Filter processor enables an application to examine the incoming payload and then applies a predicate against it which decides if the record needs to be continued.
For example, if the incoming payload is of type String and you want to filter out anything that has less than five characters, you can run the filter processor as below.
java -jar filter-processor-kafka-<version>.jar --filter.function.expression=payload.length() > 4
Change kafka to rabbit if you want to run it against RabbitMQ.
You can pass any type as payload and then apply SpEL expressions against it to filter.
If the incoming type is byte[] and the content type is set to text/plain or application/json, then the application converts the byte[] into String.