pyrolite: newbie quicker-start for Java

pyroliteJavaQuickerStart

I'm posting what I hope is useful for other newbies like me, which is an elaboration of the Pyro 
simple example greeting.py appearing in http://pythonhosted.org//Pyro4/intro.html#with-a-name-server 
but with a Java (rather than Python) client.

That is, tying together the above with an elaboration of the "small code example in Java" that appears in: 
  https://pythonhosted.org/Pyro4/pyrolite.html

FYI, I am running under Window 7 64-bit, WinPython-64bit-3.4.2.4 and Java1.6 (forced by my using ImageJ).

Install Pyro4 onto Python side:
https://pythonhosted.org/Pyro4/install.html

Install pyrolite on Java side (stick the .jar files wherever they need to be):
https://pythonhosted.org/Pyro4/pyrolite.html

Under Python, start a Pyro NameServer: python -m Pyro4.naming
refs:
     http://pythonhosted.org//Pyro4/intro.html#with-a-name-server 
     http://pythonhosted.org//Pyro4/nameserver.html#nameserver-nameserver

Under Python, following http://pythonhosted.org//Pyro4/intro.html#with-a-name-server,
type in the contents of greeting.py to Python interpreter (omitting the print statement) or execute greeting.py. 
What this does is to set up a "server" class (i.e. something you want to serve up Python library methods 
to Java client) and instantiate it, start the Pyro daemon, register the server class instance to the daemon and 
also to the (auto-found) Pyro name server (already running due to previous step above).

Under Java, essentially follow the "small code example in Java" that appears in
https://pythonhosted.org/Pyro4/pyrolite.html   but minding some clarification comments and possibly needed 
adaptations, as I show below.  What this code does is to locate|grab the NameServerProxy, construct the 
(java proxy|instance of the) Pyro-served Python server class instance (here, the class GreetingMaker), 
invoke its method (get_fortune), and cast the return value to the appropriate Java type 
(see Python-Java mappings in pyrolite readme.txt).


// Needed for pyrolite
import net.razorvine.pyro.*;
import java.io.*;   // Needed (?) for IOException thrown by some pyrolite methods


public class Greeting_Client {

//    public void run(String arg) throws IOException {
//         The above "throws" augmentation would allow various exception-throwing pyrolite methods to
//          compile, but if class Greeting_Client were implementing some interface
//          e.g. "public class Greeting_Client implements ABC", it's likely the interface "ABC" 
//          couldn't be overridden with "throws IOException" .
//          So instead, we'd be required to use try-catch blocks below!
    public void run(String arg)  {

      System.out.println("Here we go...");

      // NameServerProxy ns = NameServerProxy.locateNS(null);
      //  We have to break up the declaration and construction of the ns variable as follows, or
      //    declaring and constructing it in one line (as above) within the try block means ns
      //     is local (only) within that try block.
      //   We follow this idiom with further instances later below.
      NameServerProxy ns = null;  // needs to be initialized to null or get
                                                        // "variable might not have been initialized" compilation error
       try {
           ns = NameServerProxy.locateNS(null);
        } catch (IOException e) {
             System.out.println("Caught LocateNS IOException: " + e.getMessage());
             return;
        }


       // PyroProxy remoteobject = new PyroProxy(ns.lookup("PYRONAME:example.greeting"));
       //   The Pyro dox for the Python side uses above argument form, but the Java-side Pyrolite uses
       //      below form without the PYRONAME: prefix.
       // PyroProxy remoteobject = new PyroProxy(ns.lookup("example.greeting"));
       PyroProxy remoteobject = null;
       try {
           remoteobject = new PyroProxy(ns.lookup("example.greeting"));
        } catch (IOException e) {
              System.out.println("Caught ns.lookup IOException: " + e.getMessage());
              ns.close();
              return;
        }

       // Object result = remoteobject.call("get_fortune", "Lucifer");
      Object result = null;
       try {
           result = remoteobject.call("get_fortune", "Lucifer");
        } catch (IOException e) {
             System.out.println("Caught remoteobject.call IOException: " + e.getMessage());
             ns.close();
             remoteobject.close();
             return;
        }

       String message = (String)result;  // cast to the type that 'get_fortune' returns
       System.out.println(message);
       remoteobject.close();
       ns.close();
    }

}