Idempotent Filter in Mule

Idempotent Filter in Mule

Ensures that only unique messages are received by a service by checking the unique ID of the incoming message. Note that the ID used can be generated from the message using an expression defined in the 'idExpression' attribute. By default, the expression used is #[message:id], which means the underlying endpoint must support unique message IDs for this to work. Otherwise, a UniqueIdNotSupportedException is thrown.

Idempotent filter filters payload on the basis of an expression.We need to pass an expression in configuration and if we call api more than once with same expression then it will not allow to pass the payload.

flow of idempotent filter :

Configuration of idempotent filter :

If we pass same query param more than one time then payload will not pass.

URL : http://localhost:8085/api/idempotent

 Input :

Output :

Second time if we pass same query param then payload will not get pass.

XML project code :

<?xml version="1.0" encoding="UTF-8"?>
<mule xmlns:http="" xmlns="" xmlns:doc=""
    <http:listener-config name="HTTP_Listener_Configuration" host="" port="8085" basePath="/api" doc:name="HTTP Listener Configuration"/>
    <flow name="test_idempotentfilterFlow">
        <http:listener config-ref="HTTP_Listener_Configuration" path="/idempotent" doc:name="HTTP"/>
        <idempotent-message-filter idExpression="#[message.inboundProperties.'http.query.params'.name]" doc:name="Idempotent Message"/>