Idempotent filter with simple file

1. By Anirban Sen Chowdhary

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