Anypoint MQ Publish Operation - Mule 4

The Publish operation enables you to create a new Anypoint MQ message and send it to the specified destination: queue, FIFO queue, or message exchange. With it, you can configure both the content of the message and all the headers and properties you need.

Outgoing Message Structure

Messages contain these parameters:

body

Contains the body of the published Anypoint MQ message.
properties

Represents a simple key-value map of strings that are the message properties of the message.

Send a Message

When used in its default form, the connector publishes the content found in the incoming message payload as body of the Anypoint MQ message, serialized as a string, to the declared destination:

<anypoint-mq:publish destination="invoiceQueue" config-ref="Anypoint_MQ_config"/>

This operation produces the following output:

A copy of the body sent as payload

For example, if you are sending a "Hello world" message, the resulting payload is the "Hello world" string.
The message messageId value in the message attributes

Anypoint MQ Publish Operation Output Attributes

Configure User Properties

You can define properties for outgoing messages, for example, to provide compatibility with other messaging systems or to communicate the content type of a message. Anypoint MQ supports strings and numbers in property values.

If you create routing rules on numeric property values and you use Anypoint MQ Connector to publish messages, you must upgrade to Anypoint MQ Connector version 3.2.0 or later. Previous versions of the connector send all property values as strings, which results in messages not matching routing rules on numeric properties.

To configure these properties directly in the message, use the properties parameter of the Publish operation and define a key-value map using DataWeave.

For example:

<anypoint-mq:publish config-ref="Anypoint_MQ_Config"
    destination="invoiceQueue">
  <anypoint-mq:properties><![CDATA[#[output application/java ---
      {
          AUTH_TYPE: 'jwt',
          AUTH_TOKEN: attributes.queryParams.token
        }]]]>
      <anypoint-mq:properties>
</anypoint-mq:publish>

User properties that you define in the Publish operation appear in Anypoint MQ in the Message Browser details pane for the message:

User Properties in Message Browser details pane

Figure 1. The screen shows (1) the Message Browser option and (2) the User Properties in the details pane.

Transform the Message Body

If the payload is not in the correct format, you can transform it to the correct format.

To transform a payload, declare an inline DataWeave transformation in the body parameter of the Publish operation:

<anypoint-mq:publish config-ref="Anypoint_MQ_Config"
   destination="invoiceQueue">
      <anypoint-mq:body ><![CDATA[#[output application/json ---
      {
        customer: payload.id,
        items: payload.invoice.items
      }]]]>
      </anypoint-mq:body>
</anypoint-mq:publish>

In this case, the result of the operation is the transformed value as JSON.

Advanced Configurations

You might want to set a unique custom message ID instead of letting Anypoint MQ generate it. You can also add the content type of the message body as a property.

Set a Custom Message ID

Instead of letting Anypoint MQ generate a unique messageId value for the new published message, set a custom messageId value in the Message Id field in the Advanced tab:

Anypoint MQ Publish Advanced Tab - Message Id

The ID of an Anypoint MQ message must be unique. Make sure to choose a unique custom ID to avoid unwanted side effects of duplicated IDs. FIFO queues provide message deduplication. If multiple messages are sent to a FIFO queue containing the same message ID, the first message to arrive is kept as the valid message. See FIFO Exactly-Once Delivery for more information.

Delay Message Delivery

Anypoint MQ supports the ability to publish a message and postpone making it visible to consumers using the deliveryDelay parameter:

Select the Publish operation.
Click the Advanced tab.
Set the Delivery Delay parameter to the amount of time to delay:

By default, the deliveryDelay parameter is set to 0, which specifies to deliver messages immediately (no delay). The maximum deliveryDelay value is 15 minutes.

See Delayed Message Delivery for more information.
Select the unit from the Delivery Delay Unit menu.

Set a Message Group ID

When using FIFO queues, you can assign a message group ID to an outgoing message using the messageGroupID parameter:

Select the Publish operation.
Click the Advanced tab.
Enter an ID in the Message Group ID field:

By default, all messages sent to a FIFO queue have the same autogenerated group ID.

See FIFO Queues and Message Groups for more information.

To get the maximum value from message groups, define more granular groups with fewer messages in each group. For example, when processing messages from multiple users, to keep each user’s events in relative order, use the value of the user’s userId as the message group ID.

Propagate Content Type

To specify whether the content type of the message body is propagated as a property of the Anypoint MQ message or not, use the sendContentType parameter.

Setting this parameter to true automatically adds a contentType property to the outgoing message. This can be useful to declare that a message body is in application/json or application/xml format.