docs/_docs/quick-start/embedded-mode.adoc

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= Starting With Embedded Mode

In most scenarios, you would use Ignite CLI tool to start and manage your Ignite cluster. However, in some scenarios it is preferable to manage the cluster from a Java project. Starting and working with the cluster from code is called "embedded mode".

This tutorial covers how you can start Ignite 3 from your Java project.

NOTE: Unlike in Ignite 2, nodes in Ignite 3 are not separated into client and server nodes. Nodes started from embedded mode will be used to store data by default.

== Prerequisites

include::includes/prereqs.adoc[]

== Add Ignite to Your Project


First, you need to add Ignite to your project. The easiest way to do this is add Ignite to your project is by using Maven:

[source, xml, subs="attributes,specialchars"]
----
<build>
    <plugins>
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-compiler-plugin</artifactId>
            <configuration>
                <source>11</source>
                <target>11</target>
            </configuration>
        </plugin>
    </plugins>
</build>

<dependencies>
    <dependency>
        <groupId>org.apache.ignite</groupId>
        <artifactId>ignite-api</artifactId>
        <version>3.0.0</version>
    </dependency>

    <dependency>
        <groupId>org.apache.ignite</groupId>
        <artifactId>ignite-runner</artifactId>
        <version>3.0.0</version>
    </dependency>
</dependencies>
----

== Prepare Ignite Configuration

To start a Ignite node, you will need a Ignite configuration file that specifies all configuration properties of the node. For this tutorial, we recommend link:installation/installing-using-zip[installing] Ignite 3 and using a default configuration file from it. This file is stored in the `ignite3-db-3.0.0/etc/ignite-config.conf` file.

== Pass JVM Parameters

The following JVM parameters need to be passed to your application to make proprietary SDK APIs available:


----
--add-opens java.base/java.lang=ALL-UNNAMED
--add-opens java.base/java.lang.invoke=ALL-UNNAMED
--add-opens java.base/java.lang.reflect=ALL-UNNAMED
--add-opens java.base/java.io=ALL-UNNAMED
--add-opens java.base/java.nio=ALL-UNNAMED
--add-opens java.base/java.math=ALL-UNNAMED
--add-opens java.base/java.util=ALL-UNNAMED
--add-opens java.base/java.time=ALL-UNNAMED
--add-opens java.base/jdk.internal.misc=ALL-UNNAMED
--add-opens java.base/jdk.internal.access=ALL-UNNAMED
--add-opens java.base/sun.nio.ch=ALL-UNNAMED
-Dio.netty.tryReflectionSetAccessible=true
----

== Start Ignite Server Nodes

To start a Ignite node, use the following code snippet:

[source, java]
----
IgniteServer node = IgniteServer.start("node", configFilePath, workDir);
----

This code snippet starts a Ignite node with the name `node1`, that uses the configuration from the file specified in the `configFilePath` path parameter and uses the folder specified in the `workDir` path parameter to store data. When the node is started, this method returns an instance of `IgniteServer` class that can be used to work with the node.

== Initiate a Cluster

Started nodes find each other by default, but they do not form an intractable cluster unless the cluster is initiated. You need to initiate the cluster to activate the node. If there are multiple nodes, once the cluster is activated, they will form a topology and automatically distribute workload between each other.

Use the code snippet below to initiate a cluster:

[source, java]
----
InitParameters initParameters = InitParameters.builder()
    .metaStorageNodeNames("node")
    .clusterName("cluster")
    .clusterConfiguration({config-with-license})
    .build();

node.initCluster(initParameters);
----

NOTE: To start a Ignite 3 cluster, you need to provide a license together with the cluster configuration in the `clusterConfiguration` parameter.

== Get an Ignite Instance

Now that the cluster is started, you can get an instance of the `Ignite` class:

[source, java]
----
Ignite ignite = node.api();
----

This instance can be used to start working with the cluster. The future will be returned once the cluster is active.

In the following example, you interact with the cluster using the SQL API:

[source, java]
----
ignite.sql().execute(null, "CREATE TABLE IF NOT EXISTS Person (id int primary key, name varchar, age int);");
ignite.sql().execute(null, "insert into Person (id, name, age) values ('1', 'Person Man', '501'");
try (ResultSet<SqlRow> rs = ignite.sql().execute(null, "SELECT id, name, age from Person")) {
    while (rs.hasNext()) {
        SqlRow row = rs.next();
        System.out.println("    "
                + row.value(1) + ", "
                + row.value(2));
    }
}
----

NOTE: Session is closable, but it is safe to skip `close()` method for DDL and DML queries, as they do not keep cursor open.

More examples of working with Ignite can be found in the link:https://github.com/apache/ignite-3/tree/main/examples[examples] repository.

== Next Steps

From here, you may want to:

* Check out the link:developers-guide/table-api[Developers guide] page for more information on available APIs
* Try out our link:https://github.com/apache/ignite-3/tree/main/examples[examples]