MCIA-Level-1 Questions and Answers

SOAP API specifications are provided as WSDL. Design center doesn't provide the functionality to create WSDL file. Hence WSDL needs to be created using XML editor

Explanation

* XA transaction add tremendous latency so "Reduce Latency" is incorrect option XA transactions define "All or No" commit protocol.

* Each local XA resource manager supports the A.C.I.D properties (Atomicity, Consistency, Isolation, and Durability).

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So correct choice is "Ensure consistency"

Explanation

* An X.509 certificate is a vital safeguard against malicious network impersonators. Without x.509 server authentication, man-in-the-middle attacks can be initiated by malicious access points, compromised routers, etc.

* X.509 is most used for SSL/TLS connections to ensure that the client (e.g., a web browser) is not fooled by a malicious impersonator pretending to be a known, trustworthy website.

* Coming to the question , we can not use SLB here as SLB does not allow to define vanity domain names. * Hence we need to use DLB and add certificate in there

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Hence correct answer is Add the X 509 certificate to the cloudhub Dedicated Load Balancer (DLB), not the Mule application. Create the CNAME for api.acme.com pointing to the DLB’s record

Explanation

* The Object Store V2 API enables API access to Anypoint Platform Object Store v2.

* You can configure a Mule app to use the Object Store REST API to store and retrieve values from an object store in another Mule app. However, Object Store v2 is not designed for app-to-app communication. To share data between two Mule4 apps, use a queue in Anypoint MQ.

* The Object Store v2 APIs enable you to use REST to perform the following:

- Retrieve a list of object stores and keys associated with an application.

- Store and retrieve key-value pairs in an object store.

- Delete key-value pairs from an object store.

- Retrieve Object Store usage statistics for your organization.

- Object Store provides these APIs:

Object Store API

Object Store Stats API

Explanation

Correct answer is Only MuleSoft provided certificates can be used for server side certificate

* The CloudHub Shared Load Balancer terminates TLS connections and uses its own server-side certificate.

* You would need to use dedicated load balancer which can enable you to define SSL configurations to provide custom certificates and optionally enforce two-way SSL client authentication.

* To use a dedicated load balancer in your environment, you must first create an Anypoint VPC. Because you can associate multiple environments with the same Anypoint VPC, you can use the same dedicated load balancer for your different environments.

Additional Info on SLB Vs DLB:

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Explanation

3xx HTTP status codes indicate a redirection that the user agent (a web browser or a crawler) needs to take further action when trying to access a particular resource.

Explanation

As the Anypoint Platform organization administrator, you can configure identity management in Anypoint Platform to set up users for single sign-on (SSO).

Configure identity management using one of the following single sign-on standards:

1) OpenID Connect: End user identity verification by an authorization server including SSO

2) SAML 2.0: Web-based authorization including cross-domain SSO

Explanation

Before we answer this question , we need to understand what median (50th percentile) and 80th percentile means. If the 50th percentile (median) of a response time is 500ms that means that 50% of my transactions are either as fast or faster than 500ms.

If the 90th percentile of the same transaction is at 1000ms it means that 90% are as fast or faster and only 10% are slower. Now as per upstream SLA , 99th percentile is 800 ms which means 99% of the incoming requests should have response time less than or equal to 800 ms. But as per one of the backend API , their 95th percentile is 1000 ms which means that backend API will take 1000 ms or less than that for 95% of. requests. As there are three API invocation from upstream API , we can not conclude a timeout that can be set to meet the desired SLA as backend SLA's do not support it.

Let see why other answers are not correct.

1) Do not set a timeout --> This can potentially violate SLA's of upstream API

2) Set a timeout of 100 ms; ---> This will not work as backend API has 100 ms as median meaning only 50% requests will be answered in this time and we will get timeout for 50% of the requests. Important thing to note here is, All APIs need to be executed sequentially, so if you get timeout in first API, there is no use of going to second and third API. As a service provider you wouldn't want to keep 50% of your consumers dissatisfied. So not the best option to go with.

*To quote an example: Let's assume you have built an API to update customer contact details.

- First API is fetching customer number based on login credentials

- Second API is fetching Info in 1 table and returning unique key

- Third API, using unique key provided in second API as primary key, updating remaining details

* Now consider, if API times out in first API and can't fetch customer number, in this case, it's useless to call API 2 and 3 and that is why question mentions specifically that all APIs need to be executed sequentially.

3) Set a timeout of 50 ms --> Again not possible due to the same reason as above Hence correct answer is No timeout is possible to meet the upstream API's desired SLA; a different SLA must be negotiated with the first downstream API or invoke an alternative API

Explanation

As the stakeholders are semitechnical users , preferred option is Create Anypoint Exchange entries with pages elaborating the integration design, including API notebooks (where applicable) to help the stakeholders understand and interact with the Mule applications and APIs at various levels of technical depth

Explanation

Key to this question lies in the fact that Process API are not meant to be accessed directly by clients. Lets analyze options one by one. Client ID enforcement : This is applied at process API level generally to ensure that identity of API clients is always known and available for API-based analytics Rate Limiting : This policy is applied on Process Level API to secure API's against degradation of service that can happen in case load received is more than it can handle Custom circuit breaker : This is also quite useful feature on process level API's as it saves the API client the wasted time and effort of invoking a failing API. JSON threat protection : This policy is not required at Process API and rather implemented as Experience API's. This policy is used to safeguard application from malicious attacks by injecting malicious code in JSON object. As ideally Process API's are never called from external world , this policy is never used on Process API's Hence correct answer is JSON threat protection MuleSoft Documentation Reference : https://docs.mulesoft.com/api-manager/2.x/policy-mule3-json-threat

Explanation

Correct answer is Untill Successful scope can be implemented while calling backend API's The Until Successful scope repeatedly triggers the scope's components (including flow references) until they all succeed or until a maximum number of retries is exceeded The scope provides option to control the max number of retries and the interval between retries The scope can execute any sequence of processors that may fail for whatever reason and may succeed upon retry

Explanation

Mule 4 is built to:

•Minimize the need for custom code.

•Avoid the need for you to know or understand Java.

However, some advanced uses cases require integration with custom Java code, such as:

•Reuse of a library, such as a tax calculation library.

•Reuse of a canonical object model that is standard in the organization.

•Execution of custom logic using Java.

Mule ref doc : https://docs.mulesoft.com/java-module/1.2/

Explanation

In this scenario, both A & C will work, but A is better as it does not require repackage to the domain project at all.

Correct answer is Package the HTTPS Listener configuration in a Mule DOMAIN project, referencing it from all Mule applications that need to expose an HTTPS endpoint. Store the server-side certificate in a shared filesystem location in the Mule runtime’s classpath, OUTSIDE the Mule DOMAIN or any Mule APPLICATION.

What is Mule Domain Project?

* A Mule Domain Project is implemented to configure the resources that are shared among different projects. These resources can be used by all the projects associated with this domain. Mule applications can be associated with only one domain, but a domain can be associated with multiple projects. Shared resources allow multiple development teams to work in parallel using the same set of reusable connectors. Defining these connectors as shared resources at the domain level allows the team to: - Expose multiple services within the domain through the same port. - Share the connection to persistent storage. - Share services between apps through a well-defined interface. - Ensure consistency between apps upon any changes because the configuration is only set in one place.

* Use domains Project to share the same host and port among multiple projects. You can declare the http connector within a domain project and associate the domain project with other projects. Doing this also allows to control thread settings, keystore configurations, time outs for all the requests made within multiple applications. You may think that one can also achieve this by duplicating the http connector configuration across all the applications. But, doing this may pose a nightmare if you have to make a change and redeploy all the applications.

* If you use connector configuration in the domain and let all the applications use the new domain instead of a default domain, you will maintain only one copy of the http connector configuration. Any changes will require only the domain to the redeployed instead of all the applications.

You can start using domains in only three steps:

1) Create a Mule Domain project

2) Create the global connector configurations which needs to be shared across the applications inside the Mule Domain project

3) Modify the value of domain in mule-deploy.properties file of the applications

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Use a certificate defined in already deployed Mule domain Configure the certificate in the domain so that the API proxy HTTPS Listener references it, and then deploy the secure API proxy to the target Runtime Fabric, or on-premises target. (CloudHub is not supported with this approach because it does not support Mule domains.)

Explanation

Correct answer is Database polling continues Only HTTP requests sent to the remaining node continue to be accepted. Explanation : Architecture descripted in the question could be described as follows.When node 1 is down , DB polling will still continue via node 2 . Also requests which are coming directly to node 2 will also be accepted and processed in BAU fashion. Only thing that wont work is when requests are sent to Node 1 HTTP connector. The flaw with this architecture is HTTP clients are sending HTTP requests directly to individual cluster nodes. By default, clustering Mule runtime engines ensures high system availability. If a Mule runtime engine node becomes unavailable due to failure or planned downtime, another node in the cluster can assume the workload and continue to process existing events and messages

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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.

* Here are some examples for fallback APIs:

- An old, deprecated version of the same API.

- An alternative endpoint of the same API and version (e.g. API in another CloudHub region).

- An API doing more than required, and therefore not as performant as the primary API.

- An API doing less than required and therefore forcing the API Client to offer a degraded service, which is still better than no service at all.

* API clients implemented as Mule applications offer the ‘Until Successful Scope and Exception’ strategies at their disposal, which together allow configuring fallback actions such as a fallback API invocation.

* All HTTP response status codes within the 3xx category are considered redirection messages. These codes indicate to the user agent (i.e. your web browser) that an additional action is required in order to complete the request and access the desired resource

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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

Explanation

* As per definition of API by Mulesoft , it is Application Programming Interface using HTTP-based protocols. Non-HTTP-based programmatic interfaces are not APIs.

* HTTP-based programmatic interfaces are APIs even if they don’t use REST or JSON. Hence implementation based on Java RMI, CORBA/IIOP, raw TCP/IP interfaces are not API's as they are not using HTTP.

* One more thing to note is FTP was not built to be secure. It is generally considered to be an insecure protocol because it relies on clear-text usernames and passwords for authentication and does not use encryption.

* Data sent via FTP is vulnerable to sniffing, spoofing, and brute force attacks, among other basic attack methods.

Considering the above points only correct option is

-XML over ActiveMQ

- XML over SFTP

- XML/REST over HTTPS

Explanation

* If you need to scale a JMS provider/ message broker, - add nodes to scale it horizontally or - add memory to scale it vertically * Cons of adding another JMS provider/ message broker: - adds cost. - adds complexity to use two JMS brokers - adds Operational overhead if we use two brokers, say, ActiveMQ and IBM MQ * So Two options that mention to use two brokers are not best choice. * It's mentioned that "The Fulfillment microservice consumes Order messages, fulfills the order described therein, and then publishes an OrderFulfilled message. Each OrderFulfilled message can be consumed by any interested Mule application." - When you publish a message on a topic, it goes to all the subscribers who are interested - so zero to many subscribers will receive a copy of the message. - When you send a message on a queue, it will be received by exactly one consumer. * As we need multiple consumers to consume the message below option is not valid choice: "Order messages are sent to an Anypoint MQ exchange. OrderFulfilled messages are sent to an Anypoint MQ queue. Both microservices interact with Anypoint MQ as the message broker, which must therefore scale to support the load of both microservices" * Order messages are only consumed by one Mule application, the Fulfillment microservice, so we will publish it on queue and OrderFulfilled message can be consumed by any interested Mule application so it need to be published on Topic using same broker. * Correct Answer: Best choice in this scenario is: "Order messages are sent to a JMS queue. OrderFulfilled messages are sent to a JMS topic. Both microservices interact with the same JMS provider (message broker) instance, which must therefore scale to support the load of both microservices" Tried to depict scenario in diagram:

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Explanation

Correct Answer: XSD In this approach to developing a web service, you begin with an XML schema (XSD file) that defines XML data structures to be used as parameters and return types in the web service operations.

----------------------------------------------------------------------------------------------------------------- Reference: https://www.w3schools.com/xml/schema_intro.asp

Explanation

Correct answer is VM VM support Transactional Type. When an exception occur, The transaction rolls back to its original state for reprocessing. This feature is not supported by other connectors.

Here is additional information about Transaction management:

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