How to use async callbacks

orders.py

# -*- coding: utf-8 -*-

from __future__ import absolute_import, division, print_function, unicode_literals

# Zato
from zato.server.service import Service

ORDER_CACHE_PREFIX = 'order.{}'

class AcceptOrder(Service):
    name = 'esb.order.accept'

    def handle(self):

        # Store context in Redis
        ctx = {'my':'important data'}
        self.kvdb.conn.hmset(ORDER_CACHE_PREFIX.format(self.cid), ctx)

        # Easier to work with Bunch objects
        async_request = self.request.bunchified()
        async_request.cid = self.cid

        # Invoke the adapter in async
        self.invoke_async('esb.feasibility-study', async_request, callback='esb.order.confirm')

class FeasibilityStudy(Service):
    name = 'esb.feasibility-study'

    class SimpleIO:
        input_required = ('cid', 'address', 'product')
        output_required = ('result', 'cid')

    def handle(self):

        # Connect to inventory backend and check if we can offer a line on that address
        conn = self.outgoing.plain_http['My Inventory'].conn

        # In practice, interesting data would be extracted from response here
        response = conn.post(self.cid, {'address':'abc', 'product':'My 4G'})

        self.response.payload = {'result':'Ok, can be done', 'cid':self.request.input.cid}

class ConfirmOrder(Service):
    name = 'esb.order.confirm'

    def handle(self):

        # Look up context in Redis
        ctx = self.kvdb.conn.hgetall(ORDER_CACHE_PREFIX.format(self.request.cid))

        # Do something useful based on context here
        pass

        # Notify the initial caller of the result
        conn = self.outgoing.plain_http['My Client'].conn

        # Here we just pass the response in as-is
        conn.post(self.cid, self.request.payload)