dnaStreaming 2.3.1
Dow Jones DNA Streaming Project
License: MIT
Keywords: DOWJONES, FACTIVA, STREAMS

How To Use
----------

This a Python3 library is for Dow Jones customers consuming data from a Dow Jones Factiva Stream.

To use this we recommend 'pip installing' this by making the following addition to your requirements.txt:

.. code-block::

    # To fetch latest version from PyPi
    dnaStreaming

    # to fetch latest version from GitHub
    git+https://github.com/dowjones/dj-dna-streams-python#egg=dnaStreaming


Auth
-----------

There is currently one way to authenticate, which is by using **your user key**.

Configuring
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To run this code, you need to provide credentials from one of the authentication methods and your subscriptions. There are 3 ways to do this: you can set environment variables, use a configuration file or pass an argument to a constructor.

1. Set environment variables.
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To set your service account credentials, set the `USER_KEY` environment variable:

.. code-block::

    export USER_KEY="1234567890-098765432"


To set your subscription ID, simply set an environment variable named 'SUBSCRIPTION_ID' like so

.. code-block::

    export SUBSCRIPTION_ID="ABC1234567889"


To set your log folder path, simply set this folder variable named 'LOG_PATH' like so

.. code-block::

    export LOG_PATH="/your/custom/log/path"



2. Using the configuration file.
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In this codebase you will find a file named 'customer_config.json'. You are not required to use this file. If you prefer to use this option, fill the JSON object within by adding your user key and your subscription ID. Remember that this is a JSON file so follow basic JSON formatting and syntax conventions.

> The listener will search for the `customer_config.json` file inside your `$HOME` directory by default.

If you prefer using an explicit path to your configuration file, pass the absolute path to the Listener constructor like so:

.. code-block:: python

    from dnaStreaming.listener import Listener
    # Config. file authentication
    listener = Listener(config_file=<ABSOLUTE PATH TO YOUR CONFIG. FILE>)


3. Pass in variables as function arguments.
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You may pass your user key to the Listener constructor and your subscription ID to the listen method like so:

.. code-block:: python

    from dnaStreaming.listener import Listener
    # Use the user_key argument to provide your credentials
    listener = Listener(user_key=<YOUR USER KEY>)
    # Use the subscription_id argument to provide your subscription id to the listener
    listener.listen(callback, subscription_id=<YOUR SUBSCRIPTION ID>)
    # same parameter for the async variation
    listener.listen_async(callback, subscription_id=<YOUR SUBSCRIPTION ID>)


Or you may use the environment variables.
Remember that passing credentials and subscription ID(s) in this way will override the environment variable and the config file settings.

.. code-block:: python

    from dnaStreaming.listener import Listener

    listener = Listener()


4. Listening to messages
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You may want to listen messages synchronously like so:

.. code-block:: python

    def callback(message, subscription_id):
        print('Subscription ID: {}: Message: {}'.format(subscription_id, message.data.__str__()))
        return True  # If desired return False to stop the message flow. This will unblock the process as well.

    listener.listen(callback, maximum_messages=10)  # Omitting maximum_messages means you will continue to get messages as they appear. Can be a firehose. Use with caution.
    # You may pass subscription ID as a parameter to the listen function


You may want to listen messages asynchronously like so:

.. code-block:: python

    def callback(message, subscription_id):
        print('Subscription ID: {}: Message: {}'.format(subscription_id, message.data.__str__()))

    future = listener.listen_async(callback)
    # After calling `listed_async` you need to keep the main thread alive.

    for count in range(0, 5):
        sleep(1)

    # Stop receiving messages after 5 seconds
    if future.running():
        future.cancel()


Log Files
_________


Minimal logging is written to a file named `dj-dna-streaming-python.log`.

By default, logs are written to the first available directory from the following list:

1. A custom path set via the environment variable `LOG_PATH`.
2. A `logs/` folder located within the package installation directory.
3. A fallback directory: `~/.dj-dna-streaming-python/logs/`.

The first writable location found is selected. A message like `Will log to: /your/custom/log/path` is printed to the console on startup.

💡 The log file is overwritten each time the application starts to keep maintenance simple.

You can specify:

- **Absolute paths**: For example, `/var/log/dna-streaming`.
- **Relative paths**: For example, `./logs`, relative to the current working directory at runtime.

The code verifies that the specified path is writable. If it isn’t, it automatically falls back to the next available option.


Testing
_______

.. code-block::

    cd dnaStreaming/test
    pip install -r requirements.txt
    py.test . -s


or, alternatively, to test against python2.7 and python3.5:

.. code-block::

    tox


Flake8
______

If you are maintaining this library, ensure you run flake8 before you commit. At project root command line:

.. code-block::

    flake8 ./dnaStreaming ./tests


Running the Demonstration Code/Development
__________________________________________

If you are enhancing this codebase (and not just using it as a library), follow these example MacOS steps:

1. Checkout the Project from Git.
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2. Go to the Project Root.
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3. Create a Virtual Environment.
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.. code-block::

    virtualenv venv


4. Then activate the virtual environment by executing this command:
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.. code-block::

    source ./venv/bin/activate


5. Install the Dependencies
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.. code-block::

    pip install -r requirements.txt


6. Install the App:
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.. code-block::

    python setup.py install


7. Set the Configuration Variables
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See the config section.

8. Run the Demo Code
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Running Non-Docker Demo:

Execute the following at the project root:

.. code-block::

    python ./demo/show_stream.py -s


Or

.. code-block::

    python ./demo/show_stream_async.py -s


Running Docker Demo

Execute the following at the project root:

.. code-block::

    docker run -it \                    
    -e USER_KEY=<your user KEY> \
    -e SUBSCRIPTION_ID=<your subscription ID> \
    dj-dna-streaming-python