----boundary-LibPST-iamunique-1139131543_-_-
Content-type: text/plain
René,
Have you looked at Helmut Zinn's Info subsystem?
http://www.zinnamturm.de/DownloadsIN.htm#Info
It seems his Helpdesk's Advisor, which was implemented using Info is
similar in that it is operating over a LAN, and is using Files. You
might update a local copy of the files whenever a change has been made
in the master set, with only the changed files being rewritten.
Antony
René Dorta wrote:
> Hello Bob,
> Thanks for your advice. I am already working with the last possibility
> you mentioned.
>
> Regards, René.
>
>
>
> Bob Walkden wrote:
>
>>It seems to me that the current model for files is a reasonable
>>compromise between simplicity, usefulness and safety. As soon as you
>>introduce concurrency you are no longer dealing with a 'simple file
>>application', and you have to respond accordingly.
>>
>>If you change the model so that other processes can read while one
>>process can write, then you run the risk of some of the problems which
>>database transaction management eliminates, such as non-repeatable
>>reads and dirty reads. To eliminate these you would need a more
>>finely-grained locking strategy, such as block and record locking.
>>Even these on their own don't fully eliminate the aforementioned
>>problems (and others which arise), and you start to need transactions.
>>This takes you into the realm of DBMSs.
>>
>>So the answer, in my opinion, is to recognise that you no longer have
>>a 'simple file application', and use the right tool for the job, in
>>this case the SQL module with a suitable DBMS which handles
>>concurrency well enough.
>>
>>Another possibility might be to look at the design of your
>>application, and identify those parts which require the files to be
>>updated. Separate them from the rest of the application and make sure
>>that they hold their locks for the shortest possible time by opening
>>the files only when you need to, and closing them as soon as you have
>>finished writing.
>>
>>--
>>Regards,
>> Bob
>>
>>
>>
>>>-----Original Message-----
>>>From: blackbox{([at]})nowhere.xy>>>Behalf Of René Dorta
>>>Sent: 03 June 2007 05:31
>>>To: BlackBox Mailing List
>>>Subject: [BlackBox] - readers & writers
>>>
>>>I have been using for a long time a simple file application.
>>>Due to the
>>>small size of my data I let alone SQL and use instead modules
>>>Files and
>>>Stores directly. Every thing worked fine till now, when I
>>>need to access
>>>my data from different computers in a LAN. How to handle this?: If I
>>>
>>>
>>
>>
>>
>>>open my files in "shared" mode ("which is the rule in BlackBox"), I
>>>cannot update them; on the other hand, if I use "exclusive" (which
>>>
>>>
>>is
>>
>>
>>>what I had been doing) I cannot open those files from more
>>>than one site.
>>>
>>>What I need is a way to write my files from a master site, but to be
>>>
>>>
>>
>>
>>
>>>able to read them from any site in the LAN.
>>>
>>>Thanks folks:
>>>René Dorta.
>>>
>>>--- BlackBox
>>>--- send subject HELP or UNSUBSCRIBE to blackbox{([at]})nowhere.xy>>>
>>>
>>>
>>>
>>>
>>
>>--- BlackBox
>>--- send subject HELP or UNSUBSCRIBE to blackbox{([at]})nowhere.xy>>
>>
>>
>>
>
--- BlackBox
--- send subject HELP or UNSUBSCRIBE to blackbox{([at]})nowhere.xy
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Received on Sun Jun 03 2007 - 17:13:05 UTC