July 30, 2023

tMQTTInput – Docs for ESB 7.x

tMQTTInput

Acts as consumer of a MQTT topic to stream messages from this topic.

tMQTTInput
subscribes to a given MQTT topic, reads messages from this topic and constructs RDDs out
of these messages and then send them to its following component.

tMQTTInput properties for Apache Spark Streaming

These properties are used to configure tMQTTInput running in the Spark Streaming Job framework.

The Spark Streaming
tMQTTInput component belongs to the Messaging family.

The streaming version of this component is available in Talend Real Time Big Data Platform and in
Talend Data Fabric.

Basic settings

Broker URL

Enter the location of the MQTT broker to be used to route the published messages to the
subscriber (the tMQTTInput component).

Topic

Enter the topic you want tMQTTInput to subscribe
to.

QoS

Enter, without quotation marks around, the numeric level of QoS (Quality of Service) to be
assigned to the message to be used.

This quality level indicates how responsive you want MQTT to be to the message delivery request:

  • 0: it means a message may not be delivered or
    is delivered only once.

  • 1: it means a message is delivered at least
    once.

  • 2: it means a message is delivered exactly
    once.

For further explanation about the different levels of QoS, see http://www-01.ibm.com/support/knowledgecenter/SSFKSJ_8.0.0/com.ibm.mq.dev.doc/q029090_.htm.

Include topic column

Select this check box to add a topic column to the
schema to send the name of the topic along with its messages to the following component.

Schema and Edit
Schema

A schema is a row description. It defines the number of fields
(columns) to be processed and passed on to the next component. When you create a Spark
Job, avoid the reserved word line when naming the
fields.

The schema of this component is read-only. You can click
Edit schema to view the schema.

This read-only payload column is used to carry the body
of the MQTT message to be processed.

The input message body can use very different data formats. For example, if its format is
JSON, you need to use tExtractJSONField following tMQTTInput to extract the data to be processed from this body.

Advanced settings

Encoding

Select the encoding from the list or select Custom and define it manually.

This encoding is used by tMQTTInput to decode the input
message arrays.

Usage

Usage rule

This component is used as a start component and requires an output link.

At runtime, the tMQTTInput component keeps listening to
the topic and reads new messages once they are buffered in this topic.

This component, along with the Spark Streaming component Palette it belongs to, appears
only when you are creating a Spark Streaming Job.

Note that in this documentation, unless otherwise explicitly stated, a scenario presents
only Standard Jobs, that is to say traditional
Talend
data
integration Jobs.

Spark Connection

In the Spark
Configuration
tab in the Run
view, define the connection to a given Spark cluster for the whole Job. In
addition, since the Job expects its dependent jar files for execution, you must
specify the directory in the file system to which these jar files are
transferred so that Spark can access these files:

  • Yarn mode (Yarn client or Yarn cluster):

    • When using Google Dataproc, specify a bucket in the
      Google Storage staging bucket
      field in the Spark configuration
      tab.

    • When using HDInsight, specify the blob to be used for Job
      deployment in the Windows Azure Storage
      configuration
      area in the Spark
      configuration
      tab.

    • When using Altus, specify the S3 bucket or the Azure
      Data Lake Storage for Job deployment in the Spark
      configuration
      tab.
    • When using Qubole, add a
      tS3Configuration to your Job to write
      your actual business data in the S3 system with Qubole. Without
      tS3Configuration, this business data is
      written in the Qubole HDFS system and destroyed once you shut
      down your cluster.
    • When using on-premise
      distributions, use the configuration component corresponding
      to the file system your cluster is using. Typically, this
      system is HDFS and so use tHDFSConfiguration.

  • Standalone mode: use the
    configuration component corresponding to the file system your cluster is
    using, such as tHDFSConfiguration or
    tS3Configuration.

    If you are using Databricks without any configuration component present
    in your Job, your business data is written directly in DBFS (Databricks
    Filesystem).

This connection is effective on a per-Job basis.

Limitation

Due to license incompatibility, one or more JARs required to use
this component are not provided. You can install the missing JARs for this particular
component by clicking the Install button
on the Component tab view. You can also
find out and add all missing JARs easily on the Modules tab in the
Integration
perspective of your studio. You can find more details about how to install external modules in
Talend Help Center (https://help.talend.com)
.

Related scenarios

No scenario is available for the Spark Streaming version of this component
yet.


Document get from Talend https://help.talend.com
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