dora-rs
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dora

 
			
			   
				 
					
						
						
							
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                        <h1 id="python-api"><a class="header" href="#python-api">Python API</a></h1>
<h2 id="operator"><a class="header" href="#operator">Operator</a></h2>
<p>The operator API is a framework for you to implement. The implemented operator will be managed by <code>dora</code>. This framework enable us to make optimisation and provide advanced features. It is the recommended way of using <code>dora</code>.</p>
<p>An operator requires an <code>on_input</code> method and requires to return a <code>DoraStatus</code> of 0 or 1, depending of it needs to continue or stop.</p>
<pre><code class="language-python">class Operator:
    def on_input(
        self,
        input_id: str,
        value: bytes,
        send_output: Callable[[str, bytes], None],
    ) -&gt; DoraStatus:
</code></pre>
<blockquote>
<p>For Python, we recommend to allocate the operator on a single runtime. A runtime will share the same GIL with several operators making those operators run almost sequentially. See: <a href="https://docs.rs/pyo3/latest/pyo3/marker/struct.Python.html#deadlocks">https://docs.rs/pyo3/latest/pyo3/marker/struct.Python.html#deadlocks</a></p>
</blockquote>
<h3 id="try-it-out"><a class="header" href="#try-it-out">Try it out!</a></h3>
<ul>
<li>Create an operator python file called <code>op.py</code>:</li>
</ul>
<pre><code class="language-python">from typing import Callable
from enum import Enum

class DoraStatus(Enum):
    CONTINUE = 0
    STOP = 1

class Operator:
    &quot;&quot;&quot;
    Example operator incrementing a counter every times its been called.

    The current value of the counter is sent back to dora on `counter`.
    &quot;&quot;&quot;

    def __init__(self, counter=0):
        self.counter = counter

    def on_input(
        self,
        input_id: str,
        value: bytes,
        send_output: Callable[[str, bytes], None],
    ):
        &quot;&quot;&quot;Handle input by incrementing count by one.

        Args:
            input_id (str): Id of the input declared in the yaml configuration
            value (bytes): Bytes message of the input
            send_output (Callable[[str, bytes]]): Function enabling sending output back to dora.
        &quot;&quot;&quot;
        val_len = len(value)
        print(f&quot;PYTHON received input {input_id}; value length: {val_len}&quot;)
        send_output(&quot;counter&quot;, (self.counter % 256).to_bytes(1, &quot;little&quot;))
        self.counter = self.counter + 1

        return DoraStatus.OK
</code></pre>
<ul>
<li>Link it in your graph as:</li>
</ul>
<pre><code class="language-yaml">{{#include ../../binaries/coordinator/examples/graphs/mini-dataflow.yml:67:73}}
</code></pre>
<h2 id="custom-node"><a class="header" href="#custom-node">Custom Node</a></h2>
<p>The custom node API allow you to integrate <code>dora</code> into your application. It allows you to retrieve input and send output in any fashion you want.</p>
<h4 id="node"><a class="header" href="#node"><code>Node()</code></a></h4>
<p><code>Node()</code> initiate a node from environment variables set by <code>dora-coordinator</code> </p>
<pre><code class="language-python">from dora import Node()

node = Node()
</code></pre>
<h4 id="next-or-__next__-as-an-iterator"><a class="header" href="#next-or-__next__-as-an-iterator"><code>.next()</code> or <code>__next__()</code> as an iterator</a></h4>
<p><code>.next()</code> gives you the next input that the node has received. It blocks until the next input becomes available. It will return <code>None</code> when all senders has been dropped.</p>
<pre><code class="language-python">input_id, value = node.next()

# or

for input_id, value in node:
</code></pre>
<h4 id="send_outputoutput_id-data"><a class="header" href="#send_outputoutput_id-data"><code>.send_output(output_id, data)</code></a></h4>
<p><code>send_output</code> send data from the node.</p>
<pre><code class="language-python">node.send_output(&quot;string&quot;, b&quot;string&quot;)
</code></pre>
<h3 id="try-it-out-1"><a class="header" href="#try-it-out-1">Try it out!</a></h3>
<ul>
<li>Install python node API:</li>
</ul>
<pre><code class="language-bash">cd apis/python/node
python3 -m venv .env
source .env/bin/activate
pip install maturin
maturin develop
</code></pre>
<ul>
<li>Create a python file called <code>printer.py</code>:</li>
</ul>
<pre><code class="language-python">from dora import Node

node = Node()

for id, value in node:
    print(f&quot;From Python, id: {id}, value: {value}&quot;) if value is not [] else None

print(&quot;printer finished&quot;)
</code></pre>
<ul>
<li>Link it in your graph as:</li>
</ul>
<pre><code class="language-yaml">  - id: python-printer
    custom:
      run: python examples/nodes/python/printer.py
      inputs:
          string: static-string/string
          time2: rust-timer/time
</code></pre>

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