# Connect external applications to the EMQX broker
<a name="connect-external-applications-emqx"></a>

This guide explains how to connect external applications to your Amazon IoT SiteWise Edge gateway through an EMQX broker on your deployed MQTT-enabled, V3 gateway. External applications might include custom monitoring tools, third-party visualization software, or legacy systems that need to interact with your industrial data at the edge.

We'll cover the configuration steps for both Linux and Microsoft Windows environments, including EMQX deployment configuration, TLS setup for secure connections, and authorization rules to control access to specific topics.

**Note**  
EMQX is not a vendor or supplier for Amazon IoT SiteWise Edge.

**Important**  
For securing connections to your gateway, we strongly recommend using certificate-based authentication through the Amazon IoT Greengrass client device authentication feature. This method provides robust security through mutual TLS (mTLS) authentication. For more information, see [Connect client devices to core devices](https://docs.amazonaws.cn/greengrass/v2/developerguide/connect-client-devices.html) in the *Amazon IoT Greengrass Version 2 Developer Guide*.

If you are not able to use certificate based authentication, follow this guide to setup authentication using usernames and passwords.

## Prerequisites
<a name="emqx-broker-prerequisites"></a>
+ A SiteWise Edge MQTT-enabled, V3 gateway that has been deployed and is online
+ Access to the gateway host
+ Access to the Amazon IoT SiteWise and Amazon IoT Greengrass consoles

**Topics**
+ [Prerequisites](#emqx-broker-prerequisites)
+ [Message payload format for the EMQX broker on Amazon IoT SiteWise Edge](connect-broker-payload-format.md)
+ [Configure the EMQX broker](configure-emqx-broker.md)
+ [Connect an application to the EMQX broker on Amazon IoT SiteWise Edge](connect-app-to-broker.md)
+ [Set up authorization rules for Amazon IoT SiteWise Edge in EMQX](authorization-rules-emqx-broker.md)