geode-docs/developing/data_serialization/PDX_Serialization_Features.html.md.erb - geode - Git at Google

 <% set_title(product_name, "PDX Serialization Features") %>

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 <%=vars.product_name%> PDX serialization offers several advantages in terms of functionality.

 ## <a id="concept_F02E40517C4B42F2A75B133BB507C626__section_A0EEB4DA3E9F4EA4B65FE727D3951EA1" class="no-quick-link"></a>Application Versioning of PDX Domain Objects

 Domain objects evolve along with your application code. You might create an address object with two address lines, then realize later that a third line is required for some situations. Or you might realize that a particular field is not used and want to get rid of it. With PDX, you can use old and new versions of domain objects together in a cluster if the versions differ by the addition or removal of fields. This compatibility lets you gradually introduce modified code and data into the cluster, without bringing the cluster down.

 <%=vars.product_name%> maintains a central registry of the PDX domain object metadata. Using the registry, <%=vars.product_name%> preserves fields in each member's cache regardless of whether the field is defined. When a member receives an object with a registered field that the member is not aware of, the member does not access the field, but preserves it and passes it along with the entire object to other members. When a member receives an object that is missing one or more fields according to the member's version, <%=vars.product_name%> assigns the Java default values for the field types to the missing fields.

 ## <a id="concept_F02E40517C4B42F2A75B133BB507C626__section_D68A6A9C2C0C4D32AE7DADA2A4C3104D" class="no-quick-link"></a>Portability of PDX Serializable Objects

 When you serialize an object using PDX, <%=vars.product_name%> stores the object's type information in the central registry. The information is passed among clients and servers, peers, and clusters.

 This centralization of object type information is advantageous for client/server installations in which clients and servers are written in different languages. Clients pass registry information to servers automatically when they store a PDX serialized object. Clients can run queries and functions against the data in the servers without compatibility between server and the stored objects. One client can store data on the server to be retrieved by another client, with no requirements on the part of the server.

 ## <a id="concept_F02E40517C4B42F2A75B133BB507C626__section_08C901A3CF3E438C8778F09D482B9A63" class="no-quick-link"></a>Reduced Deserialization of Serialized Objects

 The access methods of PDX serialized objects allow you to examine specific fields of your domain object without deserializing the entire object. Depending on your object usage, you can reduce serialization and deserialization costs significantly.

 Java and other clients can run queries and execute functions against the objects in the server caches without deserializing the entire object on the server side. The query engine automatically recognizes PDX objects, retrieves the `PdxInstance` of the object and uses only the fields it needs. Likewise, peers can access only the necessary fields from the serialized object, keeping the object stored in the cache in serialized form.
	<% set_title(product_name, "PDX Serialization Features") %>

	<!--
	Licensed to the Apache Software Foundation (ASF) under one or more
	contributor license agreements. See the NOTICE file distributed with
	this work for additional information regarding copyright ownership.
	The ASF licenses this file to You under the Apache License, Version 2.0
	(the "License"); you may not use this file except in compliance with
	the License. You may obtain a copy of the License at

	http://www.apache.org/licenses/LICENSE-2.0

	Unless required by applicable law or agreed to in writing, software
	distributed under the License is distributed on an "AS IS" BASIS,
	WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	See the License for the specific language governing permissions and
	limitations under the License.
	-->

	<%=vars.product_name%> PDX serialization offers several advantages in terms of functionality.

	## <a id="concept_F02E40517C4B42F2A75B133BB507C626__section_A0EEB4DA3E9F4EA4B65FE727D3951EA1" class="no-quick-link"></a>Application Versioning of PDX Domain Objects

	Domain objects evolve along with your application code. You might create an address object with two address lines, then realize later that a third line is required for some situations. Or you might realize that a particular field is not used and want to get rid of it. With PDX, you can use old and new versions of domain objects together in a cluster if the versions differ by the addition or removal of fields. This compatibility lets you gradually introduce modified code and data into the cluster, without bringing the cluster down.

	<%=vars.product_name%> maintains a central registry of the PDX domain object metadata. Using the registry, <%=vars.product_name%> preserves fields in each member's cache regardless of whether the field is defined. When a member receives an object with a registered field that the member is not aware of, the member does not access the field, but preserves it and passes it along with the entire object to other members. When a member receives an object that is missing one or more fields according to the member's version, <%=vars.product_name%> assigns the Java default values for the field types to the missing fields.

	## <a id="concept_F02E40517C4B42F2A75B133BB507C626__section_D68A6A9C2C0C4D32AE7DADA2A4C3104D" class="no-quick-link"></a>Portability of PDX Serializable Objects

	When you serialize an object using PDX, <%=vars.product_name%> stores the object's type information in the central registry. The information is passed among clients and servers, peers, and clusters.

	This centralization of object type information is advantageous for client/server installations in which clients and servers are written in different languages. Clients pass registry information to servers automatically when they store a PDX serialized object. Clients can run queries and functions against the data in the servers without compatibility between server and the stored objects. One client can store data on the server to be retrieved by another client, with no requirements on the part of the server.

	## <a id="concept_F02E40517C4B42F2A75B133BB507C626__section_08C901A3CF3E438C8778F09D482B9A63" class="no-quick-link"></a>Reduced Deserialization of Serialized Objects

	The access methods of PDX serialized objects allow you to examine specific fields of your domain object without deserializing the entire object. Depending on your object usage, you can reduce serialization and deserialization costs significantly.

	Java and other clients can run queries and execute functions against the objects in the server caches without deserializing the entire object on the server side. The query engine automatically recognizes PDX objects, retrieves the `PdxInstance` of the object and uses only the fields it needs. Likewise, peers can access only the necessary fields from the serialized object, keeping the object stored in the cache in serialized form.