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

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)

Graphical user interface, text, application Description automatically generated

Correct answer is Validation modules Is Number operation.

Mule 4 does not use filters anymore. The functionality provided by filters in Mule 3 can be achieved by using the Validation Module.

* 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

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

} )

Correct answer is /accounts?account_type=retail&industry=finance

Query parameters are a defined set of parameters attached to the end of a url. They are extensions of the URL that are used to help define specific content or actions based on the data being passed. To append query params to the end of a URL, a ‘?’ Is added followed immediately by a query parameter.

To add multiple parameters, an ‘&’ is added in between each.

Anypoint Exchange provided a way to publish , share and search API's.

MuleSoft Doc Ref : https://docs.mulesoft.com/exchange/

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

Metadata is stored in application-types.xml flle located under src/main/resources.

Mule 4 applications contain an application-types.xml file, which is where metadata around your data types is stored. For example, if you create a new CSV type, that metadata will be added to this file. This new file is easy to share, commit, and merge when conflicts arise, which enables you to do more metadata-driven development.

MuleSoft Doc Ref : https://docs.mulesoft.com/mule-runtime/4.3/intro-studio#metadata-storage

Error in validation component will get processed by Processer level On Error Propagate block and then error will be rethrown which will get processed by flow level error handler which will set payload to "Error- main flow". Hence correct answer is Error - main flow

1) Request is received by HTTP listener

2) Try scope gets executed

3) The validator component in the Try scope creates an Error Object because the payload is not null.

4) The On Error Propagate handles the error. The payload is set to “Error – Try scope”

6) “Error – Try scope” is returned to the 'On Error Continue' block. Main flow execution stops. Payload is set to "Error - main flow"

7) “Error - main flow” is returned to the requestor in the body of the HTTP request. HTTP Status Code: 200

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Reference Diagram though not exactly same, conditions are similar. They will help you answer any new question on error handling in real exam:

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https://docs.mulesoft.com/mule-runtime/4.3/on-error-scope-concept#on-error-continue

MuleSoft Documentation Reference : https://docs.mulesoft.com/db-connector/1.9/database-connector-select

Correct answer is 8 as events are processed in parallel in case of scatter gather router

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

Option 3 is the only corect answer as it concatenates payload with String.

Below option wont work.

#["The payload is " ++ payload]

Concatenation function expects both arguments to be string. As the question says payload is json object , this will throw error while running it. You can try this in Anypoint Studio and you will get the same result which I mentioned.

hence correct answer is

The payload is: #[payload]

Returns an array that is the result of applying a transformation function (lambda) to each of the elements.

MuleSoft Doc Ref : https://docs.mulesoft.com/mule-runtime/4.3/dataweave-cookbook-map

The map operator is a function in Dataweave which iterates over the items in an array and outputs them into a new array. It basically accepts input as a list of items in an array and manipulates the items in the array in order to form a new array as an output.

I have created below chart for your easier understanding:

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Correct answer is Anypoint Visualizer

MuleSoft Doc Ref : https://docs.mulesoft.com/visualizer/

Anypoint Visualizer provides a real-time, graphical representation of the APIs, and Mule applications that are running and discoverable. It also displays third-party systems that are invoked by a Mule API, proxy, or application within your application network. The data displayed in the graph is dynamically updated and does not require prior configuration. Additionally, the data displayed is secure, as only users with the proper permissions can view the application network graph.

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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 ${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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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 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)

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': [

Correct answer is Merges elements of two lists (arrays) into a single list

MuleSoft Doc Reference : https://docs.mulesoft.com/mule-runtime/4.3/dw-core-functions-zip

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.

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

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 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

Scatter-Gather Router

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 API manager

Centre for Enablement (C4E) is an IT operating model that enables an enterprise to build reusable assets, accumulate API’s, leverage best practices and knowledge to enable self service and efficient delivery in the organization and implement new solutions faster

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 An Object containing all three Mule event Objects

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.

Sample output is as below

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MuleSoft Documentation reference : https://docs.mulesoft.com/mule-runtime/4.3/scatter-gather-concept

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

Correct answer is Patients from year 2021.

The thing to note here is that year is not a query parameter and not the uri parameter. Hence it will filter all the patients and return the ones for whom year is 2021

Option 2 is the correct answer as /api/* accespts everything starting with /api/

MuleSoft Doc Ref : https://docs.mulesoft.com/api-manager/2.x/policy-mule3-tutorial-manage-an-api#to-add-the-tier

Steps to create SLA Tier are as follows:

1) In API Manager, in API Administration, click a version.

2) Check that the API supports resource-level policies: On the API version details page, in Status, click Configure Endpoint, and check that Type is RAML.

3) Choose the SLA Tiers, and click Add SLA Tier. Set up limit on SLA tier

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 ]

The correct answer is To avoid duplicate processing of records in a database.

If a watermark column is provided, the values taken from that column are used to filter the contents of the next poll, so that only rows with a greater watermark value are returned. If an ID column is provided, this component automatically verifies that the same row is not picked twice by concurrent polls.

Mule doc reference : https://docs.mulesoft.com/db-connector/1.8/database-documentation#listener

Correct answer is Request access to the API in Anypoint Exchange. This way we can get clientId and Client secret which we can use to access the API

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

%dw 2.0

output application/json

import modules::Utility

---

Utility::encryptString( "John Smith" )

DataWeave 2.0 functions are packaged in modules. Before you begin, note that DataWeave 2.0 is for Mule 4 apps. For Mule 3 apps, refer to DataWeave Operators in the Mule 3.9 documentation. For other Mule versions, you can use the version selector for the Mule Runtime table of contents.

Functions in the Core (dw::Core) module are imported automatically into your DataWeave scripts. To use other 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:

import dw::core::Strings

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

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. For example, this import directive does not identify any functions to import from the String module, so it calls the pluralize function like this: Strings::pluralize("box").

Transform

%dw 2.0

import dw::core::Strings

output application/json

---

{ 'plural': Strings::pluralize("box") }

Option 1 is the only correct choice due to two reasons. 1) Concatenation is always with ++ sign and not with + sign which makes option 2 and 3 wrong 2) hearders can be accessed with attributes. headers and not with only headers which makes option 4 incorrect

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Here’s specifically what is happening here:

1) Payload is successfully set to “Before”

2) Is null validation is used which will pass the message only if payload is null. In this case as payload is not null, it creates an Error Object. Flow execution stops

#[error.description] = “Validation error”

3) Because no error handler is defined, the Mule default error handler handles the error

4) “Validation error” 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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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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