Get 1z0-599 Dumps : Verified Oracle WebLogic Server 12c Essentials

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.

The JMS SAF Client feature extends the JMS store-and-forward service introduced

in WebLogic Server 9.0 to standalone JMS clients. Now JMS clients can reliably send

messages to server-side JMS destinations, even when the client cannot reach a

destination (for example, due to a temporary network connection failure). While disconnected from the server, messages sent by a JMS SAF client are stored locally on

the client file system and are forwarded to server-side JMS destinations when the

client reconnects. See Reliably Sending Messages Using the JMS SAF Client.

http://docs.oracle.com/middleware/1212/wls/WLSTG/domains.htm

Load Balancing for JMS

WebLogic Server JMS supports server affinity for distributed JMS destinations and client connections. (B, not A)

By default, a WebLogic Server cluster uses the round-robin method to load balance objects. To use a load balancing algorithm that provides server affinity for JMS objects (not D), you must configure the desired method for the cluster as a whole.

A Node Manager process is not associated with a specific WebLogic domain but with a

machine. You can use the same Node Manager process to control server instances in

any WebLogic Server domain, as long as the server instances reside on the same

machine as the Node Manager process. Node Manager must run on each computer

that hosts WebLogic Server instances—whether Administration Server or Managed

Server—that you want to control with Node Manager.