MCD-Level-2 Sample Questions Answers

To enrich every log message with the order ID, the developer should use the Tracing module to set logging variables with a Mapped Diagnostic Context (MDC). The Tracing module allows adding custom key-value pairs to log messages using MDC variables. The developer can use Set Logging Variables operation to set the order ID as an MDC variable and then use it in any logger processor within the same thread or event. References:https://docs.mulesoft.com/tracing-module/1.0/tracing-module-reference#set-logging-variables

To create a new project that selects the correct API version and scaffolds the flows from the API specification, the developer should import a published API. This option allows importing an API specification that has been published to Anypoint Exchange or Design Center, and selecting a specific version of that API specification. The developer can also choose to scaffold flows based on that API specification. References:https://docs.mulesoft.com/apikit/4.x/apikit-4-new-project-task

To include a common application as a reusable module in all API implementations, the developer should add a Maven dependency in the POM file with jar as . This way, the developer can reuse Mule code from another application by packaging it as a JAR file and adding it as a dependency in the POM file of the API implementation. The classifier element specifies that it is a JAR file. References:https://docs.mulesoft.com/mule-runtime/4.3/mmp-concept#add-a-maven-dependency-to-the-pom-file

To run a test locally without the policies applied, the developer should create a properties file specifically for local development and set the API instance ID to a value that is not used in API Manager. This way, the developer can use different configuration properties for different environments and avoid triggering API autodiscovery when running tests locally. API autodiscovery is a mechanism that associates an API implementation with its corresponding API specification and policies in API Manager based on its API instance ID. By setting this ID to a value that does not exist in API Manager, the developer can prevent API autodiscovery from finding and applying any policies to the local test. References: https://docs.mulesoft.com/api-manager/2.x/api-auto-discovery-new-concept#configuring-api-autodiscovery https://docs.mulesoft.com/mule-runtime/4.3/configuring-properties

To handle a permanent error response like HTTP:UNAUTHORIZED inside Until Successful, the developer should put the HTTP Request inside a try scope in Unit Successful, and use On Error Continue to catch permanent errors like HTTP UNAUTHORIZED in the error handler. This way, the developer can avoid retrying requests that will always fail due to a permanent error, and reduce latency. On Error Continue allows the flow to continue processing after handling the error. References: https://docs.mulesoft.com/mule-runtime/4.3/until-successful-scope https://docs.mulesoft.com/mule-runtime/4.3/on-error-continue-concept

To enable mTLS authentication for HTTP Listener, the developer needs to set an appropriate keystore and truststore configuration for the listener. The keystore contains the certificate and private key of the Mule application that are used to prove its identity to clients. The truststore contains the certificates of trusted clients that are allowed to access the Mule application. References:https://docs.mulesoft.com/mule-runtime/4.3/tls-configuration#mutual-authentication

In case of a system failure, in-flight messages in persistent VM queues that have been consumed will be processed after the system comes online. This is because persistent VM queues store messages on disk and guarantee delivery even if there is a system crash or restart. Therefore, any in-flight messages that have been consumed but not processed will be recovered from disk and processed when the system is back online. References:https://docs.mulesoft.com/mule-runtime/4.3/vm-connector#persistent-queues

The HTTP Request operation will use the default truststore of the JRE to validate the certificate of the target API. If the CA’s certificate is present in the truststore, the operation will succeed. Otherwise, it will fail with a handshake exception. References:https://docs.mulesoft.com/mule-runtime/4.3/tls-configuration#tls-default

Based on the code snippet and MUnit test case below, when the MUnit test case is executed, the expected result is that the test case fails with an assertion error. This is because the assert-equals processor compares two values for equality, and fails if they are not equal. In this case, the expected value is ‘Hello World’, but the actual value returned by the implementation flow is ‘Hello Mule’. Therefore, the assertion fails and an error is thrown. References:https://docs.mulesoft.com/munit/2.3/assert-equals-processor

To use the OAuth 2.0 Authorization Code grant type for authentication, the HTTP Connector configuration requires the following properties: token URL, authorization URL, client ID, client secret, and local callback URL. The token URL is the endpoint of the authorization server that provides access tokens. The authorization URL is the endpoint of the authorization server that initiates the user consent flow. The client ID and client secret are the credentials of the Mule application registered with the authorization server. The local callback URL is the endpoint of the Mule application that receives the authorization code from the authorization server. References:https://docs.mulesoft.com/http-connector/1.6/http-authentication#oauth-2-0

To temporarily persist large files over 10MB between flow executions, and routinely query whether the file data exists on separate executions, the developer should store the contents ofthe file on separate storage, and store the key and location of the file object using Object Store v2. This way, the developer can avoid storing large files in memory or exceeding the size limit of Object Store v2 (10MB per object). The developer can also use Object Store v2 operations to query, retrieve, or delete the file object by its key. References:https://docs.mulesoft.com/object-store/osv2-faq#can-i-store-files-in-object-store-v2

When an HTTP request is received and the HTTP Caching policy is applied first, it checks if there is a cached response for that request in Object Store. If there is a cache hit, meaning that a valid cached response exists, then only the HTTP Caching policy is evaluated and the cached response is returned to the caller without invoking the OAuth policy or the API implementation. If there is a cache miss, meaning that no valid cached response exists, then both the HTTP Caching policy and the OAuth policy are evaluated before invoking the API implementation. References:https://docs.mulesoft.com/api-manager/2.x/http-caching-policy#policy-ordering

To invoke Bioinfo System API using its REST Connector, option E should be added to the pom.xml file. This option adds a dependency for Bioinfo System API REST Connector with its group ID, artifact ID, version, classifier, and type. The classifier specifies that it is a REST Connector (raml-client), and the type specifies that it is a Mule plugin (mule-plugin). References:https://docs.mulesoft.com/apikit/4.x/apikit-4-generate-from-rest-api-task#add-the-api-dependency-to-the-pom-file

To propagate the order ID as the correlation ID across each message using Anypoint MQ, the developer should wrap all Anypoint MQ Publish operations within a With CorrelationID scope from the Tracing module, setting the correlation ID to the order ID. The With CorrelationID scope allows setting a custom correlation ID for any event that occurs within it. The Tracing module also enables distributed tracing across different Mule applications and services using Anypoint Monitoring. References: https://docs.mulesoft.com/tracing-module/1.0/tracing-module-reference#with-correlation-id-scope https://docs.mulesoft.com/tracing-module/1.0/tracing-module-concepts

Based on the configuration below, when a HTTP request arrives at the Mule application’s endpoint, the execution order will be A1, B1, F1, B2, A2. This is because policies are executed before and after the API implementation flow according to their order attribute. Policy A has order 1, which means it is executed first before Policy B, which has order 2. The flow is executedafter both policies are executed before the flow. Then, Policy B is executed after the flow before Policy A is executed after the flow. References:https://docs.mulesoft.com/api-manager/2.x/policies-policy-order