[erlang-questions] inets service startup

Ingela Anderton Andin <>
Wed Apr 11 15:05:34 CEST 2007


Serge Aleynikov wrote:
> Ingela Anderton Andin wrote:
>> Hi Serge!
>>
>> I do not know why that line was ever entered, and it was a bad idea 
>> not to remove it altogether.
>> The httpd_sup supervisor is a one_for_one supervisor which means that 
>> if there is a problem
>> with one child it should not affect the other children.  It is 
>> possible to start several HTTP-servers
>> and a configuration error in one of them should not have a bearing on 
>> the others. Maybe the
>> error could be reported differently to be more "user friendly".
>
> I think it all depends on how critical that httpd service is in the 
> process interdependency.  If you have an application that cannot live 
> without an HTTP server, the current implementation doesn't allow for 
> intercepting a service startup problem (say due to a bad configuration 
> option in the HTTP config file) and reacting appropriately (perhaps by 
> aborting the boot process).
>
> The workaround I found was not to specify the HTTPD service in the 
> inets environment options, but rather introduce an environment option 
> {httpd_config_file, Filename::string()} in a custom application that 
> would manage addition/removal of a child HTTPD process to/from the 
> inets' supervisor.
>
> While this solution works, this way of error handling doesn't seem 
> appealing to me.  It looks that it would be nicer if INETS would offer 
> some sort of customization of action of what to do on httpd service 
> startup problems.
Thank you for your input.
That would be possible. We will take this under consideration when 
constructing the new API.

> Below is the code describing this workaround.  One other issue with 
> this approach is that if there are other httpd services started by 
> inets though its own environment options, if we want to stop the httpd 
> instance managed by our custom app, there doesn't seem to be an easy 
> way of figuring out which httpd service to stop.  Perhaps returning 
> httpd service's name {httpd_instance_sup, Addr, Port} by the 
> httpd_sup:start_child/1 function would help.
>
There is no easy way, that is one of the points that will be improved in 
a future release of intes.

Regards Ingela - OTP team




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