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locking across multiple computersI have several computers that I want to synchronize access to a shared
resource. Can a semephore do this? If not, what can I use to synch access to a shared resource...across computers? Thanks. Amil I don't think so, no, named semaphores can be used for inter-process
communication on the same box but not across machines. It's not recommended (for obvious reasons) but you can do a quick & dirty lock with the file system using File.Open(<name>, FileMode.CreateNew); This succeeds if the file doesn't exist, throws an IOException if it does. The first machine to create the file "owns" the lock. On failure you need to poll. The owner deletes the file when done with the critical section. Since this isn't a true blocking lock and "blocked" processes aren't on a system queue there is a potential for starvation if multiple machines are trying to access the shared resource too frequently. Better is to use some form of IPC (e.g. .NET Remoting) and establish one machine as the resource master. All other machines make Remoting calls into the master to obtain access to the shared resource. The master should use a separate thread for each caller and can then block callers by waiting on an internal semaphore that controls access to the resource. -- TB Show quote "Amil Hanish" wrote: > I have several computers that I want to synchronize access to a shared > resource. Can a semephore do this? If not, what can I use to synch access > to a shared resource...across computers? > > Thanks. > > Amil > > > Amil Hanish wrote:
> I have several computers that I want to synchronize access to a shared What kind of shared resource is it and how do you access it?> resource. Can a semephore do this? If not, what can I use to synch access > to a shared resource...across computers? Max Assume it's like a smart device plugged into something; it really doesn't
matter. I'm just wanting to know if the Windows OS supports such a mechanism. 15 years ago I could easily do this on a VAX/VMS operating system using a cluster event flag (bit flags). I can't believe a "state of the art" OS can't do this now :-) Amil Show quote "Markus Stoeger" <spamhole@gmx.at> wrote in message news:ecEJaLQhGHA.4080@TK2MSFTNGP03.phx.gbl... > Amil Hanish wrote: >> I have several computers that I want to synchronize access to a shared >> resource. Can a semephore do this? If not, what can I use to synch >> access to a shared resource...across computers? > > What kind of shared resource is it and how do you access it? > > Max Sometimes I do miss VMS :)
Cheers, Greg Young MVP - C# http://geekswithblogs.net/gyoung Show quote "Amil Hanish" <amilhan***@hotmail.com> wrote in message news:%23lkOQ%23RhGHA.1204@TK2MSFTNGP02.phx.gbl... > Assume it's like a smart device plugged into something; it really doesn't > matter. I'm just wanting to know if the Windows OS supports such a > mechanism. 15 years ago I could easily do this on a VAX/VMS operating > system using a cluster event flag (bit flags). I can't believe a "state > of the art" OS can't do this now :-) > > Amil > > "Markus Stoeger" <spamhole@gmx.at> wrote in message > news:ecEJaLQhGHA.4080@TK2MSFTNGP03.phx.gbl... >> Amil Hanish wrote: >>> I have several computers that I want to synchronize access to a shared >>> resource. Can a semephore do this? If not, what can I use to synch >>> access to a shared resource...across computers? >> >> What kind of shared resource is it and how do you access it? >> >> Max > > Knowing the exact scheme would be better but I've seen something similar (an
application able to detect another instance on the network, is this similar ?). IMO it's likely just a network broadcast at startup... -- Patrice "Amil Hanish" <amilhan***@hotmail.com> a écrit dans le message de news: %23lkOQ%23RhGHA.1***@TK2MSFTNGP02.phx.gbl...Show quote > Assume it's like a smart device plugged into something; it really doesn't > matter. I'm just wanting to know if the Windows OS supports such a > mechanism. 15 years ago I could easily do this on a VAX/VMS operating > system using a cluster event flag (bit flags). I can't believe a "state > of the art" OS can't do this now :-) > > Amil > > "Markus Stoeger" <spamhole@gmx.at> wrote in message > news:ecEJaLQhGHA.4080@TK2MSFTNGP03.phx.gbl... >> Amil Hanish wrote: >>> I have several computers that I want to synchronize access to a shared >>> resource. Can a semephore do this? If not, what can I use to synch >>> access to a shared resource...across computers? >> >> What kind of shared resource is it and how do you access it? >> >> Max > > Simple scenario. Let's pretend I have a device like a special intelligent
fax that is attached to a network. Only one thing can be talking to it at a time. If I have several computers that want to use the intelligent fax, I someone how to synchronize access it to? How? Amil Show quote "Patrice" <scr***@chez.com> wrote in message news:O01AT5VhGHA.3376@TK2MSFTNGP03.phx.gbl... > Knowing the exact scheme would be better but I've seen something similar > (an application able to detect another instance on the network, is this > similar ?). > > IMO it's likely just a network broadcast at startup... > > -- > Patrice > > "Amil Hanish" <amilhan***@hotmail.com> a écrit dans le message de news: > %23lkOQ%23RhGHA.1***@TK2MSFTNGP02.phx.gbl... >> Assume it's like a smart device plugged into something; it really doesn't >> matter. I'm just wanting to know if the Windows OS supports such a >> mechanism. 15 years ago I could easily do this on a VAX/VMS operating >> system using a cluster event flag (bit flags). I can't believe a "state >> of the art" OS can't do this now :-) >> >> Amil >> >> "Markus Stoeger" <spamhole@gmx.at> wrote in message >> news:ecEJaLQhGHA.4080@TK2MSFTNGP03.phx.gbl... >>> Amil Hanish wrote: >>>> I have several computers that I want to synchronize access to a shared >>>> resource. Can a semephore do this? If not, what can I use to synch >>>> access to a shared resource...across computers? >>> >>> What kind of shared resource is it and how do you access it? >>> >>> Max >> >> > > Not an expert but IMO it doesn't work this way usually. All requests are
just queued for later processing. Keep in mind that because the fax device is working doesn't mean network communication are blocked... Depending on what you are after I would rather suggest a networking group (or a support for the product tyou are using ?)... -- Patrice "Amil Hanish" <amilhan***@hotmail.com> a écrit dans le message de news: eHJakrYhGHA.3***@TK2MSFTNGP05.phx.gbl...Show quote > Simple scenario. Let's pretend I have a device like a special intelligent > fax that is attached to a network. Only one thing can be talking to it at > a time. If I have several computers that want to use the intelligent fax, > I someone how to synchronize access it to? > > How? > > Amil > > "Patrice" <scr***@chez.com> wrote in message > news:O01AT5VhGHA.3376@TK2MSFTNGP03.phx.gbl... >> Knowing the exact scheme would be better but I've seen something similar >> (an application able to detect another instance on the network, is this >> similar ?). >> >> IMO it's likely just a network broadcast at startup... >> >> -- >> Patrice >> >> "Amil Hanish" <amilhan***@hotmail.com> a écrit dans le message de news: >> %23lkOQ%23RhGHA.1***@TK2MSFTNGP02.phx.gbl... >>> Assume it's like a smart device plugged into something; it really >>> doesn't matter. I'm just wanting to know if the Windows OS supports >>> such a mechanism. 15 years ago I could easily do this on a VAX/VMS >>> operating system using a cluster event flag (bit flags). I can't >>> believe a "state of the art" OS can't do this now :-) >>> >>> Amil >>> >>> "Markus Stoeger" <spamhole@gmx.at> wrote in message >>> news:ecEJaLQhGHA.4080@TK2MSFTNGP03.phx.gbl... >>>> Amil Hanish wrote: >>>>> I have several computers that I want to synchronize access to a shared >>>>> resource. Can a semephore do this? If not, what can I use to synch >>>>> access to a shared resource...across computers? >>>> >>>> What kind of shared resource is it and how do you access it? >>>> >>>> Max >>> >>> >> >> > >  |
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