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MQTT Event Receiver

MQTT event receiver is an internal event receiver that comes with WSO2 products. You can configure it with XML, JSON, and text input mapping types.

Prerequisites

Follow the steps below before starting the MQTT event receiver configurations.

  1. Download MQTT client library (mqtt-client-0.4.0.jar).
  2. Add the JAR file to the <PRODUCT_HOME>/repository/components/lib/ directory.
  3. Start the MQTT-supported server.

Creating a MQTT event receiver 

For instructions on creating a MQTT event receiver, see  Configuring Event Receivers .     

Configuring adapter properties

Specify the Adapter Properties , when creating a MQTT  event receiver using the management console as shown below.

MQTT input event adapter properties

After entering the above adapter properties, select the  Event Stream  to which you want to map the incoming events, and the  Message Format  which you want to apply on the receiving events. Also, click  Advanced  to define custom input mappings based on the  Message Format  you selected. For more information on custom input mapping types, see  Input Mapping Types .

You can also d efine the respective adapter properties of the event receiver based on the transport type within the  <from>  element of the event receiver configuration in the <PRODUCT_HOME>/repository/deployment/server/eventreceivers/ directory as follows.

 <eventReceiver name="MQTTInputEventAdapter" statistics="disable" trace="disable" xmlns="http://wso2.org/carbon/eventreceiver">
    <from eventAdapterType="mqtt">
        <property name="topic">sensordata</property>
        <property name="clientId">CEP-CONSUMER</property>
        <property name="url">tcp://localhost:1883</property>
        <property name="username">mqtt-user</property>
        <property name="password">mqtt-password</property>
        <property name="cleanSession">true</property>
    </from>
   ......................
</eventReceiver>

The above adapter properties are described below.

Adapter Property
Description
Configuration file propertyExample

Topic

A valid name for the MQTT broker topic which is used to receive messages on the MQTT input event adapter.

topic
MQTTInputEventAdapter

Broker Url

MQTT broker URL. You can use the same URL f or WSO2 MB (when offset is zero).

url
tcp://localhost:1883
Username

A valid username for the broker connection .

usernamemqtt-user
Password A valid password for the broker connection .
password
mqtt-password
Clean Session Persist topic subscriptions and acknowledge positions across client sessions.
cleanSession
true/false
Client Id Unique client ID used by the server to identify a client when it reconnects. Used for durable subscriptions or reliable delivery of messages.
clientId
clientid

Related samples

For more information on MQTT event receiver type, see the following sample in WSO2 CEP Documentation.

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