You can use the Java client in multiple ways:

  • Perform standard index, get, delete and search operations on an existing cluster
  • Perform administrative tasks on a running cluster

Obtaining an Elasticsearch Client is simple. The most common way to get a client is by creating a TransportClient that connects to a cluster.

The client must have the same major version (e.g. 2.x, or 5.x) as the nodes in the cluster. Clients may connect to clusters which have a different minor version (e.g. 2.3.x) but it is possible that new functionality may not be supported. Ideally, the client should have the same version as the cluster.

We plan on deprecating the TransportClient in Elasticsearch 7.0 and removing it completely in 8.0. Instead, you should be using the Java High Level REST Client, which executes HTTP requests rather than serialized Java requests. The migration guide describes all the steps needed to migrate.

The Java High Level REST Client currently has support for the more commonly used APIs, but there are a lot more that still need to be added. You can help us prioritise by telling us which missing APIs you need for your application by adding a comment to this issue: Java high-level REST client completeness.

Any missing APIs can always be implemented today by using the low level Java REST Client with JSON request and response bodies.