MCD-Level-2 Sample Questions Answers

To use API autodiscovery to access and enforce policies for a RESTful implementation, flowRef must be set to the name of the flow that has HTTP listener to receive all incoming RESTful operation requests. This way, API autodiscovery can identify the API implementation and associate it with the corresponding API specification and policies in API Manager. The flow that has HTTP listener is usually the main flow that contains the APIKit Router. References: https://docs.mulesoft.com/api-manager/2.x/api-auto-discovery-new-concept#flowref

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

To convert a JKS keystore to PKCS12, the developer needs to use the keytool-importkeystore command with the following options: -srckeystore keystore.jks -srcstoretype JKS -destkeystore keystore.p12 -deststoretype PKCS12. This command imports all entries from a source JKS keystore (keystore.jks) into a destination PKCS12 keystore (keystore.p12). References: https://docs.oracle.com/en/java/javase/11/tools/keytool.html#GUID-5990A2E4-78E3-47B7-AE75-6D1826259549

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

To give a partial successful response in case the United Airlines API returns with a timeout, the developer should add a Scatter-Gather component inside a Try scope, and set the payload to a default value ‘Error’ inside the error handler using the On Error Continue scope. A Scatter-Gather component allows sending multiple requests concurrently and aggregating the responses into an array. A Try scope allows handling errors that occur within it using an error handler. An On Error Continue scope allows continuing the flow execution after handling an error. Therefore, by using these components, the developer can send requests to both APIs in parallel, handle any timeout errors from United Airlines API, and return a partial response with a default value for that API. References: https://docs.mulesoft.com/mule-runtime/4.3/scatter-gather-concept https://docs.mulesoft.com/mule-runtime/4.3/try-scope-concept https://docs.mulesoft.com/mule-runtime/4.3/on-error-continue-concept

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

The validate-customer flow uses an until-successful scope to validate each field of the customer data. The until-successful scope executes its processors until they succeed or exhausts the maximum number of retries. If any processor fails, it raises an error and stops executing the remaining processors. Therefore, if only the email address is invalid, a VALIDATION.INVALID_EMAIL error is raised and the validation of appointment date and customer name is skipped. References: https://docs.mulesoft.com/mule-runtime/4.3/until-successful-scope

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

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 encrypt the data before sending it to the backend application using PGP encryption, the application needs the public key from the backend service. PGP encryption uses a public-key cryptography system, which means that each party has a pair of keys: a public key and a private key. The public key is used to encrypt data, and the private key is used to decrypt data. Therefore, to encrypt data for a specific recipient (the backend service), the application needs to use the recipient’s public key. The recipient can then use its own private key to decrypt the data. References: https://docs.mulesoft.com/mule-runtime/4.3/cryptography-pgp

To get response data from the external API after it completes processing, the developer should expose an HTTP callback API in Mule and register it with the external system. This way, the external API can invoke the callback API with the response data when it is ready, instead of making the Mule application wait for a long time or poll for a response repeatedly. References: https://docs.mulesoft.com/mule-runtime/4.3/http-listener-ref#callback

To configure the Maven Resources plugin to exclude parsing binary files in the project’s src/main/resources/certs directory, option C should be used. This option specifies that any files with .cer or .jks extensions under the certs directory should be excluded from filtering. Filtering is a process of replacing placeholders with actual values in resource files during the build process. Binary files should not be filtered because they may become corrupted or unusable. References: https://maven.apache.org/plugins/maven-resources-plugin/examples/filter.html https://maven.apache.org/plugins/maven-resources-plugin/examples/include-exclude.html

To implement a readiness endpoint to monitor all system APIs, the developer should create a dedicated endpoint that responds with the API status and reachability of the underlying systems. This way, the DevOps team can check if the system API is ready to receive requests and if it can communicate with its backend systems without errors. References: https://docs.mulesoft.com/mule-runtime/4.3/deployment-strategies#readiness-probes

Based on the code snippet and schema.json file below, when testing using the API Kit console if no values are entered in client-secret, HTTP status code 403 (FORBIDDEN) is returned. This is because client-secret is defined as a required header parameter in schema.json file, which means that it must be present in every request. If no values are entered in client-secret, then it is equivalent to omitting this header parameter, which violates the schema and causes APIKit Router to return HTTP status code 403. References: https://docs.mulesoft.com/apikit/4.x/apikit-4-headers

 Based on the code snippet, schema.json file, and payload below, the outcome of the given code snippet when a request is sent with the payload is that the Mule flow will throw the exception ‘JSON:SCHEMA_NOT_HONOURED’. This is because the payload does not conform to the schema.json file, which specifies that age must be a number greater than or equal to zero. The payload has age as a string with a negative value, which violates the schema. Therefore, the validate-schema operation throws an error with type ‘JSON:SCHEMA_NOT_HONOURED’. References: https://docs.mulesoft.comhttps://www.dumpspedia.com/json-module/1.1https://www.dumpspedia.com/json-validate-schema