Re: modproxy load balancer

Graham Leggett wrote:

> Theo E. Schlossnagle wrote:
>
>>> Proxy contains a placeholder (which should be replaced with a hook) 
>>> that says "I have a list of IP addresses, decide in what order I 
>>> should try these addresses here".
>>>
>>> My understanding of backhand is that it answers the above question - 
>>> in theory we could pull the code in by hooking it in.
>>
>>
>>
>> mod_backhand can also provide the list of IPs -- in fact, it would be 
>> best that way.
>
>
> To rephrase it, mod_proxy should give an URL to one or more backend 
> modules (most likely backhand), which should return a list of IP 
> addresses saying "try these in this order".
>
> The backend module might do simple DNS

> round robin in its simplest form, going all the way up to all the 
> functionality of backhand. 


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?  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.

Bill