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Database Settings

Configuring and running the optional Redis-backed payload cache. For the internal mechanism this enables (why routing a key instead of the full payload matters), see Backends → Redis Storage.

What use_db Does​

  • Type: boolean
  • Values: true or false
  • Default: true
  • Description: When true, payloads are stored in a Redis database. The message key is routed through NSB, and the receiving client retrieves the full payload from Redis. Useful for large payloads. When false, payloads are transmitted directly through NSB without persistent storage.
database:
  use_db: true

When to Use true vs false​

Use true when...Use false when...
Payloads may exceed network buffer sizesPayloads are small and simple
You want to decouple payload size from transport performanceYou want the absolute simplest setup (e.g. first-time Quickstart)
You're running a production-scale simulationYou're testing or prototyping locally

The Quickstart deliberately uses use_db: false so first-time users don't need to start Redis at all.

Redis Connection Fields​

db_address​

  • Type: string
  • Default: 127.0.0.1
  • Description: The IP address or hostname of the Redis server.

db_port​

  • Type: integer
  • Default: 5050
  • Description: The port on which the Redis server is running.
Port 5050 vs Redis Default 6379

Redis defaults to port 6379, but NSB examples and guides use port 5050. Be sure your redis-server startup command and your config.yaml db_port value match — a mismatch here is one of the most common first-time setup errors.

db_num​

  • Type: integer
  • Default: 0
  • Description: Redis database number to use. Redis supports multiple logical databases (0–15 by default). Use 0 unless you have a specific reason to separate data.

Starting the Redis Server​

redis-server --port 5050

Or as a background daemon:

redis-server --port 5050 --daemonize yes

Verify it's running:

redis-cli -p 5050 ping    # Should return: PONG

Startup Order​

When use_db: true, start services in this order:

  1. Redis server
  2. NSB Daemon
  3. Network Simulator (with NSBSimClient code)
  4. Application (with NSBAppClient code)
tip

In most cases the simulator should be started before the application so it's ready to fetch() messages when the application begins send()-ing.

Go Deeper​