The document discusses how the Idempotent Filter in Mule ensures only unique messages are received by checking message IDs. It demonstrates configuring the Idempotent Filter with a simple-text-file-store to avoid duplicate messages. When messages are received, the filter will check the file store for duplicates and only allow unique messages to pass through the flow.

2. Idempotent Filter is an important message filter in Mule platform which ensures that only
unique messages are received by a service by checking the unique ID of the incoming message.
We use Idempotent Filter to avoid any duplicate message in our Mule flow
We will be demonstrating a simple example of Idempotent Filter using simple-text-file-
store.

3. Idempotent Filter with simple-text-file-store :-
We can configure it following way :-
Here you can see that we have configured our Idempotent Filter with simple-text-file-store.
So, now this filter will restrict any duplicates message it finds.
simple-text-file-store technique will store all the messages in file and will check the file to
detect duplicates whenever it receive a input message. For each message the files will be
generated.

4. You will see that we will run our Mule application it will generate text file in our Mule
application where it will store all the message with ID to avoid the duplicate :-

5. Now, we can configure with any of the options shown here, we will get following Mule flow :-

6. Our Mule Config will be :-

7. So, we will test our application by hitting the following url http://localhost:8081/path/test for the
first time we will get :-
For the first time we will see browser display “passed” as the message
payload is new and unique (path/test is the message payload here)

8. And then if we hit the same url http://localhost:8081/path/test again, will get the following :-
For the second time we will see browser display “EXCEPTION” as the
message payload is now same and duplicate (path/test is the message
payload here)

9. Hope I am able to make it clear on how to implement Idempotent Filter with different ways and
you can now try by your own and experiment with this powerful filter of Mule.
Hope you enjoyed this simpler version