Bug#623249: libtango7 has circular Depends on tango-common

[Picca Frédéric-Emmanuel]

Le Mon, 18 Apr 2011 19:13:29 +0200,
Bill Allombert <ballombe at debian.org> a écrit :

> Package: libtango7
> Version: 7.2.6+dfsg-1
> Severity: important
> 
> Hello Debian Science Maintainers,
> 
> There is a circular dependency between libtango7 and tango-common:
> 
> libtango7 	:Depends: tango-common
> tango-common 	:Depends: libtango7
> 
> Circular dependencies involving shared libraries are known to cause problems
> during upgrade between stable releases, so we should try to get rid of them.
> 
> See threads 
> http://lists.debian.org/debian-devel/2005/06/msg02111.html
> http://lists.debian.org/debian-devel/2005/11/msg01101.html
> 
> Cheers,

Hello Bill,

I understand the problem and I will put here my proposition:

the Tango control system [1] is a distributed system based on CORBA.
the unit cell of the system is called a "Device". Thoses devices (executable) are
linked with the libtango7 library.
To work a device must contact a daemon running somewhere on the internet
this daemon is called the Database (the tango-db package).
Then a configure file /etc/tangorc must be configure and contain
the host and the port where is running the Database.

So If you want to execute a Device it must be register into the
Database. That's why I created this tango-common package which take care of
this config file creation.

So to be usable a program linked with libtango7 must also have this configure file
set-up.

Now the init script of the Databse located in tango-db use an executable called
tango_admin which IS linked with the libtango. I put it in tango-common and 
this caused the circular dependency.

Now I propose to split tango-common (config + tango_admin) into 2 new packages
tango-common (config) and libtango-tools (tango_admin)

that way I will have

libtango7 :Depends: tango-common
libtango-tools :Depends: libtango7

Is it ok for you

If yes, I would like your advice for the transition, as tango_admin will be changed from one package
to the other, It can cause conflict during upgrade.
So is it sufficient to add

libtango-tools :Depends: libtango7 Replace: tango-common << (7.2.6+dfsg-1) Breaks: tango-common (<< 7.2.6+dfsg-1)
libtango-common : Suggest: libtango-tools (>> 7.2.6+dfsg-1)

thanks

Frederic

[1] http://tango-controls.org
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uid  Picca Frédéric-Emmanuel <picca at synchrotron-soleil.fr>
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