MCD-Level-1 Questions and Answers

Correct answer is as below. Attributes in the incoming xml payload are always accessed using @.Similarly *item is required as we have multiple items in the request

%dw 2.0

output application/csv

---

payload.sale.*item map ((value, index) -> {

index: index,

sale: value.@saleId,

itemName: value.desc,

itemPrice: (value.quantity) * (value.price),

item: value.@itemId

} )

Option1 is correct syntax to configure HTTP Listener endpoint

In this case both the flows can start without any error and requests can be received on both ports. Flow names httpListener1 can call other flow using HTTP request without any issues.

Hence correct answer is

The mule application start successfully

Web client requests can  be received at URI on port 2222 and on port 3333.

Lets check why other options are incorrect

1) The mule application fails to start. There is URL path conflict because both HTTP Listeners are configured with same path  ---- This is incorrect as port value is different in both listeners

2) The mule application start successfully. Web client requests can only be received at URI on port 2222 but not on port 3333  --- This is incorrect as there is no reason for not receiving requests on port 3333

3) The mule application fails to start because of the port binding conflict as HTTP request also use same port i.e. 3333 --- Port binding conflict will not happen in this case. It would have if both listener configurations would have been on same port . But that is not the case here.

Mule Ref Doc : HTTP Listener Reference - Mule 4 | MuleSoft Documentation

Correct answer is Creates and manages discoverable assets to be consumed by line of business developers.

C4E does not get directly involved in projects.

This helps CloudHub to dynamically allocates a port at deployment time.

MuleSoft Doc Ref : https://docs.mulesoft.com/mule-runtime/4.3/deploy-to-cloudhub#prerequisites

Lets revise few concepts RAML which can help us to find the answer of this question.

URI Parameters

Lets have a look at below example.

• /foos:
• /{id}:
• /name/{name}:

Here, the braces { } around property names define URI parameters. They represent placeholders in each URI and do not reference root-level RAML file properties as we saw above in the baseUri declaration. The added lines represent the resources /foos/{id} and /foos/name/{name}.

Query Parameters

Now we'll define a way to query the foos collection using query parameters. Note that query parameters are defined using the same syntax that we used above for data types:

• /foos:
• get:
• description: List all Foos matching query criteria, if provided;
• otherwise list all Foos
• queryParameters:
• name?: string
• ownerName?: string

Based on the above information , below is the only option which defines storeid as uri parameter and department as query parameter.

• /{storeId}:
• get:
• queryParameter:
• department:

Correct answer is Not needed as dw::core module is included by default. We don't need to include it explicitly

Empty array is returned when no rows are matched.

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

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

Lets revise few concepts RAML which can help us to find the answer of this question.

URI Parameters

Lets have a look at below example.

• /foos:
• /{id}:
• /name/{name}:

Here, the braces { } around property names define URI parameters. They represent placeholders in each URI and do not reference root-level RAML file properties as we saw above in the baseUri declaration. The added lines represent the resources /foos/{id} and /foos/name/{name}.

Query Parameters

Now we'll define a way to query the foos collection using query parameters. Note that query parameters are defined using the same syntax that we used above for data types:

• /foos:
• get:
• description: List all Foos matching query criteria, if provided;
• otherwise list all Foos
• queryParameters:
• name?: string
• ownerName?: string

Based on the above information , below is the only option which defines storeid as uri parameter and department as query parameter.

• /{storeId}:
• get:
• queryParameter:
• department:

Correct answer is MAJOR

MAJOR version when you make incompatible API changes, MINOR version when you add functionality in a backwards compatible manner, and PATCH version when you make backwards compatible bug fixes.

For details refer to this documentation : https://semver.org/

APIKIt Creates a separate flow for each HTTP method

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. As per RAML input is expected in application/xml.

Hence correct answer is Set a request header with the name Content-Type to a

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

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

* To use custom modules, you need to import the module or functions you want to use by adding the import directive to the head of your DataWeave script, for example:

1) Does not identify any functions to import from the String module:

import dw::core::Strings

2) To identify a specific function to import from the String module:

import camelize, capitalize from dw::core::Strings

3) To import all functions from the String module:

import * from dw::core::Strings

The way you import a module impacts the way you need to call its functions from a DataWeave script. If the directive does not list specific functions to import or use * from to import all functions from a function module, you need to specify the module when you call the function from your script.

* In given scenario, it's mentioned to import all of the WebStore.dwl

So correct answer is:

In this case as outbound call is made using HTTP: POST /child , all attributes will be replaced by this invocation. Hence query parameter will not be accessible at logger. Hence correct answer is option 2

Correct answer is Attributes.

Query parameters , URI parameters and headers are some of examples which are part of attributes.

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Correct answer is Subflow has no error handling implementation where as sync flow has.

Subflow

A subflow processes messages synchronously (relative to the flow that triggered its execution) and always inherits both the processing strategy and exception strategy employed by the triggering flow. While a subflow is running, processing on the triggering flow pauses, then resumes only after the subflow completes its processing and hands the message back to the triggering flow.

Synchronous Flow

A synchronous flow, like a subflow, processes messages synchronously (relative to the flow that triggered its execution). While a synchronous flow is running, processing on the triggering flow pauses, then resumes only after the synchronous flow completes its processing and hands the message back to the triggering flow. However, unlike a subflow, this type of flow does not inherit processing or exception strategies from the triggering flow.

This type of flow processes messages along a single thread, which is ideally suited to transactional processing

Correct answer is Change the method attributes value to "POST".

It can be fixed in either of the two ways as below.

1) Changing method attribute to POST in ClientRequestFlow

2) Setting allowedMethods as PUT in ShippingFlow (but doesn't fit as question mentions about changing ClientRequestFlow)

* 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

Correct answer is Configure the correct JDBC driver as error message suggests the same

• Caused by: java.sql.SQLException: Error trying to load driver: com.mysql.jdbc.Driver : Cannot load class 'com.mysql.jdbc.Driver': [
• Class 'com.mysql.jdbc.Driver' has no package mapping for region 'domain/default/app/mule_app'.,
• Cannot load class 'com.mysql.jdbc.Driver': [

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

File is not updated when FTP read operations is performed.

MuleSoft Doc Ref : https://docs.mulesoft.com/file-connector/1.3/file-read

Correct answer is vars."customer"."firstName"

Please note that you can also access firstName using this syntax vars.customer.firstName.

Mule Ref Doc : Variables in Mule Apps | MuleSoft Documentation

Correct answer is [[5, 10, 15, 20], 5]

Key thing to note here is that any changes made to payload in for each loop are not available outside for each scope where as variable value updated in for each loop is visible out side for each loop too.

In this example , sequence can be described as follows

1) Payload is set to the value [5, 10, 15, 20]

2) Variable is set to the value of 1

3) For each loop is executed four times and in each loop payload value is updated to append "Req" and variable is count is increased by 1

4) Once control comes out of for each , payload changes made within for each are not visible. Hence payload at this point of time is equal to payload available before entering for each loop which was  [5, 10, 15, 20]. Similarly variable value updated in for each loop is also available outside hence variable value is 5 as it was updated in loop.

5) Hence correct answer is [[5, 10, 15, 20], 5]

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.

For non-Java collections, such as XML or JSON, use a DataWeave expression to split data. Use the Collection field for this purpose.

Transform Message Add write_date is coverting payload in JSON format and same JSON payload is avaialble to file write processor. However, if the payload is a different format (for example, not CSV) , you can place the transformation inside the Write operation to generate content that will be written without producing a side effect on the message in transit. This is not done in this case. By default, the connector writes whatever is in the message payload. Hence JSON payload will be written to file.

Points to remember:

* XML must have a root element.

* XML only allows one root element

* To avoid multiple root issues, you must create a root element for the XML output, whenever we transform output

* When mapping array elements (JSON or JAVA) to XML, wrap the map operations in {(..)}

-{ } are defining the object

( ) are transforming each element in the array as a key/value pair

* The transformation to XML would fail if the above mentioned considerations were not taken into account.

* Thus the transformation script declares a root element as trains and wraps the data in “{( )}“.

Whenever you see such type of question, always look out for root element followed by {( )} wrapping map.

I call this a "Wrap The Map" scenario. Hope it would help you remember !

Correct answer is Array.

Flatten turns a set of subarrays (such as [ [1,2,3], [4,5,[6]], [], [null] ]) into a single, flattened array (such as [ 1, 2, 3, 4, 5, [6], null ]).

This example defines three arrays of numbers, creates another array containing those three arrays, and then uses the flatten function to convert the array of arrays into a single array with all values.

Source

%dw 2.0

output application/json

var array1 = [1,2,3]

var array2 = [4,5,6]

var array3 = [7,8,9]

var arrayOfArrays = [array1, array2, array3]

---

flatten(arrayOfArrays)

Output

[ 1,2,3,4,5,6,7,8,9 ]

Choice Router

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.

Properties of

PropertyDescription

Expression (expression)

Expression in DataWeave language to evaluate input.If the expression evaluates to true, this routing option is used:

Mulesoft Doc Ref : https://docs.mulesoft.com/mule-runtime/4.3/choice-router-concept

With respect to above information ,

Option 1 is the correct syntax as others are incorrect because of below reasons

* Single = is not the correct syntax to validate the condition. It should be ==

* If keyword is not required in when condition.

First step in creating Modern API is to create an API specification and get feedback from stakeholders so that any future issues can be identified at early stage thereby reducing overall delivery time

The List operation returns an array of messages in which: Each message holds the file’s content in its payload. The file’s attributes section carries the file’s metadata (such as name, creation time, and size). The payload is empty if the element is a folder.

In this case three configurations will be required each for port 8000, 6000 and 7000.

There would be three global elements defined for HTTP connections.

Each HTTP connection will have host and port. One example shown below with host as localhost and port 6000

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To use an HTTP listener, you need to declare a configuration with a corresponding connection. This declaration establishes the HTTP server that will listen to requests.

Additionally, you can configure a base path that applies to all listeners using the configuration.

https://docs.mulesoft.com/http-connector/1.6/http-listener-ref#http-listener-configuration

Database always return rows as an array.

Array is the correct answer

client-id-required enforces clients to add client_id and client_secret.

Please refer to below steps.

• Add a section called traits: at the root level to define query parameters:
• traits:
• - client-id-required:
• queryParameters:
• client_id:
• type: string
• client_secret:
• type: string
• 2) Reference the trait in each of the methods to specify that each of the methods require these query parameters. After each method in the RAML file, add is: [client-id-required]. For example:
• /users:
• get:
• is: [client-id-required]
• description: Gets a list of JSONPlaceholder users.

The flow can be described as below. 1) First HTTP POST requets is made in which paylaod is set to 1 and it gets returned to our mail flow. 2) Second call is initiated for JMS Publish Consume JMS: num1 which add 1 to the payload which makes it as 2. Note that pubih consume is a synchronous operation. Hence paylaod is returned to main flow. 3) Third call is initiated for JMS Publish JMS: num2 which add 1 to the payload . Note that pubih is asynchronous operation. Hence paylaod is never returned to main flow. So payload in main flow is still 2. 4) Finally Set Payload increments payload by 1 making payload as 3 which is returned by the flow. Hence option 3 is the correct answer.

Correct answer is 0.1 vCores

MuleSoft Doc Ref : https://docs.mulesoft.com/runtime-manager/cloudhub-architecture#cloudhub-workers

CloudHub Workers

Workers are dedicated instances of Mule runtime engine that run your integration applications on CloudHub. The memory capacity and processing power of a worker depends on how you configure it at the application level.

Worker sizes have different compute, memory, and storage capacities. You can scale workers vertically by selecting one of the available worker sizes:

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Correct answer is System layer

System APIs provide a means for insulating the data consumers from the complexity or changes to the underlying backend systems.

MuleSoft recommends three-layered approach to API-led connectivity, highlighting the three layers:

* System APIs

* Process APIs

* Experience APIs

System APIs are the core systems of record underlying core systems of record (e.g. ERPs, key customer and billing systems, databases, etc.). Process APIs allow you to define a common process which the organization can share, and these APIs perform specific functions, provide access to non-central data, and may be built by either Central IT or Line of Business IT. And finally, the 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.

The three-layered structure allows for a seamless flow of data from systems of record to new experiences, and allows for reusability of assets rather than point to point connections. This approach provides a distributed and tailored approach to architecture, greater flexibility through loose coupling, and deeper operational visibility into what is being built.

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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 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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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

Mule applications can be scaled vertically by changing worker size. Mule applications can be scaled horizontally by adding more workers.

Correct answer is as below as concatenation operation works only with string and not with the objects. In this case payload is object.

"You called the function '++' with these arguments:

1: String ("INFO")

2: Object ({student: {name: "Anay" as String {class: "java.lang.String"},age

* When a client application is registered in Anypoint Platform, a pair of credentials consisting of a client ID and client secret is generated.

* When the client application requests access to an API, a contract is created between the application and that API.

* An API that is protected with a Client ID Enforcement policy is accessible only to applications that have an approved contract.

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Correct Answer: In the organization's public API portal in Anypoint Exchange, from an approved client application for the API proxy

For such questions always look for Syntax:

I call it "Wrap the Map"

trains:

{(

When mapping array elements (JSON or JAVA) to XML, wrap the map operations in {(..)}

-{ } are defining the object

-( ) are transforming each element in the array as a key/value pair

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

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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

Correct Answer: Response body: "Error" Default response status code: 200.

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1) Payload is successfully set to “Success – Started Flow”

2) When HTTP Request throws an error, execution halts

#[error.description] = “ABC"

#[error.errorType] = "XYZ"

3) The On Error Continue scope handles the error. When On Error Continue scope is invoked, all the processors in error block are executed and success response is sent back to the client with payload which is set in error flow. In this case payload is set to "Error" value in error block.

4) “Error” is returned to the requestor in the body of the HTTP request with HTTP Status Code: 200 as On error continue always sends success error code.

Reference Diagram:

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By default, Debugger listens for incoming TCP connections on localhost port 6666 You can change this in a project's run configuration.

MuleSoft Doc Ref : https://docs.mulesoft.com/studio/7.5/visual-debugger-concept