Unit 5

View layer : Designing interface objects

Introduction

• UI(user interface)– Main goal of UI is to display and obtain needed

information in an accessible , efficient manner– UI design is a creative process

Designing view layer classes

• UI layer consists of – objects with which user interacts– Objects needed to manage or control UI

• Responsibility of view layer objects– Input :responding to user interaction

• Translating user’s action into an appropriate response

– Output :displaying or printing business objects

Process of designing view layer classes

• It has 4 major activities– Macro level UI design process: (identifying view layer object)

• Takes place during analysis phase• Identifying classes that interact with human actors by analysing use

cases• sequence and collaboration diagram helps to identify UI classes

– Micro level UI design activities• Designing the view layer objects by applying design axioms and

corollaries– Decide how to use and extend the components so they best support

application specific functions and provide the most usable interface• Prototyping the view layer interface

– Useful in the early design process– Testing usability and user satisfaction – Refining and iterating the design

Zoom in by utilizing sequence or collaboration

diagrams

Identify the interface objects for the class

Define the relationships among the view objects

Next class refine and iterate

The class interacts with a human actor

The class doesn’t interacts with the human actor

Macro level design process

Relationship among view objects, business objects, access objects

View objects

Business objects

Access objects

Micro level design process

Apply micro level UI design rules and GUI

guidelines to each interface object identified

to develop the UI

Done

Next interface objects refine and iterate

Design rules• Making the interface simple ( application of corollary 2)

– Ex:• Car engine is complex• But driver interface remains simple

– User must be able to work with our screen without asking much questions

– Factors affecting UI• Dead lines• Comparative evaluations• Addition features• Shortcuts

– Things to be considered while designing UI• Additional features affect performance, complexity• Fixing problem, after the release of product is difficult