What is required so that application A can ensure that the length and order of the list of objects in RESP and REQU match, while at the same time maximizing message throughput?

Mule application A receives a request Anypoint MQ message REQU with a payload containing a variable-length list of request objects. Application A uses the For Each scope to split the list into individual objects and sends each object as a message to an Anypoint MQ queue.

Service S listens on that queue, processes each message independently of all other messages, and sends a response message to a response queue.

Application A listens on that response queue and must in turn create and publish a response Anypoint MQ message RESP with a payload containing the list of responses sent by service S in the same order as the request objects originally sent in REQU.

Assume successful response messages are returned by service S for all request messages.

What is required so that application A can ensure that the length and order of the list of objects in RESP and REQU match, while at the same time maximizing message throughput?
A . Use a Scatter-Gather within the For Each scope to ensure response message order Configure the Scatter-Gather with a persistent object store
B . Perform all communication involving service S synchronously from within the For Each scope, so objects in RESP are in the exact same order as request objects in REQU
C . Use an Async scope within the For Each scope and collect response messages in a second For Each scope in the order In which they arrive, then send RESP using this list of responses
D . Keep track of the list length and all object indices in REQU, both in the For Each scope and in all communication involving service Use persistent storage when creating RESP

Answer: D

Explanation:

Correct answer is Perform all communication involving service S synchronously from within the For Each scope, so objects in RESP are in the exact same order as request objects in REQU: Using Anypoint MQ, you can create two types of queues: Standard queue These queues don’t guarantee a specific message order. Standard queues are the best fit for applications in which messages must be delivered quickly. FIFO (first in, first out) queue These queues ensure that your messages arrive in order. FIFO queues are the best fit for applications requiring strict message ordering and exactly-once delivery, but in which message delivery speed is of less importance Use of FIFO queue is no where in the option and also it decreased throughput. Similarly persistent object store is not the preferred solution approach when you maximizing message throughput. This rules out one of the options. Scatter Gather does not support ObjectStore. This rules out one of the options. Standard Anypoint MQ queues don’t guarantee a specific message order hence using another for each block to collect response wont work as requirement here is to ensure the order. Hence considering all the above factors the feasible approach is Perform all communication involving service S synchronously from within the For Each scope, so objects in RESP are in the exact same order as request objects in REQU