Multi-server setups

Multi-server setups help you to handle many client connections. Using the forwarding proxy feature, you can have multiple servers accepting omnibus connections.

How it works

+---------------+                                   +-------------------+
|omnibusd Master|                                   |omnibusd Slave1    |
|PUB: *:4244    |<---------------------------------+|Web clients connect|
|SUB: *:4243    |                                   |to this node.      |
+---------------+                                   +-------------------+
           ^
           |                                   FORWARDER_ENABLED
           |                                   True
           |                                   DIRECTOR_SUBSCRIBER_ADDRESS
           |                                   masterip:4243
           |                                   DIRECTOR_PUBLISHER_ADDRESS
           |                                   masterip:4244
           |
           |                                        +-------------------+
           |                                        |omnibusd Slave2    |
           +---------------------------------------+|Web clients connect|
                                                    |to this node.      |
                                                    +-------------------+

This is how you can build a multi server setup.

Assume you have one master server which has OMNIBUS_DIRECTOR_ENABLED set to True and OMNIBUS_FORWARDER_ENABLED set to False. This server will be your main message hub. Now, you can have one or more slave servers, which connect to your master server.

On the slave servers you then have the OMNIBUS_FORWARDER_ENABLED set to True and OMNIBUS_DIRECTOR_ENABLED set to False. Together with the right settings for OMNIBUS_DIRECTOR_SUBSCRIBER_ADDRESS and OMNIBUS_DIRECTOR_PUBLISHER_ADDRESS the forwarding proxy establishes one subscriber and one publisher connection to your master server.

The client connections to the different slave servers only connect to local addresses reducing the network IO. This is possible because the forwarding proxy fetches all messages from the master and publishes all messages back to the master instance.

Hint

Remember to rebind the publisher and subscriber addresses of your master servers. The defaults only bind to localhost. Remote servers can’t connect to these sockets.

Example configuration with 4 servers

Assuming you have four servers with the ip addresses 192.168.1.10, .11, .12 and .13. This is, how your configuration could look like.

# Master server
OMNIBUS_SUBSCRIBER_ADDRESS = 'tcp://192.168.1.10:4243'
OMNIBUS_PUBLISHER_ADDRESS = 'tcp://192.168.1.10:4243'

# slave servers
OMNIBUS_DIRECTOR_ENABLED = False
OMNIBUS_FORWARDER_ENABLED = True
OMNIBUS_DIRECTOR_SUBSCRIBER_ADDRESS = 'tcp://192.168.1.10:4243'
OMNIBUS_DIRECTOR_PUBLISHER_ADDRESS = 'tcp://192.168.1.10:4243'

You now could define a DNS round-robin entry like “omnibus.myfancydomain.com” pointing to 192.168.1.11, 192.168.1.12 and 192.168.1.13 to create some kind of a poor man’s load balancing.