Business Information Systems Dersi 3. Ünite Özet

The System Concept and Information System in General

Changes in the business environment causes organizations to build new information systems. However, building an information system is a challenging process due to its complexity and costs associated with it. An information system development involves dealing with software, hardware, data, communication, and network. There has been proposed many system development models to overcome the obstacles building an information system over the years. Companies that adopt the right development model can successfully manage the process of building an information system and take advantage against their competition.

System development methods ease managing the phases of information development process. This way project managers can take the control of the development activities, define data and processes, build diagrams and documentation and create forms and reports. These methods also help managers to improve the quality of the information system under development.

There may be many reasons for companies to initiate a new information system. One of them is to improve the performance problems associated with the poor business operations in the company. Sometimes companies seek a new information system for taking the advantages of new enabling technologies. A new information system usually enhances the competition capability of a company.

There occurs many changes in companies due to the induction of an information system. They are automating business processes, improving productivity, and reengineering business operations.

System Development Life Cycle

System Development Life Cycle (SDLC) is a conceptual model on developing information systems. This conceptual model shows the phases of system development, their contents, the activities and tasks of each phase, the interrelations of the activities, and the precedence relations of the phases.

Selecting and applying the right methodology might prevent companies from losing money and time. An Information System is usually provides a strategic advantage to companies, henceforth it creates a long-run impact which must be carried out succinctly.

SDLC consists of phases that contain scope and planning, requirements analysis, design, realization and testing, setup and distribution, operation and maintenance respectively. Although the phases are given in sequence, they may not be applied in the same order. These phases show that if necessary, they may be used in the project.

Scope and planning is the first phase of SDLC. Therefore, in this phase the most important features and key capabilities of the Information System project are determined by stakeholders. What is also important is the selection of the right stakeholders.

Feasibility study addresses the doability issues of the project. The concerns about the necessity and challenges of the project are clarified. The estimated budget and the expected completion time of the project are also planned.

Feasibility analysis answers many questions about technical, operational, scheduling and economic attainability of the project. Also legal regulations are considered.

Requirements Analysis is one of the critical stages of the SDLC. The analysts are supposed to transform the business requirements into the specifications of the Information System during the requirements analysis. User requirements can be collected by using interviews, observing the work environment, sampling of business records, surveys, prototyping and joint application designs.

In system design , alternative solution suggestions are transformed into logical and physical system features. At the end of the design phase, the physical process models, physical data models, architectural design, program design, hardware and software features, a document including interface design, input and output design and database design are obtained.

In realization and test phase, programmers develop the system-building software and interface between old and new system. Also test engineers check if the system satisfies the requirements. Testing system involves debugging errors, testing user interfaces, and system performance along with new hardware tests.

Testing the whole information system with sample data is called Alfa test and testing the system in real environment with real data is called Beta test. This way errors are detected for correction. Documentation of the Information System is part of this phase and it deals with writing user manuals, FAQs, Online help web pages and installation guides.

Setup and distribution phase takes the tested system and deploys it to the real-world business environment. System analysts train system users, transfer old data to the new system, and perform the final system tests. Type of the system transition strategy is also adopted in this phase. These strategies are: parallel, pilot, phased, and direct.

Operation and maintenance is the last step of SDLC. System users are supported against system’s failures and operative problems. This way software errors that are found are repaired.

System support activities are: helping user, repairing software errors, system recovery and updating the system to comply with the new requirements.

Maintenance deals with keeping the system up and running. For achieving longer uptimes of the system four types of maintenance are used: Corrective maintenance, adaptive maintenance, perfective maintenance, and preventive maintenance.

Information System Acquisition

Information system acquisition task involves the identification and analysis of alternative solutions each of which are compared with the specifications of the new system. The Information System can be supplied by an In-House development, or purchasing a commercial package or with service procurement.

Each Information System supply option has positive and negative aspects. The organization should make the best choice for itself. This choice can be made easily by using the outputs of the analysis work done in the previous phase. In the in-house development, system design and implementation are carried out by using in-house resources. The commercial software package purchase alternative can be defined as the purchase and use of one of the many packaged software systems sold on the market. Service procurement can be defined as hiring a specialized firm to develop the required system. In addition, instead of designing the system from scratch and developing, only usage price is paid for usage period and system software, maintenance liability, system infrastructure may belong to the service supplier.

Information System Development Models

System development models define the development and maintenance activities of information systems, methods, applications, outputs, automated tools used by system developers and administrators. The conventional approach is the linear sequential model. This model has a stepwise structure. Due to its look, this approach is sometimes called waterfall approach. Each model has its advantages and shortcomings.

In this section; The Linear Sequential Model, the Incremental Model, The Spiral model, Component Based Development Model and The Agile Models are mentioned.

Approaches using Agile Models are: eXtreme Programming, Adaptive Software Development, Scrum and Feature Driven Development.

The Alternative System Development Models in Different Types of Projects

Selecting one of these system development models should be based on some facts such as cost and change requests, the existence of non-functional requirements, and delivery time and the planned lifetime of the system.

The cost of the changes will be high in the systems that require costly preliminary analysis and systems that show requirements consistently and accurately cover all customer requests. A Linear Sequential Model is used in such systems. Iterative models (Incremental Model, Spiral Model, Component Based Development Model or Agile Model) are preferred in the development of the information system if frequent changes are required by the customer. Some systems should be delivered quickly if the useful operation time is short. Techniques with short-term development and rapid delivery are preferred in such systems. For this reason, in small and medium sized software development companies and in systems in which the technologies used change rapidly, agile and iterative models are preferred.

Computer Aided System Development Tools

Computer-Aided Software Engineering (CASE) tools help system developers complete complicated information systems at high quality, on scheduled time and on budget. By using CASE tools, the intended software development models can be controlled, scaled and managed easily. CASE resources are; diagramming tools, computer display and reporting tools, analyst tools, quality management tools, project management tools, design and code generator tools, testing tools and documentation tools.

Process management tools are used to manage and document processes in the system development model. The project management tools support the project manager’s activities to improve the information system with the requirements, within the time frame and budget as well as reporting support. Due to the demand for rapid and high quality software development, the use of programming languages and compilers has been replaced by application development environments (ADE). With these application development environments, programs can be developed more simply and efficiently. ADEs support system development by providing user interface design software, network connectivity and middleware software, testing tools, version control software, help authoring tools among many others.