plugin XEP-0353, XEP-0234, jingle: WebRTC data channel signaling implementation: Implement XEP-0343: Signaling WebRTC Data Channels in Jingle. The current version of the XEP (0.3.1) has no implementation and contains some flaws. After discussing this on xsf@, Daniel (from Conversations) mentioned that they had a sprint with Larma (from Dino) to work on another version and provided me with this link: https://gist.github.com/iNPUTmice/6c56f3e948cca517c5fb129016d99e74 . I have used it for my implementation. This implementation reuses work done on Jingle A/V call (notably XEP-0176 and XEP-0167 plugins), with adaptations. When used, XEP-0234 will not handle the file itself as it normally does. This is because WebRTC has several implementations (browser for web interface, GStreamer for others), and file/data must be handled directly by the frontend. This is particularly important for web frontends, as the file is not sent from the backend but from the end-user's browser device. Among the changes, there are: - XEP-0343 implementation. - `file_send` bridge method now use serialised dict as output. - New `BaseTransportHandler.is_usable` method which get content data and returns a boolean (default to `True`) to tell if this transport can actually be used in this context (when we are initiator). Used in webRTC case to see if call data are available. - Support of `application` media type, and everything necessary to handle data channels. - Better confirmation message, with file name, size and description when available. - When file is accepted in preflight, it is specified in following `action_new` signal for actual file transfer. This way, frontend can avoid the display or 2 confirmation messages. - XEP-0166: when not specified, default `content` name is now its index number instead of a UUID. This follows the behaviour of browsers. - XEP-0353: better handling of events such as call taken by another device. - various other updates. rel 441

--- a/libervia/backend/plugins/plugin_xep_0166/models.py	Sat Apr 06 12:21:04 2024 +0200
+++ b/libervia/backend/plugins/plugin_xep_0166/models.py	Sat Apr 06 12:57:23 2024 +0200
@@ -156,6 +156,18 @@
 
 class BaseTransportHandler(abc.ABC):
 
+    def is_usable(self, client, content_data: "ContentData") -> bool:
+        """Return True if this transport is usable with given content
+
+        This method provides a default implementation that always returns True. It can
+        be overridden in subclasses to provide custom usability logic.
+
+        @param client: SatXMPPEntity instance
+        @param content_data: Jingle content data.
+        @return: True if the transport is usable with this content, False otherwise
+        """
+        return True
+
     @abc.abstractmethod
     def jingle_session_init(
         self,