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<p class=MsoNormal><span style='color:navy'>No, TCP/IP is used for the message
stream I am thinking of. Basically, the client opens a TCP/IP connection to
the server, and then sends HL7 messages (a message format used in the
healthcare industry) over the connection, delimited by beginning– and end-of-message
control codes. If the connection is closed (e.g., server fails), the client
will attempt to reconnect. My thought is that if the secondary can remap the network
so that connections to that IP address are now routed to it, the reconnect would
automatically go to the secondary.</span></p>
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<p class=MsoNormal><b><span style='font-family:Tahoma'>From:</span></b><span
style='font-family:Tahoma'> erlang-questions-bounces@erlang.org
[mailto:erlang-questions-bounces@erlang.org] <b>On Behalf Of </b>Rick R<br>
<b>Sent:</b> Wednesday, July 16, 2008 09:35<br>
<b>To:</b> erlang-questions@erlang.org<br>
<b>Subject:</b> Re: [erlang-questions] Fault-Tolerant TCP/IP Servers</span></p>
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<p class=MsoNormal style='margin-bottom:12.0pt'>You mentioned TCP/IP, but is
SCTP an option? If so, your problem is solved automatically and (almost)
instantly via SCTP's multi-homing. </p>
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<p class=MsoNormal>2008/7/16 David Mercer <<a href="mailto:dmercer@gmail.com">dmercer@gmail.com</a>>:</p>
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<p><span style='color:navy'>I must admit, I am disappointed that there is no
Erlang solution. This seems like a basic building block to fault-tolerant
systems. So, I am going to toy with my idea of having the secondary
detect the failure and send the appropriate commands to the network to redirect
traffic for the primary server's IP address to the secondary. Am thinking
there must be some DHCP commands to reassign the IP address. Before I
begin, does anyone see any obvious flaws in my thinking. I am not a
networking expert. Thanks.</span></p>
<p><span style='color:navy'> </span></p>
<p><span style='color:navy'>David</span></p>
<p><span style='color:navy'> </span></p>
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<p><b><span style='font-family:Tahoma'>From:</span></b><span style='font-family:
Tahoma'> David Mercer [mailto:<a href="mailto:dmercer@gmail.com" target="_blank">dmercer@gmail.com</a>]
<br>
<b>Sent:</b> Friday, July 11, 2008 10:59<br>
<b>To:</b> '<a href="mailto:erlang-questions@erlang.org" target="_blank">erlang-questions@erlang.org</a>'<br>
<b>Subject:</b> Fault-Tolerant TCP/IP Servers</span></p>
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<p> </p>
<p>Say I have a TCP/IP server (e.g., a web server, FTP server, etc.) written in
Erlang, and I want it to work through hardware failures; I need at least two of
them. The problem is, clients are connecting to the primary's IP address,
so when it fails, client connections are refused instead of being rerouted to
the secondary. What is the Erlang approach to solving this?</p>
<p> </p>
<p>My thought is that you have the secondary detect the failure and send the
appropriate commands to the network to redirect traffic for the primary
server's IP address to the secondary. That's my idea, but I don't really
know if this is the appropriate solution, nor how to implement something like
this in Erlang.</p>
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<p>Please advise. Thank-you.</p>
<p> </p>
<p>David Mercer</p>
<p> </p>
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<br>
-- <br>
An idea that is not dangerous is unworthy of being called an idea at all. --
Oscar Wilde </p>
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