Databases Reference
In-Depth Information
2.5
Transaction Management
CSCW systems have to support both short transactions and long transactions,
because various types of cooperative work of users require both of them. One of
the typical solution to support long transactions is to provide two types of
workspaces (or databases), public and private ones, with check-in and check-out
mechanisms. A user can import data from a public workspace into her/his own
private workspace by checking out. When the user finished modification of the
data, s/he can return the modified data to the public workspace by checking in.
Though most of the existing CSCW systems support the two types of workspaces,
more flexible solutions are expected to support more extensive cooperative work.
2.6
Security and Privacy
To support practical cooperative work, CSCW systems need to provide mechanisms
protecting security and privacy of users. There is a trade-off between protection of
security and privacy and flexibility in sharing and collaboration in CSCW systems.
Thus, security mechanisms of CSCW systems should offer a dynamic access control
framework to users so that they can change security levels during collaboration.
3
VIEW Media: a Framework for CSCW systems
VIEW Media is a framework for CSCW systems developed by our laboratory. It
adopts database technology as a foundation of its architecture. VIEW Media is
designed as a collaborative hypermedia system. Developers can build applications
for specific purposes on the system, such as a distance education system, a
distributed conference system, and so forth.
3.1
The Fundamental Objects of VIEW Media
VIEW Media defines four types of fundamental objects constructing workspace
of the system:
•
User surrogate objects
represent users participating in workspace. A user
surrogate object contains profile and state information of a corresponding
user.
•
Hypermedia component objects
organize shared hypermedia documents.
Hypermedia is used as a basic data format for cooperative work on VIEW
Media. Results of collaboration are stored as hypermedia component objects
in an object repository of VIEW Media. The hypermedia model of VIEW
Media was designed for flexible customization, which is based on the Dexter
Hypertext Reference Model
28)
.
•
Equipment objects
provide various communication methods for interaction
among users such as chat tools, shared pointers and so forth.
