---
title:  Configuring Multi-Site (WAN) Event Queues
---

<!--
Licensed to the Apache Software Foundation (ASF) under one or more
contributor license agreements.  See the NOTICE file distributed with
this work for additional information regarding copyright ownership.
The ASF licenses this file to You under the Apache License, Version 2.0
(the "License"); you may not use this file except in compliance with
the License.  You may obtain a copy of the License at

     http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
-->

In a multi-site (WAN) installation, <%=vars.product_name%> uses gateway sender queues to distribute events for regions that are configured with a gateway sender. AsyncEventListeners also use an asynchronous event queue to distribute events for configured regions. This section describes additional options for configuring the event queues that are used by gateway senders or AsyncEventListener implementations.

<a id="configure_multisite_event_messaging__section_1BBF77E166E84F7CA110385FD03D8453"></a>
Before you begin, set up your multi-site (WAN) installation or configure asynchronous event queues and AsyncEventListener implementations. See [Configuring a Multi-site (WAN) System](../../topologies_and_comm/multi_site_configuration/setting_up_a_multisite_system.html#setting_up_a_multisite_system) or [Implementing an AsyncEventListener for Write-Behind Cache Event Handling](implementing_write_behind_event_handler.html#implementing_write_behind_cache_event_handling).

-   **[Persisting an Event Queue](configuring_highly_available_gateway_queues.html)**

    You can configure a gateway sender queue or an asynchronous event queue to persist data to disk similar to the way in which replicated regions are persisted.

-   **[Configuring Dispatcher Threads and Order Policy for Event Distribution](configuring_gateway_concurrency_levels.html)**

    By default, <%=vars.product_name%> uses multiple dispatcher threads to process region events simultaneously in a gateway sender queue for distribution between sites, or in an asynchronous event queue for distributing events for write-behind caching. With serial queues, you can also configure the ordering policy for dispatching those events.

-   **[Conflating Events in a Queue](conflate_multisite_gateway_queue.html)**

    Conflating a queue improves distribution performance. When conflation is enabled, only the latest queued value is sent for a particular key.