[[java-rest-high-update-aliases]]
=== Index Aliases API

[[java-rest-high-update-aliases-request]]
==== Indices Aliases Request

The Index Aliases API allows aliasing an index with a name, with all APIs
automatically converting the alias name to the actual index name.

An `IndicesAliasesRequest` must have at least one `AliasActions`:

["source","java",subs="attributes,callouts,macros"]
--------------------------------------------------
include-tagged::{doc-tests}/IndicesClientDocumentationIT.java[update-aliases-request]
--------------------------------------------------
<1> Creates an `IndicesAliasesRequest`
<2> Creates an `AliasActions` that aliases index `test1` with `alias1`
<3> Adds the alias action to the request

The following action types are supported: `add` - alias an index, `remove` - 
removes the alias associated with the index, and `remove_index` - deletes the
index. 

["source","java",subs="attributes,callouts,macros"]
--------------------------------------------------
include-tagged::{doc-tests}/IndicesClientDocumentationIT.java[update-aliases-request2]
--------------------------------------------------
<1> Creates an alias `alias1` with an optional filter on field `year`
<2> Creates an alias `alias2` associated with two indices and with an optional routing
<3> Removes the associated alias `alias3`
<4> `remove_index` is just like <<java-rest-high-delete-index>>

==== Optional arguments
The following arguments can optionally be provided:

["source","java",subs="attributes,callouts,macros"]
--------------------------------------------------
include-tagged::{doc-tests}/IndicesClientDocumentationIT.java[update-aliases-request-timeout]
--------------------------------------------------
<1> Timeout to wait for the all the nodes to acknowledge the operation as a `TimeValue`
<2> Timeout to wait for the all the nodes to acknowledge the operation as a `String`

["source","java",subs="attributes,callouts,macros"]
--------------------------------------------------
include-tagged::{doc-tests}/IndicesClientDocumentationIT.java[update-aliases-request-masterTimeout]
--------------------------------------------------
<1> Timeout to connect to the master node as a `TimeValue`
<2> Timeout to connect to the master node as a `String`

[[java-rest-high-update-aliases-sync]]
==== Synchronous Execution

["source","java",subs="attributes,callouts,macros"]
--------------------------------------------------
include-tagged::{doc-tests}/IndicesClientDocumentationIT.java[update-aliases-execute]
--------------------------------------------------

[[java-rest-high-update-aliases-async]]
==== Asynchronous Execution

The asynchronous execution of an update index aliases request requires both the `IndicesAliasesRequest`
instance and an `ActionListener` instance to be passed to the asynchronous
method:

["source","java",subs="attributes,callouts,macros"]
--------------------------------------------------
include-tagged::{doc-tests}/IndicesClientDocumentationIT.java[update-aliases-execute-async]
--------------------------------------------------
<1> The `IndicesAliasesRequest` to execute and the `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.

A typical listener for `IndicesAliasesResponse` looks like:

["source","java",subs="attributes,callouts,macros"]
--------------------------------------------------
include-tagged::{doc-tests}/IndicesClientDocumentationIT.java[update-aliases-execute-listener]
--------------------------------------------------
<1> Called when the execution is successfully completed. The response is
provided as an argument
<2> Called in case of failure. The raised exception is provided as an argument

[[java-rest-high-update-aliases-response]]
==== Indices Aliases Response

The returned `IndicesAliasesResponse` allows to retrieve information about the
executed operation as follows:

["source","java",subs="attributes,callouts,macros"]
--------------------------------------------------
include-tagged::{doc-tests}/IndicesClientDocumentationIT.java[update-aliases-response]
--------------------------------------------------
<1> Indicates whether all of the nodes have acknowledged the request