title: Meta-Database Views / Data Integration
body: <p>Is there a (free) tool or framework which allows defining views over multiple data backends (preferably for java and based on objects)?</p>
  
  <p>For example I have 2 databases:
  One database provides a table or class (doesn't matter much)
  PersonX(name, address), and the other one provides PersonY(name, dateOfBirth)</p>
  
  <p>Now I want to create a view which joins them into <code>Person(name, address, dateOfBirth)</code> like (pseudo code):</p>
  
  <pre><code>Person(n, a, dob) :=
      Couple(x.name, y.name) as n, x.address as a, y.dateOfBirth as dob From PersonX as x outer join PersonY as y on (x.name = y.name)
  </code></pre>
  
  <p>But I don't only want the view, I also want to be able to do updates on the view which should delegate changes back to the sources.
  This "Couple" keyword here should mean, that an update on the field Persion.name should be delegated to both underlying sources.</p>
  
  <p>So from what I have seen about data integration it's all about creating views of some kind, so my question is related to that, but i don't have much experience on that topic.</p>
  
  <p>any help on that is appreciated - thx :)</p>