MCIA-Level-1 - MuleSoft Certified Integration Architect - Level 1

Explanation

Correct answer is EACH item VM message is processed AT LEAST ONCE by ONE ARBITRARY CloudHub worker. Each of the four CloudHub workers can be expected to process some item VM messages In Cloudhub, each persistent VM queue is listened on by every CloudHub worker - But each message is read and processed at least once by only one CloudHub worker and the duplicate processing is possible - If the CloudHub worker fails , the message can be read by another worker to prevent loss of messages and this can lead to duplicate processing - By default , every CloudHub worker's VM Listener receives different messages from VM Queue Referenece: https://dzone.com/articles/deploying-mulesoft-application-on-1-worker-vs-mult

Explanation

Correct answer is using below set of activities Until Successful component ActiveMQ long retry Queue ActiveMQ Dead Letter Queue for manual processing We will see why this is correct answer but before that lets understand few of the concepts which we need to know. Until Successful Scope The Until Successful scope processes messages through its processors until the entire operation succeeds. Until Successful repeatedly retries to process a message that is attempting to complete an activity such as: - Dispatching to outbound endpoints, for example, when calling a remote web service that may have availability issues. - Executing a component method, for example, when executing on a Spring bean that may depend on unreliable resources. - A sub-flow execution, to keep re-executing several actions until they all succeed, - Any other message processor execution, to allow more complex scenarios. How this will help requirement : Using Until Successful Scope we can retry sending the order to backend systems in case of error to avoid manual processing later. Retry values can be configured in Until Successful Scope Apache ActiveMQ It is an open source message broker written in Java together with a full Java Message Service client ActiveMQ has the ability to deliver messages with delays thanks to its scheduler. This functionality is the base for the broker redelivery plug-in. The redelivery plug-in can intercept dead letter processing and reschedule the failing messages for redelivery. Rather than being delivered to a DLQ, a failing message is scheduled to go to the tail of the original queue and redelivered to a message consumer. How this will help requirement : If backend application is down for a longer duration where Until Successful Scope wont work, then we can make use of ActiveMQ long retry Queue. The redelivery plug-in can intercept dead letter processing and reschedule the failing messages for redelivery. Mule Reference: https://docs.mulesoft.com/mule-runtime/4.3/migration-core-until-successful

Explanation

Correct choice is: "The external API reported an error with the HTTP request that was received from the outbound HTTP Request operation of the Mule application"

Understanding HTTP 4XX Client Error Response Codes : A 4XX Error is an error that arises in cases where there is a problem with the user’s request, and not with the server.

Such cases usually arise when a user’s access to a webpage is restricted, the user misspells the URL, or when a webpage is nonexistent or removed from the public’s view.

In short, it is an error that occurs because of a mismatch between what a user is trying to access, and its availability to the user — either because the user does not have the right to access it, or because what the user is trying to access simply does not exist. Some of the examples of 4XX errors are

400 Bad Request The server could not understand the request due to invalid syntax. 401 Unauthorized Although the HTTP standard specifies "unauthorized", semantically this response means "unauthenticated". That is, the client must authenticate itself to get the requested response. 403 Forbidden The client does not have access rights to the content; that is, it is unauthorized, so the server is refusing to give the requested resource. Unlike 401, the client's identity is known to the server. 404 Not Found The server can not find the requested resource. In the browser, this means the URL is not recognized. In an API, this can also mean that the endpoint is valid but the resource itself does not exist. Servers may also send this response instead of 403 to hide the existence of a resource from an unauthorized client. This response code is probably the most famous one due to its frequent occurrence on the web. 405 Method Not Allowed The request method is known by the server but has been disabled and cannot be used. For example, an API may forbid DELETE-ing a resource. The two mandatory methods, GET and HEAD, must never be disabled and should not return this error code. 406 Not Acceptable This response is sent when the web server, after performing server-driven content negotiation, doesn't find any content that conforms to the criteria given by the user agent. The external API reported that the API implementation has moved to a different external endpoint cannot be the correct answer as in this situation 301 Moved Permanently The URL of the requested resource has been changed permanently. The new URL is given in the response. ----------------------------------------------------------------------------------------------------------------------------------------------- In Lay man's term the scenario would be: API CLIENT —> MuleSoft API - HTTP request “Hey, API.. process this” —> External API API CLIENT <– MuleSoft API - http response "I'm sorry Client.. something is wrong with that request" <– (4XX) External API