How to get from =markus/+email to the actual data

Hello XDI TC,

Someone asked me a question about the XDI4j library in Higgins and about how XDI endpoints relate to XRI resolution. So I put together some commented sample code which uses OpenXRI and XDI4j:
http://wiki.eclipse.org/XDI4j_Tutorial_6

The task is, given an XRI such as =markus/+email and nothing else, how do you actually find and read the value (the e-mail address)?

Step by step, the code does the following:
1. It resolves the authority part of the XRI (=markus) using standard XRI resolution with an XDI service type, i.e. it looks for an XDI endpoint in the i-name's XRD.

2. After discovering that endpoint, it prepares and sends an XDI message which looks like this:
$
   $get
      /
         =markus
            +email
3. The XDI endpoint answers with the statement that matches the $get query:

=markus
   +email
      ""
4. In the end, the code prints out the literal from that statement.

In total, a few simple lines of actually working code that should demonstrate how XRI and XDI work together.

Markus