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Basic foilset Shared Places on the Web: XML for Web-based Collaboration and Distance Education

Given by Geoffrey C. Fox, Lukasz Beca, Marek Podgorny at XML Developers Conference Montreal on August 19-20 1999. Foils prepared August 21 99
Outside Index Summary of Material

We describe the essentials of shared event collaboration and how it is naturally integrated with the Web for both replicated client and server side shared objects.
We describe TangoInteractive and its applications
One use of XML is to define Shared Web Pages which implement both asynchronous (portal) and synchronous collaboration
Another use of XML is to support universal access and to link diverse display devices in collaborative sessions
We define the resultant event based architecture to be used in a new implementation of TangoInteractive
We conclude with original presentation abstract

Table of Contents for full HTML of Shared Places on the Web: XML for Web-based Collaboration and Distance Education

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1 Shared Places on the Web: XML for Web-based collaboration and Distance Education http://www.gca.org/conf/xmldev99/ http://www.npac.syr.edu/users/gcf/montrealxmlaug99 XML Developers Conference Montreal August 19-20 1999
2 Abstract of XML and Collaboration
3 Overview of Collaboration with XML I
4 Overview of Collaboration with XML II
5 Overview of Collaboration with XML III
6 What is Web-based Collaboration?
7 Simplest Shared Object is Client Side Java Applet
8 Architecture of Tango Distance Education
9 Courses at Jackson State
10 So putting these ideas together for Distance Education
11 Shared Simulations -- Fluid Flow and Planetary Motion
12 Applications of Web-based Collaboration
13 More General Shared server side Objects
14 Sharing Server Side Objects II
15 Shared Event Model of Collaboration?
16 So what do we have now--TangoInteractive
17 TangoInteractive System Architecture
18 Next Generation TangoInteractive
19 Collaboration Framework I
20 State of a Web Page is
21 Each Collaborating Client Receives Events
22 Shared Places on the Web I
23 Shared Places on the Web II
24 SPW and Portals
25 SPW as Shared Portal on the Web
26 SPW and Window Clutter
27 Two Uses of XML in Collaboration?
28 JSSB Currently Shares Existing Web DOM in Netscape 4.5
29 JavaScript Shared Browser with Dynamic HTML -- Shared Pointer
30 Basic JSSB Architecture
31 Shared Form Illustrated by Shared Access to NCSA Biology Workbench showing how general server objects can be shared from web interface
32 User and System Events
33 JSSB and Shared Card Games
34 Sharing XML Content Pages
35 XML JSSB Architecture
36 Applications of Shared XML Content Pages
37 XML and Universal Access I
38 XML and Universal Access II
39 Some Technical and System Comments
40 Where are we today?
41 Shared Places and SPDL - Overview
42 Shared Places - Technology Components
43 Shared Place Example: Introduction
44 Overview of Typical SPDL Document
45 SPDL Document Header
46 Declare the Shared Objects
47 What does SPDL Document Define
48 What SPDL Document Defines- continued
49 Definition of Groups of Users
50 Access to the Shared Place
51 Define User Roles I
52 Define User Roles II
53 Define Collaborative Sessions
54 Define Data Synchronization
55 Define source of Data
56 Shared Place Components
57 A Collection of Shared Place Components
58 Web Page with 2 Shared Objects
59 Continuing the HTML File: Load Shared Place and 2 Java Applets
60 The Real Stuff in HTML Page
61 Shared Places Interfaces
62 Shared Place Architecture
63 Shared Place Architecture - continued
64 Conclusions
65 Overview of Collaboration with XML I
66 Overview of Collaboration with XML II
67 Overview of Collaboration with XML III

Outside Index Summary of Material

HTML version of Basic Foils prepared August 21 99

Foil 1 Shared Places on the Web: XML for Web-based collaboration and Distance Education http://www.gca.org/conf/xmldev99/ http://www.npac.syr.edu/users/gcf/montrealxmlaug99 XML Developers Conference Montreal August 19-20 1999

From XML and Shared Places on the Web XML Developers Conference Montreal -- August 19-20 1999. *
Full HTML Index
NPAC
111 College Place
Syracuse NY 13244 4100
Phone: 3154432163
Lukasz Beca
Geoffrey Fox
Marek Podgorny
Syracuse University
HTML version of Basic Foils prepared August 21 99

Foil 2 Abstract of XML and Collaboration

From XML and Shared Places on the Web XML Developers Conference Montreal -- August 19-20 1999. *
Full HTML Index
We describe the essentials of shared event collaboration and how it is naturally integrated with the Web for both replicated client and server side shared objects.
We describe TangoInteractive and its applications
One use of XML is to define Shared Web Pages which implement both asynchronous (portal) and synchronous collaboration
Another use of XML is to support universal access and to link diverse display devices in collaborative sessions
We define the resultant event based architecture to be used in a new implementation of TangoInteractive
We conclude with original presentation abstract
HTML version of Basic Foils prepared August 21 99

Foil 3 Overview of Collaboration with XML I

From XML and Shared Places on the Web XML Developers Conference Montreal -- August 19-20 1999. *
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Over the last two years, we have built a web-based collaborative system TangoInteractive (http://www.webwisdom.com) which has been very successfully used for synchronous distance education.
Key features of TangoInteractive were its well defined API to applications in any language and its powerful shared browser built around a JavaScript Interface.
XML offers at least two important opportunities to advance this technology. Firstly the current shared HTML browser becomes a shared XML browser allowing custom style sheets on each collaborating client to present different views to each user. We are exploring this for distance education as a mechanism for universal access for both students and teachers of different capabilities and to support sessions where clients could simultaneously be PC's, palmtop and high end virtual environments such as CAVE's.
A second area where XML will play a key role is as the infrastructure with which to build collaborative web pages containing many different shared objects with both different functionalities and different collaboration configurations. In this talk we describe our prototype SPW (Shared Places on the Web) which we are building to explore both these ideas. The dynamic customizable configuration possibilities offered by this architecture, appears a dramatic improvement over current collaborative models which tend to offer rather rigid collaboration capabilities and policies.
HTML version of Basic Foils prepared August 21 99

Foil 4 Overview of Collaboration with XML II

From XML and Shared Places on the Web XML Developers Conference Montreal -- August 19-20 1999. *
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Our Shared Place is a virtual place on the Web where people can meet and work together.
They can use provided content and tools for collaborative work.
They can bring their own content and share it with others.
They can possibly create new content and take it with them to another Shared Place or store it on local disk for standalone work.
From the user's point of view, the Shared Place is an ordinary Web page with added collaboration functionality.
HTML version of Basic Foils prepared August 21 99

Foil 5 Overview of Collaboration with XML III

From XML and Shared Places on the Web XML Developers Conference Montreal -- August 19-20 1999. *
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The Shared Place technology has several architectural components.
First of all, the Shared Place Definition Language (SPDL) is an XML based language for defining properties of the Shared Places. SPDL describes all aspects of the the environment including collaboration functionality, shared object structure and user related configuration data.
  • This information includes session management and synchronization information; object initial state and persistence as well as communities and security.
The Shared Tool is a piece of software that can be embedded as a part of a Web page content and offers collaboration functionality using mechanisms provided by the Shared Place Framework. To interact with the Shared Place Framework, the Shared Tools must implement the Shared Place interface that can be in form of Java applet, plug-in, ActiveX object, or JavaScript applications.
Shared Place Framework is a set of mechanisms that implement collaboration services and expose them to Shared Tools using Shared Place interfaces. The Shared Place Framework will be implement in terms of existing Java based TangoInteractive infrastructure but linking the much richer SPDL based web pages.
HTML version of Basic Foils prepared August 21 99

Foil 6 What is Web-based Collaboration?

From XML and Shared Places on the Web XML Developers Conference Montreal -- August 19-20 1999. *
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Collaboration means sharing objects
Web-based Collaboration implies use of Web to share distributed objects accessible through the Web
  • Shared Web Pages; Resources accessed through Web Servers or Brokers; Client-side applications with programmatic interfaces
Specify Page
Receive Identical Page
Web Site
HTML version of Basic Foils prepared August 21 99

Foil 7 Simplest Shared Object is Client Side Java Applet

From XML and Shared Places on the Web XML Developers Conference Montreal -- August 19-20 1999. *
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Web Pages are an example where there is a single copy of an object; perhaps simpler is the replicated object model used in chat-rooms and more generally shared applets where sharing is maintaining consistent state of replicas
Server Shares Events
Java Chat Rooms (applications or applets). Share text typed by users
HTML version of Basic Foils prepared August 21 99

Foil 8 Architecture of Tango Distance Education

From XML and Shared Places on the Web XML Developers Conference Montreal -- August 19-20 1999. *
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NPAC Web Server
JSU Web Server
Java Tango Server
.......
Share URL's
Audio Video
Conferencing Chat Rooms
White Boards etc.
Address at JSU of Curriculum Page
Teacher's View of Curriculum Page
Student's View of Curriculum Page
Participants at JSU
Teacher/Lecturer at NPAC
.......
Java Sockets
HTTP
Java Control Clients
All Curricula placed on the Web
HTML version of Basic Foils prepared August 21 99

Foil 9 Courses at Jackson State

From XML and Shared Places on the Web XML Developers Conference Montreal -- August 19-20 1999. *
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Taught using Tango since fall 97 over Internet and defense high performance network DREN twice a week from Syracuse
  • Course material based on Syracuse Senior Undergraduate class CPS406(Web Technologies) and graduate classes CPS615/616(Base Computational science/Internetics)
  • Curricula, Homework, Grading, Facilities done by Syracuse
  • Students get JSU NOT Syracuse Credit
Jackson State major HBC University with many computer science graduates
Do not compete with base courses but offer addon courses with "leading edge" material (Web Technology, modern scientific computing) which give JSU (under)graduates skills that are important in their career
  • Job fair employers liked Java Programming!
Needs guaranteed 30 (audio) to 100 (video) kilobits per second bandwidth
  • Use a proxy server or mirror site
  • Actually get around one megabit/sec Syracuse to Jackson State
HTML version of Basic Foils prepared August 21 99

Foil 10 So putting these ideas together for Distance Education

From XML and Shared Places on the Web XML Developers Conference Montreal -- August 19-20 1999. *
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We have curricula authored in some fashion and placed on the Web -- it is shared by sharing specification of current Web Page
  • At simplest this is URL but also supported using JavaScript API and Shared Web Page Events are:
  • Shared Scrolling position
  • Shared Pointer as DHTML layer
We have shared client side C++ object -- the digital audio-video conferencing subsystem
We have several shared Java applets
  • One or more Chat rooms
  • Whiteboard
  • "Raised Hand" / Quiz applets for specialized teacher-student interactions
HTML version of Basic Foils prepared August 21 99

Foil 11 Shared Simulations -- Fluid Flow and Planetary Motion

From XML and Shared Places on the Web XML Developers Conference Montreal -- August 19-20 1999. *
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These educational resources are
shared replicated client side objects
HTML version of Basic Foils prepared August 21 99

Foil 12 Applications of Web-based Collaboration

From XML and Shared Places on the Web XML Developers Conference Montreal -- August 19-20 1999. *
Full HTML Index
Multi Player Games: Use Chat Rooms and digital VTC to establish context
  • Share Java, JavaScript, VRML etc. games
  • Tango has Card Games, Othello, Chess, Snakes and Ladders
Crisis Management: Again use general tools (including whiteboard) and add shared maps and multimedia situation reports
Command and Control: Military, Test and Evaluation -- any real time control of complex system
  • support distributed experts who can be on call remotely and shared object is visualization of test results
Collaborative Computing and Engineering: Here specialized shared objects are CAD, simulation and planning tools
Socializing .....
HTML version of Basic Foils prepared August 21 99

Foil 13 More General Shared server side Objects

From XML and Shared Places on the Web XML Developers Conference Montreal -- August 19-20 1999. *
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Web Page Sharing is a special case of sharing server side objects -- CGI Scripts, Databases, Object Repositories etc.
This can be done by sharing the Web specification of these objects which can be done client side without ANY change to basic object
This is sharing of client side interface (proxy) to server side object
Specify Object
Collaboration Server Shares Object Specification
Receive Identical Specification
Fetch Identical Objects
HTML version of Basic Foils prepared August 21 99

Foil 14 Sharing Server Side Objects II

From XML and Shared Places on the Web XML Developers Conference Montreal -- August 19-20 1999. *
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We have used the shared proxy notion to implement
  • Shared Browser
  • Shared Form to access Server side computation (NCSA Biology Workbench -- bunch of CGI scripts)
  • Shared access to Web-linked database
Server does not need to know about detail of
collaboration.
It is more efficient if it
caches information for
re-use.
Thus use custom data-base
caching or general
proxy server
HTML version of Basic Foils prepared August 21 99

Foil 15 Shared Event Model of Collaboration?

From XML and Shared Places on the Web XML Developers Conference Montreal -- August 19-20 1999. *
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So if all clients want exactly same view at all times, then the "shared event" model is a waste.
Might as well, just share the display produced on originating client (cf. Microsoft NetMeeting)
In fact, shared event typically enables each client to get the same view but instead one shares the object but has different presentation layers on each client
For instance, share a single XML document but apply different style sheets on each client
Again in command and control, basic application is a 3D map (Geographical Information System) but not so interested clients can present a simple 2D view
HTML version of Basic Foils prepared August 21 99

Foil 16 So what do we have now--TangoInteractive

From XML and Shared Places on the Web XML Developers Conference Montreal -- August 19-20 1999. *
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http://www.npac.syr.edu/tango
Largely Java system enabling collaboration between general client side objects
  • If client side object is a Server proxy, then this ruse enables sharing of server side objects
  • Has API for Java applet/application, C++, JavaScript
API Enables sharing of events in applications
  • This is just a fancy way of saying it forwards messages
API Enables applications to find out about participants
Currently ONLY deployed for Netscape version 4.5 as uses LiveConnect to connect JavaScript to Java
  • Internet Explorer version not fully debuggd
HTML version of Basic Foils prepared August 21 99

Foil 17 TangoInteractive System Architecture

From XML and Shared Places on the Web XML Developers Conference Montreal -- August 19-20 1999. *
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N: Netscape Browser
LD: Local Daemon
CA: Control Application
AP: Applet
LA: Local Application
CS: Tango Java Server
DB: Collaboration Database (XML now)
HTTP: Web Server / Object Broker
Client
Client
Collaboration Server
Object/Content Server
HTML version of Basic Foils prepared August 21 99

Foil 18 Next Generation TangoInteractive

From XML and Shared Places on the Web XML Developers Conference Montreal -- August 19-20 1999. *
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So let us imagine that we can redo all of this and assume that
  • The proxy ruse is correct and one does only need to share client side Web Pages
  • There are plenty of conventional web pages but full support for XML and W3C DOM in browsers
  • XML can be used for control pages and specialized pages such as those produced by web-linked databases and education portals
Collaboration implies sharing of electronic objects and is needed in Asynchronous and Synchronous modes
Asynchronous mode is MOST important (in all applications including distance education) and will be supported by run of the mill object web infrastructure
  • shared web pages and documents
  • electronic mail
Synchronous mode has important applications and not done fully by giants ...
HTML version of Basic Foils prepared August 21 99

Foil 19 Collaboration Framework I

From XML and Shared Places on the Web XML Developers Conference Montreal -- August 19-20 1999. *
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Objects register and then define their state via a stream of events
Need to share (federate) events between domains (your PC and mine) whose event services are normally isolated
"Tango Server"
Clients which receive events which are either queued (asynchronous)
or processed synchronously
HTML version of Basic Foils prepared August 21 99

Foil 20 State of a Web Page is

From XML and Shared Places on the Web XML Developers Conference Montreal -- August 19-20 1999. *
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Initial Load plus
Stream of events reflecting
  • Scroll,
  • DHTML,
  • Form etc. changes
HTML version of Basic Foils prepared August 21 99

Foil 21 Each Collaborating Client Receives Events

From XML and Shared Places on the Web XML Developers Conference Montreal -- August 19-20 1999. *
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Event Stream becomes set of time stamped XML messages
  • Control Messages: e.g. New Participant Joined
  • Shared Object Definition/Update Messages (e.g. Page Scrolled by such and such amount done as XML serialization of JavaScript Event object)
One or More Shared Places
One or More Shared Places
.............
HTML version of Basic Foils prepared August 21 99

Foil 22 Shared Places on the Web I

From XML and Shared Places on the Web XML Developers Conference Montreal -- August 19-20 1999. *
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Each "Shared Place on the Web" or SPW is a set of XML and HTML documents
An XML document defines the collaboration Structure -- who is allowed in "Shared Place"; what objects can be there; where they are stored
  • This replaces the suite of undocumented rigid policies in TangoInteractive as well as scattered configuration files
  • There is one such XML document for each type of SPW e.g. there would be distedtojacksonstate.xml or xmldevelopersconf.xml etc.
  • We have developed SPDL (Shared Place Definition Language) which is currently quite simple and is used in the SPW structure definition
HTML version of Basic Foils prepared August 21 99

Foil 23 Shared Places on the Web II

From XML and Shared Places on the Web XML Developers Conference Montreal -- August 19-20 1999. *
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There is an HTML document defines the shared place itself; it instantiates particular objects and is presentation layer
  • There is an associated XSL style sheet which invokes necessary programmatic capabilities and interprets XML islands in HTML document. These islands are defined in SPDL
  • There can be many SPW's presentation layers with a given SPDL structure
  • This (HTML + Style sheet) combination replaces the current TangoInteractive "Control Applet"
We will re-use some existing client side Java as SP agent and control objects invoked from style sheets
The TangoInteractive Server can also be largely re-used
HTML version of Basic Foils prepared August 21 99

Foil 24 SPW and Portals

From XML and Shared Places on the Web XML Developers Conference Montreal -- August 19-20 1999. *
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There is a lot of interest in portals these days
We build Web-based computing environments which are portals to Supercomputers and Web-based education or portals to a virtual university
Merrill Lynch predicts that Enterprise Information portal market will be $15B by 2002
Portals are built (by us) as a customizable set of XML components ( e.g. Run a Particular Program or display thumbnail of the next web-page in lecture)
SPW's can be thought of as customizable collaborative portals which define both synchronous and asynchronous shared components
HTML version of Basic Foils prepared August 21 99

Foil 25 SPW as Shared Portal on the Web

From XML and Shared Places on the Web XML Developers Conference Montreal -- August 19-20 1999. *
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Electronic Mail and News Updates are just "events" which can be handed to viewer objects in an SPW
  • In synchronous collaboration, events are typically generated on a client and immediately shared with other clients
  • Asynchronous events typically are generated by a server (which offers persistent store) and transmitted to client
Integration of Synchronous and Asynchronous Events is essential in "Next Generation" TangoInteractive
Customization is available as you can choose which objects are in your SPW and you can define customization parameters such as area for which you want weather and which sports results should be displayed
Such customized portals are commonplace but SPDL has the advantage that it specifies both synchronous and asynchronous portal components.
HTML version of Basic Foils prepared August 21 99

Foil 26 SPW and Window Clutter

From XML and Shared Places on the Web XML Developers Conference Montreal -- August 19-20 1999. *
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Currently TangoInteractive produces a very cluttered desktop as each capability is invoked as a separate window
We build Java and JavaScript window managers to help out but doesn't seem right ...
SPW will allow one design more coherent systems using either frames or windows as appropriate
For instance, for distance education, one could put chat room, audio-video conferencing controls and whiteboard as separate frames of a single window
HTML version of Basic Foils prepared August 21 99

Foil 27 Two Uses of XML in Collaboration?

From XML and Shared Places on the Web XML Developers Conference Montreal -- August 19-20 1999. *
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We have introduced XML used to define the nature of collaboration in terms of objects, clients, policies
We have discussed user customization in terms of portals
Consider the JavaScript Shared Browser (JSSB) in TangoInteractive
It is an example of collaborative content built around sharing events defined in Web Page
  • Difficulties with "version 4 DOM" as bugs and inconsistent or incomplete implementations
  • However it can be made to work very effectively
Here we discuss "content" Web pages and not the "Collaboration Definition" Web pages we discussed already
Remember that "shared event" Collaborative systems share the object and not its particular presentation layer on each client
HTML version of Basic Foils prepared August 21 99

Foil 28 JSSB Currently Shares Existing Web DOM in Netscape 4.5

From XML and Shared Places on the Web XML Developers Conference Montreal -- August 19-20 1999. *
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Clicks on form/link in layers or frames
Clicks on layers
mouseover and mouseout ...
Can veto default action on clicks or other events on nonmaster side
  • Don't know how to veto changes on nonmaster in Netscape4
Save Form Contents at any time
  • can reload any dump at any time
Resizing so all clients have same scaling
Scrolling
Sharing can be customized from dialog window
Download times to monitor bad networks at application level
JSSB does monitor client page to detect unwanted page changes (One can capture clicks on Page links but not on "back button" )
HTML version of Basic Foils prepared August 21 99

Foil 29 JavaScript Shared Browser with Dynamic HTML -- Shared Pointer

From XML and Shared Places on the Web XML Developers Conference Montreal -- August 19-20 1999. *
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Shared Pointer added to Internet Assistant PowerPoint on the Web
Illustrates sharing of Web Object Model internal to document
HTML version of Basic Foils prepared August 21 99

Foil 30 Basic JSSB Architecture

From XML and Shared Places on the Web XML Developers Conference Montreal -- August 19-20 1999. *
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Null Window Holds All
Permanent
Data
Tango Control Applet
Launches and Positions auxiliary windows
Cannot be signed Cannot do SetTimeout
(has LiveConnect restrictions)
Clock and Event Record
Signed JavaScript Capture Events Control Clock
and Inspect Shared Page for events
Shared Page is a frame
Dummy Page
Position Control Bar
Can be Destroyed without restarting Tango Session
HTML version of Basic Foils prepared August 21 99

Foil 31 Shared Form Illustrated by Shared Access to NCSA Biology Workbench showing how general server objects can be shared from web interface

From XML and Shared Places on the Web XML Developers Conference Montreal -- August 19-20 1999. *
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Shared Multiple List
Shared Buttons
Shared Text field
Shared Checkbox
HTML version of Basic Foils prepared August 21 99

Foil 32 User and System Events

From XML and Shared Places on the Web XML Developers Conference Montreal -- August 19-20 1999. *
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One can either share raw system message (click event occurred) or higher level user event generated by JavaScript invoked by event
Note Netscape 4.5 does NOT allow you to generate a general event in a page
  • You can invoke "click" events on form elements but not so events associated with layers
  • You can parse JavaScript invoked by event and transmit but this is unreliable
So User events are convenient and sometimes required
Function process() ...
Invoke Tango JS Interface
with user defined meaning
Click on Button which happens to
invoke some User JavaScript Code
Capture Click and
Invoke Tango JS Interface
with meaning that click occurred
Or
HTML version of Basic Foils prepared August 21 99

Foil 33 JSSB and Shared Card Games

From XML and Shared Places on the Web XML Developers Conference Montreal -- August 19-20 1999. *
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Dialog Box Invokes Shared User Events
Cards are 56 DHTML Layers
All of this
implies XML
Framework
for Card Games
and Internet Gambling
HTML version of Basic Foils prepared August 21 99

Foil 34 Sharing XML Content Pages

From XML and Shared Places on the Web XML Developers Conference Montreal -- August 19-20 1999. *
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So "new version of JSSB" for SPW should implement:
  • Share XML content of a document
  • Allow each collaborating client to generate personalized presentation layer using customized stylesheet or equivalent
Note TangoInteractive can map object specification on each client and so customization can be performed either before or after web page generated
  • Currently we map URL's before submission so each client accesses optimal mirror site (if available)
HTML version of Basic Foils prepared August 21 99

Foil 35 XML JSSB Architecture

From XML and Shared Places on the Web XML Developers Conference Montreal -- August 19-20 1999. *
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Content Server
Shared by SPW
Events
Trapped by XML JSSB
Master
Nonmaster
HTML version of Basic Foils prepared August 21 99

Foil 36 Applications of Shared XML Content Pages

From XML and Shared Places on the Web XML Developers Conference Montreal -- August 19-20 1999. *
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Support of Collaboration between PC client, Palmtop and high graphics devices such as CAVE's
So in education, can support a mix of wireless palmtops and laptops in the class, with distance PC's
  • Laptops and PC's get all the information including shared PowerPoint/Web Curricula pages etc.
  • Palmtops just get quizzes, chatrooms, whiteboard etc.
Linkage of geographically distributed researchers is necessary to support collaborative computational science
  • One researcher may be in a 3D virtual environment
  • Others will be looking at traditional scientific visualization on workstations
A common XML specification of visualization is mapped according to display capabilities of client device
HTML version of Basic Foils prepared August 21 99

Foil 37 XML and Universal Access I

From XML and Shared Places on the Web XML Developers Conference Montreal -- August 19-20 1999. *
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It is essential that collaborative technologies support all users independent of their hardware and physical capabilities
Hardware issues are essentially illustrated by palmtop to CAVE example on previous foil
Suppose we wish to teach a class where some students and/or teachers have impaired sight and hearing.
Then we need to share same object content but render it differently on each client.
  • Possibly want to render a given object in multiple ways on a given machine
Essential to share content (as in XML JSSB) and this enables you to choose right presentation for given client
  • Typical HTML layout aimed at fully capable users and needs to be redone for physically impaired users
Concepts of XML JSSB for universal access developed with Al Gilman from Trace Center
HTML version of Basic Foils prepared August 21 99

Foil 38 XML and Universal Access II

From XML and Shared Places on the Web XML Developers Conference Montreal -- August 19-20 1999. *
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Assume that all education will be web-based
Assume that we need to provide web resources of equal quality for all citizens
This will not work if one has to translate each course from material for "regular user" to that for "user for different access capabilities"
Thus only chance is to define curriculum in XML and produce customized presentation layers
One will need a powerful indexing/abstracting scheme to be able design appropriate navigation schemes for all users and clients
  • Natural framework is XML based Education Portals with SPW implementing collaboration (a.k.a. teaching)
HTML version of Basic Foils prepared August 21 99

Foil 39 Some Technical and System Comments

From XML and Shared Places on the Web XML Developers Conference Montreal -- August 19-20 1999. *
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There is a lot of TangoInteractive Software lying around to implement collaboration and so natural to implement customization in Java or JavaScript as an alternative to XSL
  • 15,000 lines JavaScript and a lot more Java
Note JavaScript very fast but phenomenological
  • Undefined thread behaviour etc. makes for experimental programming
  • However there is usually way of getting things to work
Note that on detects events at presentation layer but must share at object layer -- only works if this object- presentation layer connection well defined
XML Content
Pages
Events Trapped
by XML JSSB
define object state
Converted by Browser etc.
Shared Object
HTML version of Basic Foils prepared August 21 99

Foil 40 Where are we today?

From XML and Shared Places on the Web XML Developers Conference Montreal -- August 19-20 1999. *
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Current Web-based Curriculum are rarely based on XML
  • PowerPoint
  • WebCT
  • Blackboard
  • We have an unknown system WebWisdom based on XML
Largest concern of (some) universities is the 80% of the faculty, who have little or no web expertise
  • There is another group of zealots who would be happy to litter their pages with Java applets
Note advantage of XML and DOM is that seems relatively clear how to make collaborative with universal access
Javabeans allow Java applets to be made collaborative but there is no separation between presentation and object layers
HTML version of Basic Foils prepared August 21 99

Foil 41 Shared Places and SPDL - Overview

From XML and Shared Places on the Web XML Developers Conference Montreal -- August 19-20 1999. *
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Shared Place/Portal on the Web - the virtual place on the Web where people can meet and work together. They can use provided content and tools for collaboration and possibly creating new content. Basically, it is a ordinary Web page with collaboration and customization functionality added
Shared Place Definition Language (SPDL) is an XML based application that implements the idea of collaboration as a Web page content. It enables creation of Shared Places. HTML includes Java Applets Active X etc.
SPDL offers:
  • syntax for defining collaboration functionality of Web page content
  • mechanisms for merging seamlessly collaboration content with the regular Web page content
  • constructs to customize behavior of collaboration content depending on required policy
HTML version of Basic Foils prepared August 21 99

Foil 42 Shared Places - Technology Components

From XML and Shared Places on the Web XML Developers Conference Montreal -- August 19-20 1999. *
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Shared Place Definition Language is a language for defining properties of shared places. SPDL conforms to XML specification
Shared Object is a piece of software that can be embedded as a part of a Web page content. Shared Objects offer collaboration functionality using mechanisms provided by SP framework. To interact with SP framework, Shared Objects must implement the defined SP interface. Examples: Java Applets, Plug-ins, ActiveX objects, JavaScript Applications
SP Framework is a set of mechanisms that implement (roughly equivalent to Tango server + local daemon) collaboration services and expose them to Shared Objects using SP interfaces (discussed later)
HTML version of Basic Foils prepared August 21 99

Foil 43 Shared Place Example: Introduction

From XML and Shared Places on the Web XML Developers Conference Montreal -- August 19-20 1999. *
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In this example we define a simple shared place where the results of some scientific computations are available.
The place can be used also for discussion among collaborating scientists. The discussion is supported by two shared objects: chat and data viewer.
The chat can be used for the text based discussion about presented results.
The data viewer can be used for the graphical presentation of the results. The authors of the results (`creators') have access to the advanced functionality of the data viewer. (e.g. support of particular XML dialects) They can use this functionality to present their findings visually to the `observers'.
The shared place is defined by two documents. The presentation layer is described by the HTML document and the collaboration functionality is defined by the SPDL XML/XSL document.
HTML version of Basic Foils prepared August 21 99

Foil 44 Overview of Typical SPDL Document

From XML and Shared Places on the Web XML Developers Conference Montreal -- August 19-20 1999. *
Full HTML Index
The SPDL document defines several collaboration aspects of the shared place.
The header defines the communication protocol used for contact with collaboration server. (could be CORBA or what have you)
Next, all the shared objects embedded in the shared place are enumerated.
The following fragments define the user groups that have access to the shared place, specific user roles, and types of the collaborative sessions that are established in the shared place.
Other fragments describe how the data visible by different users are synchronized and specify the sources of the content presented by the shared objects.
Note how some Shared Place properties (e.g. users and files) are useful in non-collaborative page mode and others support both synchronous and asynchronous collaboration
HTML version of Basic Foils prepared August 21 99

Foil 45 SPDL Document Header

From XML and Shared Places on the Web XML Developers Conference Montreal -- August 19-20 1999. *
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<?xml version="1.0"?>
<placedef>
<head>
<title>Result Presentation</title>
<protocol type="plain">
<server>kopernik.npac.syr.edu</server>
<port򘮓</port>
</protocol>
</head>
The Header contains the title of the place.
It also declares how the shared place communicates with the collaboration framework. (I.e. server in Tango language)
The plain client/server protocol is chosen here with the collaboration server running on the machine: kopernik.npac.syr.edu on the port: 5555.
Other protocols such as IIOP can be used as well.
Initialize shared place definition
HTML version of Basic Foils prepared August 21 99

Foil 46 Declare the Shared Objects

From XML and Shared Places on the Web XML Developers Conference Montreal -- August 19-20 1999. *
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<sharedobject name="viewer"/><location> http://www.npac.syr.edu/experiments/apps/viewer.jar
  • </location>
  • <width</width>
  • <height</height>
</shared_object>
<sharedobject name="chat">......</sharedobject>
This fragment describes shared objects that are used in the shared place.
  • Two shared objects are declared.
  • Other objects which are not declared here, will not be supported by the Shared Place Framework in the `Result Presentation' place (HTML Page).
HTML version of Basic Foils prepared August 21 99

Foil 47 What does SPDL Document Define

From XML and Shared Places on the Web XML Developers Conference Montreal -- August 19-20 1999. *
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Collaboration functionality:
Session management: Defines how the Shared Objects initiate or join collaborative sessions
Synchronization: Describes mechanisms for assuring the consistence of data observed by collaborating users
Control mechanisms: Defines how the behavior of Shared Objects can be controlled and how the state of the collaboration session can be accessed
Shared Object data:
Initial state: Defines how the Shared Object are initialized when they start running
Persistence: Describes whether and how the content of the collaborative session is stored
Content: Describes the data to be processed by Shared Objects during collaboration session
HTML version of Basic Foils prepared August 21 99

Foil 48 What SPDL Document Defines- continued

From XML and Shared Places on the Web XML Developers Conference Montreal -- August 19-20 1999. *
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Users:
Grouping: Defines user groups with possibility of assigning roles
User identity based configuration: It is possible to define different behavior of Shared Object depending on the user, user group or user role
Referencing Shared Objects:
Shared Object ID: SPDL uses Shared Object ID to define properties for specific Shared Object
Granularity: It is possible to define different behavior for individual Shared Objects, classes of Shared Objects or for the whole Shared Place
HTML version of Basic Foils prepared August 21 99

Foil 49 Definition of Groups of Users

From XML and Shared Places on the Web XML Developers Conference Montreal -- August 19-20 1999. *
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<groups>
<group name="syracuse">
<user>morgan</user>
<user>cheng</user>
</group>
<group name="boston">
<user>smith</user>
<user>johnson</user>
</group>
<group name="washington">
<user>anderson</user>
<user>brown</user>
</group>
</groups>
This fragment of the SPDL document defines user groups. Those groups are used in further sections of the SPDL document to define other properties of the shared place. Three user groups, each with two users, are defined: syracuse, boston and washington.
HTML version of Basic Foils prepared August 21 99

Foil 50 Access to the Shared Place

From XML and Shared Places on the Web XML Developers Conference Montreal -- August 19-20 1999. *
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<users>
<place_access>
<user_group>syracuse</user_group>
<user_group>boston</user_group>
<user_group>washington</user_group>
</place_access>
<users>
This fragment declares that only members of the groups: syracuse, boston, and washington can access the shared place.
The declaration uses the `place_access' tag, therefore the access restriction applies to the whole place (chat and viewer objects). However, it is possible to define separate settings for the specific objects.
HTML version of Basic Foils prepared August 21 99

Foil 51 Define User Roles I

From XML and Shared Places on the Web XML Developers Conference Montreal -- August 19-20 1999. *
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<roles>
<object_roles name="viewer">
  • <role_item name="creator" mode="static" >
  • <user_group>syracuse</user_group>
  • </role_item>
  • <role_item name="observer" mode="static" >
  • <user_group>boston</user_group>
  • <user_group>washington</user_group>
  • </role_item>
</object_roles>
</roles>
The fragment of the SPDL document on this page defines the roles for the users of the shared object: in particular we illustrate with the roles creator and observer.
HTML version of Basic Foils prepared August 21 99

Foil 52 Define User Roles II

From XML and Shared Places on the Web XML Developers Conference Montreal -- August 19-20 1999. *
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We suppose that the content handled by the viewer object were produced by scientists from Syracuse therefore the role of the creator is assigned to them. The two other groups have the observer roles.
The shared object `viewer' behaves in different way depending on the role of the user. The user that has the role of the creator (must belong to `syracuse' group) obtains access to the viewer interface with more functionality. This extended functionality enables presenting the gathered material to the observers.
On the other hand, observers obtain access to the simpler interface suitable only for viewing the content presented by the creators.
The shared object `chat' does not have this distinction. All users (that belong to the previously declared groups) can access it in the same way without any limitations.
HTML version of Basic Foils prepared August 21 99

Foil 53 Define Collaborative Sessions

From XML and Shared Places on the Web XML Developers Conference Montreal -- August 19-20 1999. *
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<sessions>
  • <place_sessions>
    • <session_item enter_mode="automatic" init_mode="none">
      • <user_group>syracuse</user_group>
      • <user_group>boston</user_group>
      • <user_group>washington</user_group>
    • </session_item>
  • </place_sessions>
</sessions>
This fragment defines how the collaboration sessions are created in the shared place.
The members of all three groups automatically enter the collaboration session when they access the result analysis page.
This means that when a user opens the page with the shared place defined by this document, she immediately starts the collaboration with other users without executing any special actions.
HTML version of Basic Foils prepared August 21 99

Foil 54 Define Data Synchronization

From XML and Shared Places on the Web XML Developers Conference Montreal -- August 19-20 1999. *
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<synchronization>
  • <place_synchronization>
    • <synchronization_item mode="instant">
      • <user_group>syracuse</user_group>
      • <user_group>boston</user_group>
      • <user_group>washington</user_group>
    • <synchronization_item>
  • </place_synchronization>
</synchronization>
This fragment of the SPDL document specifies that whenever one of the users change the state of their shared object, this change will be immediately propagated to the shared objects of the other users.
Such a "instant" mode is declared for all shared objects present in the shared place.
HTML version of Basic Foils prepared August 21 99

Foil 55 Define source of Data

From XML and Shared Places on the Web XML Developers Conference Montreal -- August 19-20 1999. *
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<content>
  • <object_content name="viewer" location="http://www.npac.syr.edu/experiments/results/" >
    • <content_access mode="readonly">
      • <user_group>everybody</user_group>
    • </content_access>
  • </object_content>
</content>
</placedef>
This fragment of the SPDL document states that the shared object that implements the result viewer has access to the data from the location: http://www.npac.syr.edu/experiments/results/ in "read-only" mode.
This place should be used for storing the data that can be displayed by the viewer.
HTML version of Basic Foils prepared August 21 99

Foil 56 Shared Place Components

From XML and Shared Places on the Web XML Developers Conference Montreal -- August 19-20 1999. *
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HTML documents containing:
  • ordinary content: text, pictures, etc.
  • collaborative content: Shared Objects embedded using SPDL tags
  • reference to valid SPDL document
SPDL XML document defining collaboration functionality of Shared Objects embedded in the HTML document
Style Sheet for SPDL XML file defining applet that interprets page
HTML version of Basic Foils prepared August 21 99

Foil 57 A Collection of Shared Place Components

From XML and Shared Places on the Web XML Developers Conference Montreal -- August 19-20 1999. *
Full HTML Index
<placedef>
.
. .
</placedef>
SPDL document
Web browser
Regular content
Web page
Shared objects
So Web Page is defined as a set of Nodes
-- You choose which nodes (and their children)
that you wish to share and then events are exchanged
maintaining state consistency
HTML version of Basic Foils prepared August 21 99

Foil 58 Web Page with 2 Shared Objects

From XML and Shared Places on the Web XML Developers Conference Montreal -- August 19-20 1999. *
Full HTML Index
<HTML>
<head><title>Page with the computation results</title></head>
<body>
<xml id="placeDocument" src="results.xml"></xml>
<xml id="chatDef">
<embedobject name="chat">
<location>http://www.npac.syr.edu/experiments/apps/chat.jar
</location ></embedobject></xml>
<xml id="viewerDef">
<embedobject name="viewer">
<location>http://www.npac.syr.edu/experiments/apps/viewer.jar
</location ></embedobject></xml>
<xml id="style" src="spdl.xsl"></xml>
SPDL Definitions Page
Style Sheet
Shared Objects
HTML version of Basic Foils prepared August 21 99

Foil 59 Continuing the HTML File: Load Shared Place and 2 Java Applets

From XML and Shared Places on the Web XML Developers Conference Montreal -- August 19-20 1999. *
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Interpret 3 XML islands in style sheet and instantiate them in three (other) regions of document. ( Previously we loaded XML islands but they were not instantiated by browser)
<SCRIPT FOR="window" EVENT="onload">
docTarget.innerHTML = placeDocument.transformNode(style.XMLDocument);
chatTarget.innerHTML = chatDef.transformNode(style.XMLDocument);
viewerTarget.innerHTML = viewerDef.transformNode(style.XMLDocument);
</SCRIPT>
HTML version of Basic Foils prepared August 21 99

Foil 60 The Real Stuff in HTML Page

From XML and Shared Places on the Web XML Developers Conference Montreal -- August 19-20 1999. *
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<div id="docTarget"></div>
<p>This page contains the results of our latest computations.
The most interesting fragments are presented below.
<p>results here ..... ANY OLD HTML
<p>The authors of those computations will come here to discuss latest results on Monday at 3:00pm.
Please join them in the discussion:
<p>Visualization of some results presented by the authors is
available here:
<div id="viewerTarget"></div>
<p>Talk with others about the results here: ANY OLD HTML
<div id="chatTarget"></div> </body></HTML>
The display of two shared objects
Control Display
HTML version of Basic Foils prepared August 21 99

Foil 61 Shared Places Interfaces

From XML and Shared Places on the Web XML Developers Conference Montreal -- August 19-20 1999. *
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Now we turn to implementation and architecture
We remarked that SP Framework exposed a set of interfaces to Shared Objects and tools that manipulate them
SP Interfaces are the entry points for accessing collaboration functionality provided by SP Framework (major extension of functionality provided by Tango API in Java applet, application, C++ and JavaScript):
  • Configuration interface enables initialization of Shared Objects based on the content of SPDL document
  • Data sharing interface offers data passing and synchronization services to the Shared Objects
  • Control interface provides means for accessing and manipulation of collaboration state
HTML version of Basic Foils prepared August 21 99

Foil 62 Shared Place Architecture

From XML and Shared Places on the Web XML Developers Conference Montreal -- August 19-20 1999. *
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Shared Objects
  • Offer high-level collaboration functionality to the users
  • Communicate with Shared Place Framework
Shared Place Framework
  • SP Agent
    • Interprets SPDL document for specific Shared Place
    • Initializes Shared Objects
    • Exposes collaboration services to Shared Objects
    • Communicates with Collaboration Framework
Collaboration Framework offers low-level collaboration services to SP Agent (messaging and event service shared between collaborating clients as in current Tango Server)
HTML version of Basic Foils prepared August 21 99

Foil 63 Shared Place Architecture - continued

From XML and Shared Places on the Web XML Developers Conference Montreal -- August 19-20 1999. *
Full HTML Index
Web browser
Collaboration Framework
SP Agent
Shared Object
Web page
Other Clients
HTML version of Basic Foils prepared August 21 99

Foil 64 Conclusions

From XML and Shared Places on the Web XML Developers Conference Montreal -- August 19-20 1999. *
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We have analyzed a successful Web-based collaboration system TangoInteractive and in particular its JavaScript interface enabling shared interactive web pages
We have noted that it is very helpful to
  • use XML and new W3C DOM
  • Link Asynchronous and Synchronous events
  • Link Portal and Collaboration technology
XML can be used in defining portal/shared collaboration space
XML can support universal access to collaborative environments to those with disabilities -- hence giving them access to education
XML can support collaboration between clients from palmtops, to PC's and high-end virtual environments
TangoInteractive is available now at http://www.npac.syr.edu/tango
Prototypes involving SPDL and Collaborative PC's/palmtops will be available in Jan 00
This talk is: http://www.npac.syr.edu/users/gcf/montrealxmlaug99
HTML version of Basic Foils prepared August 21 99

Foil 65 Overview of Collaboration with XML I

From XML and Shared Places on the Web XML Developers Conference Montreal -- August 19-20 1999. *
Full HTML Index
Over the last two years, we have built a web-based collaborative system TangoInteractive (http://www.webwisdom.com) which has been very successfully used for synchronous distance education.
Key features of TangoInteractive were its well defined API to applications in any language and its powerful shared browser built around a JavaScript Interface.
XML offers at least two important opportunities to advance this technology. Firstly the current shared HTML browser becomes a shared XML browser allowing custom style sheets on each collaborating client to present different views to each user. We are exploring this for distance education as a mechanism for universal access for both students and teachers of different capabilities and to support sessions where clients could simultaneously be PC's, palmtop and high end virtual environments such as CAVE's.
A second area where XML will play a key role is as the infrastructure with which to build collaborative web pages containing many different shared objects with both different functionalities and different collaboration configurations. In this talk we describe our prototype SPW (Shared Places on the Web) which we are building to explore both these ideas. The dynamic customizable configuration possibilities offered by this architecture, appears a dramatic improvement over current collaborative models which tend to offer rather rigid collaboration capabilities and policies.
HTML version of Basic Foils prepared August 21 99

Foil 66 Overview of Collaboration with XML II

From XML and Shared Places on the Web XML Developers Conference Montreal -- August 19-20 1999. *
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Our Shared Place is a virtual place on the Web where people can meet and work together.
They can use provided content and tools for collaborative work.
They can bring their own content and share it with others.
They can possibly create new content and take it with them to another Shared Place or store it on local disk for standalone work.
From the user's point of view, the Shared Place is an ordinary Web page with added collaboration functionality.
HTML version of Basic Foils prepared August 21 99

Foil 67 Overview of Collaboration with XML III

From XML and Shared Places on the Web XML Developers Conference Montreal -- August 19-20 1999. *
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The Shared Place technology has several architectural components.
First of all, the Shared Place Definition Language (SPDL) is an XML based language for defining properties of the Shared Places. SPDL describes all aspects of the the environment including collaboration functionality, shared object structure and user related configuration data.
  • This information includes session management and synchronization information; object initial state and persistence as well as communities and security.
The Shared Tool is a piece of software that can be embedded as a part of a Web page content and offers collaboration functionality using mechanisms provided by the Shared Place Framework. To interact with the Shared Place Framework, the Shared Tools must implement the Shared Place interface that can be in form of Java applet, plug-in, ActiveX object, or JavaScript applications.
Shared Place Framework is a set of mechanisms that implement collaboration services and expose them to Shared Tools using Shared Place interfaces. The Shared Place Framework will be implement in terms of existing Java based TangoInteractive infrastructure but linking the much richer SPDL based web pages.
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