Loading a Knowledge Base#

The central class of the knowledge base persistence is the PersistenceManager that organizes the reading and writing of a knowledge base by a collection of plugins (KnowledgeReader, KnowledgeWriter, FragmentHandler). A d3web knowledge base is a jar file consisting of several files (mostly XML), and different plugins handle the different files contained in the jar. We refer to Knowledge Persistence for a detailed description of how to implement your own PersistenceHandler plugin.

Initializing and Loading#

Usually, the main application take care of loading all required plugins at start-up. When writing your own small demo program, you need to initialize the plugins yourself by

InitPluginManager.init();

After initialization, you are able to load the knowledge base into a KnowledgeBase instance by the following call

KnowledgeBase knowledgeBase = persistenceManager.load(new File(knowledgeFilename));

where knowledgeFilename is a simple file path, such as "/temp/carDiagnosis.jar".

Play a little bit around#

You are able to return the list of all solutions (Solution instances) by

List<Solution> solutions = knowledgeBase.getSolutions();

Analogously, you retrieve a flat list of all questions of the knowledge base by

List<Question> questions = knowledgeBase.getQuestions();

The Complete Code Example#

// Initializing the plugins for the persistence 
InitPluginManager.init();
PersistenceManager persistenceManager = PersistenceManager.getInstance();
// Load knowledge base
KnowledgeBase knowledgeBase = persistenceManager.load(new File(knowledgeFilename));

List<Solution> solutions = knowledgeBase.getSolutions();
System.out.println(solutions);

List<Question> questions = knowledgeBase.getQuestions();
System.out.println(questions);