Mulesoft MCPA-Level-1 Exam Questions

A.   

Implement (or generate) an API proxy Mule application for each of the APIs, then deploy the API proxies to the Mule runtimes

D.   

Spike control

Explanation: Explanation
Correct Answer: Spike control
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>> First things first, HTTP Caching policy is for purposes different than avoiding the
backend system from overloading. So this is OUT.
>> Rate Limiting and Throttling/ Spike Control policies are designed to limit API access, but
have different intentions.
>> Rate limiting protects an API by applying a hard limit on its access.
>> Throttling/ Spike Control shapes API access by smoothing spikes in traffic.
That is why, Spike Control is the right option

A.   

Invoke the system API deployed to the primary environment; add timeout and retry logic to
the process API to avoid intermittent failures; if it still fails, invoke the system API deployed
to the DR environment

Explanation: Explanation
Correct Answer: Invoke the system API deployed to the primary environment; add timeout
and retry logic to the process API to avoid intermittent failures; if it still fails, invoke the
system API deployed to the DR environment
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There is one important consideration to be noted in the question which is - System API in
DR environment provides only 20% of the rate limiting offered by the primary environment.
So, comparitively, very less calls will be allowed into the DR environment API opposed to
its primary environment. With this in mind, lets analyse what is the right and best faulttolerant
invocation strategy.
1. Invoking both the system APIs in parallel is definitely NOT a feasible approach because
of the 20% limitation we have on DR environment. Calling in parallel every time would
easily and quickly exhaust the rate limits on DR environment and may not give chance to
genuine intermittent error scenarios to let in during the time of need.
2. Another option given is suggesting to add timeout and retry logic to process API while
invoking primary environment's system API. This is good so far. However, when all retries
failed, the option is suggesting to invoke the copy of process API on DR environment which
is not right or recommended. Only system API is the one to be considered for fallback and
not the whole process API. Process APIs usually have lot of heavy orchestration calling
many other APIs which we do not want to repeat again by calling DR's process API. So this
option is NOT right.
3. One more option given is suggesting to add the retry (no timeout) logic to process API to
directly retry on DR environment's system API instead of retrying the primary environment
system API first. This is not at all a proper fallback. A proper fallback should occur only
after all retries are performed and exhausted on Primary environment first. But here, the
option is suggesting to directly retry fallback API on first failure itself without trying main
API. So, this option is NOT right too.
This leaves us one option which is right and best fit.
- Invoke the system API deployed to the primary environment
- Add Timeout and Retry logic on it in process API
- If it fails even after all retries, then invoke the system API deployed to the DR
environment.

C.   

When a pragmatic approach with only limited isolation from the backend system is deemed appropriate

Explanation: Explanation
Correct Answer: When a pragmatic approach with only limited isolation from the backend
system is deemed appropriate.
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General guidance w.r.t choosing Data Models:
>> If an Enterprise Data Model is in use then the API data model of System APIs should
make use of data types from that Enterprise Data Model and the corresponding API
implementation should translate between these data types from the Enterprise Data Model
and the native data model of the backend system.
>> If no Enterprise Data Model is in use then each System API should be assigned to a
Bounded Context, the API data model of System APIs should make use of data types from
the corresponding Bounded Context Data Model and the corresponding API
implementation should translate between these data types from the Bounded Context Data
Model and the native data model of the backend system. In this scenario, the data types in
the Bounded Context Data Model are defined purely in terms of their business
characteristics and are typically not related to the native data model of the backend system.
In other words, the translation effort may be significant.
>> If no Enterprise Data Model is in use, and the definition of a clean Bounded Context
Data Model is considered too much effort, then the API data model of System APIs should
make use of data types that approximately mirror those from the backend system, same
semantics and naming as backend system, lightly sanitized, expose all fields needed for
the given System API’s functionality, but not significantly more and making good use of
REST conventions.
The latter approach, i.e., exposing in System APIs an API data model that basically mirrors
that of the backend system, does not provide satisfactory isolation from backend systems
through the System API tier on its own. In particular, it will typically not be possible to
"swap out" a backend system without significantly changing all System APIs in front of that
backend system and therefore the API implementations of all Process APIs that depend on
those System APIs! This is so because it is not desirable to prolong the life of a previous
backend system’s data model in the form of the API data model of System APIs that now
front a new backend system. The API data models of System APIs following this approach
must therefore change when the backend system is replaced.
On the other hand:
>> It is a very pragmatic approach that adds comparatively little overhead over accessing
the backend system directly
>> Isolates API clients from intricacies of the backend system outside the data model
(protocol, authentication, connection pooling, network address, …)
>> Allows the usual API policies to be applied to System APIs
>> Makes the API data model for interacting with the backend system explicit and visible,
by exposing it in the RAML definitions of the System APIs
>> Further isolation from the backend system data model does occur in the API

C.   MuleSoft-hosted runtime plane (CloudHub)

Explanation:
For a European company with requirements such as zero-downtime redeployment, deployment to multiple runtime versions, secure and fast performance, and the use of Anypoint MQ without additional network configuration, CloudHub is the best choice for the following reasons:

• Zero-Downtime Redeployment: CloudHub supports zero-downtime deployment, which allows seamless redeployment of applications without impacting availability. Support for Multiple Runtime Versions: CloudHub allows deploying applications across different Mule runtime versions, giving flexibility to test and migrate applications as needed.
• Integrated Anypoint MQ: Anypoint MQ, which is fully integrated with CloudHub, provides reliable messaging across applications. Choosing CloudHub removes the need for additional network configurations, as Anypoint MQ can be directly accessed in this hosted environment.
• Security and Performance: CloudHub offers secure networking, automatic scaling, and optimized performance without requiring a complex setup. This is managed by MuleSoft’s infrastructure, meeting the speed and security requirements with minimal overhead.

Explanation of Incorrect Options:
References:
For more information on CloudHub’s capabilities regarding zero-downtime deployments and integration with Anypoint MQ, refer to MuleSoft documentation on CloudHub.

D.   

Use a horizontal CloudHub autoscaling policy that triggers on CPU utilization greater
than 70%

Explanation: Explanation
Correct Answer: Use a horizontal CloudHub autoscaling policy that triggers on CPU
utilization greater than 70%
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The scenario in the question is very clearly stating that the usual traffic in the year is pretty
well handled by the existing worker configuration with CPU running well below 70%. The
problem occurs only "sometimes" occasionally when there is spike in the number of orders
coming in.
So, based on above, We neither need to permanently increase the size of each worker nor
need to permanently increase the number of workers. This is unnecessary as other than
those "occasional" times the resources are idle and wasted.
We have two options left now. Either to use horizontal Cloudhub autoscaling policy to
automatically increase the number of workers or to use vertical Cloudhub autoscaling
policy to automatically increase the vCore size of each worker.
Here, we need to take two things into consideration:
1. CPU
2. Order Submission Rate to JMS Queue
>> From CPU perspective, both the options (horizontal and vertical scaling) solves the
issue. Both helps to bring down the usage below 90%.
>> However, If we go with Vertical Scaling, then from Order Submission Rate perspective,
as the application is still being load balanced with two workers only, there may not be much
improvement in the incoming request processing rate and order submission rate to JMS
queue. The throughput would be same as before. Only CPU utilization comes down.
>> But, if we go with Horizontal Scaling, it will spawn new workers and adds extra hand to
increase the throughput as more workers are being load balanced now. This way we can
address both CPU and Order Submission rate.
Hence, Horizontal CloudHub Autoscaling policy is the right and best answer.

C.   

System Layer

Explanation: Explanation
Correct Answer: System Layer

D.   

The remaining capacity allowed by the API implementation

Explanation: Explanation
Correct Answer: The remaining capacity allowed by the API implementation.
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>> Reference: https://docs.mulesoft.com/api-manager/2.x/rate-limiting-and-throttling-slabased-
policies#response-headers