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From Bill Stoddard <b...@wstoddard.com>
Subject Re: modproxy load balancer
Date Tue, 08 Jul 2003 14:39:39 GMT
Perhaps I am being silly, but do we need to standardize on a definition 
of 'downstream' and 'upstream'?  Here is a comment from proxy_http.c:

  /* Note: Memory pool allocation.
   * A downstream keepalive connection is always connected to the existence
   * (or not) of an upstream keepalive connection. If this is not done then
   * load balancing against multiple backend servers breaks (one backend
   * server ends up taking 100% of the load), and the risk is run of
   * downstream keepalive connections being kept open unnecessarily. This
   * keeps webservers busy and ties up resources.
   * As a result, we allocate all sockets out of the upstream connection
   * pool, and when we want to reuse a socket, we check first whether the
   * connection ID of the current upstream connection is the same as that
   * of the connection when the socket was opened.

If I am reading this correctly, my polarity must be different that the 
author of this comment.  The way I look at it, most bytes flow from the 
webserver to the web client. Analogous to water, the bytes flow 
'downstream' from the server to the client.  Now a proxy maintains two 
connections, one to the client and one to the webserver. I would call 
the connection from the client to the proxy the 'downstream' connection 
and the connection from the proxy to the server the 'upstream' 
connection.  What say you?


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