Design III Due today: User Manual Next Class:Pressman 8; Homework #4 Questions? Team Status Reports Design Principles (UI related) Bio Break ( 5 minutes ) Design Principles (Architecture related) Predictwallstreet.com’s architecture

Usability’s Three Golden Rules 1.Place the User in Control 2.Reduce User’s Memory Load 3.Make the Interface Consistent Source: Theo Mandel, cited in Pressman Chap 15

1. Place User in Control Mode issues Flexible interaction choices Interruptible and undoable actions Macros for streamlining Hide technical workings … transparency Design direct interaction w/ screen objects

2. Reduce User’s Memory Load Reduce short term memory load Establish meaningful defaults Intuitive shortcuts (Alt P for Print) Real world metaphors Progressive disclosure of information

3. Make UI Consistent Provide cues for context Cross-application consistency Follow established standards (Alt S is Save)

Other UI Design Issues Experts vs. Novices Frequent vs. Occasional Users Importance of Task Analysis Online Help Error Messages Error Checking

Design Model Data Design Architectural Design Interface Design Component Design

Architecture Design Issues Modularity –Cohesion –Coupling (IBM’s 4* Modules) Flexibility Scalability Reliability Performance Capability

Basic Architectural Styles Data-centered Data Flow Call and Return Object Oriented Layered Architecture (See Pressman text for diagrams of these styles)