INFS 6225 Object-Oriented Systems Analysis & Design

1. INFS 6225 Object-Oriented Systems Analysis & Design Chapter 10: Human Computer Interaction Layer

2. User Interface Structure Design • Plan for how a system will interact with external entities (e.g., people & other systems) • Part of the Human-Computer Interface Layer • Three parts: • Navigation Mechanism • Input Mechanism • Output Mechanism

3. 6 Principles of User Interface Design • Layout – arrangement of objects on screen • Content Awareness – feedback to user • Aesthetics – pleasing to eye • User Experience – works with expert & novice users • Consistency – uniformity • Minimal User Effort – ease of use

4. User Interface Design Process

5. Window Navigation Diagram (WND)

6. Interface Design Prototypes • Three Types: • Storyboard – hand-drawn sample screens • HTML – sample screens created in HTML • Language – sample screens created using the actual programming language

7. Interface Evaluation • Heuristic – compare to principles/rules • Walk-Through – demo meeting with users • Interactive – “test drive” by users • Formal Usability Testing – formal, in-depth session • Uses observation • Large amount of data gathered • One to Two hour sessions with each user • Five to Ten users involved

8. UI Design Components • Three parts: • Navigation Mechanism • Input Mechanism • Output Mechanism • Good design is not noticed by users • Analysts should assume users have not read manual

9. Types of Navigation • Language (Command Language) – user enters special syntax to direct system (e.g., DOS SQL) • Menus – user selects from limited set of listed choices (most popular method) • Direct Manipulation – users work directly with interface objects (e.g., drag & drop)

10. Input Design • On-Line Processing (Transactional Processing) – each input item is entered/saved to system individually • Batch Processing – inputs are collected over time & entered into system as a “batch” • Capture Data at Source – capture data at original source or as close as possible to source • Minimize Keystrokes – keystrokes cost time & money. Extra keystrokes may lead to mistakes.

11. Input Validation • Completeness Check – ensure all required data are entered • Format Check – ensures proper format is used • Range Check – puts valid range limit on input • Check Digit – math formula used to compute digit(s) • Consistency Check – ensure data combinations are valid • Database Checks – data verified with previously stored information

12. Output Design • Understand Report/Information usage • Manage information load • Minimize bias • Sort options • Scaling in graphical displays

13. Design Tips & Guidelines What tips/guidelines are offered throughout Chapter 10?