G063 – Prototyping

Learning Objective:At the end of this topic you should be able to:

• describe prototyping as a software development methodology

Prototyping

Prototyping• normal design process involves producing a

requirements specification – in consultation with the end users

Prototyping• normal design process involves producing a

requirements specification – in consultation with the end users

• prototyping involves producing a working system early in the design process– possibly without consultation with the end users

Prototyping• normal design process involves producing a

requirements specification – in consultation with the end users

• prototyping involves producing a working system early in the design process– possibly without consultation with the end users

• prototype system will not necessarily be efficient– because a full analysis has not been done. – will not have all the functionality end user requires.

Prototyping• normal design process involves producing a

requirements specification – in consultation with the end users

• prototyping involves producing a working system early in the design process– possibly without consultation with the end users

• prototype system will not necessarily be efficient– because a full analysis has not been done. – will not have all the functionality end user requires.– will be a step towards what the end user wants.

Steps in Prototyping

Steps in Prototyping1. basic requirements identified

Steps in Prototyping1. basic requirements identified2. prototype developed

Steps in Prototyping1. basic requirements identified2. prototype developed3. prototype tested by end user

– shortcomings in the prototype are identified

Steps in Prototyping1. basic requirements identified2. prototype developed3. prototype tested by end user

– shortcomings in the prototype are identified

4. prototype is improved – production of a further prototype

Steps in Prototyping1. basic requirements identified2. prototype developed3. prototype tested by end user

– shortcomings in the prototype are identified

4. prototype is improved – production of a further prototype

• repeat steps 3&4 – until end user satisfied

Steps in Prototyping1. basic requirements identified2. prototype developed3. prototype tested by end user

– shortcomings in the prototype are identified

4. prototype is improved – production of a further prototype

• repeat steps 3&4 – until end user satisfied

• this process is called Iteration

Steps in PrototypingInitial Investigation Basic requirements for the new

system identified.

Prototype Developed This stage is repeated with each prototype being closer to meeting the end user's needs.

Use the prototype Prototype is tested. Input from end user.

End User's needs met?

Working system The prototype has developed into a working system.

Feedback from End User used to evaluate the effectiveness of the prototype

No

Yes

Advantages of Prototyping

Advantages of Prototyping• a usable system produced early in the process,

– allows the end users to evaluate it

Advantages of Prototyping• a usable system produced early in the process,

– allows the end users to evaluate it • gives end users the opportunity to provide input

– to the next stage of development

Advantages of Prototyping• a usable system produced early in the process,

– allows the end users to evaluate it • gives end users the opportunity to provide input

– to the next stage of development• constant feedback should ensure that the resulting

system really does match their needs

Advantages of Prototyping• a usable system produced early in the process,

– allows the end users to evaluate it • gives end users the opportunity to provide input

– to the next stage of development• constant feedback should ensure that the resulting

system really does match their needs• user becomes comfortable with the HCI

– has been part of the on-going development

Disadvantages of Prototyping• once prototype is working, it may not be modified

– management see early prototype to be working• implement partially complete system too early

– inefficient systems may never be tidied up• early prototypes used instead of fully functional systems

– may cause problems later • if data usage increases • if the system is to be adapted to meet new processing needs.

Examination QuestionA firm is going to introduce on-line ordering of its products.

The user interface for the on-line ordering system will be developed using prototyping.

(a) Describe the process of prototyping. [2]

(b) Explain the process of iteration and why it is used. [4]

January 2007 Q2

Iteration

Iteration• “repeated design and refine”.

Iteration• “repeated design and refine”. • design is reviewed repeatedly

– by the users

Iteration• “repeated design and refine”. • design is reviewed repeatedly

– by the users• users suggestions lead to changes

Why use Iteration?

Why use Iteration?• users feel more confident about the outcome and so

are more likely to use it.

Why use Iteration?• users feel more confident about the outcome and so

are more likely to use it.

• system correctly matches the needs & expectations of the users – because they have had an input in the design.

Why use Iteration?• users feel more confident about the outcome and so

are more likely to use it.

• system correctly matches the needs & expectations of the users – because they have had an input in the design.

• no waste of waste time & money producing something that’s not right.