1 2 1. Introduction  A system‟s user interface includes    [1] Screens for navigation through system [2] Screens and forms that capture data [3] Reports produced by system (paper, screen, other media)  User-interface design requires:     Principles and processes Interface structure and standards I/O design Navigation design  Interface design defines how system interacts with other external entities  Humans and other software systems  System interfaces designed during integration  Defined as part of physical architecture and data management layers  HCI layer defines:    Way in which users interact with system I/O accepted/generated by system Has three parts:  [1] Navigation mechanism (in a WIMPS environment, e.g. buttons, menus, etc)  [2] Input mechanism (e.g. windows containing dialogues, forms, etc)  [3] Output mechanism(e.g. web pages, reports, etc) 3 1. The Nature of UI Design        UI design may be significant portion of overall development effort, e.g. <=50% UI design may be:   “mission critical” - UI to a commercial organisation‟s web site “safety critical” – UI to aircraft Engine Instrument System (EIS)          graphic designers interaction / interface designers information architects technical writers marketers test engineers usability engineers software engineers users Users are unpredictable, designer’s intuition may be incorrect Ideally, UI design involves a team of specialists, e.g. UI design is inevitably constrained by the I/O devices available I/O now exploits graphical (non-persistent) displays, via keyboards, cursors and pointing devices (mouse, pen, tablet, etc) Major physical constr