--- schema_version: "1" id: 839617ade23b0551d66bec6f9dee056c709a5317cc87e58b608d555316b801cf title: VM Connector Propagate Message Attributes Example collection: mulesoft version: current locale: en-us portal_url: https://docs.salesforce.com/mulesoft/current/en-us/vm-connector/latest/vm-propagate-messages.md canonical_url: https://docs.mulesoft.com/vm-connector/latest/vm-propagate-messages source_site: docs.mulesoft.com content_type: documentation content_hash: 6eafe1d6fcd70e83a78a3595428e59ed8e20d9db1f98240b1d3e59109f939638 description: MuleSoft Documentation Site release: "2.0" latest: true --- --- product: VM Connector version: 2.0 is-latest-version: true --- # VM Connector Propagate Message Attributes Example > For the full documentation index, see: https://docs.mulesoft.com/llms.txt The following example illustrates how you can propagate message attributes through a VM queue via a message payload. The first flow takes incoming HTTP message attributes and additionally creates a custom attribute of its own, and then adds both of these attributes into a message payload so the **VM Publish** operation can publish the message to a VM queue. In the second flow, the **VM Listener** source receives the message payload from the previous flow and sets its own message attributes, and the message payload is finally stored in an object store. The following screenshot shows the Anypoint Studio app flow for this example: ![VM Connector example flow](/mulesoft/current/en-us/vm-connector/latest/_images/vm-example-messageflow.png) Figure 1. VM Connector Propagate message attributes flow ## Create the VM Publishing Flow The VM publishing flow first listens for incoming HTTP message attributes and then transforms the message attributes into a JSON structure message. Finally the **VM Publish** operation publishes the message in a VM queue. To create the VM publishing flow: 1. Create a new Mule project in Studio. 2. In the **Mule Palette** view, select the **HTTP Listener** source and drag it into the canvas. The source listens for incoming HTTP messages attributes. 3. On the **HTTP Listener** configuration screen, set the **Path** field to `/message`. 4. Click the plus sign (+) next to the **Connector configuration** field to configure a global element that can be used by all instances of the **HTTP Listener** in the app. 5. In the **Connection** section, set **Protocol** to `HTTP (Default)`, **Host** to `All Interfaces [0.0.0.0] (default)`, and **Port** to `8081`. 6. Set **Base path** to `/publish`. 7. Click **Test Connection** to confirm that Mule can connect with the specified server. 8. Click **OK**. 9. Drag the **Transform Message** component to the right of **HTTP Listener**. The component transforms the incoming HTTP message attributes into a JSON structure that contains the `listenerPath` and `method` attributes, as well as a new custom `sizeAttribute` attribute. 10. In the **Output Payload** script view of the **Transform Message** component, define the `listenerPath` and `method` attributes using the following DataWeave code: ```DataWeave %dw 2.0 output application/json --- { listenerPath: attributes.listenerPath, method: attributes.method } ``` 11. In the **Output Attributes** script view of the **Transform Message** component, define a new custom `sizeAttribute` attribute using the following DataWeave code: ```DataWeave %dw 2.0 output application/json --- { sizeAttribute: sizeOf(attributes.listenerPath) + sizeOf(attributes.method) } ``` 12. Drag the **VM Publish** operation to the right of the **Transform Message** component. The operation publishes the created JSON message in the VM queue. 13. On the **VM Publish** configuration screen, click the plus sign (+) next to the **Connector configuration** field to configure a global element for the VM queue. 14. On the **VM Config** window, for **Queues** select `Edit inline`. 15. On the **Queue** window, set **Queue name** to `testqueue1`, **Queue type** to `TRANSIENT (Default)`, and **Max outstanding message** to `o`. 16. Click **Finish**. 17. Click **OK**. In Studio, the **VM Config** global element configuration looks like this: ![VM Config global element configuration](/mulesoft/current/en-us/vm-connector/latest/_images/vm-example-publish2.png) Figure 2. VM Config global element configuration 18. In the **General > Content** field of the **VM Publish** configuration screen, define the following DataWeave code: ```DataWeave %dw 2.0 output application/json --- {'listenerPath': payload.listenerPath, 'method': payload.method, 'messageSize': attributes.sizeAttribute } ``` In Studio, the **VM Publish** operation configuration looks like this: ![VM Publish operation configuration](/mulesoft/current/en-us/vm-connector/latest/_images/vm-example-publish1.png) Figure 3. VM Publish operation configuration ## Create the VM Listening Flow The VM listening flow listens for incoming messages attributes in the VM queue from the previous VM Publish flow, then set its own attributes via the **VM Listener** source. Finally stores the message payload in an object store. To create the VM listening flow: 1. In the **Mule Palette** view, select the **VM Listener** source and drag it onto the canvas below the first VM Publish flow. The source listens for the incoming message attributes from the previous flow. 2. On the **VM Listener** configuration screen, click the plus sign (+) next to the **Connector configuration** field and select the VM queue configuration created in the VM Publish flow. In Studio, the **VM Listener** source configuration looks like this: ![VM Listener source configuration](/mulesoft/current/en-us/vm-connector/latest/_images/vm-example-listener.png) Figure 4. VM Listener source configuration 3. Drag a **Logger** component to the right of the **VM Listener**. 4. On the **Logger** configuration screen, set the **Message** field to `payload`. 5. Drag another **Logger** component to the right of the first **Logger** component. 6. On the **Logger** configuration screen, set the **Message** field to `'VM message attributes: queue name ' ++ attributes.queueName as String`. 7. Drag an **ObjectStore Store** operation to the right of the second **Logger** component. The operation stores the received `'method':'listenerPath'` pair attributes in an object store. 8. On the **ObjectStore Store** configuration screen, set the **Display Name** field to `Add Http Request`. 9. In the **General** section, set **Key** to `payload.method` and **Value** to `payload.listenerPath`. 10. Click the plus sign (+) next to the **Object Store** field to set the global object store configuration. 11. Set the default values and click **OK**. 12. Save the project and run the app. 13. Test the app by sending a request to `http://127.0.0.1:8081/publish/message`. ## XML for Propagating Message Attributes Through the VM Queue Paste this code into the Studio XML editor to quickly load the flow for this example into your Mule app: ```xml ``` ## See Also - [Introduction to Anypoint Connectors](https://docs.mulesoft.com/connectors/introduction/introduction-to-anypoint-connectors) - [Salesforce Help](https://help.salesforce.com)