FACULTY OF INFORMATION TECHNOLOGY AND MULTIMEDIA COMMUNICATION

MEI 2015

CDAD2103

METHODOLOGY OF INFORMATION SYSTEM DEVELOPMENT

Contents 1.1 Introduction 1

1.2 Methodology 1

1.3 Types of Software developing life cycles (SDLC) 2

1. Waterfall Model 2 2. V-Shaped Model 4 3. Evolutionary Prototyping Model 5 4. Spiral Method (SDM) 7 5. Iterative and Incremental Method 8 6. Extreme programming (Agile development) 10 1.4 CASE (computer-aided software engineering) 11 1.5 Conclusion 16

Introduction
System development methodology is a standard process followed in an organization to conduct all the steps necessary to analyze, design, implement, and maintain information systems. Organizations use a standard set of steps, called system development methodology to develop and support their information systems. Like many processes, the development of information systems often follows a life cycle.
For example, a commercial product such as a Nike sneaker or a Honda car follows a life cycle; it is created, tested and introduced to the market. Its sales increase, peak and decline. Finally, the product is removed from the market and is replaced with something else.
Many options exist for developing information systems, but the most common methodology for system development in many organizations is system development life cycle. However, it is important to know other alternative development methodology available in order to maximize the development process. there are four important terminologies in information systems, namely methodology, model, tools and techniques.
Methodology
Methodology in information system refers to system development methodology. (System development methodology is a comprehensive plan to be followed, which covers all the necessary activities in the system's development life cycle. )
Methodologies include the model that needs to be followed, plus the tools and techniques that need to be used. It is normally developed in-house; which is developed by experts in the organisation, based on their knowledge and experiences. Some methodologies are made outside; purchased and obtained from other organisations, either from consulting firms or other suppliers. For example, structured systems analysis and design method (SSADM), dynamic system development method (DSPM) and system development life cycle (SDLC).
Methodologies are seen as written information in the form of books and other documents by detailing every activity which needs to be implemented by system developers. This includes documentation forms and reports that need to be provided by the project team. There are also methodologies in a more shortened form, which contains general instructions on what needs to be implemented. Do you know that many methodologies today have been shaped from other methodologies? This has been done after some adaptations to suit the needs of the new system development.
Types of Software developing life cycles (SDLC):

1. Waterfall Model 2. V-Shaped Model 3. Evolutionary Prototyping Model 4. Spiral Method (SDM) 5. Iterative and Incremental Method 6. Extreme programming (Agile development)

1. Waterfall Model
Description
The waterfall Model is a linear sequential flow. In which progress is seen as flowing steadily downwards (like a waterfall) through the phases of software implementation. This means that any phase in the development process begins only if the previous phase is complete. The waterfall approach does not define the process to go back to the previous phase to handle changes in requirement. The waterfall approach is the earliest approach that was used for software development.

The usage
Projects did not focus on changing requirements, for example, responses for request for proposals (RFPs)

Advantages and Disadvantages Advantages | Disadvantages | · Easy to explain to the user· Structures approach.· Stages and activities are well defined· Helps to plan and schedule the project· Verification at each stage ensures early detection of errors / misunderstanding· Each phase has specific deliverables | · Assumes that the requirements of a system can be frozen· Very difficult to go back to any stage after it finished.· Little flexibility and adjusting scope is difficult and expensive.· Costly and required more time, in addition to detailed plan | *

2. V-Shaped Model
It is an extension for waterfall model, Instead of moving down in a linear way, the process steps are bent upwards after the coding phase, to form the typical V shape. The major difference between v-shaped model and waterfall model is the early test planning in v-shaped model.

The usage
· Software requirements clearly defined and known
· Software development technologies and tools is well-known
Advantages and Disadvantages Advantages | Disadvantages | · Simple and easy to use.· Each phase has specific deliverables.· Higher chance of success over the waterfall model due to the development of test plans early on during the life cycle.· Works well for where requirements are easily understood. | · Very inflexible, like the waterfall model.· Little flexibility and adjusting scope is difficult and expensive.· Software is developed during the implementation phase, so no early prototypes of the software are produced.· Model doesn’t provide a clear path for problems found during testing phases.· Costly and required more time, in addition to detailed plan | * 3. Evolutionary Prototyping Model
Description
It refers to the activity of creating prototypes of software applications, for example, incomplete versions of the software program being developed. It is an activity that can occur in software development. It used to visualize some component of the software to limit the gap of misunderstanding the customer requirements by the development team. This also will reduce the iterations may occur in waterfall approach and hard to be implemented due to inflexibility of the waterfall approach. So, when the final prototype is developed, the requirement is considered to be frozen.
It has some types, such as:
· Throwaway prototyping: Prototypes that are eventually discarded rather than becoming a part of the finally delivered software

· Evolutionary prototyping: prototypes that evolve into the final system through iterative incorporation of user feedback.

· Incremental prototyping: The final product is built as separate prototypes. At the end the separate prototypes are merged in an overall design.

· Extreme prototyping: used at web applications mainly. Basically, it breaks down web development into three phases, each one based on the preceding one. The first phase is a static prototype that consists mainly of HTML pages. In the second phase, the screens are programmed and fully functional using a simulated services layer. In the third phase the services are implemented
The usage
· This process can be used with any software developing life cycle model. While this shall be focused with systems needs more user interactions. So, the system do not have user interactions, such as, system does some calculations shall not have prototypes.
Advantages and Disadvantages Advantages | Disadvantages | · Reduced time and costs, but this can be disadvantage if the developer lose time in developing the prototypes· Improved and increased user involvement | · Insufficient analysis· User confusion of prototype and finished system· Developer misunderstanding of user objectives· Excessive development time of the prototype· Expense of implementing prototyping | * 4. Spiral Method (SDM)
Description
It is combining elements of both design and prototyping-in-stages, in an effort to combine advantages of top-down and bottom-up concepts. This model of development combines the features of the prototyping model and the waterfall model. The spiral model is favored for large, expensive, and complicated projects. This model uses many of the same phases as the waterfall model, in essentially the same order, separated by planning, risk assessment, and the building of prototypes and simulations.

The usage
It is used in shrink-wrap application and large system which built-in small phases or segments.
Advantages and Disadvantages Advantages | Disadvantages | · Estimates (i.e. budget, schedule, etc.) become more realistic as work progresses, because important issues are discovered earlier.· Early involvement of developers· Manages risks and develops system into phases | · High cost and time to reach the final product.· Needs special skills to evaluate the risks and assumptions· Highly customized limiting re-usability | * 5. Iterative and Incremental Method
Description
It is developed to overcome the weaknesses of the waterfall model. It starts with an initial planning and ends with deployment with the cyclic interactions in between. The basic idea behind this method is to develop a system through repeated cycles (iterative) and in smaller portions at a time (incremental), allowing software developers to take advantage of what was learned during development of earlier parts or versions of the system.
It consists of mini waterfalls

The usage
It is used in shrink-wrap application and large system which built-in small phases or segments. Also can be used in system has separated components, for example, ERP system. Which we can start with budget module as first iteration and then we can start with inventory module and so forth.

Advantages and Disadvantages Advantages | Disadvantages | · Produces business value early in the development life cycle· Better use of scarce resources through proper increment definition· Can accommodate some change requests between increments· More focused on customer value than the linear approaches· Problems can be detected earlier | · Requires heavy documentation· Follows a defined set of processes· Defines increments based on function and feature dependencies· Requires more customer involvement than the linear approaches· Partitioning the functions and features might be problematic· Integration between iteration can be an issue if this is not considered during the development. |

* 6. Extreme programming (Agile development)
Description
It is based on iterative and incremental development, where requirements and solutions evolve through collaboration between cross-functional teams.

The usage
It can be used with any type of the project, but it needs more involvement from customer and to be interactive. Also, it can be used when the customer needs to have some functional requirement ready in less than three weeks.

Advantages and Disadvantages Advantages | Disadvantages | · Decrease the time required to avail some system features.· Face to face communication and continuous inputs from customer representative leaves no space for guesswork.· The end result is the high quality software in least possible time duration and satisfied customer | · Scalability· Skill of the software developers· Ability of customer to express user needs· Documentation is done at later stages· Reduce the usability of components.· Needs special skills for the team. |

CASE (computer-aided software engineering) * The use of a computer-assisted method to organize and control the development of software, especially on large, complex projects involving many software components and people.
CASE is the use of a computer-assisted method to organize and control the development of software, especially on large, complex projects involving many software components and people. Using CASE allows designers, code writers, testers, planners, and managers to share a common view of where a project stands at each stage of development. CASE helps ensure a disciplined, check-pointed process. A CASE tool may portray progress (or lack of it) graphically. It may also serve as a repository for or be linked to document and program libraries containing the project's business plans, design requirements, design specifications, detailed code specifications, the code units, test cases and results, and marketing and service plans.

Environment having CASE:

Role of CASE tools:
CASE tools play a major role in the following activities: * Project management * Data dictionary * Code generation * User interface design * Schema generation * Creation of meta-data for data warehouse * Reverse engineering * Re-engineering * Document generation * Version control * OO analysis and design * Software testing * Data modeling * Project scheduling * Cost estimation
Need of CASE tools:
The software development process is expensive and as the projects become more complex in nature, the project implementations become more demanding and expensive. That's why software developers always looking for such CASE tools that help them in many different ways during the different development stages of software, so that they can understand the software and prepare a good end product that efficiently fulfill the user requirements. CASE tools provide the integrated homogenous environment for the development of complex projects. These tools provide computerized setting to software developers to analyze a problem and then design its system model. The CASE tools also provide the environment for monitoring and controlling projects such that team leaders are able to manage the complex projects.

Basically, the CASE tools are used to * Reduce the cost as they automate many repetitive manual tasks. * Reduce development time of the project as they support standardization and avoid repetition and reuse. * Develop better quality complex projects as they provide greater consistency and coordination. * Create good quality documentation. * Create systems that are maintainable because of proper control of configuration item that support traceability requirements.

The phases that are supported by the Lower and upper CASE tools are shown in the Waterfall model as under:

Positioning of CASE tools in a Software Application development:

Advantages and Disadvantages of CASE Tools:

Characteristics of a successful CASE Tool:

A CASE tool must have the following characteristics in order to be used efficiently: * A standard methodology: A CASE tool must support a standard software development methodology and standard modeling techniques. In the present scenario most of the CASE tools are moving towards UML. * Flexibility: Flexibility in use of editors and other tools. The CASE tool must offer flexibility and the choice for the user of editors' development environments. * Strong Integration: The CASE tools should be integrated to support all the stages. This implies that if a change is made at any stage, for example, in the model, it should get reflected in the code documentation and all related design and other documents, thus providing a cohesive environment for software development. * Integration with testing software: The CASE tools must provide interfaces for automatic testing tools that take care of regression and other kinds of testing software under the changing requirements. * Support for reverse engineering: A CASE tools must be able to generate complex models from already generated code. * On-line help: The CASE tools provide an online tutorial.
CASE originated in the 1970s when computer companies were beginning to borrow ideas from the hardware manufacturing process and apply them to software development (which generally has been viewed as an insufficiently disciplined process). Some CASE tools supported the concepts of structured programming and similar organized development methods. More recently, CASE tools have had to encompass or accommodate visual programming tools and object-oriented programming. In corporations, a CASE tool may be part of a spectrum of processes designed to ensure quality in what is developed. Conclusion * Some of the benefits of CASE and similar approaches are that, by making the customer part of the process (through market analysis and focus groups, for example), a product is more likely to meet real-world requirements. Because the development process emphasizes testing and redesign, the cost of servicing a product over its lifetime can be reduced considerably. An organized approach to development encourages code and design reuse, reducing costs and improving quality. Finally, quality products tend to improve a corporation's image, providing a competitive advantage in the marketplace. * To build a grill of comparison for system development methodologies. We listed the criteria we judged are important for the evaluation of a system development methodology. methodologies build upon each other and improve on each other, all methodologies have common components, implementing a methodology is always better than having none.
The purpose of having a methodology is the increase of probability of success of a system development project. At certain point an organization might need to question the methodology they are using and opt for another one. But how can the organization decide on what methodology to use?
By using this grill of comparison IT professionals and system analyst can adopt a methodology versus another by examining the 9 criteria we defined in this paper. As the example shows this framework for system development methodologies comparison sounds useful and can help in eliminating some alternatives.