How to load dataset from Java application to a Rapidminer process?

Not sure on where all your data is coming from but if you want to load multiple data sets you could use a Read CSV or Read XLS operator in conjuction with a Loop Files or Loop operator, instead of the Retrieve operator. The Retrieve operator is a RapidMiner optimized data repository, but the data can come from CSV, databases, Hadoop, etc. You don't really need to Load Data > Store in Repository > Retrieve Data > Process, you can just Load Data > Process

Thanks, it's really useful, I see that. Another thing, I wrote a sample code, to run a process within Java code, I'd like to say to the loaded process, before it runs, what csv file it has to use, is it possible?

RapidMiner.setExecutionMode(RapidMiner.ExecutionMode.COMMAND_LINE);
RapidMiner.init();

Process process = new Process(new File("testProcess.rmp"));
System.out.println(process.run());