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									                                     INFORMATION SHEET


1. Networking / Security:
The actual decisions about the implementation of the WAN is up to the network / hardware provider
and the client. Medical Spectrum recommend ISDN as we believe it provides excellent reliability and
communications latency. We will continue to recommend ISDN, if however the client chooses to use a
different connectivity method the onus is on them if the system fails to perform as expected or is
'dropping out'.

Medical Spectrum has been using ISDN successfully at locations in QLD, VIC and WA (some for over 2
years) and in all cases the performance and reliability of ISDN has been outstanding. To date, we are
not aware of any site that has had networking / communications type problems.

The ultimate requirement is for the network configuration employed to allow us to:

    1. Map 2 network drives on every PC - 1 to the primary server (over the WAN) and 1 to the sub-
        server at the computer’s local site
    2. Create 2 ODBC connections to 2 separate SQL Servers - 1 to the primary server and 1 to the
        sub-server at the computer’s local site
    3. Access shared folders on the primary and sub servers (mspdata) using UNC pathnames (i.e.
        \\servername\mspdata) from any computer
    4. Be permanently connected allowing automated after-hours processes to run, improving
        performance of in-hours operations.

We recommend that this be achieved, in part, though the use of a Windows NT ‘User Group’ that all
users that need access to Plexus are a member of. This group, preferably called ‘Plexus Users’, should
then be granted appropriate security access to any resources required to achieve points 1 to 3 above.
Before Plexus can be installed, the Name of the Domain and the ‘User Group’ will need to be supplied
to the Medical Spectrum consultant performing the installation.

2. Firewalls:
The use of firewalls is at the client’s discretion - as long as the Medical Spectrum Support Team is able
to run pcAnywhere through the firewall to the all the servers on the network (primary server and any

3. SQL Server vs. MSDE:
Plexus ships with MSDE 2000, the free version of SQL Server, called Microsoft Desktop Engine, not to
be confused with its predecessor MSDE 1.0 – Microsoft Database Engine.

MSDE 2000 is the equivalent of SQL Server 2000.
MSDE 1.0 is the equivalent of SQL Server 7.0

MSDE is suitable in a lot of circumstances but the following limitations make it unsuitable in some

    •   The primary server in a multi-site Plexus installation MUST be a full version of SQL Server
        2000 (MSDE does not support being the publisher of a transactional replication publication)

    •   MSDE is limited internally to executing 5 simultaneous processes, which make it unsuitable for
        use at large sites. Large sites (even sub-sites) will need a full version of SQL Server 2000.
              -   We have no direct evidence of what a 'large' site is at this stage.
              -   The situation is that MSDE will only process 5 simultaneous processes, therefore if the
                  site has 5 computers or less MSDE would clearly be suitable.
              -   As you go above 5 computers the question becomes how many of the computers will
                  be trying to simultaneously access the server?
              -   We believe that once a site has somewhere between 10 and 20 computers they
                  should be changing to the full version of SQL Server.
              -   In general use of Plexus, even if you have 20 computers, it would be unlikely that
                  they would all be making requests all the time and at the same time.
              -   Since Plexus makes many short requests (in normal operations), it is likely that MSDE
                  would be suitable for these larger numbers (10 - 20) of computers at a site without
                  the users noticing significant reduction in performance.
              -   The limitation of 5 processes does not prevent 5 or more computers connecting to the
                  SQL Server - it simply won’t process more then 5 queries at a time (this is not the full
                  story - for more information on this process see the Microsoft SQL Server 2000
                  literature and look for 'governor').

The limitations mentioned above are not the only limitations in MSDE - there are others such as a 2Gb
limitation on database sizes. For more information about these limitations see the Microsoft literature
regarding MSDE 2000.

MSDE is suitable for web-access however the 5 simultaneous processes still apply.


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