Elasticsearch supports RESTful APIs, which allows you to use HTTP APIs to perform add, delete, modify, and search operations and configure aliases. This topic describes how to use RESTful APIs.

References from open source Elasticsearch documentation

Use a Java REST client to access a cluster

Only access over HTTP or TCP is supported. We recommend that you use a Java REST client that is provided by open source Elasticsearch.

Use the Java API to access a cluster

Elasticsearch is preinstalled with Transport Client and a Java REST client for Java users. Transport Client falls into disuse in Elasticsearch 7.0 and is no longer available in Elasticsearch 8.0. We recommend that you use Java REST clients. For more information about the Java API, see Java API and Overview.
Note
The version of Elasticsearch used by a Java REST client must match that of the related Elasticsearch cluster. Otherwise, the Java REST client may fail to identify the Elasticsearch cluster.

RESTful API-based requests over HTTP

You can use RESTful APIs or cURL commands to communicate with Elasticsearch over port 9200. For more information about request parameters and specific examples, see Use curl commands and API operations to manage an Alibaba Cloud Elasticsearch cluster.