Free Practice Questions for Oracle 1z0-599 Exam

Note:

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* When to Use Work Managers

Following are guildelines to help you determine when you might want to use Work Managers to customize thread management:

/ The default fair share is not sufficient.

This usually ocurrs in situations where one application needs to be given higher priority over another.

/ A response time goal is required.

/ A minimum thread constraint needs to be specified to avoid server deadlock

JCA Adapter

This product is a wrapper to the WebLogic Tuxedo Connector (WTC) found as part of the WebLogic Server (WLS) product. WTC can only be used on WebLogic, but the JCA adapter allows deploying WTC capabilities on other Java Application Servers that support the Java EE JCA specification.

Note:

* Tuxedo (Transactions for Unix, Extended for Distributed Operations) is a middleware platform used to manage distributed transaction processing in distributed computing environments. Tuxedo is a transaction processing system or transaction-oriented middleware, or enterprise application server for a variety of systems and programming languages. Developed by AT&T in the 1980s, it became a software product of Oracle Corporation in 2008.

When an application that references a shared library or package is deployed, WebLogic Server checks the names and version string requirements against the libraries registered with the server. If an exact match for a library or package name is not found, or if the version requirements are not met, the application deployment fails.

If WebLogic Server finds a name and version string match for all of the libraries referenced in the application, the server adds the libraries' classes to the classpath of the referencing application and merges deployment descriptors from both the application and libraries in memory. The resulting deployed application appears as if the referenced libraries were bundled with the application itself.

Note:

As a best practice, your development team should always include version string information for a library or optional package in the manifest file for the deployment. See Editing Manifest Entries for Shared Libraries in Developing Applications for Oracle WebLogic Server for more information.

If you are deploying a library or package that does not include version string information, you can specify it at the command line using one or both of the following options:

libspecver—Defines a specification version for the library or package.

libimplver—Specifies an implementation version for the library or package.

By default, JMS messages never expire. When applications send messages to queues or topics with durable subscribers, WebLogic must retain the message until it is consumed. This is fine in most point-to-point messaging applications because consumers are constantly consuming messages. Any message sent to a queue will typically be consumed in a relatively short period of time. If the consumers get disconnected, they will usually reconnect as soon as possible and start processing any messages that might have built up in the queue.

D: For durable subscribers to a topic, this is not necessarily true. The messaging system is forced to retain any message that has not been consumed by a durable subscriber, regardless of whether that durable subscriber will ever return. In this case, WebLogic is at the mercy of the durable subscriber to unsubscribe when it no longer wishes to receive the messages. If the durable subscriber logic is flawed in such a way that the subscribers do not unsubscribe properly, the messaging system will start to fill up with messages that may never be delivered. This calls for real caution in using durable subscribers. Fortunately, there is another way to help deal with this problem. Message expiration can be set at the connection factory level. Using a connection factory’s default time-to-live attribute, we can specify the number of milliseconds that WebLogic should retain an undelivered message after it is sent.

Note:

* It is recommended that you shutdown WebLogic Server instances through the Administration Console.

* If automatic server migration is enabled, the servers are required to contact the cluster leader and renew their leases periodically. Servers will shut themselves down if they are unable to renew their leases. The failed servers will then be automatically migrated to the machines in the majority partition.

Use multi-node and clustering to get performance suitable for a product environment.

Note:

* The FilteringClassLoader provides a mechanism for you to configure deployment descriptors to explicitly specify that certain packages should always be loaded from the application, rather than being loaded by the system classloader. This allows you to use alternate versions of applications such as Xerces and Ant.

* To configure the FilteringClassLoader to specify a certain package is loaded from an application, add a prefer-application-packages descriptor element to the weblogic-application.xml which details the list of packages to be loaded from the application. The following example specifies that org.apache.log4j.* and antlr.* packages are loaded from the application, not the system classloader:

org.apache.log4j.*

antlr.*