20: Lesson Review Answers in .NET

Generator PDF-417 2d barcode in .NET 20: Lesson Review Answers

1. Correct Answer: B A. Incorrect: The message ID uniquely identifies the message but does not provide an order to messages. B. Correct: Each message is tagged with a sequence number that is used to ensure that messages are processed in order. C. Incorrect: A conversation can contain many messages; therefore, the conversation ID cannot provide a way to order messages. D. Incorrect: The contract ID uniquely identifies the contract being enforced for the conversation but does not have any capability to order messages.

1. Correct Answers: A and B A. Correct: The SEND command must be the first statement in a batch. If it is not the first statement in a batch, the previous command must be explicitly terminated with a semicolon. B. Correct: To place a message on a queue, the conversation has to be specified in the SEND command by using the conversation handle. C. Incorrect: The message type is an optional parameter. To build implementation-independent applications, the message-type checking should be left up to the contract and message type elements. D. Incorrect: The queue is not specified for the SEND command because the conversation provides the necessary infrastructure to determine the correct queue to use.

2. Correct Answer: C and D A. Incorrect: The RECEIVE command does not perform any type checking via the contract because that capability is handled when a message is placed on the queue. B. Incorrect: The RECEIVE command does not perform any type checking via the message type because that capability is handled when a message is placed on the queue. C. Correct: The RECEIVE command must be the first statement in a batch. If it is not the first statement in a batch, the previous command must be explicitly terminated with a semicolon. D. Correct: The RECEIVE command is built to generically process messages on a queue. However, it needs to know which queue to process to retrieve messages.

1. Although the business has rather complex processes and routing requirements, from an IT perspective, it is actually quite straightforward. The entire side of the business that deals with customer orders and inventory is simply a very large message queue. You would convert all the custom code into a Service Broker application. Converting all the code, however, shouldn t be a single-step operation. You should accomplish the conversion in stages to minimize the impact on operations. 2. The first piece to convert is customer requests. Instead of the requests being submitted via the existing code, requests should be submitted to a Service Broker queue. Messages in this queue would then be forwarded to the custom code handling the next part of the process. 3. The second piece to be converted is the logic required to process a request. This logic evaluates the request and generates one or more orders, along with possibly forwarding all or part of a request to a user. The advantage in this step is that Service Broker can be used to manage the process that generates the orders processed by the existing code and to drop the restocking notices on a queue for later processing. Within the same conversation, Service Broker can also be used to send messages to Notification Services with order status updates, restock notices, and brokerage requests. This integration produces a more proactive process that alerts applications and people to processing that needs to be done instead of requiring them to poll for new work.

4. You would then continue replacing custom code with Service Broker functionality for each additional business process down the chain. You could also layer in Notification Services to handle all the customer and internal notifications so that all the custom code for this could be eliminated, freeing up developers even more. Service Broker would provide the messaging infrastructure, with SQL Server providing the security and availability aspects of the solution. And eventually, you would eliminate all the custom code with a request being managed from submission to customer delivery using Service Broker. This implementation would free up significant resources to focus on other projects.