Hello world
===========

This is a basic example on how to communicate with the INTERSECT SDK. One Service and one Client are deployed. The client sends a message with a string payload to the service, which responds with a string telling the string payload "Hello".

To run these locally, you must first make sure that you have all necessary backing services running; see the :doc:`../installation` page for details on how to do this.

Afterwards, you can start the service in one terminal, wait a brief moment, then finally run the client in another terminal.

Service walkthrough
-------------------

.. literalinclude:: ../../examples/1_hello_world/hello_service.py

Client walkthrough
------------------

.. literalinclude:: ../../examples/1_hello_world/hello_client.py

Running it yourself: Using a Python environment
-----------------------------------------------

.. code-block:: bash

   # to suppress progress messages and only show stdout, you can add
   # 2>/dev/null
   # to the end of your command on UNIX systems

   # First, run the service
   python -m examples.1_hello_world.hello_service

   # Next, run the client in a separate terminal
   python -m examples.1_hello_world.hello_client

After several seconds, the output from ``hello_client`` will be:

.. code-block:: text

   Hello, hello_client!

The client will exit automatically; you will have to use Ctrl+C on the terminal running the service process.

Running it yourself: Using Docker
---------------------------------

First, you will need to build the latest INTERSECT-SDK image; run the following command from the repository root:

.. code-block:: bash

   docker build -t intersect-sdk .

Then you can run the examples like this:

.. code-block:: bash

   # to suppress progress messages and only show stdout, you can add
   # 2>/dev/null
   # to the end of your command on UNIX systems

   # First, run the service
   docker run --rm -it --name intersect-service --network host intersect-sdk python -m examples.1_hello_world.hello_service

   # Next, run the client in a separate terminal
   docker run --rm -it --name intersect-client --network host intersect-sdk python -m examples.1_hello_world.hello_client

After several seconds, the output from ``hello_client`` will be:

.. code-block:: text

   Hello, hello_client!

The client will exit automatically; you will have to use Ctrl+C on the terminal running the service process.

(If you ran Docker in detached mode (``-d``), you can instead run ``docker stop intersect-client``.)