// This module is included in the following assemblies:
// as_connecting-to-mqtt.adoc

[id='adding-mqtt-connection-start_{context}']
= Obtaining a message from an MQTT broker to trigger integration execution

To trigger execution of an integration based on receiving a message
from an MQTT broker, add an MQTT connection as the start connection. When 
the integration is running, the MQTT connection continuously watches for messages
on the MQTT queue or topic that you specify. When the connection finds a 
message, it passes it to the next step in the integration. An MQTT 
connection handles one message at a time. 

.Prerequisite
You created an MQTT connection. 

.Procedure

. In the {prodname} panel on the left, click *Integrations*.
. Click *Create Integration*.
. On the *Choose a connection* page, click the MQTT connection that
you want to use to start the integration. 
. On the *Choose an action* page, select the *Subscribe* action
to receive messages from the queue or topic that you specify. 
. In the *MQTT queue/topic name* field, enter the name of the queue or topic 
to subscribe to in order to receive data. 
. Click *Next* to specify the action's output type. 

. In the *Select Type* field, if the data type does not need to be known, 
accept *Type specification not required* 
and click *Next*. You do not need to follow the rest of these
instructions. 
+
However, a structured data type is recommended. For example, if you want 
to map the connection output in a data mapper step then you must specify 
the data type. The data mapper cannot display fields for unstructured data.
+
To specify the data type, click in the *Select Type* field and select one of the following as the schema type:
+
* *JSON schema* is a document that describes the structure of JSON data.
The document's media type is `application/schema+json`. 
* *JSON instance* is a document that contains JSON data. The document's 
media type is `application/json`. 
* *XML schema* is a document that describes the structure of XML data.
The document's file extension is `.xsd`.
* *XML instance* is a document that contains XML data. The
document's file extension is `.xml`. 
* *CSV instance* is a document that contains comma-separated value (CSV) data. The document's file extension is `.csv`. 
ifeval::["{location}" == "downstream"]
+
*Note* _Data Mapper support for CSV data is a Technology Preview feature only._
endif::[]

. In the *Definition* input box, paste a definition that conforms to the
schema type you selected. 
For example, if you select *JSON schema* then you would paste the content of
a JSON schema file, which has a media type of `application/schema+json`.

. In the *Data Type Name* field, enter a name that you choose for the
data type. For example, if you are specifying a JSON schema for
vendors then you might specify `*Vendor*` as the data type name. 
+
You will see this data type name when you are creating 
or editing an integration that uses the connection
for which you are specifying this type. {prodname} displays the type name
in the integration visualization and in the data mapper. 

. In the *Data Type Description* field, provide information that helps you
distinguish this type. This description appears in the data mapper when 
you hover over the step that processes this type. 
. Click *Next*. 

.Result
The integration now has a start connection and {prodname} is 
prompting you to choose the finish connection. 
