OpenSearch/docs/java-rest/high-level/execution-no-req.asciidoc

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This file is included by high level rest client API documentation pages
where the client method does not use a request object.
For methods with requests, see execution.asciidoc
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[id="{upid}-{api}-sync"]
==== Synchronous execution

When executing the +{api}+ API in the following manner, the client waits
for the +{response}+ to be returned before continuing with code execution:

["source","java",subs="attributes,callouts,macros"]
--------------------------------------------------
include-tagged::{doc-tests-file}[{api}-execute]
--------------------------------------------------

Synchronous calls may throw an `IOException` in case of either failing to
parse the REST response in the high-level REST client, the request times out
or similar cases where there is no response coming back from the server.

In cases where the server returns a `4xx` or `5xx` error code, the high-level
client tries to parse the response body error details instead and then throws
a generic `ElasticsearchException` and adds the original `ResponseException` as a
suppressed exception to it.

[id="{upid}-{api}-async"]
==== Asynchronous execution

The +{api}+ API can also be called in an asynchronous fashion so that
the client can return directly. Users need to specify how the response or
potential failures will be handled by passing a listener to the
asynchronous {api} method:

["source","java",subs="attributes,callouts,macros"]
--------------------------------------------------
include-tagged::{doc-tests-file}[{api}-execute-async]
--------------------------------------------------
<1> The `RequestOptions` and `ActionListener` to use when the execution
    completes

The asynchronous method does not block and returns immediately. Once it is
completed the `ActionListener` is called back using the `onResponse` method
if the execution successfully completed or using the `onFailure` method if
it failed. Failure scenarios and expected exceptions are the same as in the
synchronous execution case.

A typical listener for +{api}+ looks like:

["source","java",subs="attributes,callouts,macros"]
--------------------------------------------------
include-tagged::{doc-tests-file}[{api}-execute-listener]
--------------------------------------------------
<1> Called when the execution is successfully completed.
<2> Called when the +{api}+ call fails.