| <!-- |
| 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. |
| --> |
| <HTML> |
| <BODY> |
| |
| <P>The base package of the GemFire Java product, featuring highly |
| concurrent distributed {@linkplain org.apache.geode.cache.Cache caching} |
| with {@linkplain org.apache.geode.cache.CacheEvent cache event} delivery, |
| <a href="{@docRoot}/org/apache/geode/cache/query/package-summary.html#package_description">OQL querying</a>, and |
| <a href="{@docRoot}/org/apache/geode/admin/package-summary.html#package_description">remote cache administration</a>, built using a {@linkplain |
| org.apache.geode.distributed.DistributedSystem} which includes a |
| {@linkplain org.apache.geode.distributed.DistributedLockService}. |
| </P> |
| |
| <p>This package contains classes that are used throughout GemFire, |
| providing enhanced serialization performance using the {@link |
| org.apache.geode.DataSerializable} feature and the ability to |
| profile your GemFire application using a handy {@link |
| org.apache.geode.Statistics} infrastructure. |
| <p> |
| |
| <!-- ------------------------------------------------------------ --> |
| |
| <A NAME="statistics"><H2>GemFire Statistics</H2></A> |
| |
| <P>The ability to monitor and analyze the behavior and performance of |
| an application can ease the job of optimization. To aid in this |
| analysis, GemFire provides the ability to register and capture |
| application statistics. An application statistic is simply a number |
| that the application is free to modify and that is monitored by |
| the GemFire's statistics collector. |
| The statistics may be |
| monitored at runtime using the Admin API or GemFire JMX Agent.</P> |
| |
| <P>Each application statistic is described by a |
| {@link org.apache.geode.StatisticDescriptor} instance. |
| Logical groupings of application statistics are described by a |
| {@link org.apache.geode.StatisticsType} instance that contains the name |
| and description of each statistic. Each instance of an type |
| is represented by an instance of |
| {@link org.apache.geode.Statistics}. |
| The {@link org.apache.geode.StatisticDescriptor descriptors}, |
| {@link org.apache.geode.StatisticsType types}, and |
| {@link org.apache.geode.Statistics instances} are created using an |
| instance of the {@link org.apache.geode.StatisticsFactory} interface. |
| Each statistics instance |
| (there may be multiple instances of a statistics type) can be identified |
| by a {@link org.apache.geode.Statistics#getTextId text id} |
| and/or a {@link org.apache.geode.Statistics#getNumericId numeric id}. |
| The name, description, etc. of the statistic and its type |
| are available in the Admin API or GemFire JMX Agent.</P> |
| |
| <P>An application can get, set, and increment the value of a statistic |
| using methods of the <code>Statistics</code> interface. If statistics |
| sampling has been <A |
| href="distributed/DistributedSystem.html#statistic-sampling-enabled">enabled</A> |
| a thread in the application VM <A |
| href="distributed/DistributedSystem.html#statistic-sample-rate">periodically</A> |
| reads the values of application statistics allowing them to be viewed |
| by the Admin API and GemFire JMX Agent. Statistics may also be archived |
| to a file, the <A |
| href="distributed/DistributedSystem.html#statistic-archive-file ">name |
| and location</A> of which may be configured when creating a {@link |
| org.apache.geode.distributed.DistributedSystem}. </P> |
| |
| <P>In addition to application statistics, GemFire maintains statistics |
| about the distributed system, the distributed cache, |
| and the physical machine on which it runs. These statistics can be |
| monitored, viewed, and archived just like application statistics.</P> |
| |
| </BODY> |
| </HTML> |
