QUESTION: 21

Based on the publisher and subscriber roles established by the application of the Event-Driven Messaging pattern, which of the following statements are true?

a service, acting as a publisher, issues event notification messages to an event management program that is responsible for broadcasting the messages
a service consumer, acting as a subscriber, can selectively subscribe to specific events
an intermediate event management program enters the role of subscriber when accepting event subscriptions
upon receiving a message associated with an event that a service consumer subscribed to, the service consumer enters the publisher role

Answer(s): A,B

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QUESTION: 22

The messaging framework established by the application of the Event-Driven Messaging pattern positions a(n) ___________ as being responsible for the broadcast of event notification messages.

event management program
synchronous queue
event-driven Web service
database

Answer(s): A

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If a service consumer program needs to get data from a service that is not available, it can poll the service by periodically issuing a request message. This type of interaction can be inefficient because it can lead to unnecessary message transmissions.
Which of the following statements describes a solution to this problem?

By applying the Messaging Metadata pattern, the service consumer can write a request identifier in the message header. Service agents then intercept the request messages and do not forward those that contain a previously detected identifier. This practice eliminates the delivery of the duplicate messages to the service.
The Event-Driven Messaging pattern can be applied to establish a messaging framework in which service consumers are automatically notified of relevant runtime service events.
By applying the Atomic Service Transaction pattern, a service can be designed to invoke an alternative exception handling process when it is unavailable to receive a given message.
None of the these statements describe solutions that directly solve this problem.

Answer(s): B

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