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# Create and Run a Server Component

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.

Many XMPP applications eventually graduate to requiring to run as a server component in order to meet scalability requirements. To demonstrate how to turn an XMPP client bot into a component, we’ll turn the echobot example (Slixmpp Quickstart - Echo Bot) into a component version.

The first difference is that we will add an additional import statement:

    from slixmpp.componentxmpp import ComponentXMPP

Likewise, we will change the bot’s class definition to match:

    class EchoComponent(ComponentXMPP):

        def __init__(self, jid, secret, server, port):
            ComponentXMPP.__init__(self, jid, secret, server, port)

A component instance requires two extra parameters compared to a client instance: `server` and `port`. These specify the name and port of the XMPP server that will be accepting the component. For example, for a MUC component, the following could be used:

    muc = ComponentXMPP('muc.slixmpp.com', '******', 'slixmpp.com', 5555)

Note

The `server` value is NOT derived from the provided JID for the component, unlike with client connections.

One difference with the component version is that we do not have to handle the session_start event if we don’t wish to deal with presence.

The other, main difference with components is that the `'from'` value for every stanza must be explicitly set, since components may send stanzas from multiple JIDs. To do so, the `send_message()` and `send_presence()` accept the parameters `mfrom` and `pfrom`, respectively. For any method that uses `Iq` stanzas, `ifrom` may be used.

## Final Product

    #!/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
    from slixmpp.componentxmpp import ComponentXMPP

    class EchoComponent(ComponentXMPP):

        """
        A simple Slixmpp component that echoes messages.
        """

        def __init__(self, jid, secret, server, port):
            ComponentXMPP.__init__(self, jid, secret, server, port)

            # You don't need a session_start handler, but that is
            # where you would broadcast initial presence.

            # 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)

        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.

            Since a component may send messages from any number of JIDs,
            it is best to always include a from JID.

            Arguments:
                msg -- The received message stanza. See the documentation
                       for stanza objects and the Message stanza to see
                       how it may be used.
            """
            # The reply method will use the messages 'to' JID as the
            # outgoing reply's 'from' JID.
            msg.reply("Thanks for sending\n%(body)s" % msg).send()

    if __name__ == '__main__':
        # Setup the command line arguments.
        parser = ArgumentParser(description=EchoComponent.__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")
        parser.add_argument("-s", "--server", dest="server",
                            help="server to connect to")
        parser.add_argument("-P", "--port", dest="port",
                            help="port to connect to")

        args = parser.parse_args()

        if args.jid is None:
            args.jid = input("Component JID: ")
        if args.password is None:
            args.password = getpass("Password: ")
        if args.server is None:
            args.server = input("Server: ")
        if args.port is None:
            args.port = int(input("Port: "))

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

        # Setup the EchoComponent and register plugins. Note that while plugins
        # may have interdependencies, the order in which you register them does
        # not matter.
        xmpp = EchoComponent(args.jid, args.password, args.server, args.port)
        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()