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From Michel Onoff <michel.on...@web.de>
Subject Re: Are requests and responses self-contained?
Date Wed, 03 Aug 2011 11:24:41 GMT
On 2011-08-03 13:08, Oleg Kalnichevski wrote:
>>> Yes, you do. One thing I do not understand, though. Why don't you simply
>>> use two connections if you really need to process two messages
>>> concurrently?
>>> Oleg
>> I'm implementing a load balancer.
>> Requests from browsers are first put on a common queue by producer
>> tasks. Requests can be part of a HTTP pipeline. Consumer tasks then take
>> them from the queue to send them to available web servers from a pool.
>> Requests from the same pipeline can be sent to different servers.
>> A similar processing happens for responses. In case a server crashes,
>> the requests sent to it that did not get a response are reallocated to
>> the other consumer tasks to be resent to the other servers.
>> Hence, processing is decoupled between the client tasks and the server
>> tasks and is thus asynchronous. I need to preserve the requests to
>> resend them in case of server failure and also need to preserve
>> responses to guarantee the right delivery order of HTTP pipelines.
>> Responses for the same pipeline can arrive to the load balancer out of
>> order.
> This still does not explain why you want to read two requests from the
> same connection at the _same_ time. Anyway, if you want to be able to
> repeat requests there is no way around buffering content in memory or on
> disk.
> Oleg

Even if requests were not repeated, in a pipeline they can be forwarded
to the servers as soon as the arrive to the connection with the browser.
Hence, I want to put them on the working queue as soon as they are
available. I cannot figure out how to do this without consuming them
from the connection and preserve them in buffered counterparts to be put
on the queue.

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