Chapter 12 - Exploring Information System Development

System Development is the process of creating and maintaining information systems is called Systems Development or systems analysis and design. It involves all seven components of an information system. In addition to technical knowledge, it requires business knowledge and management skill.

Ongoing Activities

1. Project management
2. Feasibility assessment
3. Documentation
4. Data/information gathering

Planning

1. Review project requests
2. Prioritize project requests
3. Allocate resources
4. Form project development team 

Analysis

1. Conduct preliminary investigation
2. Perform detailed analysis activities:
3. Study current system
4. Determine user requirements
5. Recommend solution

 

 Design

1. Acquire hardware and software,if necessary
2. Develop details of system 

 

Implementation

1. Develop programs,if necessary
2. Install and test new necessry
3. Train users
4. Convert to new system

 Operation,Support,and Security

1. Perform maintenance activities
2. Monitor system performance
3. Assess system security 

System development should representatives from each department in which the proposed system will be used.

Project management is the process of planning, scheduling, and then controlling the activities during system development.

To plan and schedule a project efficiently, the project leader identifies:

1. Projectscope
2. Required activities
3. Time estimates for each activity
4. Cost estimates for each activity
5. Order of activities
6. Activities that can take place at the same time

Feasibility is a measure of how suitable the development of a system will be to the organization.

1. Operational feasibility
2. Schedule feasibility
3. Technical feasibility
4. Economic feasibility

Documentation is the collection and summarization of data and information.

A project notebook contains all documentation for a single project.

Users and IT professionals refer to existing documentation when working with and modifying current systems.

During system development,members of the project team gather data and information using several techniques.

1. Review documentation
2. Observe
3. Survey
4. Interview
5. JAD Sessions
6. Research

Who Initiates a System Development Project

1. A user may request a new or modified system.
2. Organisation wants to improve hardware, software or other technology.
3. Situations beyond an organization's control might require a change.
4. Management might mandate a change.
5. A user may request a new or modified information system using a request for system services or a project request.

Planning Phase
 
The planning phase for a project begins when the steering committee receives a project request
Four major activities are performed:

1. Review and approve the project requests
2. Prioritize the project requests
3. Allocate resources
4. Form a project development team 

Analysis Phase

 

The analysis phase consists of two major activities:

 

Conduct a preliminary investigation :

1. Determines and defines the exact nature of the problem or improvement.
2. Interview the user who submitted the request 

 

Perform detailed analysis :

1. Study how the current  system works
2. Determine the users' wants, needs, and requirement
3. Recommend a solution

 

Process modeling( structured analysis and design) is an analysis and design technique that describes processes that transform inputs into outputs

1. Entity-relationship diagrams
2. Data flow diagrams
3. Project dictionary

An entity-relationship diagram (ERD) is a tool that graphically shows the connections among entities in a system.
Entities are objects in the system that have data.
A data flow diagram (DFD) is a tool that graphically shows the flow of data in a system.

1. Data flow
2. Processes
3. Data stores
4. Sources

The project dictionary contains all the documentation and deliverables of a project.
Structured English is a style of writing that describes the steps in a process.
 

A decision table is a table that lists a variety of conditions and the actions that correspond to each condition.
 

A decision tree also shows conditions and actions, but it shows them graphically.
 

The  data dictionary stores the data item's name, description, and other details about each data item.
 

Object modeling combines the data with the processes that act on that data into a single unit, called an object.
 

UML (Unified Modeling Language) has been adopted as a standard ntation for object modelig and development
 

UML includes 13 different diagrams
Two diagrams include:

 

Case diagram:

1. A use case diagram graphically shows how actors (users) interact with the information system.
2. Diagrams are considered easy to understand.

Class diagram

1. A class diagram graphically shows classes and subclasses in a system.
2. Each class can have one or more subclasses.
3. Subclasses use inheritance methods and attributes of higher levels.

The system proposal assesses the feasibility of each alternative solution.
The steering committee discusses the system proposal and decides which alternative to pursue .

1. Packaged software
2. Custom software
3. Outsourcing

Design Phase

The design phase consists of two major activities
Acquire hardware and software
Develop all of the details of the new or modified information system
To acquire the necessary hardware and software:
Identify technical specifications

1. Use research techniques such as e-zines

Solicit vendor proposals

1. RFQ,RFP. or RFI is sent to potential vendors VARs

Test and evaluate vendor proposals

1. Various techniques are used to determine the best proposal

Make a decision

1. System analyst makes recommendation to steering committee

Next step to develop detailed design specifications 

Sometimes called a physical design:

1. Database design
2. Input and output design
3. Program design

Systems analyst typically develop two types of designs fr each input and output.
A prototype (proof of concept) is a working model of the proposed system

1. Prototypes have inadequate or missing documentation
2. Users tend to embrace the prototype as a final system
3. Should not eliminate or replace activities

Computer-aided software engineering (CASE) tools are designed to support one or more activities of system development.
CASE  tools sometimes contain the following tools:

1. Project repository
2. Graphically
3. Prototyping
4. Quality assurance
5. Code generator
6. Housekeeping

Many people should review the detailed design specifications.
An inspection is a formal review of any system development deliverable
A team examines the deliverables to identify errors.

Implementation Phase

The purpose of the implementation phase is to construct the new or modified system and then deliver it

1. Develop programs
2. Install and test the new system 
3. Train users
4. Convert to the new system

The program development life cycle follows these steps:

1. Analyze the requirements
2. Design the solution
3. Validate the design
4. Implement the design
5. Test the solution
6. Document the solution

Various tests should be performed on the new system
Unit test

• Verifies that each individual program or object works by itself

System test

• Verifies that all programs in an application work together properly

Integration test

• Verifies that an application work with other applications

Acceptance test

•  Checks the new system to ensure that it works with actual data

 

Training involves showing users exactly hoe they will use the new hardware and software in the system.

1. One on one sessions
2. Classroom style lectures
3. Web based training

 One or more f four conversion strategies can be used to change from the old system to the new system.

 

Operation, Support, and Security Phase

The purpose of the operation, support, and security phase is to provide ongoing assistance for an information system and its users after the system is implemented.

1. Perform maintenance activities
2. Monitor system performance
3. Assess system security

 A computer security plan should do the following:

1. Identify all information assets of an organization
2. Identify all security risks that may cause an information asset loss
3. For each risk, identify the safeguard that exist to detect, prevent, and recover from a loss