title: What's the Difference Between Apache Jackrabbit and Jackrabbit Oak?
body: <p>I'm sorry if this sounds stupid, but what's the difference between Jackrabbit and Oak? I'm looking into JCR170, specifically how to migrate content between two jackrabbit installations, and I've come across both JackRabbit and Oak.</p>
  
  <blockquote>
    <p>The Apache Jackrabbit™ content repository is a fully conforming
    implementation of the Content Repository for Java Technology API (JCR,
    specified in JSR 170 and JSR 283).</p>
    
    <p>A content repository is a hierarchical content store with support for
    structured and unstructured content, full text search, versioning,
    transactions, observation, and more.</p>
    
    <p>Jackrabbit Oak is a complementary implementation of the JCR
    specification. It is an effort to implement a scalable and performant
    hierarchical content repository for use as the foundation of modern
    world-class web sites and other demanding content applications. See
    the Jackrabbit Oak website for more information.</p>
    
    <p>Apache Jackrabbit is a project of the Apache Software Foundation</p>
  </blockquote>
  
  <p><a href="http://jackrabbit.apache.org/jcr/index.html" rel="noreferrer">http://jackrabbit.apache.org/jcr/index.html</a></p>
  
  <p>Their own home page says that Jackrabbit is a content repository implementing JCR and that Oak is a complementary implementation of JCR. Why is there two implementations of JCR by the same project?</p>