[rules-dev] KIE api verbosity

I've upgraded OptaPlanner to use the KIE api and I have some feedback :) What I want to do: *Given of list of DRL's on the classpath, build a KieSession.* Here's how I did it with the new KIE api: public KieBase newKieBase(List<String> scoreDrlList) { KieServices kieServices = KieServices.Factory.get(); KieResources kieResources = kieServices.getResources(); KieFileSystem kieFileSystem = kieServices.newKieFileSystem(); for (String scoreDrl : scoreDrlList) { InputStream scoreDrlIn = getClass().getResourceAsStream(scoreDrl); // TODO newClassPathResource() instead, but that breaks (mfusco is looking at it) String path = "src/main/resources/optaplanner-kie-namespace/" + scoreDrl; kieFileSystem.write(path, kieResources.newInputStreamResource(scoreDrlIn, "UTF-8")); } KieBuilder kieBuilder = kieServices.newKieBuilder(kieFileSystem); kieBuilder.buildAll(); Results results = kieBuilder.getResults(); if (results.hasMessages(Message.Level.ERROR)) { throw new IllegalStateException("There are errors in the scoreDrl's:\n" + results.toString()); } else if (results.hasMessages(Message.Level.WARNING)) { logger.warn("There are warning in the scoreDrl's:\n" + results.toString()); } KieContainer kieContainer = kieServices.newKieContainer(kieBuilder.getKieModule().getReleaseId()); KieBase kieBase = kieContainer.getKieBase(); return kieBase; } public KieSession newKieSession() { ... KieSession kieSession = kieBase.newKieSession(); return kieSession; } *Feedback* (note: these are suggestions, not demands): 1) To do this, I needed to get acquainted with 9 new concepts: KieServices, KieResources, KieFileSystem, KieBuilder, Results, KieModule, KieContainer, KieBase, KieSession. I only care about 2 of those: - KieSession - KieBase (= the factory to build a new KieSession, which I do regularly). The other 7 concepts probably represent wonderful advanced features which I might want to use later on, so they should exist, But in a simple use case like this, I should not have to see them or deal with them. 2) The kie filesystem features leaks into the simple api, even if I don't care about the KieFileSystem at all. - I should not explicitly need to create a KieFileSystem: KieFileSystem kieFileSystem = kieServices.newKieFileSystem(); - Adding certain Resource types fails if you don't specify the fileSystem's path. This fails for example: kieFileSystem.write(kieResources.newInputStreamResource(...)); - For the default KieBase to work, the path needs to start with a magical prefix String path = "src/main/resources/.../" + ...; 3) To create a KieBase from that kieFileSystem, I need to explicitly do 5+ calls, in the right order: - call kieServices.newKieBuilder(...) - call kieBuilder.buildAll() - call kieBuilder.getKieModule() - call kieServices.newKieContainer(...) - call kieContainer.getKieBase() Some of these have non-obvious parameters. I'd rather just call: kieFileSystem.buildKieBase() 4) I don't like having to write the boilerplate code to check if the are errors: if (results.hasMessages(Message.Level.ERROR)) {...} If there are errors, then kieFileSystem.buildKieBase() should just throw a DroolsRuntimeException. *Solution* proposal: A) Write a facade class that presumes there is only 1 module and the user doesn't need (or want to) to access any of those 7 other concepts. public KieBase newKieBase(List<String> scoreDrlList) { KieBaseFactory kieBaseFactory = kieServices.newKieBaseFactory(); for (String scoreDrl : scoreDrlList) { kieBaseFactory.addInputStreamResource(scoreDrl, "UTF-8"); } return kieBaseFactory.buildKieBase; // throws exception upon compilation error } Mario's KieHelper is similar, but slightly different. wkr, Geoffrey