From: On Behalf Of
Art
Sent: Tuesday, November 13, 2007 9:20 AM
To:
Subject: [ts-7000] In memory data shaired.
Hello all,
I have been working for sometime now on a web based control system.
This has both a configuration and operational interface from the web.
As well as the same controls in hardware. I have been currently
using a sqlite database for storage of the main data. This doesn't
seem to be a problem when reading but when I write to the data base
this could take some time. I really need this to be real time as in
fractions of a second. I have been looking at shared memory(shm.h) to
share resources between applications. My problem is the shared memory
is not big enuf for 4mg to 10 mg worth of data. there is not much I
can do to shrink that size. I really need to share a data structure
between applications or process that resides in memory. I would hope
there would be a way for me to create that data structure in own
program and pass a pointer to another program to access it. I know i
would normally get a segmentation error if I try to access memory in
another programs space. I may need to other IPC methods but I really
want to allow the programs to function independent from each other. I
don't really care about race conditions because the data is all last
action. I just care what the last change was.
---------------------------------------------------
Hi,
Can you build a server that keeps the database open then send it
transactions from a client? The transactions between the components could be
as simple as an AF_UNIX file system socket... If you used TCP or UDP sockets
you could keep the database on the same machine or distribute it to another
machine.
See
http://www.linuxhowtos.org/C_C++/socket.htm
for a coherent example of some approaches.
Bob
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