Glossary

We will list here the terms that are related to the Socket.IO ecosystem:

• Adapter
• Engine.IO
• Namespace
• Room
• Transport

Adapter

An Adapter is a server-side component which is responsible for:

• storing the relationships between the Socket instances and the rooms
• broadcasting events to all (or a subset of) clients

There are currently two official adapters:

• the in-memory adapter, which is included by default with the Socket.IO server
• the Redis adapter, which is useful when scaling horizontally (see here)
• the MongoDB adapter

The in-memory adapter can be extended to add support for other messaging systems, like RabbitMQ or Google Pub/Sub for example.

Please see the documentation here.

Engine.IO

Engine.IO is an internal component of Socket.IO, which is responsible for establishing the low-level connection between the server and the client.

You will find more information here.

Namespace

A Namespace is a concept that allows splitting the application logic on the server-side.

Please see the documentation here.

Room

A Room is a server-side concept that allows broadcasting data to a subset of clients.

Please see the documentation here.

Transport

A Transport represents the low-level way of establishing a connection between the server and the client.

There are currently two implemented transports:

• HTTP long-polling
• WebSocket

Please see the documentation here.