[erlang-questions] supervising applications

Moe Aboulkheir <>
Wed Sep 20 17:35:26 CEST 2006



On Tue, 19 Sep 2006 17:12:10 -0700, Bob Ippolito <> wrote:
>On 9/19/06, Moe Aboulkheir <> wrote:
>>Hi,
>>
>>I'm very new to this.  I've written a trivial Erlang application, and i am 
>>trying to write a second one which provides a superset of the functionality 
>>of the first.  The supervisor that is started from start/2 in the second 
>>application tries to start the first application by including an entry for 
>>it in the list returned from init/1.  I tried the following two methods, 
>>but neither works:
>>
>>1) Having StartFunc (in the init/1 term) as {application, start, [app1]}. 
>>This doesn't work because application:start/1 returns ok instead of {ok, 
>>Pid} like the supervisor interface wants.  Ideally i'd have liked to be 
>>able to this, because app1:start/2 passes some stuff from its environment 
>>as the argument to app1_supervisor:start_link/1, but i guess i could move 
>>that stuff further into app1, though i saw an example that did the setup 
>>here, and it makes sense to me
>>
>>2) Having StartFunc as {app1_supervisor, start_link, ...}.  This doesn't 
>>work because some code inside app1 depends on things in the environment of 
>>app1's .app file - things that don't seem to be available when i start it 
>>like this.  Again, i could move these variables into app2's environment, 
>>but i'd like to be able to use app1 without using app2, and would rather 
>>not maintain the information in two places.
>>
>>Any ideas?
>
>Isn't this what you'd use the {applications, [app1, ...]} list for in
>the .app file?

Hooray, looks like {included_applications, [app1]} does the thing I want - loads the applications without expecting them to be started.

Thanks

--
Moe Aboulkheir



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