Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!uunet!dptechno!dave
From: dave@dptechno.UUCP (Dave Lee)
Newsgroups: comp.databases
Subject: Re: db_VISTA III -vs- Relational DBMS'
Message-ID: <554@dptechno.UUCP>
Date: 9 Aug 90 20:27:16 GMT
References: <15660@s.ms.uky.edu> <1990Aug8.144318.10203@dg-rtp.dg.com> <2660@lamont.ldgo.columbia.edu>
Reply-To: dave@dptechno.UUCP (Dave Lee)
Organization: D.P. Technology Corp. Camarillo California
Lines: 45

In article <2660@lamont.ldgo.columbia.edu> paulf@lamont.ldgo.columbia.edu (paul friberg) writes:
>Another addition to the list of problems with db_vista III is its
>lack of networking (i.e., client/server communications). This is 
>fine if you are operating in a homogeneous network where you can
>NFS mount your data disk on every host from which you wish to access 
>the data base. For a heterogeneous network, however, you are basically
>screwed. 
>
>Can anyone offer any insight into db_vista as to how it does
>its IPC?

I use db_vista III under unix and have developed a product that
uses it in a multi-user,multi-computer network.

DB_vista has support for multi-computer networks under DOS,
using LAN manager system locking.


Under unix, there is direct support for  multi-USER, single CPU 
systems.  Data is stored in binary form in the host`s native format.
IPC is through the OS-specific system calls (message queues on SYSV,
sockets on BSD).  

There is support for a system independant locking
stratagy that relies solely on lock files in a common directory.
This technique is not recomended due to high file access overhead.
This MAY work on multi-computer networks using NFS, but I havent
tried it. However, all CPU's must share the same basic data representation.

The system I constructed used a server host running a db_vista back end
for every active user.  A front end on the client cpu communicates with
the back end on the host via  a RPC interface.  All data transmited
to/from the backend is in ASCII and encoded/decoded at each end.

Also high level commands are implemented such as update,create,query ...

I find this scheme quite acceptable, although it did require a good
deal of my coding to implement.
 
 
 

-- 
Dave Lee
uunet!dptechno!dave