Investigate ext app for node backend

[juliushaertl]

As a replacement for https://github.com/nextcloud/whiteboard/issues/27 we should see if we can build a AppAPI app https://docs.nextcloud.com/server/latest/admin_manual/ai/app_api_and_external_apps.html that just runs a docker container for the backend.

• [x] Build an ext app that runs the node backend
• [ ] Checkout if existing proxy methods https://cloud-py-api.github.io/app_api/notes_for_developers/ExAppOverview.html#frontend-routing works with longpolling
• [ ] See what is needed to proxy the websocket

Started adding this for the local dev environment https://github.com/juliushaertl/nextcloud-docker-dev/commit/a3e7cb8f985bb35dacf98602ccd94d2209583cc3

[hweihwang]

Initial efforts for ExApps:

https://github.com/hweihwang/whiteboard_websocket

[hweihwang]

Current progress:

• Using docker-install and dockersocketproxy
• The ExApp has been built out seems okay (Dockerfile for a express node server with socket.io, appinfo xml configs)
• Successfully enabled the app and proxied the request at https://nextcloud.local/apps/app_api/proxy/whiteboard_websocket
• The request to the express HTTP server route works fine.

=> However, I'm facing problems with the socket connection. Both websocket and polling connections are failing. The AppAPI documentation mentions: "There is a limitation of AppAPI ExApp proxy—the WebSocket connections are not supported." I was hoping polling might work, but it doesn't seem to connect.

[hweihwang]

Updates:

• When I debugged the Guzzle request in the app_api source, I noticed that the necessary query parameters for the socket connection (EIO, transport, t) are not being proxied. After modifying the code to include these queries, the request now proxies successfully, but some requests still fail while others succeed. I'm investigating why this inconsistency occurs—perhaps there's still missing information needed for the proxy.

=> In the app_api source, I've been modifying the ExAppProxyController a bit to include this to proxy the queries:

$queryParams = $this->request->getRequestUri();
$queryParams = explode('?', $queryParams);
$queryParams = $queryParams[1];
$path = $other . '?' . $queryParams;