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Weblogic Application Server FAQs

111.What is a Connection Pool?

    • A connection pool is a group of ready-to-use database connections associated with a data source.
    • Connection pools:
      • Are created at Oracle WebLogic Server startup
      • Can be administered using the Administration Console
      • Can be dynamically resized to accommodate increasing load

112.What are the benefits of having Data Sources and Connection Pools in Weblogic?

    • The following are some advantages of this approach:
      • Time and overhead are saved by using an existing database connection.
      • Connection information is managed in one location in the Administration Console.
      • The number of connections to a database can be controlled.
      • The DBMS can be changed without the application developer having to modify the underlying code.
  • A connection pool allows an application to “borrow” a DBMS connection

113.How Data Sources are used in Weblogic?
A client retrieves a data source through a JNDI lookup and uses it to obtain a database connection.
114.What is Multi Data Sources?

    • Multi data source:
      • Is an abstraction around a group of data sources
      • Determines which data source to use to satisfy the request depending on the algorithm selected in the multi data source configuration:
        • Load balancing or failover
      • Is bound to the JNDI tree
    • XA support for multi data sources:
      • The WLS JDBC supports using multi data sources in XA transactions.
      • You can configure the data sources contained within the multi data source to use XA JDBC drivers.

115.What is the functionality of “Message-Oriented Middleware”?

  • Message-oriented middleware refers to an infrastructure that supports messaging.
  • Typical message-oriented middleware architectures define the following elements:
  • Message structure
  • The way to send and receive messages
  • Scaling guidelines

116.Explain about Point-to-Point (Queue)?
Many producers can serialize messages to multiple receivers in a queue.
117.Explain about Publish-Subscribe (Topics)?
Publishing and subscribing to a topic decouples producers from consumers.
118.Explain about Oracle WebLogic Server JMS Features?
Oracle WebLogic Server JMS supports:

    • PTP and pub/sub domains
    • Guaranteed and transactional message delivery
    • Durable subscribers
    • Distributed destinations
    • Recovery from failed servers

119.How will you implement “Messaging Service” in Weblogic?

    • In Oracle Weblogic Server, the messaging service is implemented through a JMS server.
    • A JMS server receives and distributes messages.

120.What is the user of “Connection Factories” in JMS?

    • JMS connection factories are used to set default client connection parameters, including:
      • Message priority
      • Message time-to-live (TTL)
      • Message persistence
      • Transactional behavior
      • Acknowledgement policy
      • Flow control
    • WLS provides a default client connection factory that:
      • Uses WebLogic’s default connection settings
      • Is located on the server JNDI tree at weblogic.jms.ConnectoryFactory