geode-docs/managing/statistics/application_defined_statistics.html.md.erb - geode - Git at Google

 ---
 title:  Application-Defined and Custom Statistics
 ---

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 <%=vars.product_name%> includes interfaces for defining and maintaining your own statistics.

 <a id="application_defined_statistics__section_88C31FA62A194947BF71AD54B5F9BAB3"></a>
 The <%=vars.product_name%> package, `org.apache.geode`, includes the following interfaces for defining and maintaining your own statistics:

 -   **StatisticDescriptor**. Describes an individual statistic. Each statistic has a name and information on the statistic it holds, such as its class type (long, int, etc.) and whether it is a counter that always increments, or a gauge that can vary in any manner.
 -   **StatisticsType**. Logical type that holds a list of `StatisticDescriptors` and provides access methods to them. The `StatisticDescriptors` contained by a `StatisticsType` are each assigned a unique ID within the list. `StatisticsType` is used to create a `Statistics` instance.
 -   **Statistics**. Instantiation of an existing `StatisticsType` object with methods for setting, incrementing, getting individual `StatisticDescriptor` values, and setting a callback which will recompute the statistic's value at configured sampling intervals.
 -   **StatisticsFactory**. Creates instances of `Statistics`. You can also use it to create instances of `StatisticDescriptor` and `StatisticsType`, because it implements `StatisticsTypeFactory`. `DistributedSystem` is an instance of `StatisticsFactory`.
 -   **StatisticsTypeFactory**. Creates instances of `StatisticDescriptor` and `StatisticsType`.

 The statistics interfaces are instantiated using statistics factory methods that are included in the package. For coding examples, see the online Java API documentation for `StatisticsFactory` and `StatisticsTypeFactory`.

 As an example, an application server might collect statistics on each client session in order to
 gauge whether client requests are being processed in a satisfactory manner. Long request queues or
 long server response times could prompt some capacity-management action such as starting additional
 application servers. To set this up, each session-state data point is identified and defined in a
 `StatisticDescriptor` instance. One instance might be a `RequestsInQueue` gauge, a non-negative
 integer that increments and decrements. Another could be a `RequestCount` counter, an integer that
 always increments. A list of these descriptors is used to instantiate a `SessionStateStats`
 `StatisticsType`. When a client connects, the application server uses the `StatisticsType` object to
 create a session-specific `Statistics` object. The server then uses the `Statistics` methods to
 modify and retrieve the client’s statistics. The figures below illustrate the relationships between the
 statistics interfaces and show the implementation of this use case.

 <img src="../../images/Statistics-interfaces.png" class="image" />

 *The Statistics Interfaces*

 Each `StatisticDescriptor` contains one piece of statistical information. `StatisticalDesriptor` objects
 are collected into a `StatisticsType`. The `StatisticsType` is instantiated to create a `Statistics`
 object.

 <img src="../../images/Statistics-implementation.png" class="image" />

 *Statistics Implementation*

 The `StatisticDescriptor` objects shown here hold three pieces of statistical information about client
 session state. These are collected into a `SessionStateStats StatisticsType`. With this type, the
 server creates a `Statistics` object for each client that connects.
	---
	title: Application-Defined and Custom Statistics
	---

	<!--
	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%> includes interfaces for defining and maintaining your own statistics.

	<a id="application_defined_statistics__section_88C31FA62A194947BF71AD54B5F9BAB3"></a>
	The <%=vars.product_name%> package, `org.apache.geode`, includes the following interfaces for defining and maintaining your own statistics:

	- StatisticDescriptor. Describes an individual statistic. Each statistic has a name and information on the statistic it holds, such as its class type (long, int, etc.) and whether it is a counter that always increments, or a gauge that can vary in any manner.
	- StatisticsType. Logical type that holds a list of `StatisticDescriptors` and provides access methods to them. The `StatisticDescriptors` contained by a `StatisticsType` are each assigned a unique ID within the list. `StatisticsType` is used to create a `Statistics` instance.
	- Statistics. Instantiation of an existing `StatisticsType` object with methods for setting, incrementing, getting individual `StatisticDescriptor` values, and setting a callback which will recompute the statistic's value at configured sampling intervals.
	- StatisticsFactory. Creates instances of `Statistics`. You can also use it to create instances of `StatisticDescriptor` and `StatisticsType`, because it implements `StatisticsTypeFactory`. `DistributedSystem` is an instance of `StatisticsFactory`.
	- StatisticsTypeFactory. Creates instances of `StatisticDescriptor` and `StatisticsType`.

	The statistics interfaces are instantiated using statistics factory methods that are included in the package. For coding examples, see the online Java API documentation for `StatisticsFactory` and `StatisticsTypeFactory`.

	As an example, an application server might collect statistics on each client session in order to
	gauge whether client requests are being processed in a satisfactory manner. Long request queues or
	long server response times could prompt some capacity-management action such as starting additional
	application servers. To set this up, each session-state data point is identified and defined in a
	`StatisticDescriptor` instance. One instance might be a `RequestsInQueue` gauge, a non-negative
	integer that increments and decrements. Another could be a `RequestCount` counter, an integer that
	always increments. A list of these descriptors is used to instantiate a `SessionStateStats`
	`StatisticsType`. When a client connects, the application server uses the `StatisticsType` object to
	create a session-specific `Statistics` object. The server then uses the `Statistics` methods to
	modify and retrieve the client’s statistics. The figures below illustrate the relationships between the
	statistics interfaces and show the implementation of this use case.

	<img src="../../images/Statistics-interfaces.png" class="image" />

	The Statistics Interfaces

	Each `StatisticDescriptor` contains one piece of statistical information. `StatisticalDesriptor` objects
	are collected into a `StatisticsType`. The `StatisticsType` is instantiated to create a `Statistics`
	object.

	<img src="../../images/Statistics-implementation.png" class="image" />

	Statistics Implementation

	The `StatisticDescriptor` objects shown here hold three pieces of statistical information about client
	session state. These are collected into a `SessionStateStats StatisticsType`. With this type, the
	server creates a `Statistics` object for each client that connects.