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     <li class="toctree-l3"><a href="#register-a-class-before-serialization">Register a class before serialization.</a></li>


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                 <p>Gearpump has a built-in serialization framework with a shaded Kryo version, which allows you to customize how a specific message type can be serialized. </p>
 <h4 id="register-a-class-before-serialization">Register a class before serialization.</h4>
 <p>Note, to use built-in kryo serialization framework, Gearpump requires all classes to be registered explicitly before using, no matter you want to use a custom serializer or not. If not using custom serializer, Gearpump will use default com.esotericsoftware.kryo.serializers.FieldSerializer to serialize the class. </p>
 <p>To register a class, you need to change the configuration file gear.conf(or application.conf if you want it only take effect for single application).</p>
 <pre class="codehilite"><code class="language-json">gearpump {
   serializers {
     ## We will use default FieldSerializer to serialize this class type
     &quot;org.apache.gearpump.UserMessage&quot; = &quot;&quot;

     ## we will use custom serializer to serialize this class type
     &quot;org.apache.gearpump.UserMessage2&quot; = &quot;org.apache.gearpump.UserMessageSerializer&quot;
   }
 }</code></pre>


 <h4 id="how-to-define-a-custom-serializer-for-built-in-kryo-serialization-framework">How to define a custom serializer for built-in kryo serialization framework</h4>
 <p>When you decide that you want to define a custom serializer, you can do this in two ways.</p>
 <p>Please note that Gearpump shaded the original Kryo dependency. The package name <code>com.esotericsoftware</code> was relocated to <code>org.apache.gearpump.esotericsoftware</code>. So in the following customization, you should import corresponding shaded classes, the example code will show that part.</p>
 <p>In general you should use the shaded version of a library whenever possible in order to avoid binary incompatibilities, eg don't use:</p>
 <pre class="codehilite"><code class="language-scala">import com.google.common.io.Files</code></pre>


 <p>but rather</p>
 <pre class="codehilite"><code class="language-scala">import org.apache.gearpump.google.common.io.Files</code></pre>


 <h5 id="system-level-serializer">System Level Serializer</h5>
 <p>If the serializer is widely used, you can define a global serializer which is available to all applications(or worker or master) in the system.</p>
 <h6 id="step1-you-first-need-to-develop-a-java-library-which-contains-the-custom-serializer-class-here-is-an-example">Step1: you first need to develop a java library which contains the custom serializer class. here is an example:</h6>
 <pre class="codehilite"><code class="language-scala">package org.apache.gearpump

 import org.apache.gearpump.esotericsoftware.kryo.{Kryo, Serializer}
 import org.apache.gearpump.esotericsoftware.kryo.io.{Input, Output}

 class UserMessage(longField: Long, intField: Int)

 class UserMessageSerializer extends Serializer[UserMessage] {
   override def write(kryo: Kryo, output: Output, obj: UserMessage) = {
     output.writeLong(obj.longField)
     output.writeInt(obj.intField)
   }

   override def read(kryo: Kryo, input: Input, typ: Class[UserMessage]): UserMessage = {
     val longField = input.readLong()
     val intField = input.readInt()
     new UserMessage(longField, intField)
   }
 }</code></pre>


 <h6 id="step2-distribute-the-libraries">Step2: Distribute the libraries</h6>
 <p>Distribute the jar file to lib/ folder of every Gearpump installation in the cluster.</p>
 <h6 id="step3-change-gearconf-on-every-machine-of-the-cluster">Step3: change gear.conf on every machine of the cluster:</h6>
 <pre class="codehilite"><code class="language-json">gearpump {
   serializers {
     &quot;org.apache.gearpump.UserMessage&quot; = &quot;org.apache.gearpump.UserMessageSerializer&quot;
   }
 }</code></pre>


 <h6 id="all-set">All set!</h6>
 <h5 id="define-application-level-custom-serializer">Define Application level custom serializer</h5>
 <p>If all you want is to define an application level serializer, which is only visible to current application AppMaster and Executors(including tasks), you can follow a different approach.</p>
 <h6 id="step1-define-your-custom-serializer-class">Step1: Define your custom Serializer class</h6>
 <p>You should include the Serializer class in your application jar. Here is an example to define a custom serializer:</p>
 <pre class="codehilite"><code class="language-scala">package org.apache.gearpump

 import org.apache.gearpump.esotericsoftware.kryo.{Kryo, Serializer}
 import org.apache.gearpump.esotericsoftware.kryo.io.{Input, Output}

 class UserMessage(longField: Long, intField: Int)

 class UserMessageSerializer extends Serializer[UserMessage] {
   override def write(kryo: Kryo, output: Output, obj: UserMessage) = {
     output.writeLong(obj.longField)
     output.writeInt(obj.intField)
   }

   override def read(kryo: Kryo, input: Input, typ: Class[UserMessage]): UserMessage = {
     val longField = input.readLong()
     val intField = input.readInt()
     new UserMessage(longField, intField)
   }
 }</code></pre>


 <h6 id="step2-put-a-applicationconf-in-your-classpath-on-client-machine-where-you-submit-the-application">Step2: Put a application.conf in your classpath on Client machine where you submit the application,</h6>
 <pre class="codehilite"><code class="language-json">### content of application.conf
 gearpump {
   serializers {
     &quot;org.apache.gearpump.UserMessage&quot; = &quot;org.apache.gearpump.UserMessageSerializer&quot;
   }
 }</code></pre>


 <h6 id="step3-all-set">Step3: All set!</h6>
 <h4 id="advanced-choose-another-serialization-framework">Advanced: Choose another serialization framework</h4>
 <p>Note: This is only for advanced user which require deep customization of Gearpump platform.</p>
 <p>There are other serialization framework besides Kryo, like Protobuf. If user don't want to use the built-in kryo serialization framework, he can customize a new serialization framework. </p>
 <p>basically, user need to define in gear.conf(or application.conf for single application's scope) file like this:</p>
 <pre class="codehilite"><code class="language-bash">gearpump.serialization-framework = &quot;org.apache.gearpump.serializer.CustomSerializationFramework&quot;</code></pre>


 <p>Please find an example in gearpump storm module, search "StormSerializationFramework" in source code.</p>

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	<p>Gearpump has a built-in serialization framework with a shaded Kryo version, which allows you to customize how a specific message type can be serialized. </p>
	<h4 id="register-a-class-before-serialization">Register a class before serialization.</h4>
	<p>Note, to use built-in kryo serialization framework, Gearpump requires all classes to be registered explicitly before using, no matter you want to use a custom serializer or not. If not using custom serializer, Gearpump will use default com.esotericsoftware.kryo.serializers.FieldSerializer to serialize the class. </p>
	<p>To register a class, you need to change the configuration file gear.conf(or application.conf if you want it only take effect for single application).</p>
	<pre class="codehilite"><code class="language-json">gearpump {
	serializers {
	## We will use default FieldSerializer to serialize this class type
	"org.apache.gearpump.UserMessage" = ""

	## we will use custom serializer to serialize this class type
	"org.apache.gearpump.UserMessage2" = "org.apache.gearpump.UserMessageSerializer"
	}
	}</code></pre>


	<h4 id="how-to-define-a-custom-serializer-for-built-in-kryo-serialization-framework">How to define a custom serializer for built-in kryo serialization framework</h4>
	<p>When you decide that you want to define a custom serializer, you can do this in two ways.</p>
	<p>Please note that Gearpump shaded the original Kryo dependency. The package name <code>com.esotericsoftware</code> was relocated to <code>org.apache.gearpump.esotericsoftware</code>. So in the following customization, you should import corresponding shaded classes, the example code will show that part.</p>
	<p>In general you should use the shaded version of a library whenever possible in order to avoid binary incompatibilities, eg don't use:</p>
	<pre class="codehilite"><code class="language-scala">import com.google.common.io.Files</code></pre>


	<p>but rather</p>
	<pre class="codehilite"><code class="language-scala">import org.apache.gearpump.google.common.io.Files</code></pre>


	<h5 id="system-level-serializer">System Level Serializer</h5>
	<p>If the serializer is widely used, you can define a global serializer which is available to all applications(or worker or master) in the system.</p>
	<h6 id="step1-you-first-need-to-develop-a-java-library-which-contains-the-custom-serializer-class-here-is-an-example">Step1: you first need to develop a java library which contains the custom serializer class. here is an example:</h6>
	<pre class="codehilite"><code class="language-scala">package org.apache.gearpump

	import org.apache.gearpump.esotericsoftware.kryo.{Kryo, Serializer}
	import org.apache.gearpump.esotericsoftware.kryo.io.{Input, Output}

	class UserMessage(longField: Long, intField: Int)

	class UserMessageSerializer extends Serializer[UserMessage] {
	override def write(kryo: Kryo, output: Output, obj: UserMessage) = {
	output.writeLong(obj.longField)
	output.writeInt(obj.intField)
	}

	override def read(kryo: Kryo, input: Input, typ: Class[UserMessage]): UserMessage = {
	val longField = input.readLong()
	val intField = input.readInt()
	new UserMessage(longField, intField)
	}
	}</code></pre>


	<h6 id="step2-distribute-the-libraries">Step2: Distribute the libraries</h6>
	<p>Distribute the jar file to lib/ folder of every Gearpump installation in the cluster.</p>
	<h6 id="step3-change-gearconf-on-every-machine-of-the-cluster">Step3: change gear.conf on every machine of the cluster:</h6>
	<pre class="codehilite"><code class="language-json">gearpump {
	serializers {
	"org.apache.gearpump.UserMessage" = "org.apache.gearpump.UserMessageSerializer"
	}
	}</code></pre>


	<h6 id="all-set">All set!</h6>
	<h5 id="define-application-level-custom-serializer">Define Application level custom serializer</h5>
	<p>If all you want is to define an application level serializer, which is only visible to current application AppMaster and Executors(including tasks), you can follow a different approach.</p>
	<h6 id="step1-define-your-custom-serializer-class">Step1: Define your custom Serializer class</h6>
	<p>You should include the Serializer class in your application jar. Here is an example to define a custom serializer:</p>
	<pre class="codehilite"><code class="language-scala">package org.apache.gearpump

	import org.apache.gearpump.esotericsoftware.kryo.{Kryo, Serializer}
	import org.apache.gearpump.esotericsoftware.kryo.io.{Input, Output}

	class UserMessage(longField: Long, intField: Int)

	class UserMessageSerializer extends Serializer[UserMessage] {
	override def write(kryo: Kryo, output: Output, obj: UserMessage) = {
	output.writeLong(obj.longField)
	output.writeInt(obj.intField)
	}

	override def read(kryo: Kryo, input: Input, typ: Class[UserMessage]): UserMessage = {
	val longField = input.readLong()
	val intField = input.readInt()
	new UserMessage(longField, intField)
	}
	}</code></pre>


	<h6 id="step2-put-a-applicationconf-in-your-classpath-on-client-machine-where-you-submit-the-application">Step2: Put a application.conf in your classpath on Client machine where you submit the application,</h6>
	<pre class="codehilite"><code class="language-json">### content of application.conf
	gearpump {
	serializers {
	"org.apache.gearpump.UserMessage" = "org.apache.gearpump.UserMessageSerializer"
	}
	}</code></pre>


	<h6 id="step3-all-set">Step3: All set!</h6>
	<h4 id="advanced-choose-another-serialization-framework">Advanced: Choose another serialization framework</h4>
	<p>Note: This is only for advanced user which require deep customization of Gearpump platform.</p>
	<p>There are other serialization framework besides Kryo, like Protobuf. If user don't want to use the built-in kryo serialization framework, he can customize a new serialization framework. </p>
	<p>basically, user need to define in gear.conf(or application.conf for single application's scope) file like this:</p>
	<pre class="codehilite"><code class="language-bash">gearpump.serialization-framework = "org.apache.gearpump.serializer.CustomSerializationFramework"</code></pre>


	<p>Please find an example in gearpump storm module, search "StormSerializationFramework" in source code.</p>

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