 
System
What environment variables does the system use, and what does it use them for ?
Why do errors occur when I run more than one collaborative application on
my PC ?
Modules
What happens when I Duplicate a collaborative module?
What happens when I Replace a collaborative module?
Why can't I get MSharePointer to create a pointer?
Server
When attempting a collaborative session with another user, we both get our
systems connected to the COVISAServer, but no data seems to pass.
When attempting a dynamic collaborative session, I get error messages telling me that
explorer could not start a particular module, even though my collaborator has one.
Sometimes when we run a collaborative session I get data as soon as I join the session,
and other times my collaborator has to send it to me.
Environment Variables
A number of environment
variables can be used to ease the setting up of a collaborative session.
- COVISA_CENTRAL_PORT - this should be set to the port number that the
COVISA_server is using. Some port numbers are reserved and are not available
at the user level, the port number that we typically use is 5127.
- COVISA_CENTRAL_MACHINE - this should be set to the machine name where the
COVISA_server is running. It should be set in the form: csindy12.leeds.ac.uk
- USER - this is used to identify a collaborator in the session and is
usually set by default on most UNIX systems. On Windows NT, this variable may
need to be explicitly set by the user using the
settings->control panel->system windows tool.
The MServer module picks up this information and uses it as default values
for some of its widgets. These can be altered at run time using the
module control panel. These values are particularly useful when creating
collaborative applications, or if the COVISAServer is always run at a
default location.
The COVISA_server, by default, uses the COVISA_CENTRAL_PORT variable to set
its port number. This can be changed by using the -port <PORT NUMBER>
command line argument.
Multiple Collaborative Applications
The MServer module creates a file in which it
stores session information. On UNIX systems this file is unique to each
session, hence many sessions may be executing on a single central
machine. Under Windows NT this file is not unique, hence only a single
session may be run on an individual machine.
Duplicating a Collaborative Module
When a module is duplicated (using the duplicate option from the popup menu
on the module), the effect varies depending on the current state of the module. If it
had not been initiated into the collaborative session (by pressing the Initiate button)
then the duplicated module automatically joins the collaborative session and forms a new
group. If it had been initiated and was already a group member, then the duplicate appears
to be a second member of the same group. The COVISAServer will not allow more than a single
member of a group by one collaborator, and will eventually kill the duplicate module (usually
when it attempts to become connected for the first time).
Replacing a Collaborative Module
When you replace a collaborative module (using the replace option from the popup menu
on the module), it deletes the old module and starts a new one. When this module is enabled
it initiates itself into the collaborative session and start a new group
(i.e. it will have a different group number and hence belong to a different group). This
happens irrespective of whether the module had previously been initiated or not.
MSharePointer
The MSharePointer module's Output port should be wired to the Render module's Input
port, and the Render module's Pick port should be wired to Input port of MSharePointer.
The Render module then needs to be set into the appropriate
mode.
One COVISAServer Per Session
Although both parties have successfully connected to a COVISAServer, it sounds
like you have connected to different servers. For data to be passed between
collaborators, they all have to be connected to a single COVISAServer.
Missing Modules ?
For a collaborative session to work correctly, the COVISA module suite must be
installed on all collaborator's machines, with the
modules appearing in the librarian of each collaborator. Also, any other user
written modules that need to be used within the session should be installed
locally for each collaborator. The system is not currently capable of downloading
module code at run time.
Different Server Modes
The COVISAServer can be run in one of two different modes:
-
Store and Forward (default mode) - in this mode the server keeps a copy of the last
shared data object passed to it for each collaborative group. When a collaborator joins
late, a copy of any stored data is automatically passed on.
-
Pass - in this mode the server merely passes data to collaborators who are currently
members of the session. No data is stored at the server.
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