Hi all, In Plone2.5.5(with Zope2.9.6-final) I use zasync as my schedule task framework, it works well. Then I update my site to Plone3.1.7, and go further update to use Zope2.11.2 and ZODB3.9.0. Now I want to replace zasync with zc.async. As I know in Zope3 there is a event 'zope.app.appsetup.IDatabaseOpenedEvent' that you can subscribe to start your zc.async dispatcher. But in Zope2.11.2, the event never be fired, so I have to find other point to start the dispatcher. My method is start it when you first use it, see the snip following: =============== class AsyncTool( UniqueObject, SimpleItem, ActionProviderBase ): ... def addJob( self, *args ): ''' ''' self._startZCAsync() portal = getToolByName(self,'portal_url').getPortalObject() # get queue from portal root queue = zc.async.interfaces.IQueue( portal ) # insert a job job = queue.put( Job(...) ) def _startZCAsync( self ): # create volatile attributes if not hasattr( self, '_v_start_zcasync' ): self._v_start_zcasync = 0 if not self._v_start_zcasync: db = Zope2.DB # zc.async does not startup, start it now zc.async.configure.base() zc.async.configure.start( db, poll_interval=1, twisted=False ) self._v_start_zcasync = 1 =============== It works, but fragile. Any of my jobs execute failure will cause the 'volatile' attribute '_v_start_zcasync' lost, and dispatcher start process will run again, this cause error. So I want to know the right time to start zc.async dispatcher in Zope2? best regards eastxing