if(context == null) {
String serviceUrl = "https://" + vCenterAddress + "/sdk/vimService";
String[] params = new String[] {"--url", serviceUrl, "--username", vCenterUserName, "--password", vCenterPassword };
ExtendedAppUtil appUtil = ExtendedAppUtil.initialize(vCenterAddress + "-" + s_seq++, params);
appUtil.connect();
context = new VmwareContext(appUtil, vCenterAddress);
context.registerStockObject("username", vCenterUserName);
context.registerStockObject("password", vCenterPassword);
s_contextMap.put(vCenterAddress, context);