Provides services for java client-side communication to a Greenstone Digital Library via CORBA.

Further Requirements

Sun Java 2 version 1.3 (or later)
Corbaserver, a server-side application for communicating to a Greenstone Digital Library.

Java Interface Data Flows

A Typical Query

From a users perspective, a typical query may work as follows:

Create instances of the necessary NZDL Java-Client objects:

a NzdlQuery object
a NzdlRequest object using your NzdlQuery object
a NzdlResponse object that will eventually hold response data
a NzdlService object to service CORBA interface requests to a Greenstone collection

Use the NzdlService object (with collection name and NzdlRequest object) to query the CORBA interface and place the reply into the NzdlResponse object.
Create an instance of the NzdlResultSet object. Use NzdlResponse.getResultSet() to extract response data into the NzdlResultSet object.
Use the NzdlResultSet methods to view data such as document IDs

NzdlService.getDocument()

Sample Code

Below is a trivial example of a client application. For a more elaborate example, see SimpleClient.

In order to function, this app needs Corbaserver running on the same machine.

/**
* TrivialDemo.java.
* A very simple client application that:
* - Creates a service object using an Interoperable
* Object Reference (IOR) from a file;
* - lists all available collections;
* - searches "demo" collection for "snail farming";
* - prints the number of hits;
* - lists first 10 titles found;
* - displays the unformatted text of first document found.
*/
import java.io.*;
import java.util.*;
import java.lang.*;
import org.nzdl.gsdl.service.*; //the java-client stuff
import org.nzdl.gsdl.util.NzdlIORs; //for obtaining the IOR

public class TrivialDemo {
public static void main( String [] args )
{
    String myIorFile = "/tmp/localcorba.objid";
    String myQueryString = "snail farming";
    String myCollection = "demo";

    // Create a Service Object
    NzdlService myService = NzdlIORs.findIOR(null, null,
                    myIorFile, null);

// Use getCollectionSet to obtain List of Collections
Set myCollections = myService.getCollectionSet();

//Display List of Collections
System.out.println("\nThe available collections:");

    for (Iterator i = myCollections.iterator(); i.hasNext(); )
    {
        String collName = (String) i.next();
        System.out.println(" "+ collName);
    }

    // Find The Number of documents in my collection
    NzdlCollectionInfo myInfo = myService.getCollectionInfo(myCollection);
    System.out.println("\nNum Of Collection docs = "+myInfo.getNumOfDocs());

// Create query object
NzdlQuery query = new NzdlQuery( myQueryString );

// Create request object
NzdlRequest request = new NzdlRequest( query );

// create response object
NzdlResponse response = new NzdlResponse( );

// use service to get response from request to myCollection
myService.service( myCollection, request, response );

// use getResultSet to get results from response
NzdlResultSet results = response.getResultSet();

// getNumOfDocs
System.out.println("\nNumber of hits = "+results.getNumOfDocs());

    // Use getDocumentIDs to build list of titles (defaults: 1 - 10)
    List docIDs = results.getDocumentIDs();
    System.out.println("\nThe titles:");
    for (ListIterator i = docIDs.listIterator(); i.hasNext(); )
    {
        Set metaData
        = myService.getMetaData( myCollection,(String)i.next(),"Title");
        Iterator j = metaData.iterator();
        System.out.println(j.next()); //print title metadata
    }
    System.out.println("\nThe first document returned was:");

    // Print first document returned
    String myDoc
        = myService.getDocument(myCollection,(String)docIDs.get(0));
    System.out.println(myDoc);

} // end of main
} // end of demo class