Understanding Agile Methodology and principles

In 2001, At a summit seventeen practitioners of different software methodologies met together and created the agile manifesto. Principles of Agile Manifesto are implemented in various projects for agile development.

The Manifesto for agile development states developing keeping the following values as focus:

·         Individuals and interactions over processes and tools

·         Working software over comprehensive documentation

·         Customer collaboration over contract negotiation

·         Responding to change over following a plan

Agile Methodology thus focuses on close interaction between resources and customers to create working software and responding to changes in software based on feedback between the teams. 

If we go back to Iterative and Incremental model, we can say Agile Methodology as a subset of IID Model. Software Testers works in a collaborative model as a part of Agile teams providing necessary feedback together with reporting defects in the development.

Agile as per dictionary definition means:  able to move quickly and easily and able to think and understand quickly. The Definition defines agile methodology in a nice manner. Using Agile in projects, we can move in quick manner thinking over the problem and understanding it quickly and easily by working in a collaborative manner.

In terms of Software testing, agile methodology is different from previously used methodology, e.g. Waterfall and V-Model, as it allows tester a role early in the development in a collaborative manner, thus uncovering the issues from early analysis phase. Also Testers are integral part of agile teams instead of independent teams. The Collaborative approach separates agile from other SDLC Models, and helps better communication between various stakeholders including customer, managers, developers, testers, and analysts bringing responsiveness to changing requirements and a more efficient product developed since all the stakeholders works as a team with better understanding of the requirements.

Key Principles of Agile Manifesto:

1.  Satisfying the customer through early and continuous delivery of valuable software.

2.  Agile processes harness change for the customer competitive advantage.

3.  Delivering working software frequently, from a couple of weeks to a couple of months, with a preference to the shorter timescale.

4.  Business people and developers must work together daily throughout the project.

5.  Build projects around motivated individuals. Give them the environment and support they need, and trust them to get the job done.

6.  The most efficient and effective method of conveying information to and within a development team is face-to-face conversation.

7.  Working software is the primary measure of progress.

8.  Agile processes promote sustainable development. The sponsors, developers, and users should be able to maintain a constant pace indefinitely.

9.  Continuous attention to technical excellence and good design enhances agility.

10. Simplicity–the art of maximizing the amount of work not done–is essential.

11. The best architectures, requirements, and designs emerge from self-organizing teams.

12. At regular intervals, the team reflects on how to become more effective, then tunes and adjusts its behavior accordingly.

Reference:  http://agilemanifesto.org/principles.html

Where to Use and Where not to use Agile?

• In case, most of the project in the organization is handled through traditional development Model, it is better to start with a smaller project. The reason we cannot predict the success or failure of the agile is the collaborative nature of the project and this includes developers, management, Customers, and testers. The traditional models do not allow regular interactions between the stakeholders. E.g. we get the requirement from the customers, based on requirements the analyst prepares the design, developers code the design and testers test the code. Thus each of the groups works as individual units with collaboration missing which is a must for Agile.

• Since the individual as well as customer had worked in the traditional model for a longer part of their career, it becomes difficult to switch to agile methodologies, where we need to work collaboratively. So to understand the approach and mindset for Agile methodologies before working on larger project with large number of resources and stakeholder.

• Agile Methodologies should be used in project whose business severity is neither too high nor too low, so that proper importance is provided to the project.

• Agile should not be used on Projects where large documentation is required e.g. Legal or Compliance Projects.

Understand Iterative and Incremental Development Model

In Iterative and Incremental Model, the whole requirement is divided into various sub–requirements or builds. Each build in itself follows waterfall model, i.e. each build passes through requirement, design, implementation and coding. The need for incremental and iterative model arise and is very useful in scenario where requirement changes frequently or we are working on an idea and the detailed requirement may not be clear at the start of development but a high level vision of the end product is available to us.

As the name suggest, this model will consider both iterative and incremental development. Before we discuss this in detail, let us know what iterative and incremental means. Various parts of the system are developed at different time and are integrated into the existing developed work once they are completed. And iterative strategy assigns time for rework and improvement in the part of system developed, thus continuously working in iterations to rework and improve the system adding more features in an iterative manner.

IID Model

To start with this model, we divide the project in a number of modules or stories. Each module/story represents functionality or use case in the product. Stories should be created or planned in such a manner that each story covers a feature of product, has set of entry and acceptance criteria and needs to be of shorter span of time, may be few days to few weeks. 

This is the analysis phase where we have analyzed the various stories from the requirement based on the features expected from the product. With each story having its own story means features  which will have a short span of time to complete.

Now once we have analyzed all the stories in the requirement, how do we react to stories, Do we start working on all stories together in a bang bang manner or do we need to priority to the stories, We will start with the story with most risk and complexity, and before this will complete on other smaller stories on which the most complex and risk story is developed. Once the complex piece is selected, we work on following a small waterfall on the story, 

We start with analysis, then design, coding and then testing the code, but with regular feedback at each of the steps.

The first piece will take a longer time compared to next stories but will provide useful immense information on the feasibility of the project, Knowledge to team on the product and possible bottlenecks in the development of project. It is strictly advised not to set deadlines for the initial few pieces as it will act as guidance to rest of stories on how long it will take to develop another story in the project.

Once we develop another story, we add it to existing product thus increment the functionality added to existing product and at the same time, we do iteration to improve and rework to existing developed piece based on defects, feedback from various stakeholder. 

All the pieces are developed, integrated with existing developed functionality, once the piece is fitted with rest of the developed pieces, we can have feedback and testing on the incremented product so that we can do rework and review the product. The development happens in an incremental and iterative manner unless the completed product is developed.

Where to Use IID Model

• Major functionality and goal of development are well defined, but features and enhancement mayevolve with time.

• IID is very useful in case of development with new technologies to validate a prototype filling preparing the complete.

• High Risk features which may change in future.

Positives in the Model

• An initial working product is developed in the early stages quickly.

• Developing the initial product early helps in getting feedback and defect Identification early in the lifecycle.

• We can work on different stories/pieces at the same time.

• Continuously improving the product by rework and review is possible based on iterative nature of development.

• Risks are identified in a better manner and can be implemented in the remaining project development.

Negatives in the model

• The timelines of the project are not fixed and can change drastically based on requirement change.

• Sometimes incorrect implementation of model can lead of frequent requirement change and estimation of project.

• Initial development which helps in identifying risks in the system required experienced risk analysts as incorrect risk analysis during initial phase may lead to failure of development.

• Management complexity is higher.

Understanding Waterfall Model from a tester's perspective

      In this article, I will describe the waterfall model and understand it in a better way myself too.

      Waterfall Model is a sequential process model used in SDLC in which sequence of activities flows from top to bottom in a linear manner with next activity starting once previous activity is completed. Normally, The Output of the first activity acts as an input to the subsequent phase in waterfall model, also changes in the analysis can be traced back to previous phases if any change is identified in later phases of SDLC.

      Waterfall model can also be described as a document driven approach as communication depends on the quality and quantity of documentation.

This was first of the models used in Software Engineering provided by Winston W. Royce in an article published in 1970. Since the Software Industry evolved a lot in the past 40 years, new models and methodologies have also evolved which covers the shortcoming of Traditional waterfall model, but some or other features of waterfall Model are used in various other software methodologies. Therefore it is useful to understand the waterfall model before discussing other models.

Different Phases in Waterfall Model are described in the section below:

a. Requirement Analysis: 

In this phase, the requirements are understood from the client and analyzed. To Understand requirement , customer are consulted, the feasibility of the requirements are understood and based on all the inputs, business requirement specification is developed and is signed off by client as an agreement between client and supplier on the agreed functionality.

b. System Design: 

Before starting with system design, all the requirements are freeze in the requirement phase. The requirement documents acts as an input to this phase and based on this a system design is prepared in this phase.

c. Architecture Design:

  The system design is analysed and an architecture design dividing requirement into module based on functionality is developed. The input for this phase is the system requirement documents and output helps in preparation of low level design for the projects.

d. Low Level Design: 

In this phase, low level design at module level is developed which acts as input to coding phase. The high level design or Architecture design acts as input to this phase.

e. Coding: 

The Low level design is implemented to code. All the code is merged together and various modules are integrated together to form a system as defined in System design.

f. Testing:  

When Coding is completed, the code is passed on for testing and various testing types are conducted on the code and the defects are passed on to development team . Based on the defect impact, there needs to be changes implemented at code level or can impact the previous levels. The more the impacted phases, more will be the cost of fix.

g. Operations and Maintenance:

 Once testing is completed, the system goes to Production. Support and maintenance team helps in maintenance of the product.

Waterfall Model

Where to Use Waterfall Model: 

Waterfall model is most useful to be followed in projects where:

a.  Requirement is very well documented and probability of requirement changes is low.

b.  Expertise of resources is available to ensure each phase is completed with minimum gaps and rework.

c.  The time span of the project is short.

d.  The Project is stable with minimal requirement changes 

 Waterfall Model Positives:

a. Easy to understand and manage as the milestones in project are defined and mostly at a time only one phase is active, so needs to manage one phase only at times.

b. Processes are well defined.

c. Documentation is done properly for each of the stages in the life cycle.

d. Developing a culture of analysis before coding as there is thorough analysis from requirement to design to coding.

  

Waterfall Model Negatives:

a. The major negative of the model is the risk and uncertainty associated with the model which can arise due to below reason:
        a. Requirement change at a later stage.
        b. Since the application is not developed till a major part of life cycle, Actual feedback on functionality happens late in the life cycle

        c. The cost of fixes is high if uncovered late in the life cycle

b. Most of the defects are uncovered in system testing phase which results in a lot of rework and at times changes in the design, which can impact the timeline and acts as major threat to the success of the project.

c. At times, the testing time shrinks in the waterfall model due to delay in earlier stages of model. This can led to defects escaping the testing phase, which if uncovered in production can result in higher costs and can impact business too.

 Conclusion: 

Waterfall model was first of the model to be used in Software development model and acted as a basic framework to track and relate various phases of development. With time, various new models of Software development life cycle evolved, for e.g. V-Model, Iterative model, agile Model and so on, but somewhere we can see glimpses of waterfall in each of the models. Hence Understanding the most basic of models is highly useful before going to understand newer model that evolved over the years in SDLC.