WebSocket with free RDMBS (PostgreSQL, SQLite, etc) and without JavaScript ecosystem - postgresql

Question

I'm searching a simple implementation to push changes from a free relational database (PostgreSQL, MySQL, SQLite, etc.) to clients' browsers via WebSocket or WebPush.
I want to avoid all the server-side JavaScript ecosystem (Node.js, npm & cie) and the NoSQL databases.
All must be hosted in the servers of my company, I can't use third-party services.
I found these interesting solutions :
http://initd.org/psycopg/articles/2010/12/01/postgresql-notifications-psycopg2-eventlet/ [with Python]
https://gist.github.com/drocco007/6e44ac1a581546c16e67 [the same one slightly improved]
https://coussej.github.io/2015/09/15/Listening-to-generic-JSON-notifications-from-PostgreSQL-in-Go/ [with Go]
Do you know other ways to get this done?
Is PostgreSQL the more suitable free RDBMS to do this?
Can it be accomplished with a SQLite database?
Can Apache or NGinx abilities be used to achieve this?

Answer 1

Update 01/23/17: I wrote an application called postgresql2websocket in order to send PostgreSQL notifications over websockets using Python 3 with asyncio + aiohttp + asyncpg https://github.com/frafra/postgresql2websocket; you could combine it with PostgREST in order to have both standard REST APIs and realtime updates using WebSockets.
As far I know, there is no HTTP server extension for using SQL databases with Websockets without anything in the middle.
You can use Python on the server side, like this: Real Time Web Apps with (just) Python and Postgres. I think it could be improved thanks to aiopg. If you don't need Websockets, you can just use ngx_postgres.
If you like Django, Django Channels will be probably included in Django 1.10 (Redis/in-memory/... layer for channels and SQL backend).
You could use SQLite, but bear in mind that you have to implement a separate server side publish/subscribe mechanism (like Django channel does), because SQLite doesn't have one.
If you're just interested in pub/sub over Websockets, you could use Webdis (Redis-based solution): it would be probably lighter than a full SQL database.