The registration of new application services depends on the homeserver used.
In synapse, you need to create a new configuration file for your AS and add it
to the list specified under the
option in your synapse config.
app_service_config_files: - /home/matrix/.synapse/<your-AS>.yaml
The format of the AS configuration file is as follows:
id: <your-AS-id> url: <base url of AS> as_token: <token AS will add to requests to HS> hs_token: <token HS will add to requests to AS> sender_localpart: <localpart of AS user> namespaces: users: # List of users we're interested in - exclusive: <bool> regex: <regex> group_id: <group> - ... aliases:  # List of aliases we're interested in rooms:  # List of room ids we're interested in
exclusive: If enabled, only this application service is allowed to register users in its namespace(s).
group_id: All users of this application service are dynamically joined to this group. This is useful for e.g user organisation or flairs.
See the spec for further details on how application services work.