tMQTTInput - 6.1

Talend Components Reference Guide

EnrichVersion
6.1
EnrichProdName
Talend Big Data
Talend Big Data Platform
Talend Data Fabric
Talend Data Integration
Talend Data Management Platform
Talend Data Services Platform
Talend ESB
Talend MDM Platform
Talend Open Studio for Big Data
Talend Open Studio for Data Integration
Talend Open Studio for Data Quality
Talend Open Studio for ESB
Talend Open Studio for MDM
Talend Real-Time Big Data Platform
task
Data Governance
Data Quality and Preparation
Design and Development
EnrichPlatform
Talend Studio

Warning

The streaming version of this component is available in the Palette of the studio on the condition that you have subscribed to Talend Real-time Big Data Platform or Talend Data Fabric.

Function

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.

Purpose

The tMQTTInput component acts as consumer of a MQTT topic to stream messages from this topic.

tMQTTInput properties in Spark Streaming Jobs

Warning

The streaming version of this component is available in the Palette of the studio on the condition that you have subscribed to Talend Real-time Big Data Platform or Talend Data Fabric.

Component Family

Messaging / MQTT

 

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. The schema is either Built-In or stored remotely in the Repository.

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 in Spark Streaming Jobs

In a Talend Spark Streaming Job, it is used as a start component and requires an output link. The other components used along with it must be Spark Streaming components, too. They generate native Spark code that can be executed directly in a Spark cluster.

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.

Log4j

If you are using a subscription-based version of the Studio, the activity of this component can be logged using the log4j feature. For more information on this feature, see Talend Studio User Guide.

For more information on the log4j logging levels, see the Apache documentation at http://logging.apache.org/log4j/1.2/apidocs/org/apache/log4j/Level.html.

Spark Connection

You need to use the Spark Configuration tab in the Run view to define the connection to a given Spark cluster for the whole Job. In addition, since the Job expects its dependent jar files for execution, one and only one file system related component from the Storage family is required in the same Job so that Spark can use this component to connect to the file system to which the jar files dependent on the Job are transferred:

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. For details, see https://help.talend.com/display/KB/How+to+install+external+modules+in+the+Talend+products or the section describing how to configure the Studio in the Talend Installation Guide.

Related scenarios

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