Agile Software Architecture Written By Christine Miyachi

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“Agile” was first introduced in 2001, by a team of software engineers looking to improve their adaptiveness and responsiveness to ever-changing requirements. Not knowing where to begin, the team began by formulating principles, which they would use to guide their new development process. Which, in turn, lead to the creation of the Agile Manifesto, and thus a new methodology was born.

This article by Phillip A. Laplante and Colin J. Neill of Penn State University explores the rumors of the demise of the waterfall model. The Waterfall process model progresses software products linearly from conception, through requirements, design, code, and test (Neill, 2004). The Waterfall method was developed in 1970 by Winston Royce when computer systems were monolithic, number-crunching entities with rudimentary front ends and users’ needs were filtered through the partisan minds of the computer illuminati building the systems (Neill, 2004). Most systems built in that time did not pay much attention to input from stakeholders, which is a good environment for the Waterfall method to work in – an environment where requirements seldom change after specification due to the fact that users are not involved in the development and therefore cannot provide feedback regarding incorrect assumptions or missing features (Neill, 2004).

SC will compare traditional and various iterative implementations of the SDLC. For example, Braude and Bernstein (2011) state that the popular and mature waterfall process model promotes simple comprehension, project management, and resource distribution of small project development lifecycles. The serial nature of the traditional SDLC leans toward the gathering of all requirements at the beginning of the project whereas the majority of testing occurs at the end of the lifecycle. The waterfall model’s linear design creates disastrous risks for large projects if the project team does not understand the core requirements during the initial phase of the project or the detection of major problems occurs toward the end of the project. On the other hand, a spiral model significantly reduces risks for large projects whereas complexity causes overkill for smaller projects. The project’s physical scope, timeline, budget, and resource determine which the most optimal process model for a project. Table 1.1 displays a comparison chart that SC uses to weigh advantages and disadvantages of traditional SDLC and Agile development methodologies. SC will utilize this chart to determine which development methodology is utilized based on the primary amount of questions answered positively weighed with the clients business case requirements. “Agile software development is a

In 2001 a group of individuals came together to form the “Agile Manifesto” This was to address Dr. Royce’s earlier discussed issues with the traditional method of software development and a possible methodology to solve this ever existing problem. The agile Manifesto was birthed and thus 4 major values and 12 principles for the agile methodology was set.

Agile is an iterative and incremental (evolutionary) approach to software development which is performed in a highly collaborative manner by self-organizing teams within an effective governance framework, with "just enough" ceremony, that produces high quality solutions, in a cost effective and timely manner which meets the changing needs of its stakeholders [1].

In the year of 2001 many proponents met in Utah and came to discuss and agree on underlying principles (Hoffer, George, & Valacich, 2011). Through this discussion they came up with the “The Agile Manifesto” (Hoffer, George, & Valacich, 2011). There is

There are many agile methodologies and frameworks. Some of them are discipline agile delivery (DAD), scaled agile framework (SAFe), scrum, kanban, Extreme programming (XP), dynamic system development method (DSDM), test-driven development (TDD), team software process (TSP) etc.

The waterfall model was legally introduced as an idea through a paper that had been published by a man called Winston Royce in the year 1970. However, due to the waterfall model being introduced by Winston Royce himself, it had been introduced as an example of a flawed software development method, which was vulnerable due to its shortcomings. The waterfall model philosophy had been inherited from the hardware manufacture and construction strategies that had been in practice in the year 1970s; therefore it had a structured approach to the software development itself. In comparison to the agile methodology, which developed in the year 1990s where the developers had decided to break away from the traditional structured, segmented and administrative approaches, which were being made to the developed software, and progressed towards more of the flexible development styles. The term Agile can be referred to as being lightweight methods, which had been declared in a research paper in the year 1974 by Edmonds. Furthermore, some of the most noticeable and common agile methods of the software development that subsequently had been evolved were known as Scum in the year 1995, 'Extreme Programming ' in 1996, 'Adaptive Software Development ', 'Dynamic Systems Development Method ' in 1995 and 'Feature Driven Development '. In the year 2001, a team of developers in the agile software development had declared the agile manifesto. The agile

The waterfall model of software engineering for the systems development life cycle model is the most popular version. Often considered classic approach to life cycle of systems development , linear and sequential waterfall model describes the development system. Waterfall development objectives are different for each stage of a development .Imagine a waterfall on the cliff of an alp. Water has flowed over the edge of a steep mountain side and has started walking down , it cannot turn back. It is same as the waterfall development. Once a phase of development is completed, there is no turning back when the development proceeds to the next phase.

The original Waterfall model has a foundation that is supported by two distinct characteristics. First, the methodology is rooted in the fact that that the software be developed in stages. “Originally created by Benington in 1956 and later modified by Royce in 1970, the quintessential Waterfall model is linear and sequential in evolution, typically with milestones at each phase of development. (Pavolka, 2005). As seen in figure 1 (Ruparelia, May 2010), the typical thresholds consisted of Evaluation, Requirements, Analysis, Design, Development, Validation, and ultimately Deployment. The evaluation phase, at the aggregate level, helps to reveal the situation at hand. The requirements phase is arguably the most important phase of the Waterfall plan as it lays out the project statement and sets the framework and expectations for the project. The next phase, Analysis, works as a comparison between what capabilities are needed versus what constraints currently exist. That leads into the Design phase in which the software developers determine the architecture required to meet the customer’s expectations taking into account the constraints previously identified. Development is the next phase that takes the inputs from the Design phase and outputs a tangible product ready for testing. The testing or Validation phase is the process in which the software is checked for two things: a) any and all bugs are identified and removed and b) the original scope of work including all

A major and initial influential force in agile methodology was Dr. Winston Royce. In 1970, he published an article entitled “Managing the Development of Large Software Systems”. In this paper, he argues software development is unlike the sequentially, siloed group phased execution auto-manufacturing sector and proposed an iterative and incremental approach, while also acknowledging its risks, that today is commonly referred to as agile methodology. Throughout my reading on the topic, I noted that the push for the use of agile methods in software development has been referred to as a movement. And at the forefront of this movement is the Agile Alliance. In 2001, the Agile Alliance published the “Manifesto for Agile Software Development”. I will not explore this group or its manifesto further other than citing its opening salvo, listed on its website, in order to further demonstrate the essence

At the Trinidad Gas Company (TGC), software development is done using an adaptive version of the Waterfall Methodology and the US Department of Justice Systems Development Life Cycle. The stages used by TGC in this mainly Waterfall Method involves the Initiation Phase, System Concept Development Phase, Planning Phase, Requirements Analysis Phase, Design Phase, Development Phase, Integration and Test Phase, Implementation Phase and Operations and Maintenance Phase. This methodology is a predictable, rigid and sequential design process, which means, that as each of the nine stages are completed, the developers move on to the next stage. In this sequential process there also exists a stage gate between each stage. This stage gate is simply a review of the project status to determine if to proceed or not. However, the stage gate approach is not always followed on many of the development projects undertaken by TGC. A brief description of each stage is mentioned below:

The traditional approach to software development can be illustrated through the waterfall model which is time tested and easy to understand. The waterfall model approaches software development in sequential manner, completing one activity before the other. It brakes up project in stages: requirement analysis, design, coding and testing, operation and maintenance (see fig. 1 below).