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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">The answer is “sort of”. Most projects (including Nova) publish to an RPC “notifications” channel (e.g. in rabbitMQ or whichever you use in your deployment).
 This is how Ceilometer gets some of its data.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">There is common code for connecting to the notification queue in Oslo (the “rpc” and “notifier” modules, particularly), but the exercise of actually setting
 up your consumer is left up to you, and there are various gotchas that aren’t well-documented. Ceilometer’s code is a reasonable starting point for building your own.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">As this is an area I’ve been experimenting with lately I’ll say that once you get it all working it is certainly functional and will deliver exactly what you’re
 asking for, but it can be a fair bit of engineering effort if you’re not familiar with how these things work already.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">This is an area I hope can be improved in OpenStack in future releases.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Hope that helps,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
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<![if !supportLists]><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><span style="mso-list:Ignore">-<span style="font:7.0pt "Times New Roman"">         
</span></span></span><![endif]><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Gabriel<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">From:</span></b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif""> openstack learner [mailto:openstackleaner@gmail.com]
<br>
<b>Sent:</b> Friday, October 18, 2013 11:57 AM<br>
<b>To:</b> openstack@lists.openstack.org; openstack-dev@lists.openstack.org<br>
<b>Subject:</b> [openstack-dev] Does openstack have a notification system that will let us know when a server changes state ?<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt">Hi all,<br>
<br>
<br>
I am using the openstack python api. After I boot an instance, I will keep polling the instance status to check if its status changes from BUILD to ACTIVE.<br>
<br>
My question is:<br>
<br>
does openstack have a notification system that will let us know when a vm changes state (e.g. goes into ACTIVE state)? then we won't have to keep on polling it  when we need to know the change of the machine state.<o:p></o:p></p>
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<p class="MsoNormal">Thanks<o:p></o:p></p>
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<p class="MsoNormal">xin<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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