Past, Present and Future of User Interface Software Tools Brad A. Myers, Scott E. Hudson, and Randy Pausch Human-Computer Interaction Institute School of Computer Science Carnegie Mellon University http://www.cs.cmu.edu/~bam bam@cs.cmu.edu

Introduction User Interface Software Tools Help developers design and implement user interfaces Focus on Tools, but influenced by future UIs Today’s tools are highly successful Window Managers, Toolkits, Interface Builders ubiquitous Most software built using them Are based on HCI research Brad A. Myers. “A Brief History of Human Computer Interaction Technology.” ACM interactions. Vol. 5, no. 2, March, 1998. pp. 44-54. http://www.cs.cmu.edu/~amulet/papers/uihistory.tr.html Future tools must be different

Talk Outline Historical Perspective Future Prospects and Visions What worked What didn’t catch on Why Lessons Learned Future Prospects and Visions UI Trends that will require new tools Important issues

Historical Perspective Themes Address the useful & important aspects of UIs Tools that succeeded helped (just) where needed Threshold / Ceiling Threshold = How hard to get started Ceiling = how much can be achieved Path of Least Resistance Tools influence user interfaces created Predictability If not predictable, then not accepted by programmers Moving Targets Changing user interface styles makes tools obsolete

What Worked Window Managers and Toolkits Event Languages Graphical, Interactive Tools Component Architectures Scripting Languages Hypertext Object Oriented Programming

Window Managers Multiple (tiled) windows in research systems of 1960’s: NLS, etc. Overlapping introduced in Alan Kay’s thesis (1969) Smalltalk, 1974 at Xerox PARC Successful because multiple windows help users manage scarce resources: Screen space and input devices Attention of users Affordances for reminding and finding other work

Toolkits A collection of widgets Toolkits help with programming Menus, scroll bars, text entry fields, buttons, etc. Toolkits help with programming Help maintain consistency among UIs Key insight of Macintosh toolbox Path of least resistance translates into getting programmers to do the right thing Successful partially because address common, low-level features for all UIs Address the useful & important aspects of UIs

Event Languages Create programs by writing event handlers Many UIMSs used this style Univ. of Alberta (1985), Sassafras (1986), etc. Now used by HyperCard, Visual Basic, Lingo, etc. Toolkits with call-backs or action methods are related Advantages: Natural for GUIs since generate discrete events Flow of control in user’s hands rather than programmer’s Discourages moded UIs Won’t work well in future

Graphical Interactive Tools Create parts of user interface by laying out widgets with a mouse Examples: Menulay (1983), Trillium (1986), Jean-Marie Hullot from INRIA to NeXT Now: Interface Builders, Visual Basic’s layout editor, resource editors, “constructors” Advantages: Graphical parts done in an appropriate, graphical way Address the useful & important aspects of UIs Accessible to non-programmers Low threshold

Component Architectures Create applications out of components which are separately developed and compiled In UI software, each component controls an area of the screen Example: drawing component handles picture inside a document Invented by Andrew research project at CMU (1988) Now: OLE, OpenDoc, ActiveX, Java Beans Address the useful & important aspects of UIs Just the “glue” to hold together components

Scripting Languages First GUIs used interpreted languages Smalltalk, InterLisp Rapid development, supports prototyping Low threshold Then C and C++ became popular Now, bringing back advantages in scripting languages tcl/tk, Python, perl Visual Basic, Javascript But language must contain general-purpose control structures

Hypertext Ted Nelson named it in 1965 and developed Hypertext system at Brown University Important systems: NLS (1967), Hyperties (1986) World-Wide Web Phenomenal success due to: Ease of use of Mosaic browser Support for embedded graphics Support for easy authoring Low threshold both for authoring and viewing

Object Oriented Programming Success of OO owes much to UI software field Popularized by Smalltalk GUI elements (widgets) seem like objects Have state, accept events (messages) Rise parallels GUIs C++ with Windows 3.1 Java for behaviors in WWW

What Hasn’t Caught On User Interface Management Systems Formal Language-Based Tools Constraints Model-Based and Automatic Techniques

User Interface Management Systems Original goal: like databases, provide high-level language that abstracts details of input and output devices This separation has not worked in practice Good user interfaces must take into account the pragmatics and detailed behavior of all objects Standardization of GUI input and output devices has made goal somewhat moot Doesn’t address the useful & important aspects of UIs

Formal Language Based Tools Early UIMSs used grammars and state-transition diagrams Focus on dialog management Moving Targets Direct manipulation made dialog management less important Path of Least Resistance State diagrams afford worse user interfaces High threshold Formal languages are often hard to learn

Constraints Declare a relationship and system maintains it Sketchpad (1963), ThingLab (1979), Higgens (85), Garnet (1990), Amulet (1997), SubArctic (1996) Predictability Constraint networks can be hard to debug Especially in multi-way constraints Programmer must specify (or deduce) solving order High threshold Constraints require thinking differently May be appropriate for graphical layout Address the useful & important aspects of UIs

Model-Based and Automatic Techniques Automatic techniques for generating UIs from a model or declarative specification of contents Cousin (1985), Mike (1986), UIDE (1993), MasterMind (1993) Try to separate specification of UI from content May provide automatic reformating, retargeting, customization to users, etc. Result is often unpredictable Often can be worse UI than hand-drawn Sometimes model is larger than the code it would replace

Discussion of Themes Address the useful & important aspects of UIs Narrower tools have been more successful than ones that try to do “everything” Do one thing well Threshold / Ceiling Research systems often aim for high ceiling Successful systems seem to instead aim for a low threshold Impossible to have both?

Discussion of Themes, cont. Path of Least Resistance Tools should guide implementers into better user interfaces Goal for the future: do this more? Predictability Programmers do not seem willing to release control Especially when system may do sub-optimal things Moving Targets Long stability of Macintosh Desktop paradigm has enabled maturing of tools We predict a change soon

Future Prospects and Visions Important Trends Computers becoming a commodity Ubiquitous Computing Move to recognition-based interfaces 3-D interfaces End-user customization and scripting Violate assumptions of today’s tools Assumptions limit what designers can do Often unrecognized Implications for future tools

Computers Becoming a Commodity There are no longer “high-end” computers Computer Science research’s trick of buying faster computers to “time travel” may no longer be possible Moore’s law continues to operate New opportunities Quantitative change makes qualitative change possible Enables the diversity of platforms UIs more cinematic Smooth transitions, animation, visual

Ubiquitous Computing Computation embedded in many kinds of devices Digital pagers and cell phones, Palm Pilots, CrossPads, laptops, wall-size displays, “smart” rooms Next wave: easy communication with radio E.g., BlueTooth: www.bluetooth.com Significant Implications for tools Tools for coordinating multiple, distributed, communicating devices “Multi-computer” user interfaces Moving target problem

Varying Input and Output Today’s Desktop screens vary by a factor of 2.5 in size and a factor of 4 in pixels Tomorrow’s screen will vary by factors of 100 in size and a factor of 625 in pixels Cell phone to Stanford’s wall (3796 x 1436 pixels)

Need New Interaction Techniques Interaction techniques for desktop will not work No room on small devices Can’t reach menubar on wall-size devices Want to run same application on different devices

Need for Prototyping Devices User interface will be in hardware Rapid design and prototyping needed for hardware Pragmatics and usability cannot be evaluated from a simulation on a screen

Multiple, Distributed, Communicating Computers more for communication, not for computation Already true for WWW, email, digital pagers, cell-phones Computers as intermediaries between people CSCW But can’t assume have similar systems Single person with multiple devices Room-area networks like BlueTooth or HomeRF People communicating with themselves Tools will need to help with data sharing and synchronization

Limitations of Today’s Tools for UbiComp Tools assume a Pointing Device Hidden reliance on specific characteristics of common devices Size of display Many tools cannot handle a different number of mouse buttons Change to a stylus on a touchpad requires different techniques Assumptions about the setting Assume user is sitting and looking at UI Assume has user’s full attention

Move to Recognition-Based Interfaces Speech, gestures, camera-based vision Multimodal interaction User will pick which modality to use Use multiple modalities at same time Today, programming these requires knowing about Hidden-Markov Models, grammars, feature vectors, etc. Need tools to hide these complexities

Fundamental Differences of Recognition-based UIs Input is uncertain Recognition can make errors Requires monitoring, feedback, correction Interpreting input requires deep knowledge of data Context of the application “Move the red truck to here”

Implications of Recognition-based UIs GUI event model no longer works Do not produce discrete events Separation of UI from application no longer works Need a architecture based on accessible application data structures “Reflection”, “Open Data Model”

3-D Interfaces Difficult to design the right abstractions for tools Demise of VRML for Web Need to settle on the 3-D widgets and interaction techniques that will be standard Requirement for near-real-time interactivity Need to hide the mathematics

End-user Customization and Scripting Spreadsheet enables end users to specify their own computation Visual Basic, other “scripting” languages Needed in all applications Threshold for programming is too high Need “gentle slope systems”

Gentle Slope Systems Visual Basic Director (v6) HyperCard Goal Programming in C Visual Basic Director (v6) HyperCard C Programming MFC Difficulty of Use C Programming xCmds Click and Create Lingo HyperTalk Goal Basic Sophistication of what can be created

More Assumptions of Today’s Tools Skill and Dexterity of users Older users Makes single, fixed library of widgets untenable Non-overlapping and opaque components Preclude translucency, magic lens interactions Fixed libraries of components (widgets) Creating new widgets is very difficult New devices will require new interaction techniques Interactive tools provide freedom of design Aim for “Mechanism not Policy”

Operating Systems Considerations What is in the OS? Window Manager? Toolkit? Communication? Scripting facilities? Need ever increasing services for applications Need more access to low-level information E.g., hardware buttons, whether on network Ideally, API to support competition and research into these components

Some Design Guidelines for Future Tools Many things require further research Organize around providing rich context Of application and device state To inquire about data & methods; “reflection” Enables EUP, Recognition-Based UIs, data sharing for UbiComp Rather than event-based

More Design Guidelines Replaceable User Interfaces Ability to have multiple UIs Enabled by procedural interface to everything in UI Enables UbiComp devices, EUP Aim for low threshold, rather than high ceiling But cover the right parts of the interface Predictable for programmers rather than “smart” or automatic Need for support for evaluation

Conclusions Research in tools necessarily trails innovation in UI design Due to consolidation on desktop metaphor, significant progress in tools UI design poised for radical changes New opportunities and challenges for tools