Linking two Pids of nodes that are in the same machine - noconnection signal!

Sean Hinde <>
Fri Oct 1 22:10:21 CEST 2004


I suspect it might depend on whether your machine has a permanent IP 
address. Certainly my laptop shows this behaviour when I pull out the 
LAN cable because the address was assigned by DHCP. It runs OS X.

Sean

On 1 Oct 2004, at 20:21, Inswitch Solutions - Erlang Evaluation wrote:

>
> Hi Sean,
>
> But in that case the node can't be seen from another machine.
>
> I have node1 in machine1 and node2 and node3 in machine2
>                 --node1 in Mach1--
>                 |                             |
>   node2  in Mach2----- node3 in Mach2
>
> Node1 in Machine1 links to resources asked  to node2,  Node2 in 
> Machine2
> links to resources asked to node3 in Machine2.
> If disconnecting the LAN on Machine2 node2 will lost connection with 
> node1
> but should not lost connection with node3.
>
> Setting localhost on node2 will not allow node1 to see it.
>
> Does this happen in other OS? Any ideas to solve this?
> One of my last email questions should have been: Can I force Erlang to 
> use
> 192.168.0.30 as the IP for a machine (desgn in my case)?
>
>
> thanks,
> Eduardo Figoli
> INSwitch Solutions
>
>
>
>
> ----- Original Message -----
> From: "Sean Hinde" <>
> To: "Inswitch Solutions - Erlang Evaluation" <>
> Cc: <>
> Sent: Friday, October 01, 2004 4:58 PM
> Subject: Re: Linking two Pids of nodes that are in the same machine -
> noconnection signal!
>
>
> You could use erl -sname  - this at least works on non
> windows OSs.
>
> Windows 2000 doesn't sound like a very good option for delivering telco
> solutions..
>
> Sean
>
> On 1 Oct 2004, at 13:36, Inswitch Solutions - Erlang Evaluation wrote:
>
>>
>> I'll try to explain the problem from another point of view.
>> The machine I'm using is named design (IP=192.168.0.30).
>>
>> In Windows 2000:
>> With LAN cable disconnected:
>> ping design
>> Response from 127.0.0.1: bytes=32 tieme<10ms TTL=128
>> With LAN cable connected:
>>
>> ping design
>> Response from 192.168.0.30: bytes=32 tieme<10ms TTL=128
>>
>>
>> Having two Erlang nodes in the same machine the TCP socket connections
>> are different:
>> 1- if LAN cable disconnected the connection between nodes is
>> established using 127.0.0.1:PORT
>>  2- if LAN cable connected the connection between nodes is established
>> using 192.168.0.30:PORT
>>
>> The problem is that in situation 2) and then if the LAN cable is
>> disconnected the connections established with 192.168.0.30:PORT are
>> lost. This can be also verified when "ping design" in W2000 command
>> prompt.
>>
>> - Can I force Erlang to use 127.0.0.1 for local nodes connection
>> instead of 192.168.0.30 ?
>> - How can I solve this problem so not to lose local connections in any
>> case?
>> - Does the same behaviour happen in other OS?
>>
>>
>> thanks in advance,
>> Eduardo Figoli
>> INSwitch Solutions
>>
>> ----- Original Message -----
>>  From: Inswitch Solutions - Erlang Evaluation
>> To: 
>> Sent: Thursday, September 30, 2004 10:46 AM
>> Subject: Linking two Pids of nodes that are in the same machine -
>> noconnection signal!
>>
>>
>> The attached code links to pids of nodes that are in the same machine
>> and I don't know why I receive a noconnection signal when the LAN
>> cable is disconnected. This does no happen when running the code with
>> the LAN cable disconnected and connecting/disconnecting it later.
>>
>> If someone wants to give a try, I send a code to test this situation
>> and you should modify on node1.erl the blue text line below:
>> {node2Pid, } ! {self()},
>> with the corresponding machine name where you will run it.
>>
>>
>> On the same machine do the following:
>>
>>
>> 1 - "erl -sname node2"
>> 2 - "node2:start()."
>>
>>
>> 2 - "erl -sname node1"
>> 3 - "node1:start()."
>>
>> 4 - The pid is linked and a message is shown on node1.
>> 5 - node2Pid shows a message every 1 sec while checking the queue
>> message
>> 6 - node1 process loops checking the queue message
>>
>> 7 - Disconnect LAN cable
>> 8 - node2Pid receives a noconnection signal
>> 9 - node1 process receives an {'EXIT',Pid,noconnection}
>>
>>
>> - When linking Pids of different nodes that are in the same machine
>> why do I receive a "noconnection" signal?
>> - Having the LAN cable disconnected and doing steps 1..6 8..9, if I
>> connect/disconnect the LAN cable the "noconnection" signal is never
>> received (correct behaviour).
>>  - If in the source code I do not use "process_flag(trap_exit,
>> true)," the processes terminate, why is this happenning as no kill
>> signal is sent?
>>
>>
>> thanks in advance,
>> Eduardo Figoli
>> INSwitch Solutions
>>
>>
>>
>>
>
>
>




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