Re: modproxy load balancer

Bill Stoddard wrote:

> Thinking out loud..... Should this be a hook or an optional function?  A 
> hook could be useful for iterating across multiple load balancing 
> modules, routing requests for different urls using different algorithms; 
> would this be a common configuration?

If given many options, I would want the ability to select more than one. 
Even though in 90% of the cases the default round robin may suffice, I 
would probably be annoyed if the last 10% of the time I needed the 
ability and it was not available to me.

> The load balance module would 
> also need to be told when the request was complete (it needs to keep 
> track of how many active connections there are to each backend machine) 
> and when an ip address was unsuccessfully tried (so that ip address can 
> be taken out of the list of candidates). The former can be done by 
> registering a cleanup against the request pool. The latter could be done 
> with a callback function, optional function or hook back into the load 
> balance module.

All of these can be achieved by registering hooks.

For example, a simple DNS round robin module would hook into the "give 
me an URL I'll give you some IP addresses" bit, but would leave the 
other hooks alone.

A more advanced backhand module might do the URL to IP translation, then 
would hook into the end of the request to gather stats about that 
request for it's own purposes.

I would also like to specify the order in which the modules are tried 
somehow, in the same way that mod_cache chooses either memory or disk 
for its cache.

Regards,
Graham
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