HTTP Callback Tasks (Webhooks)

• Basics
• Django webhook example
• Calling webhook tasks

The HTTP callback tasks uses GET/POST data to pass arguments and returns result as a JSON response. The scheme to call a task is:

or using POST:

注解

POST data needs to be form encoded.

The web page should then return a response in the following format if the execution was successful:

{'status': 'success', 'retval': …}

or if there was an error:

To enable the HTTP dispatch task you have to add to CELERY_IMPORTS, or start the worker with -I celery.task.http.

With this information you could define a simple task in Django:

from anyjson import serialize
def multiply(request):
    x = int(request.GET['x'])
    y = int(request.GET['y'])
    response = {'status': 'success', 'retval': result}
    return HttpResponse(serialize(response), mimetype='application/json')

def multiply
    @x = params[:x].to_i
    @y = params[:y].to_i
    @status = {:status => 'success', :retval => @x * @y}
end

You can easily port this scheme to any language/framework; new examples and libraries are very welcome.

To call a task you can use the class:

URL is a shortcut to the HttpDispatchTask. You can subclass this to extend the functionality.

>>> from celery.task.http import HttpDispatchTask
>>> res = HttpDispatchTask.delay(
...     url='http://example.com/multiply',
...     method='GET', x=10, y=10)
>>> res.get()
100

The output of celery worker (or the log file if enabled) should show the task being executed:

[INFO/MainProcess] Task celery.task.http.HttpDispatchTask