MQTT Client Publish And Subscribe Samples

About The Samples

In this sample, the TIBCO StreamBase® Output Adapter for MQTT Client Subscribe and TIBCO StreamBase® Input Adapter for MQTT Client Publish are used together to subscribe to and send data to an MQTT broker. The sample will initially subscribe to three message queues (Streambase0, Streambase1, Streambase2), each corresponding to their quality of service number.

The sample server configuration file in this sample contains connection information that is shared between the subscribe and publish adapters. This demo uses the open Eclipse iot.eclipse.org mqtt sandbox server. Please see http://iot.eclipse.org/sandbox.html for further details about this sandbox server.

Importing This Sample into StreamBase Studio

In StreamBase Studio, import this sample with the following steps:

  • From the top-level menu, select FileLoad StreamBase Sample.

  • Type mqtt to narrow the list of samples.

  • Select MQTT Client Adapters from the StreamBase Messaging Adapters category.

  • Click OK.

StreamBase Studio creates a single project containing the sample files.

Running Demo.sbapp in StreamBase Studio

  1. In the Project Explorer, open the sample you just loaded.

  2. Open the src/main/eventflow folder.

  3. Open the package folder (most samples contain a single package folder. Open the top-level package folder if your sample contains more than one folder).

  4. Open the named application file and click the Run button. This opens the SB Test/Debug perspective and starts the application.

    If you see red marks, wait a moment for the project in Studio to load its features.

    If red marks do not resolve themselves in a moment, select the project and right-click MavenUpdate Project from the context menu.

  5. Select the PublishData Stream in the Manual Input window.

    Enter the following values:

    1. Topic: Streambase2

    2. Payload: This is a test message

    3. Qos: 2

    And click the Send Data button.

  6. Repeat this step sending messages to the various message queues. Note that Qos can only be set as high as the message queue default allows. For example, you cannot send a Qos level 2 message to Streambase0 because that message queue was set up to only handle Qos level 0 messages.

  7. In the Application Output view, observe tuples emitted on the PublishStatus and Data output streams.

  8. Select individual tuples emitted from the PublishStatus and Data streams, to analyze and understand their structure.

  9. When done, press F9 or click the Stop Running Application button.

Sample Location

When you load the sample into StreamBase Studio, Studio copies the sample project's files to your Studio workspace, which is normally part of your home directory, with full access rights.

Important

Load this sample in StreamBase Studio, and thereafter use the Studio workspace copy of the sample to run and test it, even when running from the command prompt.

Using the workspace copy of the sample avoids permission problems. The default workspace location for this sample is:

studio-workspace/sample_adapter_embedded_mqtt-client

See Default Installation Directories for the default location of studio-workspace on your system.