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

User Interface Structure Design Plan for how a system will interact with external entities (e.g., people & other systems) Plan for how a system will interact with external entities (e.g., people & other systems) Part of the Human-Computer Interface Layer Part of the Human-Computer Interface Layer Three parts: Three parts: 1. Navigation Mechanism 2. Input Mechanism 3. Output Mechanism

6 Principles of User Interface Design 1. Layout – arrangement of objects on screen 2. Content Awareness – feedback to user 3. Aesthetics – pleasing to eye 4. User Experience – works with expert & novice users 5. Consistency – uniformity 6. Minimal User Effort – ease of use

User Interface Design Process

Window Navigation Diagram (WND)

Interface Design Prototypes Three Types: Three Types: 1. Storyboard – hand-drawn sample screens 2. HTML – sample screens created in HTML 3. Language – sample screens created using the actual programming language

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

UI Design Components Three parts: Three parts: 1. Navigation Mechanism 2. Input Mechanism 3. Output Mechanism Good design is not noticed by users Good design is not noticed by users Analysts should assume users have not read manual Analysts should assume users have not read manual

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

Input Design On-Line Processing (Transactional Processing) – each input item is entered/saved to system individually 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” 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 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. Minimize Keystrokes – keystrokes cost time & money. Extra keystrokes may lead to mistakes.

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

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

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