Consume Messages with the JMS Connector | MuleSoft Documentation
# Consume Messages with the JMS Connector
Anypoint Connector for JMS (JMS Connector) **Consume** operation enables you to consume a message at any time in the flow, from any given specified destination.
## Consume a Message from a Queue
In the following example, you configure the **Consume** operation to consume new messages in the queue specified in the **Destination** field. The operation returns a Mule message each time a JMS message is available in the queue. The Mule message consists of:
  * The message content as payload
  * The message metadata in the message attributes


The metadata has three parts that map all the information available in a JMS message:
  * AckId
  * Headers
  * Properties


By default, the message consumed is acknowledged ("ACKed") only when the execution of the flow receiving the message completes successfully. If you want to control the ACK of the message after some processing, configure the `ackMode` to `MANUAL`. For more information regarding a Message ACK, review the Manage Message Acknowledgement documentation.
To configure the source in Studio, follow these steps:
  1. In the **Mule Palette** view, select **JMS > Consume**.
  2. Drag **Consume** to the Studio canvas.
  3. In the **Consume** configuration screen, optionally change the value of the **Display Name** field.
  4. In the **Consume** configuration screen, in **Destination** , specify the name of the destination from which to consume the message, for example, `#[vars.destination]`.


Figure 1. JMS Connector Consume configuration
In the XML editor, the `<jms:consume>` configuration looks like this:
```
<jms:consume config-ref="JMS_config" destination="#[vars.destination]"/>
```

## Consume a Message from a Topic Subscription
In the following example, you configure the **Consume** operation to consume new messages from a topic subscription by setting the **Consumer type** field to **Topic consumer**.
To configure the source in Studio, follow these steps:
  1. In the **Mule Palette** view, select **JMS > Consume**.
  2. Drag **Consume** to the Studio canvas.
  3. In the **Consume** configuration screen, optionally change the value of the **Display Name** field.
  4. In the **Consume** configuration screen, in **Destination** , specify the name of the destination from which to consume the message for example `#[vars.destination]`.
  5. Set the **Consumer type** field to **Topic consumer** :


Figure 2. JMS Connector Consume on Topic subscription configuration
In the XML editor, the `<jms:consume>` and `<jms:topic-consumer/>` configuration looks like this:
```
<jms:consume config-ref="JMS_config" destination="#[vars.destination]">
  <jms:consumer-type>
    <jms:topic-consumer/>
  </jms:consumer-type>
</jms:consume>
```

## Wait for a Message
By default, the **Consume** operation waits for a message for up to 10000 milliseconds, after which you receive the error `JMS:TIMEOUT`. To better suit your use case, configure the **Maximum wait** and **Maximum wait unit** fields. To wait indefinitely for a message to arrive, set the **Maximum wait** field to `-1`, which prevents a `JMS:TIMEOUT` error.
## Poll for a Message
When polling for a message with a certain frequency, you don’t want the consumer to block waiting for the message, but instead just try to consume it if one is present. In this case, set the **Maximum wait** field to `0`, which indicates that no waiting occurs, and neither an error is thrown if no message is available in the specified destination. The output of the **Consume** operation is `null` when no message is present for consumption and no error is thrown.
## Filter Incoming Messages
JMS Connector supports filtering messages to consume based on the standard JMS selector language you specify in the **Selector** field of the **Consume** operation. By doing so, you receive only the messages matching the selector language, ignoring any other messages in the destination.
In the following example, you configure a priority queue that processes messages faster than others queues:
  1. In Studio, select the **Consume** operation from your flow.
  2. Set the **Destination** field to `openTickets`.
  3. Set the **Selector** field to `JMSPriority=8`:


JMS Connector On New Message Filtering messages image::jms-consume-selector.png[In the Consume operation screen, set the Selector field to filter incoming messages]
In the XML editor, the `selector` configuration looks like this:
```
<jms:consume config-ref="JMS_config" destination="openTickets" selector="JMSPriority=8"/>
```

## Configure Mime Types and Encoding
JMS Connector determines a message’s mime type (`contentType`) based on the `MM_MESSAGE_CONTENT_TYPE` property. However, when you must manage the message’s content, configure the **Content-Type** field to the particular content type value you need.
By default, JMS Connector assumes that Mule runtime engine default encoding matches the encoding in the message if no other information is provided. Use the **Encoding** field to configure a different type of encoding.
In the following example, you configure the content-type and encoding:
  1. In Studio, select the **Consume** operation from your flow.
  2. Set the **Content-Type** field to `application/JSON`.
  3. Set the **Encoding** field to `UTF-8`.


Figure 3. JMS Connector Consume Content-Type and Encoding
In the XML editor, the `contentType` and `encoding` configuration looks like this:
```
	<jms:consume destination="#[vars.destination]" contentType="application/JSON" encoding="UTF-8"/>
```

## See Also
  * Configure Topic Subscriptions
  * Listen For New Messages
  * Troubleshoot Prefetch Issues