richard furuta furuta@csdl.tamu.edu texas a&m university center for the study of digital...
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Richard Furutafuruta@csdl.tamu.edu
Texas A&M UniversityCenter for the Study of Digital Libraries
and The Department of Computer Science
Firing a transition(following a link)
Link Choice
Join
Fork
Counter
3
Petri net constructs as hypertext features
AccessControl
Active Place
Token
Inactive Place
Enabled Transition
(contents are displayed)
(representation of user)
(link can be followed)
(contents are hidden)
Disabled Transition
Overview
caT •Introduces context-awareness in Trellis
•caT hypertexts respond to
—Characteristics of users
—Characteristics of environment
—Repeated viewing
—Passage of time
—Activities of other users
•Formal, Petri net-based specification
•Places map to content, transitions to links
•Multi-user, multi-browser hypertext documents
•Specifies the browsing behavior of hypertexts
•Separates
—structure from content
—presentation from content
•Formality allows analysis of structure
•Colored, timed Petri nets
—Colors represent users or roles
—Timed nets can browse themselves
Trellis
Resource Realizer
Resource Realizer
ResourcesResourcesText, images, audio,video,etcText, images, audio,video,etc
Reso
urc
es
Reso
urc
es
Request
R
eso
urc
es
Request
R
eso
urc
es
Abstract resources handle and data format preferences
Abstract resources handle and data format preferences
Resources or pointer to resources
Resources or pointer to resources
Information server (Petri net Engine)Information server (Petri net Engine)
Browser MangerBrowser Manger
Global Data storeGlobal Data store
User Models, Petri net definition files, etc
User Models, Petri net definition files, etc
Server (linux)Server (linux)
Http SubsystemHttp Subsystem ServicesServices
ClientsClients
DevicesDevices
Browser CoordinatorBrowser Coordinator
Browser CoordinatorBrowser Coordinator
Web BrowserWeb Browser
xtbxtb
Authoring ToolAuthoring Tool
Anaysis ToolAnaysis Tool
Image BrowserImage Browser
Text BrowserText Browser
Browser CoordinatorBrowser Coordinator
Desktop (Windows)Desktop (Windows)
PDAPDADesktop (linux)Desktop (linux)
•Server maintains the state of browsing
•Browsers render the information content
•Multiple clients can reflect the state of browsing to users
—Collaborative browsing—Various users may view and navigate a hypertext in parallel
•Browsers may join or leave during a browsing session without affecting other browsers
•caT supports media-specific browsers
System Architecture
xTed: caT Authoring ToolxTed: caT Authoring Tool
canvascanvas
move to firstmove to first
titletitle
arcarc
placeplace
transitiontransition
cutcut
labellabel
firefire auto fireauto fire
transitiontransition
movemove
tokentoken
recordrecord playplay
stopstop clearclear
move to lastmove to last
forwardforwardbackwardbackward
token colorstoken colors
Image Browser Image Browser
Text BrowserText Browser
Web Browser Web Browser (Composite representation
of text and images)
SelectorSelector
Audio/VideoAudio/VideoBrowser
Browsers
Current DirectionsBrowser Development
•To support new media types—we currently support text, images, audio and video
•Understanding and addressing issues in simultaneous presentation of multiple audio/video elements
•To support a variety of behaviors, representations and metaphors—spatial browser
Large hypertext Development Support
•Identification of higher-level authoring specifications
•Libraries of these structures will enable uniformity of structure across larger-sized hypertexts
Parallel Browsing via Multiple Devices
•Find mechanisms to flexibly display content over different devices
•Customize the content and media type for achieving optimal effect on the target device
•Allow effects of user actions to propagate across devices
Examples•Hypertexts that display different content at different times of the day
- Outside of working hours, links to light reading may augment a collection of job-related reference materials
•Hypertexts that use different presentation mechanisms for different types of display
- Customized text-based browser for readers with slow internet connections
- Web-based interface for external readers
- Audio browser for readers using cell phones
• Hypertexts that reflect the material seen previously
- Rereading may change the content to include more details
•Hypertext that provide different services depending on availability of other users
- Clicking on a “help” links may direct a reader to a human subject expert she is not occupied but to a computer-based reference database otherwise
- Collaborative browsing behavior may be different than when a user browses the hypertext alone
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