Re: Servlet / Jini lookup

[Olivier Dusacq]

Hello,
I think I have found something very interesting to solve my problem. I 
tried to put the Jini jar-files (jini-core.jar, jini-ext.jar and 
sun-util.jar) in $CATALINA_HOME/common/lib, or 
$CATALINA_BASE/shared/lib, or anywhere if I set correctly the classpath 
in setclasspath.sh (instead of placing these jars in WEB-INF/lib as I 
did before). After that, the LookupDiscoveryManager() seems OK. I 
suspect a classloader issue, but I'm not sure. Maybe somebody on this 
list could explain this ?

But now, I'm stuck with some NoClassDefFoundError or 
ClassCastException... I think it's the "same" classloader problem. In 
fact, I don't know if it's good idea to place jars in the common 
folders. But is there any other solution to make Jini and Tomcat working 
together ? Is it possible to tell to Tomcat: "now use the Webapp 
classloader when dealing with these 3 Jini jars" ??

Thanks, Olive
Olivier Dusacq wrote:
Hello,
I'm trying to contact a Jini lookup service (reggie) from a simple 
servlet. I'm using Tomcat 5.5.7, Java 1.5.0_01, Jini 1.2.1 and Solaris8.

The problem is that, after the call to LookupDiscoveryManager() (see 
source code below), the "discovered()" method is never called back.

Here is what I get in my browser after an exec :
********
before LookupDiscoveryManager
end
********
I have successfully run a similar code in a standalone Java app (i.e. 
without Tomcat / servlet), and everything is OK.

In fact, I have no error message nor Exception thrown. :-( I simply 
don't have any response from reggie.

Any help would be appreciate,
Olive
PS: I'm new to Tomcat and Jini.

=====================
== core servlet
=====================
    protected void doGet(HttpServletRequest request,
             HttpServletResponse response)
         throws ServletException, IOException {
        response.setContentType("text/plain");
        PrintWriter out = response.getWriter();
        new searchALookup(out).start();
        try {
            Thread.sleep(30000);
        } catch (InterruptedException ie) {
            out.println("InterruptedException: " + ie.getMessage());
        }
        out.println("end");
        out.close();
    }

======================
== searchALookup.java
======================
import java.io.*;
import net.jini.core.discovery.LookupLocator;
import net.jini.core.lookup.*;
import net.jini.discovery.*;
public class searchALookup extends Thread implements DiscoveryListener {
    private LookupDiscoveryManager discover;
    private PrintWriter sortie;
    public chercheLookup(PrintWriter out) {
        sortie = out;
    }
    public void run() {
        try {
            startServiceDiscovery();
        } catch (IOException ioe) {
            sortie.println("Error while connecting to service");
        }
    }
    public synchronized void discovered(DiscoveryEvent dev) {
        sortie.println("--> Discovered");
        ServiceRegistrar[] lookup = dev.getRegistrars();
        // We may have discovered one or more lookup services
    sortie.println(lookup.length +" lookups decouverts");
    }
    public synchronized void discarded(DiscoveryEvent dev) {
        sortie.println("discarded");
    }
    private void startServiceDiscovery()
        throws IOException {
    String[] groups = null;
    LookupLocator[] locators = null;
    try{
        LookupLocator locator =
        new LookupLocator("jini://REGGIE_HOSTNAME");
        locators = new LookupLocator[]{locator};
        groups=DiscoveryGroupManagement.NO_GROUPS;
    }catch(java.net.MalformedURLException e){
        groups = new String[]{"public"};
        sortie.println("Groups ="+groups[0]);
    }
    
        // Initialize for receiving events from the lookup service
        sortie.println("before LookupDiscoveryManager");
    discover = new LookupDiscoveryManager(groups, locators, this);
    }
}

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