OpenSearch/docs/java-api/index.asciidoc

[[java-api]]
= Java API

include::../Versions.asciidoc[]

[preface]
== Preface
This section describes the Java API that elasticsearch provides. All
elasticsearch operations are executed using a
<<client,Client>> object. All
operations are completely asynchronous in nature (either accepts a
listener, or returns a future).

Additionally, operations on a client may be accumulated and executed in
<<java-docs-bulk,Bulk>>.

Note, all the APIs are exposed through the
Java API (actually, the Java API is used internally to execute them).

WARNING: Starting from version 5.6.0, a new Java client has been
released: the {java-rest}/java-rest-high.html[Java High Level REST Client].
This new client is designed to replace the `TransportClient` in Java
applications which will be deprecated in future versions of Elasticsearch.

== Javadoc

The javadoc for the transport client can be found at {transport-client-javadoc}/index.html.

== Maven Repository

Elasticsearch is hosted on
http://search.maven.org/#search%7Cga%7C1%7Ca%3A%22elasticsearch%22[Maven
Central].

For example, you can define the latest version in your `pom.xml` file:

["source","xml",subs="attributes"]
--------------------------------------------------
<dependency>
    <groupId>org.elasticsearch.client</groupId>
    <artifactId>transport</artifactId>
    <version>{version}</version>
</dependency>
--------------------------------------------------

[[java-transport-usage-maven-lucene]]
=== Lucene Snapshot repository

The very first releases of any major version (like a beta), might have been built on top of a Lucene Snapshot version.
In such a case you will be unable to resolve the Lucene dependencies of the client.

For example, if you want to use the `6.0.0-beta1` version which depends on Lucene `7.0.0-snapshot-00142c9`, you must
define the following repository.

For Maven:

["source","xml",subs="attributes"]
--------------------------------------------------
<repository>
    <id>elastic-lucene-snapshots</id>
    <name>Elastic Lucene Snapshots</name>
    <url>http://s3.amazonaws.com/download.elasticsearch.org/lucenesnapshots/00142c9</url>
    <releases><enabled>true</enabled></releases>
    <snapshots><enabled>false</enabled></snapshots>
</repository>
--------------------------------------------------

For Gradle:

["source","groovy",subs="attributes"]
--------------------------------------------------
maven {
    url 'http://s3.amazonaws.com/download.elasticsearch.org/lucenesnapshots/00142c9'
}
--------------------------------------------------

=== Log4j 2 Logger

You need to also include Log4j 2 dependencies:

["source","xml",subs="attributes"]
--------------------------------------------------
<dependency>
    <groupId>org.apache.logging.log4j</groupId>
    <artifactId>log4j-core</artifactId>
    <version>2.9.1</version>
</dependency>
--------------------------------------------------

And also provide a Log4j 2 configuration file in your classpath.
For example, you can add in your `src/main/resources` project dir a `log4j2.properties` file like:


["source","properties",subs="attributes"]
--------------------------------------------------
appender.console.type = Console
appender.console.name = console
appender.console.layout.type = PatternLayout
appender.console.layout.pattern = [%d{ISO8601}][%-5p][%-25c] %marker%m%n

rootLogger.level = info
rootLogger.appenderRef.console.ref = console
--------------------------------------------------

=== Using another Logger

If you want to use another logger than Log4j 2, you can use http://www.slf4j.org/[SLF4J] bridge to do that:

["source","xml",subs="attributes"]
--------------------------------------------------
<dependency>
    <groupId>org.apache.logging.log4j</groupId>
    <artifactId>log4j-to-slf4j</artifactId>
    <version>2.9.1</version>
</dependency>
<dependency>
    <groupId>org.slf4j</groupId>
    <artifactId>slf4j-api</artifactId>
    <version>1.7.24</version>
</dependency>
--------------------------------------------------

http://www.slf4j.org/manual.html[This page] lists implementations you can use. Pick your favorite logger
and add it as a dependency. As an example, we will use the `slf4j-simple` logger:

["source","xml",subs="attributes"]
--------------------------------------------------
<dependency>
    <groupId>org.slf4j</groupId>
    <artifactId>slf4j-simple</artifactId>
    <version>1.7.21</version>
</dependency>
--------------------------------------------------


== Dealing with JAR dependency conflicts

If you want to use Elasticsearch in your Java application, you may have to deal with version conflicts with third party
dependencies like Guava and Joda.  For instance, perhaps Elasticsearch uses Joda 2.8, while your code uses Joda 2.1.

You have two choices:

* The simplest solution is to upgrade. Newer module versions are likely to have fixed old bugs.
The further behind you fall, the harder it will be to upgrade later. Of course, it is possible that you are using a
third party dependency that in turn depends on an outdated version of a package, which prevents you from upgrading.

* The second option is to relocate the troublesome dependencies and to shade them either with your own application
or with Elasticsearch and any plugins needed by the Elasticsearch client.

The https://www.elastic.co/blog/to-shade-or-not-to-shade["To shade or not to shade" blog post] describes
all the steps for doing so.

== Embedding jar with dependencies

If you want to create a single jar containing your application and all dependencies, you should not
use `maven-assembly-plugin` for that because it can not deal with `META-INF/services` structure which is
required by Lucene jars.

Instead, you can use `maven-shade-plugin` and configure it as follow:

[source,xml]
--------------------------------------------------
<plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-shade-plugin</artifactId>
    <version>2.4.1</version>
    <executions>
        <execution>
            <phase>package</phase>
            <goals><goal>shade</goal></goals>
            <configuration>
                <transformers>
                    <transformer implementation="org.apache.maven.plugins.shade.resource.ServicesResourceTransformer"/>
                </transformers>
            </configuration>
        </execution>
    </executions>
</plugin>
--------------------------------------------------

Note that if you have a `main` class you want to automatically call when running `java -jar yourjar.jar`, just add
it to the `transformers`:

[source,xml]
--------------------------------------------------
<transformer implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
    <mainClass>org.elasticsearch.demo.Generate</mainClass>
</transformer>
--------------------------------------------------

include::client.asciidoc[]

include::docs.asciidoc[]

include::search.asciidoc[]

include::aggs.asciidoc[]

include::query-dsl.asciidoc[]

include::indexed-scripts.asciidoc[]

include::admin/index.asciidoc[]