_call.setOperationName(new javax.xml.namespace.QName("https://soap.sforce.com/schemas/class/TAAFetchObjectsController", "getObjectMap"));

The above is the line from BindingStub class. So, my understanding is, the request goes to  https://soap.sforce.com/schemas/class/TAAFetchObjectsController

Also, the error from the log also shows the same url.

The partner API that I am using is https://cs3.salesforce.com/services/Soap/u/15.0/00DQ00000008sVI

Thanks

Venkat

That's the xml namespace, not the url of the service.

Can you post your code? 

inputs:

sfdcSessionURL = https://cs3.salesforce.com/services/Soap/u/15.0/00DQ00000008sVI

sfdcSessionID = a valid Session ID.

TAAFetchObjectsConnector connectorFetch = new TAAFetchObjectsConnector(sfdcSessionId,sfdcSessionURL);
         Result thisResult = connectorFetch.getServiceStub().getObjectMap(accountID, oppAccountID, oppId, primaryContactID, sfdcUserInfoResult.getUserId());
        

public TAAFetchObjectsConnector(String sfdcSessionId, String sfdcSessionURL) throws ServiceException, RemoteException {
            this.SESSION_ID = sfdcSessionId;
            this.SESSION_URL = sfdcSessionURL;
            init();
        }

private void init() throws ServiceException, RemoteException {
            LOGGER.info("Connecting to {" + SESSION_URL  + "} with Sessiion ID {" + SESSION_ID + "}");
            initSOAPServiceStub();
            initSOAPSessionHeader();
        }

/**
         * Initializes the Service Stub
         * @throws ServiceException
         * @throws RemoteException
         */
        private void initSOAPServiceStub() throws ServiceException, RemoteException {
            TAAFetchObjectsControllerServiceLocator sLocator = new TAAFetchObjectsControllerServiceLocator();
            sLocator.setTAAFetchObjectsControllerEndpointAddress(this.SESSION_URL);
           
            this.serviceStub = (TAAFetchObjectsControllerBindingStub) sLocator.getPort(TAAFetchObjectsControllerPortType.class);
            this.serviceLocator = sLocator;
           
        }
        /**
         * Initializes the Session Header and links with the Service Stub.
         */
        private void initSOAPSessionHeader() {
            this.sessionHeader = new SessionHeader();
            this.sessionHeader.setSessionId(this.SESSION_ID);
           
            this.serviceStub._setProperty(TAAFetchObjectsControllerBindingStub.SESSION_MAINTAIN_PROPERTY, new Boolean(true));
            this.serviceStub.setHeader(this.serviceLocator.getServiceName()
                    .getNamespaceURI(), "SessionHeader", this.sessionHeader);   
            this.serviceStub._setProperty(TAAFetchObjectsControllerBindingStub.ENDPOINT_ADDRESS_PROPERTY, this.SESSION_URL);
           
        }
        public TAAFetchObjectsControllerBindingStub getServiceStub() {
            return this.serviceStub;
        }
        public SessionHeader getSessionHeader() {
            return this.sessionHeader;
        }

Don't do this, you're changing the URL that you're sending your apex request to the partner API.

his.serviceStub._setProperty(TAAFetchObjectsControllerBindingStub.ENDPOINT_ADDRESS_PROPERTY, this.SESSION_URL);