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List: openjdk-awt-dev
Subject: <AWT Dev> [11] JDK-8153732: Windows remote printer changes do not reflect in lookupPrintServices()
From: Shashidhara Veerabhadraiah <shashidhara.veerabhadraiah () oracle ! com>
Date: 2018-06-20 10:12:03
Message-ID: afa12391-489d-4997-b2b8-9925a36cf756 () default
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Hi All, Please review this code changes for the below enhancement.
Enhancement: https://bugs.openjdk.java.net/browse/JDK-8153732
Webrev: http://cr.openjdk.java.net/~sveerabhadra/8153732/webrev.00/
Details of the changes: Windows provides *PrinterChangeNotification* functions that \
provides information about printer status changes of the local printers(subset) but \
not network printers. Alternatively, Windows provides a way thro' which one can get \
the network printer status changes by using WMI, RegistryKeyChange combination, which \
is a slightly complex mechanism. The Windows WMI offers an async and sync method to \
read thro' registry via the WQL query. The async method is considered dangerous as it \
leaves open a channel until we close it. But the async method has the advantage of \
being notified of a change in registry by calling callback without polling for it. \
The sync method uses the polling mechanism to notify. RegistryValueChange cannot be \
used in combination with WMI to get registry value change notification because of an \
error that may be generated because the scope of the query would be too big to \
handle(at times). Hence an alternative mechanism is choosen via the EnumPrinters by \
polling for the count of printer status changes(add\remove) and based on it update \
the printers list(both local and remote printers - superset).
Thanks and regards,
Shashi
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vlink="#954F72"><div class=WordSection1><p class=MsoNormal>Hi All, Please review this \
code changes for the below enhancement.<o:p></o:p></p><p \
class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Enhancement: <a \
href="https://bugs.openjdk.java.net/browse/JDK-8153732">https://bugs.openjdk.java.net/browse/JDK-8153732</a><o:p></o:p></p><p \
class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Webrev: <a \
href="http://cr.openjdk.java.net/~sveerabhadra/8153732/webrev.00/">http://cr.openjdk.java.net/~sveerabhadra/8153732/webrev.00/</a><o:p></o:p></p><p \
class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Details of the changes: \
Windows provides *PrinterChangeNotification* functions that provides information \
about printer status changes of the local printers(subset) but not network \
printers. <br>Alternatively, Windows provides a way thro' which one can get the \
network printer status changes by using WMI, RegistryKeyChange combination, which is \
a slightly complex mechanism. <br>The Windows WMI offers an async and sync \
method to read thro' registry via the WQL query. The async method is considered \
dangerous as it leaves open a channel until we close it. But the async method has the \
advantage of being notified of a change in registry by calling callback without \
polling for it. The sync method uses the polling mechanism to \
notify. <br>RegistryValueChange cannot be used in combination with WMI to get \
registry value change notification because of an error that may be generated because \
the scope of the query would be too big to handle(at times). <br>Hence an \
alternative mechanism is choosen via the EnumPrinters by polling for the count of \
printer status changes(add\remove) and based on it update the printers list(both \
local and remote printers - superset).<o:p></o:p></p><p \
class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Thanks and \
regards,<o:p></o:p></p><p class=MsoNormal>Shashi<o:p></o:p></p></div></body></html>
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