151.When should I avoid using a messaging bridge?
Other methods are preferred in the following situations:

• Receiving from a remote destination—use a message driven EJB or implement a client consumer directly.
• Sending messages to a local destination—send directly to the local destination.
• Environment with low tolerance for message latency. Messaging Bridges increase latency and may lower throughput. Messaging bridges increase latency for messages as they introduce an extra destination in the message path and may lower throughput because they forward messages using a single thread.
• Forward messages between WebLogic 9.0 domains—Use WebLogic Store-and-Forward.

152.How many types of JMS stores are available?

• The JMS store can be configured to use either:
• A file store
• A JDBC store (a connection pool)

153.How will you configure a JMS JDBC Store?

• To configure JMS JDBC persistence, perform the following:
• Create a JDBC DataSource.
• Create a JMS store and refer to the JDBC DataSource.
• Refer to the JMS store from the JMS server configuration.
• The required infrastructure (tables and so on) is created automatically.

154.What Is a Transaction?

• A transaction is a mechanism to handle groups of operations as though they were one.
• Either all operations in a transaction occur or none occur
  at all.
• The operations involved in a transaction might rely on multiple servers and databases.

155.How many Types of Transactions are there? Explain?

• A local transaction deals with a single resource manager. Local transactions use the non-Extended Architecture (non-XA) interface between Oracle WebLogic Server and the resource manager.
• A distributed transaction coordinates or spans multiple resource managers.
• Global transactions can deal with multiple resource managers. Global transactions use the Extended Architecture (XA) interface between Oracle WebLogic Server and the resource managers.
• You need to create non-XA or XA resources for local transactions. However, for global transactions, you need to create only XA resources.

156.Explain about Two-Phase Commit Protocol?

• The Two-Phase Commit (2PC) protocol uses two steps to commit changes within a distributed transaction.
• Phase 1 asks the RMs to prepare to make the changes.
• Phase 2 asks the RMs to commit and make the changes permanent or to roll back the entire transaction.
• A global transaction ID (XID) is used to track all the changes associated with a distributed transaction.

157.Explain about Extended Architecture Protocol (XA)?
The Extended Architecture (XA) protocol:

• Is the interface that is used between WLS and the RMs
• Implements the 2PC protocol
• Allows programs to control the RMs that are involved in distributed transactions

158.What is the user of “Transaction Log”?

• Each server has a transaction log that stores information about committed transactions coordinated by the server that may not have been completed.
• Oracle WebLogic Server uses the transaction log when recovering from system crashes or network failures.
• You cannot directly view the transaction log because the records are in a binary format and are stored in the default persistent store for the server.

159.Explain about Logging Last Resource?

• You can configure a JDBC data source to enable the Logging Last Resource (LLR) transaction optimization, which:
• Enables one non-XA resource to participate in a global transaction
• Has improved performance and the same ACID guarantee as XA
• The LLR optimization improves performance by:
• Removing the need for an XA JDBC driver to connect to the database. XA JDBC drivers are typically inefficient compared to non-XA JDBC drivers.
• Reducing the number of processing steps to complete the transaction, which also reduces network traffic and I/O
• Removing the need for XA processing at the database level (if the database is the one non-XA resource)

160.What Is LDAP?
The Lightweight Directory Access Protocol:

• Is derived from X.500
• Provides a hierarchical lookup service
• Supports sophisticated searching
• Can be secured via SSL