BEA WebLogic Interview Questions and Answers 14

Why did the messaging bridge fail to connect to the source bridge destination?
Either an error occurred when configuring the source bridge destination parameters, or the actual source destination is not running and cannot communicate with the messaging bridge.

* Verify whether the bridge's source destination is correctly configured, by making sure that the following fields on the JMS Bridge Destination —> Configuration —> General console page have been properly completed:

o Connection URL—this must be the URL of the JNDI provider used to look up the connection factory and actual destination.
o Destination JNDI Name—this must be the JNDI name of the actual destination mapped to the source bridge destination.
o Connection Factory JNDI Name—this must be the connection factory used to create a connection for the actual destination mapped to the source bridge destination.
o User Name/Password—make sure that this user ID has permission to access the actual source destination.
* Verify that the actual source queue or topic destination mapped to the source bridge destination is running and healthy, as follows:
o Is the WebLogic Server instance hosting the source destination running?
o Is the JMS server hosting the source destination correctly deployed?

Note: This troubleshooting scenario for correcting a source bridge destination connection failure also applies to target bridge destinations.

Can the messaging bridge handle two-phase or global transactions between separate WebLogic Server domains or between different releases?
Yes, as long as the communication is between source and target WebLogic domains that are both running release 6.1 SP3 or later, and the bridge is configured to use the Exactly-once quality of service.

I configured the messaging bridge to use the Exactly-once quality of service for two-phase transactions. So why am I getting a "quality of service is unreachable" error?
There are some additional configuration requirements for the messaging bridge to handle transactions between WebLogic domains:

* The supported adapters are located in the WL_home\lib directory. For the Exactly-once QOS, the transaction adapter, jms-xa-adp.rar, must be deployed in the release 6.1 domain where the bridge is running, via the select Deployments —> Applications node on the console.
* This jms-xa-adp.rar adapter must also be identified in the Adapter JNDI Name attribute as eis.jms.WLSConnectionFactoryJNDIXA on the JMS Bridge Destination —> Configuration tab for both the source and target bridge destinations.
* For WebLogic JMS, verify that you are using the transactional XAConnectionFactory for the queue or topic destinations mapped to both the source and target bridge destinations. To verify this, the following attributes must be set on the JMS —> Connection Factory —> Configuration —> Transactions console tab or in the configuration file (config.xml):
UserTransactionsEnabled=true
XAConnectionFactory=true
* For third-party JMS vendors, verify that you are using a transactional connection factory for the destinations mapped to the source and target bridge destinations.

Can I configure the messaging bridge to automatically downgrade the quality of service if the Exactly-once service isn't available on either the source or target bridge destination?
Yes, just make sure to select the QOS Degradation Allowed check box on the Messaging Bridge —> Configuration —> General administration console page.

When configuring a source or target messaging bridge destination, do I need to set the Adapter Classpath field?
Leave the Adapter Classpath field blank when connecting to source and target destinations that are both running on release 6.1 or later. When connecting to either a source or target destination that is running on release 6.0 or earlier, the Adapter Classpath field must indicate the location of the classes for the earlier WebLogic Server release. When connecting to a third-party JMS provider, the bridge destination must supply the provider's CLASSPATH in the WebLogic Server CLASSPATH.

Can the messaging bridge forward durable subscription messages between separate WebLogic Server 6.1 and release 7.0 or later domains?
Yes, as long as the WebLogic 7.0 domain is using Service Pack 1 or later. To enable durable messages across the messaging bridge using the Administration Console, select the Durability Enabled attribute on the Messaging Bridge —> Configuration —> General tab.

How do I enable debugging for the messaging bridge?
You can enable debugging for the messaging bridge using either of the followings methods:

* Add the following lines to your WebLogic start script (before the weblogic.Server line):
-Dweblogic.Debug.DebugMessagingBridgeStartup=true
-Dweblogic.Debug.DebugMessagingBridgeRuntime=true
* Add the following statements to the ServerDebug entry in your configuration file (config.xml) for the server that the messaging bridge is running on:
DebugMessagingBridgeStartup="true"
DebugMessagingBridgeRuntime="true"
Once debugging is enabled for the messaging bridge, the debugging messages are sent to the server log by default. However, if you want them to appear in the Administration Console, add "DumpToConsole" to the statements show above. For example:
-Dweblogic.Debug.DebugMessagingBridgeStartupDumpToConsole=true

Which of the following is NOT true about the security implementation in the WebLogic Server?
a. Servlets, JSPs, EJBs, RMI objects, and Java applications use the Java Authentication and Authorization Service to authenticate WebLogic Server.
b. The default security realm in WebLogic Server is the File realm.
c. The default authentication scheme for WebLogic Server is two-way authentication.
d. An Administration Server may contain configuration information for one WebLogic Server or a cluster of WebLogic servers.

Choice C is correct because it is not true about the security in WebLogic server. A,B and D are true. Servlets, JSPs, EJBs, RMI objects, and Java applications use the Java Authentication and Authorization Service to authenticate WebLogic Server. JAAS is a standard extension to the Java 2 Software Development Kit. The authentication component of JAAS provides the ability to reliably and securely maintain client identity, regardless of whether the code is running as a Java application, a JSP, an EJB, an RMI object or a servlet.
In WebLogic Server, JAAS is layered over the existing Security Service Provider Interface (SPI) allowing the continued use of realm-based authorization. The default security realm in WebLogic Server is the File realm. When WebLogic Server is started, the File realm creates User, Group, and ACL objects from properties defined through the Administration Console in WebLogic Server and stored in the fileRealm.properties file. The File realm is designed for use with 1,000 or fewer users, for more no of users, an alternate security realm should be used. In WebLogic Server, an Administration Server is a WebLogic Server that functions as the central source of all configuration information. An Administration Server may contain configuration information for one WebLogic Server or a cluster of WebLogic servers.

For EJB applications with bean-managed transaction demarcations, which of the following is used by the client to get a reference to the UserTransaction object for the WebLogic Server domain?
a. JTA
b. JNDI
c. JMS
d. JTS
e. JMX

Choice B is correct. WebLogic Server supports the javax.transaction package and the javax.transaction.xa package, which implement the Java Transaction API (JTA) for Java applications.
javax.transaction.UserTransaction provides an interface to the transaction manager that allows the application developer to manage the scope of a transaction explicitly. The client application uses JNDI to obtain an object reference to the UserTransaction object for the WebLogic Server domain.
The code used by the client is given.
UserTransaction ut=(UserTransaction)jndicontext.lookup("javax.transaction.UserTransaction")
If a bean needs a reference to the UserTransaction object, it obtains it from the EJBContext as given.
UserTransaction ut=ejbContext.getUserTransaction()