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<li><a href="protocol-examples-createproperty.html">Create a single Property</a></li>
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<a href="#"><span></span>→ Policies examples</a>
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<li><a href="protocol-examples-policies-createpolicy.html">Create a Policy</a></li>
<li><a href="protocol-examples-policies-deletepolicy.html">Delete a Policy</a></li>
<li><a href="protocol-examples-policies-modifypolicy.html">Modify a Policy</a></li>
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<li><a href="protocol-examples-policies-createpolicyentry.html">Create a single entry</a></li>
<li><a href="protocol-examples-policies-deletepolicyentry.html">Delete a single entry</a></li>
<li><a href="protocol-examples-policies-modifypolicyentry.html">Modify a single entry</a></li>
<li><a href="protocol-examples-policies-retrievepolicyentry.html">Retrieve a single entry</a></li>
<li><a href="protocol-examples-policies-modifysubjects.html">Modify subjects</a></li>
<li><a href="protocol-examples-policies-retrievesubjects.html">Retrieve subjects</a></li>
<li><a href="protocol-examples-policies-createsubject.html">Create a single subject</a></li>
<li><a href="protocol-examples-policies-deletesubject.html">Delete a single subject</a></li>
<li><a href="protocol-examples-policies-modifysubject.html">Modify a single subject</a></li>
<li><a href="protocol-examples-policies-retrievesubject.html">Retrieve a single subject</a></li>
<li><a href="protocol-examples-policies-modifyresources.html">Modify resources</a></li>
<li><a href="protocol-examples-policies-retrieveresources.html">Retrieve resources</a></li>
<li><a href="protocol-examples-policies-createresource.html">Create a single resource</a></li>
<li><a href="protocol-examples-policies-deleteresource.html">Delete a single resource</a></li>
<li><a href="protocol-examples-policies-modifyresource.html">Modify a single resource</a></li>
<li><a href="protocol-examples-policies-retrieveresource.html">Retrieve a single resource</a></li>
<li><a href="protocol-examples-policies-errorresponses.html">Error responses</a></li>
</ul>
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<li><a href="protocol-examples-search.html">→ Search examples</a></li>
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<h1 class="post-title-main">Protocol examples</h1>
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<p>The structure of the examples in this section is as follows:</p>
<h2 id="command">Command</h2>
<p>Each example always starts with a command message that initiates an operation at Ditto (e.g. create a thing, retrieve a thing).</p>
<div class="language-json highlighter-rouge"><div class="highlight"><pre class="highlight"><code><span class="p">{</span><span class="w">
</span><span class="s2">"topic"</span><span class="p">:</span><span class="w"> </span><span class="s2">"com.acme/xdk_58/things/twin/commands/modify"</span><span class="p">,</span><span class="w">
</span><span class="s2">"headers"</span><span class="p">:</span><span class="w"> </span><span class="p">{</span><span class="w">
</span><span class="s2">"correlation-id"</span><span class="p">:</span><span class="w"> </span><span class="s2">"a780b7b5-fdd2-4864-91fc-80df6bb0a636"</span><span class="p">,</span><span class="w">
</span><span class="s2">"requested-acks"</span><span class="p">:</span><span class="w"> </span><span class="p">[</span><span class="w"> </span><span class="s2">"twin-persisted"</span><span class="p">,</span><span class="s2">"custom-ack"</span><span class="w"> </span><span class="p">]</span><span class="w">
</span><span class="p">},</span><span class="w">
</span><span class="s2">"path"</span><span class="p">:</span><span class="w"> </span><span class="s2">"/"</span><span class="w">
</span><span class="err">...</span><span class="w">
</span><span class="p">}</span><span class="w">
</span></code></pre></div></div>
<h2 id="response">Response</h2>
<p>A command always has a response which either reports the success or the failure. The example contains the success response.
See Thing Error responses for examples of messages that will be returned in case of an error.</p>
<div class="language-json highlighter-rouge"><div class="highlight"><pre class="highlight"><code><span class="p">{</span><span class="w">
</span><span class="s2">"headers"</span><span class="p">:</span><span class="w"> </span><span class="p">{</span><span class="w">
</span><span class="s2">"correlation-id"</span><span class="p">:</span><span class="w"> </span><span class="s2">"a780b7b5-fdd2-4864-91fc-80df6bb0a636"</span><span class="w">
</span><span class="p">},</span><span class="w">
</span><span class="s2">"path"</span><span class="p">:</span><span class="w"> </span><span class="s2">"/"</span><span class="p">,</span><span class="w">
</span><span class="s2">"value"</span><span class="p">:</span><span class="w"> </span><span class="p">{</span><span class="w">
</span><span class="err">...</span><span class="w">
</span><span class="p">},</span><span class="w">
</span><span class="s2">"status"</span><span class="p">:</span><span class="w"> </span><span class="mi">204</span><span class="w">
</span><span class="p">}</span><span class="w">
</span></code></pre></div></div>
<h2 id="event">Event</h2>
<p>If Ditto triggers an event (e.g. Thing created, Attribute modified) as a result of the executed command, an example of such an event is also demonstrated.</p>
<div class="language-json highlighter-rouge"><div class="highlight"><pre class="highlight"><code><span class="p">{</span><span class="w">
</span><span class="s2">"topic"</span><span class="p">:</span><span class="w"> </span><span class="s2">"com.acme/thing_id_3141/things/twin/events/modified"</span><span class="p">,</span><span class="w">
</span><span class="s2">"headers"</span><span class="p">:</span><span class="w"> </span><span class="p">{</span><span class="w">
</span><span class="s2">"correlation-id"</span><span class="p">:</span><span class="w"> </span><span class="s2">"a780b7b5-fdd2-4864-91fc-80df6bb0a636"</span><span class="p">,</span><span class="w">
</span><span class="s2">"requested-acks"</span><span class="p">:</span><span class="w"> </span><span class="p">[</span><span class="w"> </span><span class="s2">"custom-ack"</span><span class="w"> </span><span class="p">]</span><span class="w">
</span><span class="p">},</span><span class="w">
</span><span class="s2">"path"</span><span class="p">:</span><span class="w"> </span><span class="s2">"/"</span><span class="p">,</span><span class="w">
</span><span class="s2">"value"</span><span class="p">:</span><span class="w"> </span><span class="p">{</span><span class="w">
</span><span class="err">...</span><span class="w">
</span><span class="p">},</span><span class="w">
</span><span class="s2">"revision"</span><span class="p">:</span><span class="w"> </span><span class="mi">1</span><span class="w">
</span><span class="p">}</span><span class="w">
</span></code></pre></div></div>
<h2 id="acknowledgements-acks">Acknowledgements (ACKs)</h2>
<p>A command issuer can require a response and specify the acknowledgements (ACKs) which have to be successfully fulfilled
to regard the command as successfully executed.</p>
<p>Below an example is given for a successfully fulfilled ACK (status 202):</p>
<div class="language-json highlighter-rouge"><div class="highlight"><pre class="highlight"><code><span class="p">{</span><span class="w">
</span><span class="s2">"topic"</span><span class="p">:</span><span class="w"> </span><span class="s2">"com.acme/thing_name_3141/things/twin/acks/custom-ack"</span><span class="p">,</span><span class="w">
</span><span class="s2">"headers"</span><span class="p">:</span><span class="w"> </span><span class="p">{</span><span class="w">
</span><span class="s2">"correlation-id"</span><span class="p">:</span><span class="w"> </span><span class="s2">"a780b7b5-fdd2-4864-91fc-80df6bb0a636"</span><span class="w">
</span><span class="p">},</span><span class="w">
</span><span class="s2">"path"</span><span class="p">:</span><span class="w"> </span><span class="s2">"/"</span><span class="p">,</span><span class="w">
</span><span class="s2">"status"</span><span class="p">:</span><span class="w"> </span><span class="mi">202</span><span class="w">
</span><span class="p">}</span><span class="w">
</span></code></pre></div></div>
<p>And here is an example for a failed ACK (aka NACK, status 400):</p>
<div class="language-json highlighter-rouge"><div class="highlight"><pre class="highlight"><code><span class="p">{</span><span class="w">
</span><span class="s2">"topic"</span><span class="p">:</span><span class="w"> </span><span class="s2">"com.acme/thing_name_3141/things/twin/acks/custom-ack"</span><span class="p">,</span><span class="w">
</span><span class="s2">"headers"</span><span class="p">:</span><span class="w"> </span><span class="p">{</span><span class="w">
</span><span class="s2">"correlation-id"</span><span class="p">:</span><span class="w"> </span><span class="s2">"a780b7b5-fdd2-4864-91fc-80df6bb0a636"</span><span class="w">
</span><span class="p">},</span><span class="w">
</span><span class="s2">"path"</span><span class="p">:</span><span class="w"> </span><span class="s2">"/"</span><span class="p">,</span><span class="w">
</span><span class="s2">"value"</span><span class="p">:</span><span class="w"> </span><span class="s2">"You better try harder"</span><span class="p">,</span><span class="w">
</span><span class="s2">"status"</span><span class="p">:</span><span class="w"> </span><span class="mi">400</span><span class="w">
</span><span class="p">}</span><span class="w">
</span></code></pre></div></div>
<p>An ACK representing a timeout would look like this:</p>
<div class="language-json highlighter-rouge"><div class="highlight"><pre class="highlight"><code><span class="p">{</span><span class="w">
</span><span class="s2">"topic"</span><span class="p">:</span><span class="w"> </span><span class="s2">"com.acme/thing_name_3141/things/twin/acks/custom-ack"</span><span class="p">,</span><span class="w">
</span><span class="s2">"headers"</span><span class="p">:</span><span class="w"> </span><span class="p">{</span><span class="w">
</span><span class="s2">"correlation-id"</span><span class="p">:</span><span class="w"> </span><span class="s2">"a780b7b5-fdd2-4864-91fc-80df6bb0a636"</span><span class="w">
</span><span class="p">},</span><span class="w">
</span><span class="s2">"path"</span><span class="p">:</span><span class="w"> </span><span class="s2">"/"</span><span class="p">,</span><span class="w">
</span><span class="s2">"value"</span><span class="p">:</span><span class="w"> </span><span class="p">{</span><span class="w">
</span><span class="s2">"status"</span><span class="p">:</span><span class="w"> </span><span class="mi">408</span><span class="p">,</span><span class="w">
</span><span class="s2">"error"</span><span class="p">:</span><span class="w"> </span><span class="s2">"acknowledgement:request.timeout"</span><span class="p">,</span><span class="w">
</span><span class="s2">"message"</span><span class="p">:</span><span class="w"> </span><span class="s2">"The acknowledgement request reached the specified timeout of 1,337ms."</span><span class="p">,</span><span class="w">
</span><span class="s2">"description"</span><span class="p">:</span><span class="w"> </span><span class="s2">"Try increasing the timeout and make sure that the requested acknowledgement is sent back in time."</span><span class="w">
</span><span class="p">},</span><span class="w">
</span><span class="s2">"status"</span><span class="p">:</span><span class="w"> </span><span class="mi">408</span><span class="w">
</span><span class="p">}</span><span class="w">
</span></code></pre></div></div>
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