[erlang-questions] Why doesn't ssh module start crypto module?

Robert Raschke <>
Tue Jul 7 15:39:52 CEST 2009


Also note that if you build an OTP release, then the boot script usually
takes care of starting all your applications in the right order. If you're
not using releases, then you need to do that yourself.

Robby

On Tue, Jul 7, 2009 at 2:05 PM, Niclas Eklund <> wrote:

>
> Hello!
>
> The 'applications' value shall list other applications that the application
> depends on. If the required applicatios hans't been started an error message
> is returned.
>
> Why doesn't SSH start crypto? For example might other applications also
> depend on crypto and the required type (permanent | transient | temporary)
> may differ. Another reason is that many applications export specific start
> functions (Mnesia, SSL, Orber etc) which in some cases require configuration
> parameters. Typically these functions do more stuff than just invoking
> application:start/1/2. Hence, you should use ssh:start/1/2 instead.
>
> Also consider that if application A depends on that B is started. If B is
> updated and require that application C i started prior to B. In that case A
> must be patched so that it starts not only B but also C. I hope you see my
> point why SSH shall not start Crypto ;-)
>
> The short version, you must start the other applications in your code.
>
> Best Regards,
>
> Niclas @ Erlang/OTP
>
>
>
> On Mon, 6 Jul 2009, Matt Reynolds wrote:
>
>  Am I misunderstanding the use of the "applications" atom in the
>> Applications configuration
>> (http://erlang.org/doc/design_principles/applications.html)?
>>
>> Erlang R13B01 (erts-5.7.2) [source] [smp:2:2] [rq:2] [async-threads:0]
>> [kernel-poll:false]
>>
>> Eshell V5.7.2  (abort with ^G)
>> 1> application:start(ssh).
>> {error,{not_started,crypto}}
>>
>> Does the "applications" configuration simply specify what must be
>> started first, without starting those modules?  So the Application
>> specifying dependencies must start it itself?  If so, why doesn't SSH
>> start crypto?
>>
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>>
>>
>
>
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