Poll Scope in Mule

Poll Scope in Mule

As integration developers, we are always faced with the need to poll a legacy resource to retrieve new data and to sync it over to another destination endpoint. MuleSoft allows developers to do this via "Poll Scope." The poll scope allows the developer to poll a particular source endpoint based on a timed interval. The poll scope also has this neat caching function known as "Watermark."

While some connectors, such as HTTP and FTP, utilize a polling process to actively retrieve messages from an external resource, most message processors in Mule are triggered when called by a previous element in a flow. If you want to arrange for a message processor to actively call a resource at regular intervals, use a Poll scope.

Here we are using Message Enricher in mule 3 in Anypoint studio 6.2

Poll scope polls the nested message processor for some new messages.

Here in our flow we have placed db connector in poll scope. Poll scope will poll data from db table by the given frequency in the scope.I have given frequency of 10 seconds means in every 10 seconds it checks the table for new data and writes the data in the file by file connector.

Poll scope settings :

we used fixed frequency scheduler with freq. of 10 seconds.We can also use cron scheduler with cron expressions. And we have disabled watermarking for now in watermark section.

File connector settings :

Here no need to make data.txt manually as we have given path and name of file in file connector so it will automatically generate the file data.txt. So, just configure it correctly as mentioned below.

Once you start the server and project gets deployed, it will start polling with given frequency.

XML project code :

<?xml version="1.0" encoding="UTF-8"?>

<mule xmlns:tracking="http://www.mulesoft.org/schema/mule/ee/tracking" xmlns:json="http://www.mulesoft.org/schema/mule/json" xmlns:db="http://www.mulesoft.org/schema/mule/db" xmlns:file="http://www.mulesoft.org/schema/mule/file" xmlns:http="http://www.mulesoft.org/schema/mule/http" xmlns:quartz="http://www.mulesoft.org/schema/mule/quartz" xmlns="http://www.mulesoft.org/schema/mule/core" xmlns:doc="http://www.mulesoft.org/schema/mule/documentation"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-current.xsd
http://www.mulesoft.org/schema/mule/core http://www.mulesoft.org/schema/mule/core/current/mule.xsd
http://www.mulesoft.org/schema/mule/quartz http://www.mulesoft.org/schema/mule/quartz/current/mule-quartz.xsd
http://www.mulesoft.org/schema/mule/http http://www.mulesoft.org/schema/mule/http/current/mule-http.xsd
http://www.mulesoft.org/schema/mule/file http://www.mulesoft.org/schema/mule/file/current/mule-file.xsd
http://www.mulesoft.org/schema/mule/db http://www.mulesoft.org/schema/mule/db/current/mule-db.xsd
http://www.mulesoft.org/schema/mule/json http://www.mulesoft.org/schema/mule/json/current/mule-json.xsd
http://www.mulesoft.org/schema/mule/ee/tracking http://www.mulesoft.org/schema/mule/ee/tracking/current/mule-tracking-ee.xsd">
    <http:request-config name="HTTP_Request_Configuration" host="localhost" port="8083" doc:name="HTTP Request Configuration"/>
    <http:listener-config name="HTTP_Listener_Configuration" host="" port="8084" doc:name="HTTP Listener Configuration"/>
    <quartz:connector name="Quartz" validateConnections="true" doc:name="Quartz"/>
    <file:connector name="File" autoDelete="true" streaming="true" validateConnections="true" doc:name="File"/>
    <db:mysql-config name="MySQL_Configuration" host="localhost" port="3306" user="root" password="*******" database="demodata" doc:name="MySQL Configuration"/>
    <flow name="test_poll">
        <poll doc:name="Poll">
            <fixed-frequency-scheduler frequency="10" timeUnit="SECONDS"/>
            <db:select config-ref="MySQL_Configuration" doc:name="Database">
                <db:parameterized-query><![CDATA[select * from info]]></db:parameterized-query>
        <json:object-to-json-transformer doc:name="Object to JSON"/>
        <file:outbound-endpoint path="src/main/resources" responseTimeout="10000" doc:name="File" outputPattern="data.txt" connector-ref="File"/>

© 2020 goformule.com

Share on :

Mule 4:

XML to JSON in mule 4 Web service consumer VM Validation in Mule 4 Until Successful
Sub flow Set Variable & Remove Variable Set Transaction ID Scatter Gather Round Robin
Consume Restful Service CRUD in Mule 4 Parse Template Object to JSON Load Static Resource
JSON to XML Invoke Idempotent Filter ForEach Flat file to JSON
Fixwidth to JSON First Successful File Execute Error Handling
Email Dynamic Evaluate Custom Business Event CSV to JSON Copybook to JSON
Choice Router Async RabbitMQ

Mule 3:

Database Connector Async CXF Attachement XSLT
Mongo DB Cache scope Custom Business Event Gzip Compress Expression
SMTP For Each Expression Javascript Filter Reference
Salesforce Message Enricher Groovy Parse Template Idempotent
VM Poll Invoke Ruby Message
Webservice consumer Python Transformer reference Message Property Not
Collection Aggregator First Sucessful Catch Exception Strategy Reference Exception Strategy Or
Choice Message Chunk Aggregator Choice Exception Strategy Global Exception Strategy Schema Validation
Custom Aggregator Scatter Gather Custom Exception Strategy Batch Processing MEL
M Unit RAML Map Operator API Mocking Dataweave