Odoo architecture

The multi-tier design: PostgreSQL, the Python server with the ORM and registry, HTTP and RPC, the OWL web client, workers and crons.

In this lesson

Three tiers and the request path
Databases, modules and the registry
Workers, gevent, crons and limits

Key points

PostgreSQL ↔ Python server (ORM, registry, HTTP, QWeb, crons) ↔ OWL web client via JSON-RPC
Registry per database built from installed modules in dependency order
Python change → restart; XML/data change → module update (-u)
Workers for HTTP, gevent (8072) for websocket bus, cron workers; resource limits

Real-world example

Users saw 'connection lost' banners all day after a move to a new server. Nginx proxied 8069 but not /websocket to 8072, so the live bus kept failing. Adding the websocket location with upgrade headers fixed notifications and Discuss instantly.

Questions and answers

Why can one Odoo server serve several databases?

Each request selects a database (dbfilter/host) and uses that database's registry.

What happens to a worker exceeding limit_memory_hard?

It's killed and replaced.

Read the full lesson, worked example and quiz