Background

1
Architecture of Internet Based Groupware
Applications

• Background
• Email
• News
• The Web

2
bscw, SiteScape, etc
Applications
News
Web
Mail
Protocols
Calendars
nntp
smtp
http
cap - calendar access p.
The World Computer - a Network of networks. The
Internet
Others rtp - real time p. nstp - notification
service p. rvp - rendezvous protocol
3
SMTP - Simple mail transfer protocol - allows
computers on the internet to pass mail to one
another
POP- post office protocol -transfers mail to
client computer, allows client to retrieve mail
from server or IMAP - Internet Message Access
Protocol - mail is delivered to server (may or
may not be replicated on client)
MTA/MTS- Mail Transfer Agent /Message
Transport System
MUA - Mail User Agent, e.g. pine
Inbox
Interacts with users to read and write mail
messages
Transfers mail messages across the network
to inboxes routes all messages
Email systems
4
Email compared to Simple File Sharing Email for
Groupwork

• It solves the unannotated data store problem - we
  can describe attachments
• It is mode of communication - unlike file sharing
• Individual mail boxes can be used to manage files
  and supercede file systems.

• Unless there is clear higher level protocol, it
  is difficult to reconstruct a group discussion
  using email.
• In theory, reconstruction may be possible, but in
  practice its infeasible.

5
Group email scenario

• Fred wants Jane to review a proposal which is
  being developed by Alice.
• So Fred emails it to Jane, ccd to Alice.
• Then Jane has a query for Fred, so she replies
  and Alice gets an unnecessary ccd message.
• New colleagues are roped into the discussion and
  ccd, but they dont have access to the earlier
  emails.
• Sally who set this job up and asked Fred to bring
  in Jane isnt involved except for her first email
  to Fred.
• Sally leaves the company and is replaced. Her
  replacement doesnt have any record of her
  original email to Fred.

6
Email vs. Doc Bases

• You may not need what I send you
• You may not need it now, but will later. And when
  you do, you may have forgotten it or deleted it.
• If you put it in a centralised document base
  (news or web log, e.g. wiki, BSCW etc), you can
  find it later.
• Doc bases organised for users
• Nonintruesive - you read when you want to
• Centralised - more reliable
• Historical record
• Searchable
• Also there are tools to convert mail archives
  into hypertext, e.g. Hughes Hypermail, also
  Internet calendaring and scheduling linked to
  email and doc bases.

7
News and the Web and email
Software has been developed to mirror news
messages into a parallel web archive - this has
the advantage that all web tools such as search
engines can be applied to newsgroups.
Usenet/newsgroup
N.b. users post to news groups using email.
Relies on replication through server to
server newsfeeds or site specific news servers
News server
News reader
News server
nntp - network news transfer protocol
8
url - universal resource locator, compare udi -
universal document identifier, uri - universal
resource identifier
The Web
MIME - Multipurpose Internet Mail extensions
http- a request-response protocol - no notion of
a session, but also ftp, nntp -
http is faster and stateless TCP
connect for each operation.
Web Server
Web Client
cgi scripts
html pages
html pages
html - hypertext mark-up language/xml -
eXtensible mark-up language
Application
9
Limitations of the Web -1

• Limited awareness
• no idea of who else is browsing a page or
  updating it
• so no notification of changes
• Poor User Interface
• no menu bars, so cluttered UI and all operations
  a click away
• difficult to reflect changes especially at the UI
  level
• no local support for interaction as web clients
  are dumb - computation is usually on the
  server, e.g. difficult to view documents through
  the hierarchy in BSCW
• Limited Configurability/Tailorability
• again because through the server - central
  administration of user preferences

10
Limitations of the Web - 2

• Communication Limited to Client-Server - a
  request-response protocol
• no (server initiated) server-client
  communications
• no client-client communications
• Pure Centralised Architecture
• no support for distribution of information and
  computation amongst servers
• no replication across servers
• No Guaranteed Quality of Service
• bursty data
• no real-time support

11
Successful Web-based Groupware
1. BSCW 2. TCBWorks 3. CoMentor 4. WinWin 5. OU
World Wide Design Lab 6. Columbias OzWeb
hypermedia collaboration environment 7. Oulus
Web-based Inspection tools
12
Recent Protocol proposals

• CAP - Calendar Access Protocol to support
  Internet calendaring and Scheduling applications
• NSTP - Notification Service Transport Protocol to
  support event notification (compare BSCW MetaWeb
  solution)
• RVP - Rendezvous Protocol to support
  synchronisation of operations
• RTP - Real-Time Protocol to support time critical
  applications

13
References

• 2 BSCW papers
• The World Wide Web as enabling technology for
  CSCW The case of BSCW
• Beyond Web Technology - Lessons Learnt from BSCW
• Columbia paper WWW-based collaboration
  environments with distributed services in World
  Wide Web Journal, 1, 1998
• OU book - The Knowledge Web
• IEEE Internet Computing paper - Collaborative
  Technologies for Evolving Software Systems,
  Nov-Dec 98

14
Architecture of Internet Based Groupware
Applications BSCW Case Study

• Review
• BSCW Users View
• Basic Architecture
• Extended Architecture

15
Limitations of the Web -1

• Limited awareness
• no idea of who else is browsing a page or
  updating it
• so no notification of changes
• Poor User Interface
• no menu bars, so cluttered UI and all operations
  a click away
• difficult to reflect changes especially at the UI
  level
• no local support for interaction as web clients
  are dumb - computation is usually on the
  server, e.g. difficult to view documents through
  the hierarchy in BSCW
• Limited Configurability/Tailorability
• again because through the server - central
  administration of user preferences

16
Limitations of the Web - 2

• Communication Limited to Client-Server - a
  request-response protocol
• no (server initiated) server-client
  communications
• no client-client communications
• Pure Centralised Architecture
• no support for distribution of information and
  computation amongst servers
• no replication across servers
• No Guaranteed Quality of Service
• bursty data
• no real-time support

17
Successful Web-based Groupware
1. BSCW 2. TCBWorks 3. CoMentor 4. WinWin 5. OU
World Wide Design Lab 6. Columbias OzWeb
hypermedia collaboration environment 7. Oulus
Web-based Inspection tools
18
BSCW - Users view
19
Common Gateway Interface
The server supporting CGI treats some HTTP
requests as calls to CGI scripts which are
invoked and handle the request usually providing
an HTML page in reply.
20
Basic BSCW Architecture
21
MetaWeb Server
This has been used to extend the Web with support
for synchronous groupware applications. The
MetaWeb server provides a event notification
service through the MetaWeb client API.
22
Extended BSCW Architecture

23
References

• 2 BSCW papers
• The World Wide Web as enabling technology for
  CSCW The case of BSCW
• Beyond Web Technology - Lessons Learnt from BSCW
• For pure Java applications - SUNs Java Shared
  Data Toolkit can be used to build groupware
  applications requiring support for synchronous
  communication. (see java.sun.com/products/java-med
  ia/jsdt/jsdt-faq.html)