traditional methods available at the time.

(Abbas, et al., 2008, pp. 4 – 6) What is new is that the principles and tenets are now amassed into a paradigm on which specific software development methods are based.

There is a deeper theme underlying agile methods; at the close of the meeting that resulted in the manifesto, one of the authors joked that he was “about to make a mushy statement.” (Beck, et al.,

2001) Another of the authors made the following observation:

THE PERFORMANCE OF AGILE METHODS:

COMPARISON TO TRADITIONAL DEVELOPMENT METHODS

At the core, I believe Agile Methodologists are really about “mushy” stuff about delivering good products to customers by operating in an environment that does more than talk about “people as our most important asset” but actually “acts” as if people were the most important, and lose the word “asset”. So in the final analysis, the meteoric rise of interest in and sometimes tremendous criticism of Agile Methodologies is about the mushy stuff of values and culture. (Beck, et al., 2001) Generically, the agile development process replaces the scope, requirements analysis, and design phases and their associated documentation with user stories, scenarios, and use cases. Development and testing are integrated, and placed into incremental “time boxes,” which are time periods of a specific predetermined length; once the length of a time box is set, it is locked and cannot be changed. The requirements are prioritized, and functionality is implemented in each incremental time box in priority order. Multiple time boxes are used to support parallel development, and iterative development occurs in response to the functionality developed in each time box; the next iteration begins with the next priority requirement. Finally, throughout the process, previously made design decisions are reviewed and evaluated in order to simplify the associated code and/or adapt to evolving needs; this is known as “refactoring.” (Pfleeger & Atlee, 2010, p. 295)





Figure 6. A Generic Agile Development Method (Dillman, 2003, p. 6)

DIFFERENCES BETWEEN TRADITIONAL AND AGILE METHODS

A definitive difference between the two approaches is that traditional methods assume that software development is a defined [i.e., linear] process; in other words, a process is delineated and, if allowed to run to completion, produces the same results each time it is run. On the other hand, the assumption behind agile methods is that software development is an empirical or non-linear process, where the actual process changes each time it is run in response to the conditions encountered during the run.

(Williams & Cockburn, 2003, p. 40) The differences between traditional methods and agile methods

are well illustrated through the four tenets of the manifesto:

1. Agile development values individuals and interactions over processes and tools. With agile methods, people and communication are emphasized, whereas with traditional methods the development process and development tools are emphasized.

2. Agile development focuses on producing working software rather than in producing comprehensive documentation. With agile development, the emphasis is on solving the problem, whereas, with traditional methods, the emphasis is on documenting the problem and the intended solution.

THE PERFORMANCE OF AGILE METHODS:COMPARISON TO TRADITIONAL DEVELOPMENT METHODS

3. Agile development focuses on customer collaboration rather than contract negotiation. In agile development, the customer is an active participant in the development process, whereas, with traditional methods, customers are usually only involved with the initial requirementsgathering phase; their next involvement is usually at delivery, where they may [or may not] be presented with a solution to the actual problem.

4. Agile development focuses on responding to change rather than on creating and following a plan. Agile methods are adaptive to changes to the problem and its environment, whereas traditional methods are predictive; they assume that the problem and its environment can be analyzed sufficiently during initial planning efforts. (Beck, et al., 2001) An analogy that illustrates the differences between traditional methods and agile methods is a road trip. Traditional methods assume that it is possible to sit down and plan the entire route to the destination by studying roads and distances on a map. Traditional methods have a hard time adapting, however, to the discovery that a road that was planned to be used in the middle of the route is closed. Agile methods, on the other hand, acknowledge that they don’t really know precisely how they are going to get to the destination; instead, they start moving in the general direction of the destination immediately. Agile methods depend on frequent stops, where feedback is gathered and digested as to the current location, and the direction needed to continue toward the destination. As such, agile methods tend to be more thoughtful processes than traditional methods, since they require constant feedback and evaluation. This constant examination is the mechanism which brings about agile thinking. (Williams & Cockburn, 2003, p. 2) In addition to the four tenets described above, the agile manifesto provides 12 principles to be used as a foundation for software development. [See Appendix A]

DIFFERENTIATION OF AGILE DEVELOPMENT PROCESSES

There are several different implementations of agile development principles into specific processes.

While they are all based upon the principles set forth in the agile manifesto, they differ in the ways in which these principles are placed into practice. This paper explores the following specific agile

processes:

• Extreme Programming, also known as XP. This process was founded by Kent Beck in 1996, during the Chrysler payroll development project. XP has been proven to be a successful agile development process for many software projects of different sizes and in different industries. XP stresses customer satisfaction; instead of delivering all the functionality of the system at some future date, the process delivers the software needed as it’s needed. XP empowers developers to respond to changing customer requirements, even late in the development cycle. XP emphasizes teamwork; managers, customers, and developers are all equal partners in a collaborative team. XP creates a simple yet effective environment, enabling teams to become highly productive. Teams self-organize around the problem to solve it as efficiently as possible. XP is based on the following

values:

• Simplicity: Do what is needed and requested, but no more. This maximizes the value added for the investment made. Take small simple steps toward the goal and mitigate failures as they happen. Create something to be proud of and maintain it over the course of its useful life for reasonable costs.

• Feedback: Take every iteration commitment seriously by delivering working software. Demonstrate the software early and often; then listen carefully and make any changes needed. Talk about the project and adapt the process to it, not the other way around.

• Respect: Everyone gives and feels the respect they deserve as a valued team member. Everyone contributes value even if it is simply enthusiasm. Developers respect the expertise of the customers and vice versa. Management respects the right to accept responsibility and receive authority over one’s own work.

THE PERFORMANCE OF AGILE METHODS:COMPARISON TO TRADITIONAL DEVELOPMENT METHODS

• Courage: Tell the truth about progress and estimates. Do not document excuses for failure but plan to succeed. Do not fear anything because no one ever works alone. Adapt to changes whenever they occur.

• Communication: Everyone is part of the team; communicate face to face daily. Work together on everything from requirements to code. Create the best solution to the problem possible, together.

(Wells, 2009)

Figure 7. The Extreme Programming Process (Wells, 2009)

• Scrum. The “scrum” framework is an agile software development process that functions as a wrapper for existing engineering-based development processes to iteratively and incrementally develop software. The name comes from the game of rugby, where a scrum is used to return an out-of-play ball to the playing field through teamwork. It is currently the most popular of the agile development processes. (Williams, Brown, Meltzer, & Nagappan, 2011, p. 1) The Scrum process is as follows: The product owner creates the requirements, prioritizes them, and documents them into a list; this list is now referred to as the product backlog. In Scrum, requirements are called features.



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