Batching Client Requests

You can batch multiple CIMClient API calls into a single remote call to reduce the delay introduced by multiple remote message exchanges. You use an instance of the BatchCIMClient class to build the list of operations that you want to execute in a batch request. Then use the performBatchOperations method of the CIMClient class to send the list of operations to the CIM Object Manager.

A batch operation does not imply a single transaction. Each operation is independent of the other operations included in the batch and has no dependencies on the success or failure of the preceding operations.

The BatchCIMClient class contains methods that enable you to perform the same CIM operations as in non-batch mode. These methods are similar to CIMClient methods except that the BatchCIMClient methods do not return the same types as their equivalents in the CIMClient class because the values are returned as a list after the batch operation is complete. The methods return an integer operation ID which you can use to get the result of the operation later. As methods of BatchCIMClient are invoked, the BatchCIMClient object builds a list of CIMOperationobjects that will be executed later.

When the client executes the batch operation list by invoking CIMClient's performBatchOperations method, a BatchResult object is returned that contains the results of the batch operation. Clients can then pass the operation ID to the getResult method of the BatchResult class to get the results of the operations. If an operation on the list generates an exception, an exception object is embedded in the BatchResult object. When you invoke the getResult method with the ID of the operation that failed, the exception is thrown by the getResult method.

Example 3-20 Batching Example

The following example shows how you can use the batching API to perform multiple operations in one remote call. In this example, three operations - enumerateInstanceNames, getClass, and enumerateInstances are performed as a single batch operation.

import java.util.Enumeration;
import java.util.ArrayList;
import java.util.Vector;
import java.lang.String;

import javax.wbem.cim.*;
import javax.wbem.client.*;
import javax.wbem.client.UserPrincipal;
import javax.wbem.client.PasswordCredential;


public class TestBatch {
    public static void main(String args[]) throws CIMException {
	       CIMClient cc = null;
	       CIMObjectPath cop = null;
	       String protocol = CIMClient.CIM_RMI;
	       if (args.length < 4) {
	           System.out.println("Usage: TestBatch host user passwd 
                                classname " + "[rmi|http]");
	           System.exit(1);
	           }
	       try {
	           CIMNameSpace cns = new CIMNameSpace(args[0]);

	           UserPrincipal up = new UserPrincipal(args[1]);
	           PasswordCredential pc = new PasswordCredential(args[2]);
	           if (args.length == 5 && args[4].equalsIgnoreCase("http")) {
	    	           protocol = CIMClient.CIM_XML;
	           }
	           cc = new CIMClient(cns, up, pc, protocol);

	           CIMObjectPath op = new CIMObjectPath(args[3]);

	           BatchCIMClient bc = new BatchCIMClient();
	           int[] ids = new int[3];

	           ids[0] = bc.enumerateInstanceNames(op);
	           ids[1] = bc.getClass(op, false, true, true, null);
	           ids[2] = bc.enumerateInstances(op, true, false, false, 
                                           false, null);

	           BatchResult br = cc.performBatchOperations(bc);

            Enumeration instanceNames = (Enumeration)br.getResult
                                        (ids[0]);
	           CIMClass cl = (CIMClass)br.getResult(ids[1]);
	           Enumeration instances = (Enumeration)br.getResult(ids[2]);

	           while (instanceNames.hasMoreElements()) {
	               System.out.println((CIMObjectPath)instanceNames.
                                    nextElement());
	           }

	           System.out.println(cl.toMOF());

	           while (instances.hasMoreElements()) {
	               System.out.println((CIMInstance)instances.
                                    nextElement());
	           }

	       }
	       catch (Exception e) {
	           e.printStackTrace();
	           System.out.println("Exception: "+e);
	       }

	       // close session.
	       if (cc != null) {
	           cc.close();
	       }
    }
}