[erlang-patches] Running mnesia across a firewall
Serge Aleynikov
saleyn@REDACTED
Wed Mar 5 13:09:21 CET 2008
Ulf Wiger (TN/EAB) wrote:
> Serge Aleynikov skrev:
>>
>> The main culprit is the net_kernel's dist_auto_connect option that is
>> an all or none setting that cannot vary depending on connecting
>> attempt to a given node. The attached patch (for R12B-1) solves this
>> issue by introducing an additional kernel option:
>>
>> {dist_auto_connect, {callback, M, F}}
>
> Have you thought about solving it with an application that
> periodically tries calling net_kernel:connect(Node)?
On which node, though? If this is one of the "master" nodes A holding a
disk copy of a table X, then the node must have {dist_auto_connect,
once} set. If the firewall prohibits inbound access to this node A from
some other node C that uses remote mnesia interface to access table X,
then the only way to establish connection to node C is to do on node A
net_kernel:connect(C). However if that connection drops, there's no way
to reestablish that connection without restarting node A. Remember that
in case of {dist_auto_connect, once} net_kernel checks if a connection
is barred and if it is it won't allow to connect to a node that
previously was connected.
Serge
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