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>.NET Thin Client</a>
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>C++ Thin Client</a>
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<li><a href="/docs/2.10.0/binary-client-protocol/key-value-queries" class=''>Key-Value Queries</a></li>
<li><a href="/docs/2.10.0/binary-client-protocol/sql-and-scan-queries" class=''>SQL and Scan Queries</a></li>
<li><a href="/docs/2.10.0/binary-client-protocol/binary-type-metadata" class=''>Binary Types Metadata</a></li>
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<a href="/docs/2.10.0/data-modeling/data-modeling"
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<a href="/docs/2.10.0/data-modeling/affinity-collocation"
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<a href="/docs/2.10.0/data-modeling/binary-marshaller"
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<a href="/docs/2.10.0/memory-configuration/data-regions"
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<a href="/docs/2.10.0/memory-configuration/eviction-policies"
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<a href="/docs/2.10.0/persistence/swap"
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<a href="/docs/2.10.0/persistence/custom-cache-store"
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<li>
<a href="/docs/2.10.0/persistence/snapshots"
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<a href="/docs/2.10.0/persistence/disk-compression"
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<a href="/docs/2.10.0/persistence/persistence-tuning"
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<button type='button' class='group-toggle collapsed '>Configuring Caches<img class="state-indicator" src="/assets/images/left-nav-arrow.svg" width="6" height="10"></button>
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<a href="/docs/2.10.0/configuring-caches/configuration-overview"
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<a href="/docs/2.10.0/configuring-caches/configuring-backups"
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<a href="/docs/2.10.0/configuring-caches/partition-loss-policy"
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>Partition Loss Policy</a>
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<a href="/docs/2.10.0/configuring-caches/atomicity-modes"
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>Atomicity Modes</a>
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<a href="/docs/2.10.0/configuring-caches/expiry-policies"
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<a href="/docs/2.10.0/configuring-caches/on-heap-caching"
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<a href="/docs/2.10.0/configuring-caches/cache-groups"
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<a href="/docs/2.10.0/configuring-caches/near-cache"
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<li>
<a href="/docs/2.10.0/data-rebalancing" class='' >Data Rebalancing</a>
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<a href="/docs/2.10.0/data-streaming" class='' >Data Streaming</a>
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<button type='button' class='group-toggle collapsed '>Using Key-Value API<img class="state-indicator" src="/assets/images/left-nav-arrow.svg" width="6" height="10"></button>
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<a href="/docs/2.10.0/key-value-api/basic-cache-operations"
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<a href="/docs/2.10.0/read-repair"
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<a href="/docs/2.10.0/key-value-api/transactions" class='' >Performing Transactions</a>
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<a href="/docs/2.10.0/SQL/sql-introduction"
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<a href="/docs/2.10.0/SQL/schemas"
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<a href="/docs/2.10.0/SQL/indexes"
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<a href="/docs/2.10.0/SQL/JDBC/jdbc-client-driver"
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<a href="/docs/2.10.0/sql-reference/ddl"
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<a href="/docs/2.10.0/sql-reference/dml"
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<a href="/docs/2.10.0/sql-reference/operational-commands"
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<a href="/docs/2.10.0/sql-reference/aggregate-functions"
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>Aggregate functions</a>
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<a href="/docs/2.10.0/sql-reference/string-functions"
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<a href="/docs/2.10.0/sql-reference/date-time-functions"
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<a href="/docs/2.10.0/sql-reference/system-functions"
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<a href="/docs/2.10.0/distributed-computing/distributed-computing"
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<a href="/docs/2.10.0/distributed-computing/cluster-groups"
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<a href="/docs/2.10.0/distributed-computing/executor-service"
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>Executor Service</a>
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<a href="/docs/2.10.0/distributed-computing/map-reduce"
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>MapReduce API</a>
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<a href="/docs/2.10.0/distributed-computing/load-balancing"
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>Load Balancing</a>
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<a href="/docs/2.10.0/distributed-computing/fault-tolerance"
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>Fault Tolerance</a>
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<a href="/docs/2.10.0/distributed-computing/job-scheduling"
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>Job Scheduling</a>
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<li>
<a href="/docs/2.10.0/distributed-computing/collocated-computations"
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>Colocating Computations with Data</a>
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<a href="/docs/2.10.0/code-deployment/deploying-user-code"
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<a href="/docs/2.10.0/code-deployment/peer-class-loading"
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<a href="/docs/2.10.0/machine-learning/machine-learning"
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<a href="/docs/2.10.0/machine-learning/partition-based-dataset"
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>Partition Based Dataset</a>
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<a href="/docs/2.10.0/machine-learning/updating-trained-models"
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<button
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<li><a href="/docs/2.10.0/machine-learning/binary-classification/introduction" class=''>Introduction</a></li>
<li><a href="/docs/2.10.0/machine-learning/binary-classification/linear-svm" class=''>Linear SVM (Support Vector Machine)</a></li>
<li><a href="/docs/2.10.0/machine-learning/binary-classification/decision-trees" class=''>Decision Trees</a></li>
<li><a href="/docs/2.10.0/machine-learning/binary-classification/multilayer-perceptron" class=''>Multilayer Perceptron</a></li>
<li><a href="/docs/2.10.0/machine-learning/binary-classification/logistic-regression" class=''>Logistic Regression</a></li>
<li><a href="/docs/2.10.0/machine-learning/binary-classification/knn-classification" class=''>k-NN Classification</a></li>
<li><a href="/docs/2.10.0/machine-learning/binary-classification/ann" class=''>ANN (Approximate Nearest Neighbor)</a></li>
<li><a href="/docs/2.10.0/machine-learning/binary-classification/naive-bayes" class=''>Naive Bayes</a></li>
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<li><a href="/docs/2.10.0/machine-learning/regression/introduction" class=''>Introduction</a></li>
<li><a href="/docs/2.10.0/machine-learning/regression/linear-regression" class=''>Linear Regression</a></li>
<li><a href="/docs/2.10.0/machine-learning/regression/decision-trees-regression" class=''>Decision Trees Regression</a></li>
<li><a href="/docs/2.10.0/machine-learning/regression/knn-regression" class=''>k-NN Regression</a></li>
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<button
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<li><a href="/docs/2.10.0/machine-learning/clustering/introduction" class=''>Introduction</a></li>
<li><a href="/docs/2.10.0/machine-learning/clustering/k-means-clustering" class=''>K-Means Clustering</a></li>
<li><a href="/docs/2.10.0/machine-learning/clustering/gaussian-mixture" class=''>Gaussian mixture (GMM)</a></li>
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</li>
<li>
<a href="/docs/2.10.0/machine-learning/preprocessing"
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<button
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<li><a href="/docs/2.10.0/machine-learning/model-selection/introduction" class=''>Introduction</a></li>
<li><a href="/docs/2.10.0/machine-learning/model-selection/evaluator" class=''>Evaluator</a></li>
<li><a href="/docs/2.10.0/machine-learning/model-selection/split-the-dataset-on-test-and-train-datasets" class=''>Split the dataset on test and train datasets</a></li>
<li><a href="/docs/2.10.0/machine-learning/model-selection/hyper-parameter-tuning" class=''>Hyper-parameter tuning</a></li>
<li><a href="/docs/2.10.0/machine-learning/model-selection/pipeline-api" class=''>Pipeline API</a></li>
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</li>
<li>
<a href="/docs/2.10.0/machine-learning/multiclass-classification"
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>Multiclass Classification</a>
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<li>
<button
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class='collapsed '>Ensemble Methods<img class="state-indicator" src="/assets/images/left-nav-arrow.svg" width="6" height="10"></button>
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<li><a href="/docs/2.10.0/machine-learning/ensemble-methods/introduction" class=''></a></li>
<li><a href="/docs/2.10.0/machine-learning/ensemble-methods/stacking" class=''>Stacking</a></li>
<li><a href="/docs/2.10.0/machine-learning/ensemble-methods/baggin" class=''>Bagging</a></li>
<li><a href="/docs/2.10.0/machine-learning/ensemble-methods/random-forest" class=''>Random Forest</a></li>
<li><a href="/docs/2.10.0/machine-learning/ensemble-methods/gradient-boosting" class=''>Gradient Boosting</a></li>
</nav>
</li>
<li>
<a href="/docs/2.10.0/machine-learning/recommendation-systems"
class=''
>Recommendation Systems</a>
</li>
<li>
<button
type='button'
class='collapsed '>Importing Model<img class="state-indicator" src="/assets/images/left-nav-arrow.svg" width="6" height="10"></button>
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<article data-swiftype-index='true'>
<a class='edit-link' href="https://github.com/apache/ignite/tree/IGNITE-7595/docs/_docs/messaging.adoc" target="_blank">Edit</a>
<h1>Topic-Based Messaging With Apache Ignite</h1>
<div class="sect1">
<h2 id="overview">Overview</h2>
<div class="sectionbody">
<div class="paragraph">
<p>Ignite distributed messaging enables topic-based cluster-wide communication between all nodes. Messages via a specified
message topic can be distributed to all or sub-group of nodes that have subscribed to that topic.</p>
</div>
<div class="paragraph">
<p>Ignite messaging is based on the publish-subscribe paradigm where publishers and subscribers are tethered together with
a common topic. When one of the nodes sends a message <code>A</code> for topic <code>T</code>, it is published on all nodes that have subscribed to <code>T</code>.</p>
</div>
<div class="admonitionblock note">
<table>
<tr>
<td class="icon">
<div class="title">Note</div>
</td>
<td class="content">
<div class="paragraph">
<p>Any new node joining the cluster automatically gets subscribed to all the topics that other nodes in the cluster
(or <a href="/docs/2.10.0/distributed-computing/cluster-groups">cluster group</a>) are subscribed to.</p>
</div>
</td>
</tr>
</table>
</div>
</div>
</div>
<div class="sect1">
<h2 id="ignitemessaging">IgniteMessaging</h2>
<div class="sectionbody">
<div class="paragraph">
<p>Distributed messaging functionality in Ignite is available via the <code>IgniteMessaging</code> interface. You can get an instance
of <code>IgniteMessaging</code> like so:</p>
</div>
<code-tabs><code-tab data-tab='Java'><div class="listingblock">
<div class="content">
<pre class="rouge highlight"><code data-lang="java"><span class="nc">Ignite</span> <span class="n">ignite</span> <span class="o">=</span> <span class="nc">Ignition</span><span class="o">.</span><span class="na">ignite</span><span class="o">();</span>
<span class="c1">// Messaging instance over this cluster.</span>
<span class="nc">IgniteMessaging</span> <span class="n">msg</span> <span class="o">=</span> <span class="n">ignite</span><span class="o">.</span><span class="na">message</span><span class="o">();</span>
<span class="c1">// Messaging instance over given cluster group (in this case, remote nodes).</span>
<span class="nc">IgniteMessaging</span> <span class="n">rmtMsg</span> <span class="o">=</span> <span class="n">ignite</span><span class="o">.</span><span class="na">message</span><span class="o">(</span><span class="n">ignite</span><span class="o">.</span><span class="na">cluster</span><span class="o">().</span><span class="na">forRemotes</span><span class="o">());</span></code></pre>
</div>
</div></code-tab></code-tabs>
</div>
</div>
<div class="sect1">
<h2 id="publish-messages">Publish Messages</h2>
<div class="sectionbody">
<div class="paragraph">
<p>Send methods help sending/publishing messages with a specified message topic to all nodes. Messages can be sent
in <em>ordered</em> or <em>unordered</em> manner.</p>
</div>
<div class="sect2">
<h3 id="ordered-messages">Ordered Messages</h3>
<div class="paragraph">
<p>The <code>sendOrdered(&#8230;&#8203;)</code> method can be used if you want to receive messages in the order they were sent. The timeout parameter
is passed to specify how long a message will stay in the queue to wait for messages that are supposed to be sent before
this message. If the timeout expires, then all the messages that have not yet arrived for a given topic on that node will be ignored.</p>
</div>
</div>
<div class="sect2">
<h3 id="unordered-messages">Unordered Messages</h3>
<div class="paragraph">
<p>The <code>send(&#8230;&#8203;)</code> methods do not guarantee message ordering. This means that, when you sequentially send message <code>A</code> and
message <code>B</code>, you are not guaranteed that the target node first receives <code>A</code> and then <code>B</code>.</p>
</div>
</div>
</div>
</div>
<div class="sect1">
<h2 id="subscribe-for-messages">Subscribe for Messages</h2>
<div class="sectionbody">
<div class="paragraph">
<p>Listen methods help to listen/subscribe for messages. When these methods are called, a listener with specified message
topic is registered on all (or sub-group of ) nodes to listen for new messages. With listen methods, a predicate is
passed that returns a boolean value which tells the listener to continue or stop listening for new messages.</p>
</div>
<div class="sect2">
<h3 id="local-listen">Local Listen</h3>
<div class="paragraph">
<p>The <code>localListen(&#8230;&#8203;)</code> method registers a message listener with specified topic only on the local node and listens for
messages from any node in the <em>given</em> cluster group.</p>
</div>
</div>
<div class="sect2">
<h3 id="remote-listen">Remote Listen</h3>
<div class="paragraph">
<p>The <code>remoteListen(&#8230;&#8203;)</code> method registers message listeners with specified topic on all nodes in the <em>given</em> cluster group
and listens for messages from any node in <em>this</em> cluster group.</p>
</div>
</div>
</div>
</div>
<div class="sect1">
<h2 id="example">Example</h2>
<div class="sectionbody">
<code-tabs><code-tab data-tab='Java'><div class="listingblock">
<div class="content">
<pre class="rouge highlight"><code data-lang="java"><span class="nc">Ignite</span> <span class="n">ignite</span> <span class="o">=</span> <span class="nc">Ignition</span><span class="o">.</span><span class="na">ignite</span><span class="o">();</span>
<span class="nc">IgniteMessaging</span> <span class="n">rmtMsg</span> <span class="o">=</span> <span class="n">ignite</span><span class="o">.</span><span class="na">message</span><span class="o">(</span><span class="n">ignite</span><span class="o">.</span><span class="na">cluster</span><span class="o">().</span><span class="na">forRemotes</span><span class="o">());</span>
<span class="c1">// Add listener for ordered messages on all remote nodes.</span>
<span class="n">rmtMsg</span><span class="o">.</span><span class="na">remoteListen</span><span class="o">(</span><span class="s">"MyOrderedTopic"</span><span class="o">,</span> <span class="o">(</span><span class="n">nodeId</span><span class="o">,</span> <span class="n">msg</span><span class="o">)</span> <span class="o">-&gt;</span> <span class="o">{</span>
<span class="nc">System</span><span class="o">.</span><span class="na">out</span><span class="o">.</span><span class="na">println</span><span class="o">(</span><span class="s">"Received ordered message [msg="</span> <span class="o">+</span> <span class="n">msg</span> <span class="o">+</span> <span class="s">", from="</span> <span class="o">+</span> <span class="n">nodeId</span> <span class="o">+</span> <span class="sc">']'</span><span class="o">);</span>
<span class="k">return</span> <span class="kc">true</span><span class="o">;</span> <span class="c1">// Return true to continue listening.</span>
<span class="o">});</span>
<span class="c1">// Send ordered messages to remote nodes.</span>
<span class="k">for</span> <span class="o">(</span><span class="kt">int</span> <span class="n">i</span> <span class="o">=</span> <span class="mi">0</span><span class="o">;</span> <span class="n">i</span> <span class="o">&lt;</span> <span class="mi">10</span><span class="o">;</span> <span class="n">i</span><span class="o">++)</span>
<span class="n">rmtMsg</span><span class="o">.</span><span class="na">sendOrdered</span><span class="o">(</span><span class="s">"MyOrderedTopic"</span><span class="o">,</span> <span class="nc">Integer</span><span class="o">.</span><span class="na">toString</span><span class="o">(</span><span class="n">i</span><span class="o">),</span><span class="mi">0</span><span class="o">);</span></code></pre>
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