1.5) Designing Solutions

• Designing a solution is the transformation of the specifications into appropriate hardware, software and information processes.

• It involves:• purchasing hardware• writing or purchasing software• specifying information processes

• Participant development occurs when people within the information system develop the solution.

• Participant development became a solution because IT personnel were often unable to provide immediate service.

• The stages of the system development cycle are affected by participant development in the following way:

• Understanding the problem—participant identifies the problem. Information system personnel might be used to advise the participant on possible tools to solve the problem.

• Making decisions—participant chooses an appropriate solution.

• Designing solutions—participant develops the solution, often using guided processes found in application packages. The participant may require some training

• Implementation—participant begins using the system. This stage is often easier to accomplish with participant development than with a system developed by information system personnel as the participant is familiar with the application and does not require further training.

• Testing, evaluating and maintaining—participant is totally responsible for the maintenance and testing of the solution and determining if any changes need to be made to the solution.

• Advantages:• Participant development is more responsive

to participant needs• Potential to save money• less need for IT staff• less time wasted on communication between

participants and IT specialists

• Disadvantages:• Participants are NOT hardware experts• Different participants within an organisation

could choose different applications• Increased costs in terms or purchasing and

training• Increased access to data leads to greater

security problems

• Design tools assist in the development of a new system.

• They include:• context diagrams• data flow diagrams• system flowcharts• decision trees• decision tables• data dictionaries

• Context diagrams are graphical methods of representing systems by using only a single process together with inputs and outputs.

• The input and output sources are also called external entities.

• The external entities are linked to the single process through data flow arrows.

• Data flow diagrams are graphical methods of representing a system that use a number of processes together with inputs, outputs and storage.

• DFD’s focus on the flows of data between information processes in a system.

• They show where data is:• collected• organised• analysed• stored• processed• transmitted• displayed

• There are four main symbols”• process• data flow• data store• external entity

• To draw a DFD, start with the processes and use data flows to link them to data stores and entities.

• The limitation of context diagrams and DFD’s is that, while they identify basic structures, they do not show sequences of operations or decisions that are required.

• Many information processes that occur are determined by various decisions.

• Two tools used to display and analyse decisions are decision trees and decision tables.

• A decision tree is a diagrammatic way of representing all possible combinations of decisions and their resultant actions.

• A decision table is a table that represents all possible conditions and actions.

• The table is divided vertically into conditions and actions, and horizontally into rules.

• A data dictionary describes the data within a system.

• A data dictionary describes each field in a database.

• It clarifies characteristics such as:• field name• field size• data type• description• example

• A system flowchart is a graphical means of representing both the flow of data and the logic of a system.

• It documents such things as:• the sequence• the processes• the selection rules and actions• the hardware used