Flexible internal API usage

The Internal “API” in slixmpp is used to override behavior or simply to override the default, in-memory storage backend with something persistent.

We will use the XEP-0231 (Bits of Binary) plugin as an example here to show very basic functionality. Its API reference is in the plugin documentation: Internal API methods.

Let us assume we want to keep each bit of binary in a file named with its content-id, with all metadata.

First, we have to load the plugin:

from slixmpp import ClientXMPP
xmpp = ClientXMPP(...)
xmpp.register_plugin('xep_0231')

This enables the default, in-memory storage.

We have 3 methods to override to provide similar functionality and keep things coherent.

Here is a class implementing very basic file storage for BoB:

from slixmpp.plugins.xep_0231 import BitsOfBinary
from os import makedirs, remove
from os.path import join, exists
import base64
import json

class BobLoader:
    def __init__(self, directory):
        makedirs(directory, exist_ok=True)
        self.dir = directory

    def set_bob(self, jid=None, node=None, ifrom=None, args=None):
        payload = {
            'data': base64.b64encode(args['data']).decode(),
            'type': args['type'],
            'cid': args['cid'],
            'max_age': args['max_age']
        }
        with open(join(self.dir, args['cid']), 'w') as fd:
            fd.write(json.dumps(payload))

    def get_bob(self, jid=None, node=None, ifrom=None, args=None):
        with open(join(self.dir, args), 'r') as fd:
            payload = json.loads(fd.read())
        bob = BitsOfBinary()
        bob['data'] = base64.b64decode(payload['data'])
        bob['type'] = payload['type']
        bob['max_age'] = payload['max_age']
        bob['cid'] = payload['cid']
        return bob

    def del_bob(self, jid=None, node=None, ifrom=None, args=None):
        path = join(self.dir, args)
        if exists(path):
            remove(path)

Now we need to replace the default handler with ours:

bobhandler = BobLoader('/tmp/bobcache')
xmpp.plugin['xep_0231'].api.register(bobhandler.set_bob, 'set_bob')
xmpp.plugin['xep_0231'].api.register(bobhandler.get_bob, 'get_bob')
xmpp.plugin['xep_0231'].api.register(bobhandler.del_bob, 'del_bob')

And that’s it, the BoB storage is now made of JSON files living in a directory (/tmp/bobcache here).

To check that everything works, you can do the following:

cid = await xmpp.plugin['xep_0231'].set_bob(b'coucou', 'text/plain')
# A new bob file should appear
content = await xmpp.plugin['xep_0231'].get_bob(cid=cid)
assert content['bob']['data'] == b'coucou'

A file should have been created in that directory.