[OSM-dev] Tirex - a renderd alternative

[Frederik Ramm]

Stefan,

Stefan de Konink wrote:
> The same host thing is not what my future is. The idea of multiple 
> render services that can be balanced by the webserver is. But since it 
> is now also unknown if one could actually connect to a remote tile 
> service, I would bias for TCP.

I agree that distributed rendering is something that must be supported. 
There are several ways to do it; either run a classic load balancer 
setup with some intelligence so that it requests odd tiles from one 
server and even tiles from another etc., or build a mesh of queue 
managers that are aware of each other, or have one master queue manager 
(a.k.a. single point of failure) distributing requests across a range of 
render servers.

If you were to attempt the latter, I would recommend a messaging deamon 
that takes UDP requests and transports them to the other side using TCP. 
That would allow you to have a steady TCP connection and monitor it 
properly. For localhost use, we decided against TCP because creating a 
new connection everytime you need one is too expensive, and re-using the 
existing one causes too much trouble.

In theory, Tirex could also be expanded to use multiple messaging 
schemes, just as it uses UDP and Unix domain sockets (for backward 
compatibility) now.

Bye
Frederik