MCD-Level-1 MuleSoft Certified Developer - Level 1 (Mule 4) Questions and Answers

Correct answer is Mule runtime

DataWeave is the MuleSoft expression language for accessing and transforming data that travels through a Mule app. DataWeave is tightly integrated with the Mule runtime engine, which runs the scripts and expressions in your Mule app.

Mule Doc Reference : https://docs.mulesoft.com/mule-runtime/4.3/dataweave

Correct answer is Publish the API to Anypoint Exchange

Anypoint Exchange makes this possible by making it discoverable in below ways

1) In private exchange for internal developers

2) In a public portal for external developers/clients

Here is diagram created by me to help you understand sequence:

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Scatter-Gather sends the event to each routes concurrently. Hence both route in this example will start in parallel. So total time to complete processing is 40 seconds

The Scatter-Gather component is a routing event processor that processes a Mule event through different parallel processing routes that contain different event processors. Each route receives a reference to the Mule event and executes a sequence of one or more event processors. Each of these routes uses a separate thread to execute the event processors, and the resulting Mule event can be either the same Mule event without modifications or a new Mule event with its own payload, attributes, and variables. The Scatter-Gather component then combines the Mule events returned by each processing route into a new Mule event that is passed to the next event processor only after every route completes successfully.

The Scatter-Gather component executes each route in parallel, not sequentially. Parallel execution of routes can greatly increase the efficiency of your Mule application and may provide more information than sequential processing.

Mule Ref Doc : https://docs.mulesoft.com/mule-runtime/4.3/scatter-gather-concept

Correct answer is process layer as all the orchestration and transformation logic should be in process layer as per Mulesoft's recommended approach for API led connectivity.

API-led connectivity is a methodical way to connect data to applications through reusable and purposeful APIs. These APIs are developed to play a specific role – unlocking data from systems, composing data into processes, or delivering an experience.

What are the APIs that enable API-led connectivity?

API-led connectivity provides an approach for connecting and exposing assets. With this approach, rather than connecting things point-to-point, every asset becomes a managed API – a modern API, which makes it discoverable through self-service without losing control.

The APIs used in an API-led approach to connectivity fall into three categories:

System APIs – these usually access the core systems of record and provide a means of insulating the user from the complexity or any changes to the underlying systems. Once built, many users, can access data without any need to learn the underlying systems and can reuse these APIs in multiple projects.

Process APIs – These APIs interact with and shape data within a single system or across systems (breaking down data silos) and are created here without a dependence on the source systems from which that data originates, as well as the target channels through which that data is delivered.

Experience APIs – Experience APIs are the means by which data can be reconfigured so that it is most easily consumed by its intended audience, all from a common data source, rather than setting up separate point-to-point integrations for each channel. An Experience API is usually created with API-first design principles where the API is designed for the specific user experience in mind.

Correct answer is as below. On complete phase only has access to batch job result statistics and payload is not available.

• Total Records Processed: 3
• Successful Records: 3
• Failed Records: 0

On Complete

During this phase, you can optionally configure the runtime to create a report or summary of the records it processed for the particular batch job instance. This phase exists to give system administrators and developers some insight into which records failed to address any issues that might exist with the input data.

Sample output is as below

Mule Ref Doc : https://docs.mulesoft.com/mule-runtime/4.3/batch-processing-concept#on-complete

Option1 is correct syntax to configure HTTP Listener endpoint

Correct answer is APP: API RESOURCE NOT FOUND

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1) A web client submits the request to the HTTP Listener.

2) The HTTP Request throws an "HTTP:NOT_FOUND" error, execution halts.

3) The On Error Propagate error Handler handles the error. In this case ,HTTP:NOT_FOUND error is mapped to custom error APP:API_RESOURCE_NOT_FOUND. This error processor sets payload to APP:API_RESOURCE_NOT_FOUND.

4) “APP:API_RESOURCE_NOT_FOUND. ” is the error message returned to the requestor in the body of the HTTP request with HTTP Status Code: 500

Reference Diagram:

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You can define your own DataWeave functions using the fun declaration in the header of a DataWeave script. Sample is as below. ----------------------------------------

%dw 2.0

output application/json

fun toUpper(aString) = upper(aString)

---

toUpper("hello")

MuleSoft Doc Ref : https://docs.mulesoft.com/mule-runtime/4.1/dataweave-functions

Correct answer is */status as it is the correct way to use wildcards while configuring path value in HTTP listener

* Batch scope has filter criteria which says paylod mod 2 = 0 whch means only 2, 4 and 6 will be in batch scope.

* So payload for each of these will be incremented by 10.

* Aggregator has batch size defined as 2. So it will process in batch of two records.

* Hence option 3 is correct answer.

[20,40]

[60]

Behavior with aggregator configured with fixed size

In this scenario, the batch step sends the processed records to an aggregator, which starts processing the records and buffering them until the configured aggregator’s size is reached. After that, the aggregator sends the aggregated records to the stepping queue.

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The batch job builds record blocks of the configured block size and sends them to their corresponding batch step for processing. Each batch step receives one or more record blocks and starts processing them in parallel. After the batch step processes a record, the batch step sends the record to the aggregator for further processing. The aggregator continues processing records until the number of aggregated records reaches the configured aggregator’s size.

https://docs.mulesoft.com/mule-runtime/4.3/batch-processing-concept

* Watermark allows the poll scope to poll for new resources instead of getting the same resource over and over again.

* The database table must be ordered so that the “watermark functionality” can move effectively in the ordered list. Watermark stores the current/last picked up “record id.”

* If the Mule application is shut down, it will store the last picked up “record id” in the Java Object Store and the data will continue to exist in the file. This watermark functionality is valuable and enables developers to have increased transparency.

* Developers do not need to create code to handle caching; it is all configurable!

* There are two columns and both are unique but user_id can't guaranty sequence whereas date_time will always be in increasing order and table content can easily be ordered on the basis of last processed date_time.

So correct answer is: Set the watermark column to the date_time column

Correct answer is The API interfaces are specified at a granularity intended for developers to consume specific aspect of integration processes

Sequence can be described as follows.

* When web client sends the request , it sends payload as Blue (mentioned in question)

* In first iteration this will go to default choice , which sets payload to Red

* Via default route , flow will call itself with payload as Red

* In second iteration , as payload is Red , it will go to first route in choice router which will set payload to Blk and second iteration will end returning back payload as Blk to first iteration.

* This Blk will be again set to payload and first iteration will end returning back response as Blk

An object store is a facility for storing objects in or across Mule applications. Mule runtime engine (Mule) uses object stores to persist data for eventual retrieval. Internally, Mule uses object stores in various filters, routers, and other message processors that need to store states between messages.

Object stores are available in all deployment targets. If you deploy your application to CloudHub, you can also use Object Store V2.

Correct answer is Key/value pair in Object store

MuleSoft Documentation reference : https://docs.mulesoft.com/mule-runtime/4.3/mule-object-stores#use-cases

Correct answer is Specify throttling , security and other policies

MuleSoft Doc Ref : https://docs.mulesoft.com/api-manager/2.x/api-gateway-capabilities-mule4

API Gateway is responsible for below functions.

1) Determine which traffic is authorized

2) Meter the traffic

3) Logs transaction

4) Apply throttling and other policies (Not specifying. These are specified in API Manager)

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Entire event would be sent to each route in parallel.

Scatter-Gather works as follows :

- The Scatter-Gather component receives a Mule event and sends a reference of this Mule event to each processing route.

- Each of the processing routes starts executing in parallel. After all processors inside a route finish processing, the route returns a Mule event, which can be either the same Mule event without modifications or a new Mule event created by the processors in the route as a result of the modifications applied.

- After all processing routes have finished execution, the Scatter-Gather component creates a new Mule event that combines all resulting Mule events from each route, and then passes the new Mule event to the next component in the flow.

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WSDL is used to define the contract in case of SOAP . RAML/OAS is used to REST services

Choice router finds the FIRST true condition, then distribute the event to the ONE matched route.

MuleSoft Doc Ref : https://docs.mulesoft.com/mule-runtime/4.1/choice-router-concept

The Choice router dynamically routes messages through a flow according to a set of DataWeave expressions that evaluate message content. Each expression is associated with a different routing option. The effect is to add conditional processing to a flow, similar to an if/then/else code block in most programming languages.

Only one of the routes in the Choice router executes, meaning that the first expression that evaluates to true triggers that route’s execution and the others are not checked. If none of the expressions are true, then the default route executes.

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This question validates you knowledge on Batch Processing. Before we analyze the question , lets revise a bit about batch filters.

Batch Filters

You can apply one or more filters as attributes to any number of batch steps.Imagine a batch job whose first batch step checks if a Salesforce contact exists for a record, and a second batch step that updates each existing Salesforce contact with new information. You can apply a filter to the second batch step to ensure it only processes records that didn’t fail during the first batch step.By having batch steps accept only some records for processing, you streamline the batch job so the Mule runtime engine can focus only on the relevant data for a particular batch step.

A batch step uses two attributes to filter records:

acceptExpression

acceptPolicy

Each batch step can accept one acceptExpression and one acceptPolicy attributes to filter records.

Use the acceptExpression attribute to process only records that evaluate to true; if the record evaluates to false, the batch step skips the record and sends it to the next one. In other words, the records with an accept expression that resolves to false are the ones that Mule filters out.

The example below filters out all records where the age is less than 21; the batch step does not process those records.

• ...

Mule Ref Doc : Refining Batch Steps Processing | MuleSoft Documentation

As we are clear with above concepts , now lets understand this solution step by step.

1) Batch Step (Less than 50)

Accept expression for this batch step is less than 50. Hence elements which will go in this batch step are amount value 40 and 2. Hence output of logger in first batch step is

{amount=140}

{amount=102}

2) Batch Step (Greater than 20)

Accept condition for this batch step is greater than 20. Note that input amount values for this batch step are 100 , 140 and 102 (last two values have been updated in batch step less than 50)

As all values satisfy this condition out put of second logger is

{step2amount=100}

{step2amount=140}

{step2amount=102}

Hence correct answer to this question is

• {amount=140}
• {amount=102}
• {step2amount=100}
• {step2amount=140}
• {step2amount=102}

2) Batch Step (Greater than 20)

Accept condition for this batch step is greater than 20. Note that input amount values for this batch step are 100 , 140 and 102 (last two values have been updated in batch step less than 50)

As all values satisfy this condition out put of second logger is

{step2amount=100}

{step2amount=140}

{step2amount=102}

Hence correct answer to this question is

{amount=140}

{amount=102}

{step2amount=100}

{step2amount=140}

{step2amount=102}

This kind of questions are best solved with filtering technique. Key thing to note here is XML attributes are always access by @ notation. So in this example orderId can be accessed as @OrderId which makes option 3 and option 4 false. Now difference in optin and option 2 is in mapping of lineItemPrice. Correct syntax to format a String in Numbse is value.price as Number. Hence option 2 is correct

Organization Administrators can approve/revoke/delete SLA tier access requests via API Manager only

The First Successful router iterates through a list of configured processing routes until one of the routes executes successfully. This is sequential execution. In all other options mentioned in the question ,we can achieve parallel execution.

The HTTP 415 Unsupported Media Type client error response code indicates that the server refuses to accept the request because the payload format is in an unsupported format. The format problem might be due to the request's indicated Content-Type or Content-Encoding , or as a result of inspecting the data directly. In this case as per RAML specification data is expected in application/json and in request Content-Type is set as "text/plain" which is incorrect. Hence solution is set the request Content-Type header to application/json

https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/415

1. Set Payload “Start”

2. 'Is Balnk String' Creates an Error object with #[error.description] =“String is not blank”

3. Default Error Handler catches and Propagates error

4. 'On Error Propogate' is 'RED IN RED OUT'. It Returns Status Code : 500 & #[error.description]

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Correct answer is String is not blank. Because validation component will throw an error as payload is not blank.

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In case of an error , batch job completes in flight steps and stops further processing.

MuleSoft Doc Ref : Handling Errors During Batch Job | MuleSoft Documentation

The default is all processing will stop but we can change it by Max Failed Record field.

General -> Max Failed Records: Mule has three options for handling a record-level error: Finish processing, Continue processing and Continue processing until the batch job accumulates a maximum number of failed records. This behavior can be controlled by Max Failed Records.

The default value is Zero which corresponds to Finish processing.

The value -1, corresponds to Continue processing.

The value +ve integer, corresponds to Continue processing until the batch job accumulates a maximum number of failed records

Process section is must to get compiles. Process section must have one or more processors

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Option 1 is the correct syntax

Below are the Key performance indicators (KPIs), to measure and track the and success of the C4E and its activities, as well as the growth and health of the application network. Most of the metrics can be extracted automatically, through REST APIs, from Anypoint Platform.

• # of assets published to Anypoint Exchange

• # of interactions with Anypoint Exchange assets

• # of APIs managed by Anypoint Platform

• # of System APIs managed by Anypoint Platform

• # of API clients registered for access to APIs

• # of API implementations deployed to Anypoint Platform

• # of API invocations

• # or fraction of lines of code covered by automated tests in CI/CD pipeline

• Ratio of info/warning/critical alerts to number of API invocations

Attributes are replaced with new attributes from the HTTP Request response.

Attributes include everything apart from Payload/body. For ex: Headers, query parameters, URI parameters.

So, when outbound HTTP request is made, new attributes need to pass the outbound HTTP request and old attributes are replaced.

I have created below diagram to make it easy for you to understand:

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The current version of the RAML specification is 1.0

You can check RAML version in RAML definition by referring to first comment. See highlighted part in below image.

Graphical user interface, text, application, email Description automatically generated

URL parameters are always accessed using { } like => {customerID}

option 3 is the correct syntz to access application properties

Web Services Description Language. WSDL is used to describe SOAP based web services

Its primary function is to design and develop fully functional Mule applications in a hosted development environment.

Correct answer is ${training.host}

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How to Configure Properties to Mule 4.X Platform?

1) Go to /src/main/resources project directory.

2) Create a configuration file with the name configuration.yaml inside the newly created config folder.

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3) Go To Project > Global Element > Create > General >select the configuration.yaml file create in step- 2)

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4) To verify develop a simple flow with HTTP listener which has above entries. Put the logger that prints the values on console.

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5) Additional info: Similarly, when you want to access this port in DataWeave you need to use p function

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Correct answer is String is not blank.

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Here’s specifically what is happening here:

1) Payload is successfully set to “Start”

2) The Is Blank String validator creates an Error Object because the payload is string "Start". Execution stops

#[error.description] = “String is not blank”

3) Because no error handler is defined, the Mule default error handler handles the error. Remember, at its heart, the Mule Default Error handler is an error handling scope with just an on error propagate

4) “String is not blank” is the error message returned to the requestor in the body of the HTTP requestHTTP Status Code: 500

Reference Diagram:

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Correct answer is Creates a mock service for an API

API Notebook is an open source, shareable web application for API documentation, interactive API tutorial and example generatation, and a client for your API endpoints. Using API Notebook, you can make requests and quickly transform the responses into readable format. However it cannot be used to mock service for an API.

MuleSoft Doc Ref : https://docs.mulesoft.com/api-manager/1.x/api-notebook-concept

POM.xml contains info about the project and configurationn details used by Maven to build the project

API portal are created by API Exchange and cannot be created by Design Center

Application properties can be defined in .yaml or in .properties file.

MuleSoft Doc Ref : https://docs.mulesoft.com/mule-runtime/4.3/configuring-properties#supported_files

For Each Scope

The For Each scope splits a payload into elements and processes them one by one through the components that you place in the scope. It is similar to a for-each/for loop code block in most programming languages and can process any collection, including lists and arrays. The collection can be any supported content type, such as application/json, application/java, or application/xml.

General considerations about the For Each scope:

By default, For Each tries to split the payload. If the payload is a simple Java collection, the For Each scope can split it without any configuration. The payload inside the For Each scope is each of the split elements. Attributes within the original message are ignored because they are related to the entire message.

For Each does not modify the current payload. The output payload is the same as the input.

Mule Doc Reference : https://docs.mulesoft.com/mule-runtime/4.3/for-each-scope-concept

Publish consume: Synchronous. Publish: Asynchronous.

Empty array is returned when no rows are matched.

MuleSoft Doc Ref : https://docs.mulesoft.com/db-connector/1.9/database-connector-select

Cloudhub expose services on port 8081 and override value in http.port with this one .

Sample log in Runtime Manager is below

21:15:53.148 08/08/2021 Worker-0 ArtifactDeployer.start.01 INFO

Listening for connections on 'http://0.0.0.0:8081 '

You can choose Attach Project Sources to include metadata that Studio requires to reimport the deployable file as an open Mule project into your workspace. You must keep the Attach Project Sources option selected to be able to import the packaged JAR file back into a Studio workspace. But requirement here is to create smallest deployable archive that will successfully deploy to Cloudhub. Hence we can ignore this option.

We need to select Include project module and dependencies

As actual modules and external dependencies required to run the Mule application in a Mule runtime engine

Hence correct answer is

Select only below option 2) Include project module and dependencies

MuleSoft Doc Ref : https://docs.mulesoft.com/studio/7.5/import-export-packages#exporting-a-studio-project-to-a-deployable-mule-application

Correct answer is 200.1234 as String {format: ".0#"} . Rest all options are not syntactically correct.