Forward data to Simple Message Queue (MNS)

How it works

The data forwarding feature forwards messages in real time from a specified topic for all or specific devices under the same product to an MNS topic subscribed to by an MNS queue.

In the preceding figure:

• Data source: For information about the supported topic types, see Data formats (for non-gateway products and devices), Custom topics (for MQTT cloud gateways), Message forwarding topics (for GB/T 32960 cloud gateways), Message forwarding topics (for JT/T 808 cloud gateways), and Message forwarding topics (for SL 651 cloud gateways).

• Data destination: The MNS topic that you create to receive device data. All messages from this topic are pushed to the MNS queues that subscribe to it.

• Parser script: A script that you configure to use the data forwarding function writeMns(destinationId, payload) to forward topic data to the MNS topic.

  For more information about the function, see Function list.

Limits

• Data forwarding to MNS is supported only by IoT Platform instances in specific regions. For more information about the supported regions, see Feature availability by region.

• Both the new and previous versions of the data forwarding feature support forwarding data to MNS. For an example of how to use the previous version, see Forward data to Message Service (previous version).

• For more information about the limits on forwarding device messages from an IoT Platform instance, see Limits.

Create a data destination

1. Log on to the IoT Platform console.

2. On the Overview page, find the instance that you want to manage and click the instance ID or instance name.

3. In the left-side navigation pane, choose Message Forwarding > Data Forwarding.

4. On the Data Forwarding page, click Go to New Version in the upper-right corner.

   Note

   If you have performed this operation before, you are automatically redirected to the new version of the Data Forwarding page.

5. Click the Data Destination tab. On this tab, click Create Data Destination.

6. In the Create Data Destination dialog box, enter a name for the data destination, such as DataPurpose. Configure the parameters as described in the following table, and then click OK.

   Parameter	Description
   Select an operation.	Select Forward data to Message Service (MNS).
   Region	Select the region where Message Service is activated.
   Topic	Select the SMQ topic that you want to use to receive data. SMQ forwards the received messages to the HTTP and queue subscriptions under this topic. Currently, you can subscribe to messages that IoT Platform pushes to an SMQ topic only using the HTTP or queue method. You can click Create Topic to go to the Simple Message Queue (formerly MNS) console to create an SMQ topic and a subscription. For more information, see the Simple Message Queue (SMQ) documentation.
   Role	Grant IoT Platform the permissions to write data to Simple Message Queue (formerly MNS). If no RAM role exists, click Create RAM Role to create a RAM role and authorization policy in the RAM console. Create a RAM role.

Configure and start the parser

1. Create a parser named DataParser. For more information, see Step 1: Create a parser.

2. On the Parser Details page, associate the parser with the created data source.

   1. In the Data Source step of the wizard, click Associate Data Source.

   2. In the dialog box that appears, select DataSource from the Data Source drop-down list, and then click OK.

3. On the Parser Details page, associate the parser with the created data destination.

   1. Click Data Destination in the wizard. In the Data Destination section, click Associate Data Destination.

   2. In the dialog box that appears, select DataPurpose from the Data Destination drop-down list, and then click OK.

   3. In the Data Destination section, view and save the data destination ID. In this example, the ID is 1000.

      When you write the parser script, you must use the data destination ID.

4. On the Parser Details page, click Parser.

5. In the script editor, enter a parser script.

   The parser script syntax is similar to JavaScript. For more information about how to edit scripts, see Script syntax.

   For more information about the function parameters, see Function list.

   // Use the payload() function to get the message content reported by the device and convert it to the JSON format.
   var data = payload("json");
   // Forward the TSL model data directly.
   writeMns(1000, data);

6. Click Test. Follow the on-screen instructions to select a product and a device, enter the topic and payload data, and verify that the script can be executed.

   The following figure shows sample parameters:

   The following output confirms a successful script execution.

   

7. Click Publish.

8. Go to the Parser tab of the Data Forwarding page. Find the DataParser parser and click Start in the Actions column to start the parser.

What to do next

• You can view the operational logs for device-to-cloud messages and data forwarding on the IoT Platform Logs tab. To go to this tab, go to the IoT Platform console, find your instance, and choose O&M > Log Service. For more information, see IoT Platform logs.

• You can log on to the Simple Message Queue (formerly MNS) console to view the messages that are pushed from the MNS topic to the queue. For more information, see Receive messages.

References

• For instructions on how to connect a device to IoT Platform to report data, see Device connection guide.

• Check the available message forwarding TPS resources on the instance details page to ensure device messages can be forwarded to Simple Message Queue (formerly MNS) for consumption. For more information, see View instance information and operational data. If resources are insufficient, upgrade the instance. For more information, see Upgrade an instance.

• You can view the metrics of the Simple Message Queue (formerly MNS) topic to check the number of received messages. For more information, see View topic metrics.

• Use the Log Management feature to push message topic operation logs to Simple Log Service. If an exception occurs during message consumption, query the message trace by MessageId to diagnose the issue. For more information, see Push logs to Simple Log Service and View logs in Simple Log Service.