libervia-backend: doc/components.rst comparison

comparison doc/components.rst @ 3734:643622ff1492

doc (components): update AP component documentation: - add `configuration` section - update instructions on AP actor handle <=> JID/node conversion - explain how to get AP messages from XMPP - explain how to get XMPP items for AP - notes to explain tricks and implementations details fix 363

author	Goffi <goffi@goffi.org>
date	Mon, 31 Jan 2022 18:35:52 +0100
parents	a1eff4e32848
children	fa3dc4ed7906

comparison

equal deleted inserted replaced

-:6cc39a3b8c14
+:643622ff1492
 **entry_point:** ``ap-gateway``
 .. note::
-this component is currently in active development, and not yet usable for end-user. This
+this component is currently in active development, and not yet fully functional. This
 documentation will be updated during evolution of component.
 You can follow the development by reading `Libervia Progress Notes`_.
 .. _Libervia Progress Notes: https://www.goffi.org/tag/Libervia%20progress
 facing internet (e.g. integrated in an existing website though a proxy), you'll have to
 redirect the requests made to those path to the HTTP server (i.e. to component host at the
 port set at ``http_port``, see configuration below). Please check your HTTP server
 documentation to find how this must be done.
-how to address an AP actor from XMPP
+Configuration
+~~~~~~~~~~~~~
+All options are to be set in ``[component ap-gateway]`` section.
+``public_url``
+Main user-facing domain of the HTTP server, this will be used to construct all AP URLs
+**default**: if not set, ``xmpp_domain`` is used. If ``xmpp_domain`` is not set either,
+an error is raised.
+``http_port``
+port where the HTTP server should listen. Port ``80`` is not used directly as it would
+require root privileges, and it is strongly recommended against launching Libervia under
+a privileged account. An HTTP Proxy or a port redirection should be set to redirect the
+``80`` port to the port specified here.
+**default**: ``8123``
+``http_connection_type``
+either ``http`` or ``https``. If you have a HTTP proxy such as Apache or NGINX which
+already handles HTTPS, you may want to use ``http``.
+**default**: ``https``
+Note that the HTTP server should always use ``https`` with end-user, the ``http`` option
+is only to be used with an HTTPS proxy.
+``local_only``
+A boolean value indicating if the gateway is allowed to convert pubsub node from
+external XMPP service or not. A JID is considered external if its domain part doesn't
+end with the gateway's server. For instance, if a gateway ``ap.example.org`` is set on
+the server ``example.org``, the JIDs ``pierre@example.org`` or
+``some-node@pubsub.example.org`` will be considered local, but
+``buenaventura@example.net`` won't (note the different domain).
+Most of time, ``local_only`` should be used.
+**default**: ``true``
+``ap_path``
+Path prefix to use for ActivityPub request. It's usually not necessary to change the
+default value.
+**default**: ``_ap``
+.. _ap-actor-from-xmpp:
+How to Address an AP Actor from XMPP
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 When addressing an ActivityPub actor from XMPP, you must use a JID corresponding to the
 actor. The domain part of the JID correspond to the gateway JID (the one set in gateway
 profile), while the local part (before the ``@``) is used to specify the AP actor.
 Of course, this is a bit cumbersome to do by hand, it is expected that XMPP clients will
 do the (un)escaping automatically for end-user, in a way that Louise could enter
 ``pierre@example.net`` directly, with an indicator to show that this is an ActivityPub
 actor identifier rather than an XMPP JID.
-how to address an XMPP entity from AP
+.. _xmpp-node-from-ap:
+How to Address an XMPP Entity from AP
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-To access an XMPP entity, just use its bare JID as AP actor.
+To access an XMPP entity, it is a little bit more complicated for 2 reasons:
+- XMPP use a wider range of allowed characters than most AP implementations [#AP_chars]_.
+- to get XMPP items, we need 2 data: the entity JID, and a pubsub node
+However, Libervia AP gateway tries to make it as user friendly as possible, thus it works
+like this:
+- in the most common case, one just wants to access the personal blog of a user, and basic
+ASCII characters (with possibly ``-``, ``_`` or ``.``) are used. in this case, the XMPP
+JID can be directly used as AP actor handle
+- when a pubsub node needs to be specified it is most of time with a pubsub JID which has
+not user part (something like ``pubsub.example.org``). In this case, the pubsub node can
+be used as AP actor handle's user part, Libervia will use XMPP discovery to know that
+it's a pubsub service. So if you want to access the blog named ``xmpp_news`` at
+``pubsub.example.org``, you can use the handle ``xmpp_news@pubsub.example.org`` (be sure
+that the domain ``pubsub.example.org`` links to the Libervia AP gateway HTTP server)
+- if you want to use a specific node with an entity which already has a user part, then a
+special encoding must be used, where ``---`` (three dashes) are used to separate node
+from entity: ``some_node--some_user@example.org``
+- if you need to use special characters, then you'll have to use ``___`` followed by the
+special encoding (see below).
+The encoding is explained in the documentation of the following method:
+.. automethod:: sat.plugins.plugin_comp_ap_gateway.APGateway.getJIDAndNode
+.. [#AP_chars] Most if not all AP implementations use webfinger `acct` URI as a de-facto
+standard to manage user-friendly handles (something like ``user@example.org``). Those
+handles, according to `RFC7565`_, should
+manage a wide variety of characters thanks to the support of percent-encoding.
+Unfortunately, at least one of the most-used AP implementation (Mastodon, which is used
+a reference implementation for this gateway), only uses a limited subset of allowed
+characters. In addition, Mastodon needs an associated handle [#m_wf]_ thus an alternate
+way to encode characters had to be found.
+An issue has been opened to improve this situation on Mastodon bug tracker:
+https://github.com/mastodon/mastodon/issues/17222
+.. _RFC7565: https://datatracker.ietf.org/doc/html/rfc7565
+.. [#m_wf] https://docs.joinmastodon.org/spec/webfinger/
 **example**
-If Pierre wants to talk Louise, he can directly use the JID which is the same as the AP
+If Pierre wants to talk to Louise, he can directly use the JID which is the same as the AP
 actor identifier, i.e. ``louise@example.org`` (note that on AP software, a ``@`` prefix is
 often required, thus Pierre will look for ``@louise@example.org``).
 .. note::
-Currently the gateway only uses bare JID, and character set must be recognised by the
-AP software to be used. This will evolve in the close future to have a way to access
-various XMPP Pubsub nodes.
 The actor endpoint can also be used directly in AP software (in the example above, it
 would be by default ``https://example.org/_ap/actor/louise%40example.org``).
-using the component
+Getting AP Message from XMPP
-~~~~~~~~~~~~~~~~~~~
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-The component is currently only usable for development purpose, and it can be used with
+To retrieve ActivityPub messages of an actor from an XMPP client with blogging
-the following method (with can be accessed through the ``APSend`` bridge method, client is
+capabilities (like Libervia or Movim), just use the associated JID as explained in
-then replaced by the ``profile`` name, as last argument):
+:ref:`ap-actor-from-xmpp`. The actor messages (from ``outbox`` collection) should appear
+as regular XMPP blog items.
+.. note::
+Due to limitation of `ActivityStream Collection Paging`_, the conversion from XMPP
+`RSM`_ requests is inneficient beyond first or last page. This problem is avoided if
+anybody subscribe to the gateway node (i.e. follow the AP actor), as the collection
+will then be cached, and efficiently delivered. Note that subscription/following is NOT
+IMPLEMENTED YET, but will be in the close future.
+.. _ActivityStream Collection Paging: https://www.w3.org/TR/activitystreams-core/#h-paging
+.. _RSM: https://xmpp.org/extensions/xep-0059.html
+.. note::
+Only "root" items are currectly converted, i.e. items which are not replies to other
+objects. Replies will be managed in the close future with AP collections caching.
+Getting XMPP Items from ActivityPub
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+To get XMPP items from an ActivityPub implementation, just use the handle as explained at
+:ref:`xmpp-node-from-ap` (often handle searches are triggered with a ``@`` before the
+handle in AP implementations, e.g.: ``@louise@example.org``).
+.. note::
+Some AP implementations such as Mastodon don't retrieve existing items, but only keep
+new ones once an actor is followed. That means that you won't see any message published
+before your entity is followed. Other implementations may work differently.
+Using the Component (for developers)
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+Publication of AP items can be tested using the following method (with can be accessed
+through the ``APSend`` bridge method, client is then replaced by the ``profile`` name, as
+last argument):
 .. automethod:: sat.plugins.plugin_comp_ap_gateway.APGateway.publishMessage
 The method can be used either with CLI's :ref:`debug bridge method
 <li_debug_bridge_method>` or with any D-Bus tool like ``qdbus`` or ``d-feet`` (only if you

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comparison doc/components.rst @ 3734:643622ff1492