Project Planning, Design Project Planning, Design & Implementation& Implementation

The steps of system development

• The method for developing systems is called the system development cycle (or system life cycle).

• It consists of the five broad stages of:• understanding the problem• making decisions• designing solutions• implementing• testing, evaluating and maintaining

• Often, in the development of a system, there is a good reason to return to a previous step.

Understanding the problem

Making decisions

Designing solutions

Implementing systems

Testing, evaluating, maintaining

Statement of problem

New System

Type of new system

Using new system

Problem with system

Change in purpose

Change type of system

Change system

Change use of system

• Before a system can be planned, the exact nature of the problem must be understood.

• This may involve redefining the problem and identifying its key elements.

• A preliminary investigation determines whether a minor adjustment to the present system will solve the problem or a new system is necessary.

• Data must be collected in order to assess feasibility and promote understanding.

• There are several methods of data collection including interviews and surveys (see Table 3.1; p.92)

• When collecting data it is important to be aware of:• bias• reliability• validity

• The requirement report is a statement about the needs of the new system.

• It outlines the aims and objectives of the new system and how it will solve the problem.

• The requirement report also provides an overview of the new system in terms of data/information to be used, the information processes and I.T. required.

• If the preliminary investigation recommends further examination, then a project plan is developed.

• A project plan organises the project by specifying:• who• what • how• when

• This means that it identifies all the tasks, who is responsible for them, any I.T. they will need and a timeframe for completion.

• It is in this planning stage that a Gantt chart is often utilised.

• Gantt charts are popular because they quickly detail all the key aspects of the project and assign them completion times.

• A Gantt chart is a bar chart with each bar representing a task to be completed. (Fig 3.2, p.94)

• Each potential solution is developed using a requirement report and the scope of the problem.

• The scope of the problem places constraints on the new system.

• A feasibility study is designed to look at various constraints and make recommendations.

• It DOES NOT attempt to find detailed solutions.• Feasibility studies examine key criteria including:

• economic (money)• technical (I.T.)• schedule (time)• organisational (people)

• Implementing a new system requires conversion and training.

• Conversion involves changing from the old system to the new.

• The actual method chosen depends upon the nature of the work and the characteristics of the new system.

• There are four main methods of conversion:• direct• parallel• phased• pilot

• Direct conversion involves an immediate change to the new system.

• Though there are minimal costs it is not popular because there is no time for ‘live’ testing or training.

• Parallel conversion involves the old and new system working together.

• It means more work in the short term, but allows users to familiarise themselves and have a ‘safety net’.

• It also allows the installers to troubleshoot any difficulties.

• Phased conversion involves the gradual implementation of a new system.

• Modules are introduced and, as they are successful, more are implemented.

• Phased is sometimes confusing as people are not sure which system they are using.

• Pilot conversion involves implementing the entire system, but only in certain locations.

• If the pilot scheme is successful then it is implemented in all locations.

[ Complete Figure 3.9 from page 107]

• There are many design tools used to describe the information processes within an information system.

• Some of these diagrammatic tools include:• context diagrams• data flow diagrams• system flowcharts

• A context diagram is a graphical method of representing an entire system using a single process together with inputs and outputs.

• E.g. Using a system to find a book in the library[use Fig. 3.5, p.101]

• The process is indicated by a circle, data flows by arrows and external entities by rectangles.

• Data flow diagrams are similar but they describe the system in more detail.

• They can have multiple processes and they also have an open-ended rectangle to indicate external storage.

• E.g. [Figure 3.6 , p.102]• A system flow chart is a graphical method of

representing both the flow of data and the sequence of the system.

• A flowchart also shows the hardware used as well as the processes.

• It uses standard flow charting symbols, plus specialised symbols for peripheral devices.

• Each symbol contains labels and is linked by lines called flowlines.

• Flowlines do not need an arrow if the direction is top to bottom.

[Draw Table 3.5 , p.103]

• E.g. this is a system flowchart for finding a book in the library.

BEGIN

Enter book details

Library software Library database

Search results

Need printout?

Finished?

END

Search report

YESNO

NO

YES