.. date: 14/04/2026
   author: Andre' Neto
   copyright: Copyright 2017 F4E | European Joint Undertaking for ITER and
   the Development of Fusion Energy ('Fusion for Energy').
   Licensed under the EUPL, Version 1.1 or - as soon they will be approved
   by the European Commission - subsequent versions of the EUPL (the "Licence")
   You may not use this work except in compliance with the Licence.
   You may obtain a copy of the Licence at: http://ec.europa.eu/idabc/eupl
   warning: Unless required by applicable law or agreed to in writing, 
   software distributed under the Licence is distributed on an "AS IS"
   basis, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
   or implied. See the Licence permissions and limitations under the Licence.

LoggerService
=============

The MARTe2 :vcisdoxygencl:`LoggerService` (see also :ref:`MARTeLogging`) enables real-time safe logging by decoupling the generation of log messages from their consumption and propagation to different outputs.

Typical LoggerService consumers include:

- :vcisdoxygencl:`ConsoleLogger`: prints log messages to the console.
- :vcisdoxygencl:`UDPLogger`: sends log messages over UDP.
- :vcisdoxygenmccl:`SysLogger`: forwards log messages to the system ``syslog``.

All :vcisdoxygencl:`LoggerConsumerI` implementations accept a ``Format`` string, which defines which log properties are included in each message.

In this example, two LoggerConsumers are configured: ``ConsoleLogger`` and ``UDPLogger``. To avoid mixing messages from different applications, the destination ``UDP`` port must be unique. This port is automatically assigned in the configuration file ``../Configurations/MassSpring/RTApp-MassSpring-55.cfg`` via ``Makefile.cfg``.

.. literalinclude:: /_static/tutorial/Configurations/MassSpring/RTApp-MassSpring-55.cfg
    :language: c++
    :lines: 4-19
    :caption: LoggerService configuration. The UDP destination port is automatically assigned.
    :linenos:
    :emphasize-lines: 6, 8, 13

Tools for receiving and visualising log messages are outside the scope of this tutorial. However, an example using the `marte2-log <https://vcis-gitlab.f4e.europa.eu/common/marte2-logview>`__ application is provided below.

Running the application
-----------------------

Start the application:

.. code-block:: bash

    make -C ../Configurations/MassSpring/ -f Makefile.cfg
    ./MARTeApp.sh -f ../Configurations/MassSpring/RTApp-MassSpring-55_Gen.cfg -l RealTimeLoader -m StateMachine::START

Verify that the application is running correctly. The log output should look similar to:

.. code-block:: console

    $ |E=Warning|TM=16:55:55 (7196770772734895)|o=|O=|C=|T=|P=x86-linux|f=void MARTe::Threads::SetPriority(const ThreadIdentifier&, const MARTe::Threads::PriorityClassType&, const uint8&)|F=Threads.cpp:185|D=Failed to change the thread priority (likely due to insufficient permissions)
    $ |E=Information|TM=16:55:55 (7196770772750327)|o=StateMachine|O=0x0000000001D490F0|C=StateMachine|T=|P=x86-linux|f=virtual MARTe::ErrorManagement::ErrorType MARTe::StateMachine::SendMultipleMessagesAndWaitReply(MARTe::ReferenceContainer, const MARTe::TimeoutType&)|F=StateMachine.cpp:340|D=In state (INITIAL) triggered message (StartNextStateExecutionRTApp)
    $ |E=Information|TM=16:55:56 (7196771773805898)|o=|O=0x0000000001DFCAB0|C=LoggerBroker|T=|P=x86-linux|f=virtual bool MARTe::LoggerBroker::Execute()|F=LoggerBroker.cpp:152|D=Time [0:0]:990000
    ...

1. Open the file ``../Configurations/MassSpring/RTApp-MassSpring-55_Gen.cfg`` and take note of the allocated ``UDPLogger`` ``Port`` number. (Alternatively, run the command ``UDP_LOGGER_DEST_PORT=`awk '/\+UDPLogger/,/}/ {if ($1=="Port") print $3}' ../Configurations/MassSpring/RTApp-MassSpring-55_Gen.cfg`;echo "UDP_LOGGER_DEST_PORT=$UDP_LOGGER_DEST_PORT"`` to extract the port number from the configuration file).:
2. Clone the `marte2-log <https://vcis-gitlab.f4e.europa.eu/common/marte2-logview>`__ application and start it with the same ``UDP`` port number as the one allocated to the ``UDPLogger`` in the configuration file:
3. Use the following command to find an available port number:

.. code-block:: bash

    LOG_HTTP_PORT=`PORT=8080;while netstat -tln | grep -q ":$PORT"; do PORT=$((PORT + 1)); done; echo $PORT`
    echo $LOG_HTTP_PORT

4. Start the logging application in web mode:

.. code-block:: bash

    python3.6 logapp.py -t WS -p $UDP_LOGGER_DEST_PORT -r $LOG_HTTP_PORT

5. Open a browser and navigate to:

::

    http://localhost:$LOG_HTTP_PORT/index.html

You should now see real-time log messages streamed from the MARTe2 application.