File notifications in Zato 2.0

One of many great things about Zato is the fact how easy it is to plug into it new data sources and input methods triggering one's SOA/API services.

For instance, Zato 2.0 does not have a web-admin GUI for file notifications but it is still possible to listen for new or updated files in directories of choice and invoke services each time a new event arrives, e.g. when a new file is dropped into a directory, effectively creating a new channel type in addition to what Zato comes with out of the box.

This is exactly what the script below does - it uses watchmedo, part of the watchdog package, to listen for events in a given directory. Each time anything of interest happens in that directory (here - in /tmp/data) a Zato service defined below is invoked with a path to that item of interest provided on input.

#!/bin/bash

watchmedo shell-command \
    --patterns="*" \
    --command='curl localhost:11223/file.notifications?path=${watch_src_path}; echo' \
    /tmp/data

It's entirely up to that service to decide how to handle the data in each file - one can decide to deliver it to any of outgoing connections in Zato using, for instance, AMQP, SMTP, FTP, ElasticSearch, Solr or do anything else that is required in a given integration scenario.

Just to exemplify the idea, in this blog post the data is simply stored in server.log:

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

from __future__ import absolute_import, division, print_function, unicode_literals

# Zato
from zato.server.service import Service

class FileNotifications(Service):
    name = 'file.notifications'

    class SimpleIO(object):
        input_required = ('path',)

    def handle(self):

        # Read data in
        data = open(self.request.input.path).read().strip()

        # Since this is just an example, only log the contents of what was read in
        self.logger.info('Data from %s is `%s`', self.request.input.path, data)