What is agile modeling (AM)? An explanation. Part 2

Read the first part of this post (Agile Modeling: An explanation - Part 1)

The modeling should be carried forward in small increments. As such it is easy to find bugs if the increment fails or some fault occur. As an agile developer, it is your duty to continuously strive to improve the code. This is just another way of showing that your code works in real, and is not just mere theory. The stakeholders know what they want better than the developers. Thus, by actively participating in the development process and providing constant feedback they can help in building a better software overall.
The principle of assuming simplicity means keeping focus on the required aspects instead of drawing out a highly detailed sketch. It also means using simple notations for depicting various model components, using simple tools, taking information from a single source, rejecting temporary models and updating models only when required. Facilitation of the communication can be improved by making a public display of the models, be it on wall or website, application of standards of agile modeling, collective ownership of artifacts and modeling in a team. Gentle application of the patterns enhances the results drastically.
The formalized contract models are required when you require integrating your system with other legacy systems such as web application or database. These models lay out a contract between you and the owners of these legacy systems. The principles, values and practices of AM have been developed by many experienced developers. With AMDD or agile model driven development we do sufficient high level modeling in the initial stages of the project for making out the scope of the project. In the later stages the modeling is carried out in iterations as a part of the development plan. You might then take model storming road for compiling your code straightaway. Agile practices can be applied to most of the projects. It is not necessary that you should be working on an agile project to benefit from these practices. Also it is not necessary to put all principles, practices and values to use to harness agile advantage. Instead it is better to tailor these practices according to the specifications of your project.
Another way of harnessing agile benefits is to follow AMDD. MDD (model driven development) in its agile form is called agile model driven development. In AMDD before writing the source code we create extensive agile models. These models are strong enough for carrying forward all the development efforts. AMDD is a strategy that seeks to multiply the scale of agile modeling. The main stages in this process are:
> Envisioning: Consists of initial architecture envisioning and initial requirements envisioning. These activities are carried out during the inception period.
> Iteration modeling
> Model storming
> Reviews
> Implementation

It is during the envisioning phase that we define the project’s scope and architecture. It is done using high level requirements and architecture modeling. The purpose of this phase is explore the requirements of the systems as far as possible and built a strategy for the project. Writing detailed specifications is a great risk to take. For short term projects you may like to pare only few hours on this matter. Agile modelers are advised to spend only required time on this phase to avoid the problem of over – modeling. For exploiting the important requirements you might require a usage model. It helps you explore how the product will be used by the users. For identifying fundamental business entity types an initial domain model is used. The issues with the user interface and its usability can be explored using an initial UI model.

What is agile modeling (AM)? An explanation. Part 1

Agile modeling is one of the most trusted development methodologies when it comes to producing an effective documentation and software system. If described at a high level, it comprises of all the best practices, best principles and values required for modeling a high quality software product (this description may seem a bit hyperbolic, but it tends to be true for the most part). These practices are lightweight in implementation, with a lot of flexibility. Although, Agile Modeling is a set of principles and therefore on its own, it is of no use. It has to be mixed with other fuller technologies such as rational unified process, extreme programming, and adaptive software development, scrum and so on. This process enables us to develop software that satisfies all of our requirements. Agile modeling is governed by the following values. Some of these values are extended from extreme programming:

- Communication: All the stakeholders should maintain an effective communication between them.

- Simplicity: Developers should strive to develop the simplest solution possible meeting all the requirements.

- Humility: As a programmer, you should have a sense of humility that you may not know everything and you should allow others to add value to your ideas.

- Feedback: There should be a mechanism for obtaining feedback early in every stage of development.

- Courage: You should have courage to make decisions and stay firm.

The principles on which the Agile Modeling is based are defined by the agile manifesto. Two of these principles are to assume simplicity and embrace changes. Assuming simplicity makes it easy to design software. You are able to cut out unnecessary secondary requirements and focus on the primary needs, thereby reducing the complexity. When you embrace the fact that there will be changes in the requirements, it adds flexibility to your project. As a result, you can develop more flexible projects that can adapt to the changes in requirements, and other changes, over time. 

The software evolves in increments. You should know that it is this incremental behavior that maintains agility of the system. The requirements are ever changing and so there should be rapid feedback mechanism in place through which early feedback can be obtained. With this early feedback it becomes easy for you to ensure that your system is fulfilling all the needs. The modeling should be done with a purpose i.e., if you don’t understand the purpose of your project, its audience or its environment you should avoid working on it unless you are pretty confident. 

It is always wise to have a contingency plan. Therefore, it’s good to have multiple models on standby. There can be a situation in which your primary model might fail, the standby models will provide a back up. One thing worth noting is that agile models are not just mere documentation; they are light weight realizations of your system’s purpose. Once the purpose is fulfilled, the models are discarded. 

One belief of agile developers is that representation is less important than the content. It is the content that matters. Also there are a number of ways in which the same content can be represented. Focus should be maintained on quality work because sloppy work is not valued anywhere. Also adapting to the principles of agile modeling for meeting the environment needs is important. Modeling in an agile manner requires practice. Agile modeling can be applied through various practices. You have to pick the most appropriate one for your project. However there are few fundamental practices that are always important for success of an agile model:

> Parallel creation of several models.

> Application of the right software artifacts depending up on the situation.

> Moving forward through continuous iteration.

One word of caution though! These models are just an abstract representation of the actual systems and therefore cannot be accurate.

Introduction to Crystal Agile Methodology and Agile Modeling

Crystal agile methodology is a software development approach. It is applicable for projects with small teams. It is a light weight approach. It is an adaptable approach. Crystal is a human powered methodology which means focus is on enhancing the work of the people. Crystal is ultra light which means it reduces the paper work, overhead involved. Crystal is stretch to fit methodology which means it grows just enough to get it to the right size. Crystal focuses on people and not processes.

Crystal consists of methodologies like Crystal Yellow, Crystal Orange, Crystal clear etc. It believes that project requires policies, practices and priorities as characteristics. Crystal methodology is based on the observation of various teams. Crystal methodology focuses on things that matter the most and make the most difference.

Agile Modeling suggests modeling is essential for all systems, but that the complexity, type, and size of the model must be in accordance with the software that is to be built. Some principles of agile methodology are:
- Agile Modeling is a practice based methodology.
- Values, principles and practices combine together for modeling.
- Agile Modeling is not a prescriptive process.
- Agile Modeling is not a complete software process.
- Agile Modeling focus on effective modeling and documentation.
- Developers using agile modeling should model with a purpose.
- Different models should be used to present different aspect and only those models should be kept that provide value.
- Traveling light is an appropriate approach for all software engineering work. Build only those models that provide value - no more, no less.
- During modeling, content is more important than representation.
- Be aware of the models and tools that are used to create them.
- The modeling approach should be able to adapt to the needs of agile team.

Agile modeling becomes difficult to implement in large teams, lack of modeling skills or team members are not co-located.