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# Slixmpp Quickstart - Echo Bot

Note

If you have any issues working through this quickstart guide join the chat room at slixmpp@muc.poez.io.

If you have not yet installed Slixmpp, do so now by either checking out a version with Git.

As a basic starting project, we will create an echo bot which will reply to any messages sent to it. We will also go through adding some basic command line configuration for enabling or disabling debug log outputs and setting the username and password for the bot.

For the command line options processing, we will use the built-in `argparse` module and the `getpass` module for reading in passwords.

## TL;DR Just Give Me the Code

As you wish: the completed example.

## Overview

To get started, here is a brief outline of the structure that the final project will have:

    #!/usr/bin/env python
    # -*- coding: utf-8 -*-

    import logging
    from getpass import getpass
    from argparse import ArgumentParser

    import asyncio
    import slixmpp

    '''Here we will create out echo bot class'''

    if __name__ == '__main__':
        '''Here we will configure and read command line options'''

        '''Here we will instantiate our echo bot'''

        '''Finally, we connect the bot and start listening for messages'''

## Creating the EchoBot Class

There are three main types of entities within XMPP — servers, components, and clients. Since our echo bot will only be responding to a few people, and won’t need to remember thousands of users, we will use a client connection. A client connection is the same type that you use with your standard IM client such as Pidgin or Psi.

Slixmpp comes with a `ClientXMPP` class which we can extend to add our message echoing feature. `ClientXMPP` requires the parameters `jid` and `password`, so we will let our `EchoBot` class accept those as well.

    class EchoBot(slixmpp.ClientXMPP):

        def __init__(self, jid, password):
            super().__init__(jid, password)

### Handling Session Start

The XMPP spec requires clients to broadcast its presence and retrieve its roster (buddy list) once it connects and establishes a session with the XMPP server. Until these two tasks are completed, some servers may not deliver or send messages or presence notifications to the client. So we now need to be sure that we retrieve our roster and send an initial presence once the session has started. To do that, we will register an event handler for the session_start event.

    def __init__(self, jid, password):
       super().__init__(jid, password)

       self.add_event_handler('session_start', self.start)

Since we want the method `self.start` to execute when the session_start event is triggered, we also need to define the `self.start` handler.

    async def start(self, event):
        self.send_presence()
        await self.get_roster()

Warning

Not sending an initial presence and retrieving the roster when using a client instance can prevent your program from receiving presence notifications or messages depending on the XMPP server you have chosen.

Our event handler, like every event handler, accepts a single parameter which typically is the stanza that was received that caused the event. In this case, `event` will just be an empty dictionary since there is no associated data.

Our first task of sending an initial presence is done using `send_presence`. Calling `send_presence` without any arguments will send the simplest stanza allowed in XMPP:

    <presence />

The second requirement is fulfilled using `get_roster`, which will send an IQ stanza requesting the roster to the server and then wait for the response. You may be wondering what `get_roster` returns since we are not saving any return value. The roster data is saved by an internal handler to `self.roster`, and in the case of a `ClientXMPP` instance to `self.client_roster`. (The difference between `self.roster` and `self.client_roster` is that `self.roster` supports storing roster information for multiple JIDs, which is useful for components, whereas `self.client_roster` stores roster data for just the client’s JID.)

It is possible for a timeout to occur while waiting for the server to respond, which can happen if the network is excessively slow or the server is no longer responding. In that case, an `IQTimeout` is raised. Similarly, an `IQError` exception can be raised if the request contained bad data or requested the roster for the wrong user. In either case, you can wrap the `get_roster()` call in a `try`/`except` block to retry the roster retrieval process.

The XMPP stanzas from the roster retrieval process could look like this:

    <iq type="get">
      <query xmlns="jabber:iq:roster" />
    </iq>

    <iq type="result" to="echobot@example.com" from="example.com">
      <query xmlns="jabber:iq:roster">
        <item jid="friend@example.com" subscription="both" />
      </query>
    </iq>

Additionally, since `get_roster` is using `<iq/>` stanzas, which will always receive an answer, it should be awaited on, to keep a synchronous flow.

### Responding to Messages

Now that an `EchoBot` instance handles session_start, we can begin receiving and responding to messages. Now we can register a handler for the message event that is raised whenever a message is received.

    def __init__(self, jid, password):
       super().__init__(jid, password)

       self.add_event_handler('session_start', self.start)
       self.add_event_handler('message', self.message)

The message event is fired whenever a `<message />` stanza is received, including for group chat messages, errors, etc. Properly responding to messages thus requires checking the `'type'` interface of the message stanza object. For responding to only messages addressed to our bot (and not from a chat room), we check that the type is either `normal` or `chat`. (Other potential types are `error`, `headline`, and `groupchat`.)

    def message(self, msg):
        if msg['type'] in ('normal', 'chat'):
            msg.reply("Thanks for sending:\n%s" % msg['body']).send()

Let’s take a closer look at the `.reply()` method used above. For message stanzas, `.reply()` accepts the parameter `body` (also as the first positional argument), which is then used as the value of the `<body />` element of the message. Setting the appropriate `to` JID is also handled by `.reply()`.

Another way to have sent the reply message would be to use `send_message`, which is a convenience method for generating and sending a message based on the values passed to it. If we were to use this method, the above code would look as so:

    def message(self, msg):
        if msg['type'] in ('normal', 'chat'):
            self.send_message(mto=msg['from'],
                              mbody='Thanks for sending:\n%s' % msg['body'])

Whichever method you choose to use, the results in action will look like this:

    <message to="echobot@example.com" from="someuser@example.net" type="chat">
      <body>Hej!</body>
    </message>

    <message to="someuser@example.net" type="chat">
      <body>Thanks for sending:
      Hej!</body>
    </message>

Note

XMPP does not require stanzas sent by a client to include a `from` attribute, and leaves that responsibility to the XMPP server. However, if a sent stanza does include a `from` attribute, it must match the full JID of the client or some servers will reject it. Slixmpp thus leaves out the `from` attribute when replying using a client connection.

## Command Line Arguments and Logging

While this isn’t part of Slixmpp itself, we do want our echo bot program to be able to accept a JID and password from the command line instead of hard coding them. We will use the `argparse` module for this.

We want to accept three parameters: the JID for the echo bot, its password, and a flag for displaying the debugging logs. We also want these to be optional parameters, since passing a password directly through the command line can be a security risk.

    if __name__ == '__main__':
        # Setup the command line arguments.
        parser = ArgumentParser(description=EchoBot.__doc__)

        # Output verbosity options.
        parser.add_argument("-q", "--quiet", help="set logging to ERROR",
                            action="store_const", dest="loglevel",
                            const=logging.ERROR, default=logging.INFO)
        parser.add_argument("-d", "--debug", help="set logging to DEBUG",
                            action="store_const", dest="loglevel",
                            const=logging.DEBUG, default=logging.INFO)

        # JID and password options.
        parser.add_argument("-j", "--jid", dest="jid",
                            help="JID to use")
        parser.add_argument("-p", "--password", dest="password",
                            help="password to use")

        args = parser.parse_args()

        if args.jid is None:
            args.jid = input("Username: ")
        if args.password is None:
            args.password = getpass("Password: ")

Since we included a flag for enabling debugging logs, we need to configure the `logging` module to behave accordingly.

    if __name__ == '__main__':

        # .. option parsing from above ..

        logging.basicConfig(level=args.loglevel,
                            format='%(levelname)-8s %(message)s')

## Connecting to the Server and Processing

There are three steps remaining until our echo bot is complete:

  1. We need to instantiate the bot.

  2. The bot needs to connect to an XMPP server.

  3. We have to instruct the bot to start running and processing messages.

Creating the bot is straightforward, but we can also perform some configuration at this stage. For example, let’s say we want our bot to support service discovery and pings:

    if __name__ == '__main__':

        # .. option parsing and logging steps from above

        xmpp = EchoBot(opts.jid, opts.password)
        xmpp.register_plugin('xep_0030') # Service Discovery
        xmpp.register_plugin('xep_0199') # Ping

If the `EchoBot` class had a hard dependency on a plugin, we could register that plugin in the `EchoBot.__init__` method instead.

Now we’re ready to connect and begin echoing messages. If you have the package `aiodns` installed, then the `slixmpp.clientxmpp.ClientXMPP.connect()` method will perform a DNS query to find the appropriate server to connect to for the given JID. If you do not have `aiodns`, then Slixmpp will attempt to connect to the hostname used by the JID, unless an address tuple is supplied to `slixmpp.clientxmpp.ClientXMPP.connect()`.

    if __name__ == '__main__':

        # .. option parsing & echo bot configuration
        xmpp.connect():
        asyncio.get_event_loop().run_forever()

The `slixmpp.basexmpp.BaseXMPP.connect()` will only schedule a connection asynchronously. To actually connect, you need to let the event loop take over. This is done the normal asyncio way, which you can learn about in the official Python documentation. Here we are making it run forever, but you can use any asyncio handling you want, for instance to integrate slixmpp into an existing event loop.

Another common usecase is to make it run only until it gets disconnected, with `asyncio.get_event_loop().run_until_complete(xmpp.disconnected)`.

Note

In previous versions of slixmpp, there was a `process()` method which handled the event loop for you, but it was a very common source of confusion for people unfamiliar with asyncio.

## The Final Product

Here then is what the final result should look like after working through the guide above. The code can also be found in the Slixmpp examples directory.

You can run the code using:

    python echobot.py -d -j echobot@example.com

which will prompt for the password and then begin echoing messages. To test, open your regular IM client and start a chat with the echo bot. Messages you send to it should be mirrored back to you. Be careful if you are using the same JID for the echo bot that you also have logged in with another IM client. Messages could be routed to your IM client instead of the bot.

    #!/usr/bin/env python3

    # Slixmpp: The Slick XMPP Library
    # Copyright (C) 2010  Nathanael C. Fritz
    # This file is part of Slixmpp.
    # See the file LICENSE for copying permission.

    import logging
    from getpass import getpass
    from argparse import ArgumentParser

    import asyncio
    import slixmpp

    class EchoBot(slixmpp.ClientXMPP):

        """
        A simple Slixmpp bot that will echo messages it
        receives, along with a short thank you message.
        """

        def __init__(self, jid, password):
            slixmpp.ClientXMPP.__init__(self, jid, password)

            # The session_start event will be triggered when
            # the bot establishes its connection with the server
            # and the XML streams are ready for use. We want to
            # listen for this event so that we we can initialize
            # our roster.
            self.add_event_handler("session_start", self.start)

            # The message event is triggered whenever a message
            # stanza is received. Be aware that that includes
            # MUC messages and error messages.
            self.add_event_handler("message", self.message)

        async def start(self, event):
            """
            Process the session_start event.

            Typical actions for the session_start event are
            requesting the roster and broadcasting an initial
            presence stanza.

            Arguments:
                event -- An empty dictionary. The session_start
                         event does not provide any additional
                         data.
            """
            self.send_presence()
            await self.get_roster()

        def message(self, msg):
            """
            Process incoming message stanzas. Be aware that this also
            includes MUC messages and error messages. It is usually
            a good idea to check the messages's type before processing
            or sending replies.

            Arguments:
                msg -- The received message stanza. See the documentation
                       for stanza objects and the Message stanza to see
                       how it may be used.
            """
            if msg['type'] in ('chat', 'normal'):
                msg.reply("Thanks for sending\n%(body)s" % msg).send()

    if __name__ == '__main__':
        # Setup the command line arguments.
        parser = ArgumentParser(description=EchoBot.__doc__)

        # Output verbosity options.
        parser.add_argument("-q", "--quiet", help="set logging to ERROR",
                            action="store_const", dest="loglevel",
                            const=logging.ERROR, default=logging.INFO)
        parser.add_argument("-d", "--debug", help="set logging to DEBUG",
                            action="store_const", dest="loglevel",
                            const=logging.DEBUG, default=logging.INFO)

        # JID and password options.
        parser.add_argument("-j", "--jid", dest="jid",
                            help="JID to use")
        parser.add_argument("-p", "--password", dest="password",
                            help="password to use")

        args = parser.parse_args()

        # Setup logging.
        logging.basicConfig(level=args.loglevel,
                            format='%(levelname)-8s %(message)s')

        if args.jid is None:
            args.jid = input("Username: ")
        if args.password is None:
            args.password = getpass("Password: ")

        # Setup the EchoBot and register plugins. Note that while plugins may
        # have interdependencies, the order in which you register them does
        # not matter.
        xmpp = EchoBot(args.jid, args.password)
        xmpp.register_plugin('xep_0030') # Service Discovery
        xmpp.register_plugin('xep_0004') # Data Forms
        xmpp.register_plugin('xep_0060') # PubSub
        xmpp.register_plugin('xep_0199') # XMPP Ping

        # Connect to the XMPP server and start processing XMPP stanzas.
        xmpp.connect()
        asyncio.get_event_loop().run_forever()