/*!
  \page SALOME_Application Salome Application Concept 


The following explains how to configure your own application with your list of
modules, how to define and run this application on one or more computers.

\section S1_sal_appl General principles

%A %SALOME application is defined by a set of modules (GEOM, SMESH, ASTER...). %A %SALOME application
lives in an application  directory.
%A %SALOME application is a virtual installation of %SALOME in the application directory 
(bin, lib, doc, share...), with, for each file (executable, script, data,
library, resources...), symbolic links to the actual files.

%A %SALOME User can define several %SALOME Applications. These applications are
runnable from the same user account. These applications may share the same 
KERNEL and modules. Thus, the application configuration is independant of
KERNEL and must not be put in KERNEL_ROOT_DIR.

Furthermore, prerequisites may not be the same on all the applications.

%A %SALOME Session can run on a several computers.

Binary modules and prerequisites are installed on the different computers.
There is no need to have all the modules on each computer (the minimum is
KERNEL).

There is no need of standardization or centralised information on the details
of configuration on each computer (PATH, LD_LIBRARY_PATH, environment
variables) provided the application modules are version - compatible. Details
of configuration stay private to the computer, and are held by scripts on each
computer.

There is no hierarchy between the computers (for example only one master
computer used to launch application).

The %SALOME user has an account on all the computers. Access between
account@computer is via rsh or ssh and must be configured for use without
password (key exchange for ssh). Account may be different on each
computer.

\section S2_sal_appl Application Directory

First, the user must create a %SALOME application configuration file by modifying a
copy of ${KERNEL_ROOT_DIR}/bin/salome/config_appli.xml.
The file describes the list of %SALOME modules used in the application, with
their respective installation path. The configuration file also defines the
path of an existing script which sets the %SALOME prerequisites (tag "prerequisites"),
and optionally, the path of samples directory (SAMPLES_SRC) (tag "samples") 
and the path of a catalog of resources (tag "resources").

The following command:

\code
python <KERNEL_ROOT_DIR>/bin/salome/appli_gen.py --prefix=<install directory> --config=<configuration file>
\endcode

creates a %SALOME application in the application directory given by the prefix option (local directory
by default) with the configuration file given by the config option (config_appli.xml by default).

Providing an existing script for %SALOME prerequisites (the same one
used for modules compilation, or given with the modules installation), the
installation works without further modification for a single computer (unless
some modules needs a special environment not defined in the above script).

For a distributed application (several computers), one must copy and adapt
CatalogResources.xml from ${KERNEL_ROOT_DIR}/bin/salome/appliskel (see below).

\section S3_sal_appl General rules

The application directory must be created on each computer of the application.
The easiest way is to use the same relative path (to ${HOME}) on each computer.
(Sometimes it is not possible to use the same path everywhere, for instance
when ${HOME} is shared with NFS, so it is possible to define different path
following the computers).

The application directory contains scripts for environment and runs. Environment
scripts must be configured (by the user) on each computer. All the environment
scripts are in the env.d subdirectory. 

The script envd sources \b all the files (*.sh) in subdirectory env.d
in alphanumeric order (after edition, think to remove backup files). The envd
script is used by run scripts.

<ol>
  <li>
<b>env.d scripts</b>

<b>env.d scripts are built automatically.</b>

You can add your own environment scripts in env.d subdirectory, they will be sourced as
the generated ones provided they have a .sh extension.

  </li>
  <li>
<b>User run scripts</b>

The %SALOME user can use 4 scripts:

- runAppli\n
   Launches a %SALOME Session
   (similar to ${KERNEL_ROOT_DIR}/bin/salome/runSalome but with a different
   name to avoid confusions). See parameters below.

- runSession\n
   Launches a shell script in the %SALOME application environment, with access
   to the current (last launched) %SALOME session (naming service), if any.
   Without arguments, the script is interactive. With arguments, the script
   executes the command in the %SALOME application environment.

- runConsole\n
   Gives a python console connected to the current %SALOME Session.
   It is also possible to use runSession, then python.

- runTests\n
   Similar to runSession, used for unit testing, but runSession tries to use an
   already existing naming service definition from a running session (hostname
   and port number), and runTests defines a new configuration for naming service
   (new port number).
  </li>
  <li>
<b>%SALOME internal run scripts</b>

- envd\n
   Sets %SALOME application environment, envd is sourced by other scripts.

For remote calls, %SALOME uses one script.

- runRemote.sh\n
   This script is mainly used to launch containers. The first 3 arguments
   define the hostname and port userd for naming service, plus a working directory, the remaining
   arguments define the command to execute.
  </li>
  <li>
<b>Other configuration files</b>

- SALOMEApp.xml\n
   This file is similar to the default given
   in ${GUI_ROOT_DIR}/share/SALOME/resources/gui


- CatalogRessources.xml\n
   This file describes all the computers the application can use. The given
   example is minimal and suppose application directory is the same relative path
   to ${HOME}, on all the computers. %A different directory can be set on a
   particular computer with a line:
   \code
appliPath="my/specific/path/on/this/computer"
   \endcode

  </li>
</ol>

\section S4_sal_appl Examples of use

<ol>
  <li>
<b>Launch a %SALOME session with a GUI interface</b>

Launch is done with a command like:

\code
./runAppli --logger
\endcode

The --logger option means here : collect all the traces from the all the
distributed process, via CORBA, in a single file : logger.log.

There are a lot of options, a complete list is given by:

\code
./runAppli --help
\endcode

Note that, without argument, runAppli is a non interactive Python application,
and, with arguments, runAppli is an interactive Python interpreter.

Several options are already defined by default in SALOMEApp.xml files. Optional
arguments given in the command override the SALOMEApp.xml configuration.

Several sessions can run simultaneously, each session use a different port for
CORBA naming service, so the sessions are totally separated from each other.

When the GUI is closed, the different %SALOME servers are still running.
  </li>
  <li>
<b>Close a %SALOME session, kill all the servers</b>

Inside the interactive python interpreter you get when you use runAppli
with arguments, you can kill all the servers of your session with:

\code
>>> killLocalPort()
\endcode

or the servers of all the sessions with:

\code
>>> killAllPorts()
\endcode

If you have no active Python interpreter connected to your session, you can
kill all the %SALOME servers of <b>all the sessions</b> on a given computer:

\code
./runSession killSalome.py
\endcode

Remember! it's the same idea in <b>Windows (R) operating system</b> (Microsoft and Windows are either registered trademarks or trademarks of
       Microsoft Corporation in the United States and/or other countries) :
use the start menu to stop...

When you use only one session at a time, you don't need more.

To kill a given session (when several session are running), one needs
the naming service port number:

\code
./runSession killSalomeWithPort 2810
\endcode

Note that the port number of the last launched session can be found on Linux,
in the prompt, within a runSession shell (see below).

It is also possible to get the Naming Service host and port number of
the last launched session with:

\code
./runSession NSparam.py
\endcode

  </li>
  <li>
<b>Launch a %SALOME session without GUI interface</b>

This is used to launch a %SALOME Python script without GUI
(no GUI %server = SALOME_session_server)

Example of script (test_session_geom.py):

\code
import salome_session
salome_session.startSession(modules=["GEOM"])
import GEOM_usinggeom
raw_input("Press a key and the servers will be killed ...")
\endcode

This script is run in a non interactive way with:

\code
./runSession python test_session_geom.py
\endcode

All the process are automatically killed when Python is closed
(with SALOME_session delete).
  </li>
  <li>
<b>Add an external Python interpretor to a running session</b>

It's often easier to develop and try Python scripts outside the GUI embedded
Python interpreter. Imagine, for instance, you are writing a script involving
geometry and mesh modules.
first, launch a %SALOME session with gui, then, on another terminal:

\code
./runSession
python
\endcode

Import salome module. salome_init() without arguments creates a new study
in the running session (note: salome_init(n) attachs to a running session whose
studyId is n):

\code
import salome
salome.salome_init()
\endcode

An example of script given with SMESH:

\code
import ex01_cube2build
\endcode

It is possible to connect the GUI interface to the study created in the above
script with the file/connect menu, then browse study and display objects.
Further modifications on study can be done either with GUI or external script
(use refresh popup in GUI %object browser to see study modifications generated
by the external script). <b>AVOID modifications with GUI when a Python script
is running</b>. Not all the modules are protected against concurrent actions...
  </li>
  <li>
<b>Different uses of the runSession shell interpreter</b>

runSession invoked without arguments gives an interactive shell with the full
environment of %SALOME (PATH, LD_LIBRARY_PATH, PYTHONPATH, other variables).
If there are running sessions of the same %SALOME application, runSession
connects to the last launched session (i.e. gets the naming service references
of the session: hostname and port)

On Linux, the shell prompt (bash) gives information on naming service
references, hostname and port:

\code
[NS=cli76cc:2811]prascle@cli76cc:~/SALOME2/Run/Virtual$
\endcode

If there is no running session, prompt looks like:

\code
[NS=:]prascle@cli76cc:~/SALOME2/Run/Virtual$
\endcode

runSession is useful to launch any script or program which needs the complete
%SALOME environment, with or without a session already running.
For instance, to launch the ddd debugger interface on the gui %server, first
launch a %SALOME session with gui, then, on another terminal:

\code
./runSession ddd
\endcode

Then attach to the running SALOME_Session_Server process.
  </li>
</ol>  

*/
