mulesoft MCIA 易错题汇总解析

1. An API implementation is being designed that must invoke an Order API which is known to repeatedly experience downtime.

For this reason a fallback API is to be called when the Order API is unavailable.
What approach to designing invocation of the fallback API provides the best resilience?

A. Redirect client requests through an HTTP 303 temporary redirect status code to the fallback API whenever the Order API is unavailable

B. Set an option in the HTTP Requester component that invokes the order API to instead invoke a fallback API whenever an HTTP 4XX or 5XX response status code is received from Order API

C. Create a separate entry for the order API in API manager and then invoke this API as a fallback API if the primary Order API is unavailable

D. Search Anypoint Exchange for a suitable existing fallback API and them implement invocations to their fallback API in addition to the Order API

Answer： A

Explanation：

   Resilience testing is a type of software testing that observes how applications act under stress. It’s meant to ensure the product’s ability to perform in chaotic conditions without a loss of core functions or data; it ensures a quick recovery after unforeseen, uncontrollable events.

   In case an API invocation fails - even after a certain number of retries - it might be adequate to invoke a different API as a fallback. A fallback API, by definition, will never be ideal for the purpose of the API client, otherwise it would be the primary API.

   Hence correct answer is Redirect client requests through an HTTP 303 temporary redirect status code to the fallback API whenever the Order API is unavailable

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2. A mule application is deployed to a Single Cloudhub worker and the public URL appears in Runtime Manager as the APP URL.

Requests are sent by external web clients over the public internet to the mule application App url. Each of these requests routed to the HTTPS Listener event source of the running Mule application. Later, the DevOps team edits some properties of this running Mule application in Runtime Manager. Immediately after the new property values are applied in runtime manager, how is the current Mule application deployment affected and how will future web client requests to the Mule application be handled?

A. Cloudhub will redeploy the Mule application to the OLD Cloudhub worker New web client requests will RETURN AN ERROR until the Mule application is redeployed to the OLD Cloudhub worker

B. CloudHub will redeploy the Mule application to a NEW Cloudhub worker New web client requests will RETURN AN ERROR until the NEW Cloudhub worker is available

C. Cloudhub will redeploy the Mule application to a NEW Cloudhub worker New web client requests are ROUTED to the OLD Cloudhub worker until the NEW Cloudhub worker is available.

D. Cloudhub will redeploy the mule application to the OLD Cloudhub worker New web client requests are ROUTED to the OLD Cloudhub worker BOTH before and after the Mule application is redeployed.

Answer: C
Explanation:
   CloudHub supports updating your applications at runtime so end users of your HTTP APIs experience zero downtime. While your application update is deploying, CloudHub keeps the old version of your application running. Your domain points to the old version of your application until the newly uploaded version is fully started. This allows you to keep servicing requests from your old application while the new version of your application is starting.

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3. One of the backend systems invoked by an API implementation enforces rate limits on the number of requests a particular client can make.

Both the backend system and the API implementation are deployed to several non-production environments in addition to production. Rate limiting of the backend system applies to all non-production environments. The production environment, however, does NOT have any rate limiting.

What is the most effective approach to conduct performance tests of the API implementation in a staging (non-production) environment?

A. Create a mocking service that replicates the backend system’s production performance characteristics. Then configure the API implementation to use the mocking service and conduct the performance tests

B. Use MUnit to simulate standard responses from the backend system then conduct performance tests to identify other bottlenecks in the system

C. Include logic within the API implementation that bypasses invocations of the backend system in a performance test situation. Instead invoking local stubs that replicate typical backend system responses then conduct performance tests using this API Implementation

D. Conduct scaled-down performance tests in the staging environment against the rate limited backend system then upscale performance results to full production scale

Answer: A

Explanation:
  创建一个模拟服务，复制后端系统的生产性能特征。然后配置API实现以使用模拟服务并执行性能测试
   MUnit is for only Unit and integration testing for APIs and Mule apps. Not for performance Testing, even if it has the ability to Mock the backend.
   By passing