[Zope3-Users] Re: lovely.remotetask question

[Jürgen Kartnaller]

Maciej Wisniowski wrote:
> Hi
> 
> I want to use lovely.remotetask in Z3 application.
> Use case is very simple:
> User views page, this causes long running function to be started
> and Ajax calls from the page check every second if there is a result.
> 
> I have:
> 1. content object (Folderish) with instance of remotetask.TaskService()
>     called 'monitor_service' inside
> 
> 2. mytask = remotetask.task.SimpleTask(myLongRunningFunction)
> 
> 3. named utility for 'mytask'
> 
> The question is how should I start and stop remotetask jobs?
> Currently, when user enters a page I call (every time):
> 
> jobid = self['monitor_service'].add(u'mytask', appdict)
> self['monitor_service'].startProcessing()
> 
> Then ajax is repeadetly checking for result and when
> status is Completed I call
> 
> self['monitor_service'].stopProcessing()
> 
> It works nice, but after looking into service.py code I see
> it will break when I'll have few concurrent users.
> 
> Seems that I should call startProcessing() on zope startup
> and stopProcessing on zope shutdown?

For startup do this :

@component.adapter(IDatabaseOpenedEvent)
def startRemoteTask(event):
     """Start the amazon remotetask on startup."""
     db = event.database
     connection = db.open()
     root = connection.root()
     root_folder = root.get(ZopePublication.root_name, None)
     for site in root_folder.values():
         service = component.queryUtility(
             ITaskService, context=site)
         if service is not None:
             if not service.isProcessing():
                 service.startProcessing()

I assume here that the remote tasks are located in one of the site 
directly contained in root.


For shutdown :

I have no solution for this right now.