WAMP Protocol - Scaling out routers on multiple machines

Question

I have been thinking a lot about scaling out the WAMP router onto multiple machines. Especially because relying on one system without having a backup-system seems a bit tough in a live scenario.

To not have a complicated master node election and all that comes with it, I had the following idea and I would love to get some feedback.

Routers would need to share some information, i.e.:

Authentication

• session ids

RPC

• check if a client has already registered for an uri when using simple registration
• forward calls for pattern based registration
• meta api information

PUB/SUB

• provide event messages to all clients in the network
• meta api information

There must be a connection between all routers. To keep the connections and traffic low, the Idea is to have a ring infrastructure:

   +----------------+    +-----------------+    +--------------+
   |                |    |                 |    |              |
+-->  First Router  +---->  Second Router  +---->  Nth Router  +--+
|  |                |    |                 |    |              |  |
|  +----------------+    +-----------------+    +--------------+  |
|                                                                 |
+-----------------------------------------------------------------+

Every router would have it's own client that is connected to the next router. By storing the incoming message id for a CALL or PUBLISH that came from a client the router could identify a round trip. Incoming calls coming from another router would be handled as is. Yields would have the correct INVOCATION.Request|id and could be forwarded to the correct router.

LOOSING A ROUTER

This infrastructure forces to have some static and identical configuration for all routers. This means dynamic scaling would not work, but therefor no leader election is necessary. If a routers is killed the next router will be connected from the list of routers. A constant polling could check for the router to be back online.

I have not done any deep research on this. So I would be happy to get some input for that.

Answer 1

nginx can work as a reverse proxy to accomplish this.

ip_hash on the upstream list will make sure a client IP get's the same server every time. You may or may not need this depending on your situation.

Essentially, you want a "Load Balancer" to stand in front of WAMP servers, and delegate connections as needed.