Top 50+ Most Asked Mulesoft Interview Questions and Answers

1) What do you understand by Mule? / What is MuleSoft?

Mule or MuleSoft is an integration platform that helps to connect devices, applications, and data. It is also used to connect enterprise and SaaS applications in the cloud and on-premise. Mule also helps to tackle the problems in developing integration applications, delivering a single view of the customer, automating business processes, and building connected experiences.

Mule or Mulesoft’s platform is called Anypoint Platform. This platform consists of several tools for developing, managing, and testing application programming interfaces (APIs), which support such connections. MuleSoft’s Anypoint Platform is the world’s leading integration platform for Service-oriented architecture (SOA) and Software as a Service (SaaS).

2) What are some problems that Mule or Mmulesoft tackles?

Following is a list of some problems that Mule or Mulesoft tackles:

Error handling
Monitoring
Lifecycle and management
Data format, etc.

After solving these problems, Mule focuses on the application’s core requirements, such as scalability and efficiency.

3) Who is known as the father of Mulesoft?

MuleSoft was founded by Ross Mason in 2006, so he is known as the father of Mulesoft.

According to the company’s website, the name MuleSoft comes from the ability of this platform to eliminate the hard work (“donkey work”) and provide a simpler solution. The company chose this name because it reflects its platform’s hybrid capabilities and also because mules are a hybrid combination of donkeys and horses.

4) What are the different types of variables used in MuleSoft?

Following is the list of different types of variables in MuleSoft:

Flow Variable: The Flow Variable is used to either set or remove the variables tied to a particular message in the current flow.
Record Variable: The Record Variable is used for batch processing flows.
Session Variable: The Session Variable is used to either set or remove the variables tied to a particular message for the complete lifecycle.

5) What is Mule ESB? What are some of the key features of Mule ESB?

Mule ESB is an acronym that stands for Mule Enterprise Service Bus. It is an architecture developed for programmers to make it easy for the development teams to connect, access, and exchange data easily. It provides a facility that even though the application is running into different VMs, their interactions are easy. Mule ESB facilitates developers to integrate a range of applications together using the bus-like infrastructure. It can also be easily integrated with HTTP, web service, JMS, etc.

Following is a list of some of the important features of Mule ESB:

Message Transformation Service
Set of Service Container
Web Service Security
Message Routing Service
Simple drag-and-drop graphical design
Centralized monitoring and administration

6) What do you understand by fan-in and fan-out?

In Mulesoft, fan-in and fan-out both are used in a combination. Fan-in is used to help in making a decision to continue flow execution, and it is always used with the combination of fan-out. On the other hand, fan-out is primitive and mainly used to input messages through the output terminal once or twice, and it can also be used with the combination of fan-in.

7) What are the different tools and services Mulesoft provides?

MuleSoft is used to make data integration efficiently and diligently. It also provides a lot of tools and services. Following is the list of main tools and services offered by MuleSoft:

API Designer: MuleSoft provides API Designer, a web-based tool containing a console and a scripting notebook for JavaScript.
API Manager: MuleSoft offers API Manager, which is a management tool that allows organizations in managing users, traffic, and service level agreements.
Anypoint Studio: MuleSoft offers Anypoint Studio, a graphical design environment used to build and edit APIs and integrations.
API Portal: MuleSoft provides an API Portal, a portal that offers developers different kinds of documents, tutorials, and code snippets related to APIs.
API Analytics: MuleSoft offers API Analytics, an analytics tool that facilitates users to track the specifications of an API. This also includes its performance, usage, and reliability. Additionally, it offers a dashboard and charts.

8) What are the different types of messages used in MuleSoft?

Following are the various types of messages used in MuleSoft:

Echo and log message
Bridge message
Build message

9) What are the different types of primitives used in Mediation?

Following is the list of different types of primitives in Mediation:

Type Filter
Message Filter
Endpoint Lookup
Service Invoke
Fan-in
Fan-out
XSLT
BO Map
Message Element Setter
DB lookup
Data Handler
Custom Mediation
Header Setters
Message Logger
Even Emitter
Stop
Fail
Sub Flow

10) What are the most prominent features of Mule ESB?

Following is a list of the most prominent features of Mule ESB:

Mule ESB is easy to use and provides a drag and drop graphical design.
Mule ESB also provides SLA (Service Level Agreement) monitoring and API management facility.
It is highly scalable.
It facilitates developers to deploy in the one-click cloud or on-premise deployments.

11) What are the different types of messages in MuleSoft?

Following is the list of different types of messages in MuleSoft:

Echo and Log message: The Echo and Log messages are used for logging and moving them from inbound to outbound routers. A single event is received via an endpoint in the inbound routers, and the router controls how this event gets routed into the system. Once a message has been processed by a component in outbound routers, it will determine which components get the result event.

Bridge Message: The Bridge Messages are the passed messages from inbound to outbound routers.

Build Message: The Build Messages are the messages created from fixed or dynamic values.

12) What are the basic principles of ESB Integration?

The basic principles of ESB integration are:

Transportation: Transportation is used to negotiate between different formats like JDBC, HTTP, JMS, etc.
Transformation: Transformation is used to deal with data transportation between data formats required by the ESP connector.
Non-functional consistency: Non-functional consistency is used to provide how monitoring and security policies should be applied and consistent.
Mediation: Mediation provides different interfaces to enable different channels to the same component implementation and support various service versions for backward compatibility.

13) How can we develop and consume SOAP services in Mule?

We can similarly create the SOAP services as we create a Mule project by using RAML. The only difference between them is that the Concert WSDL is imported instead of RAML, and SOAP services are consumed using Web Service consumer or Mule flow CXF components.

14) What is the full form of SDO?

SDO is an acronym that stands for Service Data Object.

15) What is the difference between Callout and Service Invoke in Mulesoft?

Differences between Callout and Service Invoke in Mulesoft:

Callout: The callout is used to receive the messages and call the requested services and operations. For every connected target operation, there is a callout node in the median flow. In the case of a successful call, the callout response node in the response flow receives a response message. If the call is unsuccessful, the callout is set to retry service invocations according to the type of fault received.

Service Invoke: The Service Invoke is used to make a service request. It would either be a request or a response to a mediation flow. The service can be a request/response or a one-way. A series of service invocations are performed after permitting the multiple instances of a service to invoke primitives in a flow.

16) What do you understand by MEL or Mule Expression Language?

MEL is an acronym that stands for Mule Expression Language. It is a lightweight mule-specific language that can be used to access and evaluate data in the payload.

17) What are the different types of Exception Handling in Mulesoft?

Following are the different types of Exception Handling in Mulesoft:

Default exception handling.
Rollback exception handling.
Choice exception handling.
Global exception handling.
Catch exception handling.

18) What are the different types of endpoints in Mule ESB?

Following is a list of different types of endpoints in Mule:

JMS
HTTP
SMTP
IMAP
AJAX

19) What are the key advantages of using Mulesoft ESB?

Following is the list of the key advantages of using Mule ESB:

Mule ESB provides several connectivity options using SaaS-based applications.
It offers a high level of operational controlling facility from the portal based on the web.
It also provides API and analytics management.
Mule ESB is incorporated with several bug fixing and automated testing facilities.
Mule ESB offers EDI (Electronic Data Interchange) and B2B (Business to Business) integration.
It provides a batch integration feature using real-time integration methods.

20) What are the various types of endpoints in Mulesoft ESB?

Following are the different types of Endpoints used in Mulesoft ESB:

HTTP
SMTP
JMS
IMAP
AJAX

21) What are the Batch Jobs in Mulesoft ESB?

In Mule ESB, Batch Jobs are the elements that can split large messages into records. These records are then processed asynchronously in a Batch Job.

When a Batch Job scope is initiated within an application, it splits messages into individual records. It performs actions upon each record, and then reports on the results are pushed the processed output to other systems or queues. Using this, we can handle a huge quantity of incoming data from an API into a legacy system. We can also synchronize data sets between business applications.

22) What do you understand by the transient context in Mulesoft?

In Mulesoft, transient context is used to pass the values within the existing flow, and it may either request flow or the responding flow.

23) What is the difference between ESB and JMS?

ESB provides the middleware and interfaces services that facilitate the business enterprises to connect their applications without writing any code. On the other hand, JMS provides the communication facility and messaging capability between the modules of an application.

24) What is the Mule Transformer or Mulesoft Transformer?

Mule Transformer or Mulesoft Transformer is an event instance used to refer to a library, org.mule.api.MuleEvent. This is used to carry the messages with the event. The main aim of the Mule transformer is to create a chain of transformers.

25) What are the Models in Mulesoft studio?

In Mulesoft studio, the grouping of services, i.e., application objects and their created attributes, are called Models. Models enable a user to start and stop the services inside a given model.

26) What is API in Mulesoft, and what are its main features?

In Mulesoft, API is an acronym that stands for Application Programming Interface. It is a software interface that allows two applications to interact with each other without any user interference.

API is used to enable products or services to communicate with other products and services without knowing how they are implemented.

Following is the list of some essential features of API:

API is efficient enough to allow two applications to interact with each other without any user interference.
It provides wide reachability.
It is customizable.
It provides the facility of personalization.
It provides data ownership.
It can easily be integrated with GUI.
It is time-effective.
It is language-independent.

27) What parameters are used in configuring a scheduler in Mulesoft?

Following is a list of related parameters which are used to configure a scheduler:

Frequency: Frequency is used by the scheduler for triggering flows.

Start Delay: Start Delay is the waiting time used before triggering any flow.

Time Unit: It is used to specify the time unit for frequency and start delay.

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28) What is the payload in Mulesoft?

In Mulesoft, the payload is a Mule runtime variable used to store objects or arrays. It helps developers to access payload under different forms.

29) What are the various parts of composing a message in Mulesoft?

Following are the different parts of composing a message in Mulesoft:

Properties: Properties are used to store the header or meta-information similar to the SOAP (Simple Object Access Protocol) message.
Payload: Payload is the main data context carried by a particular message.
Multiple name attachments: Multiple name attachments are used to support multiple messages or payloads during event processing.

30) What is Mule Data Integrator?

A Mule Data Integrator is a tool used to map data by visualizing it. It also provides a drag and drops feature interface, which facilitates developers to code easily.

31) What do you understand by a shared resource in Mulesoft?

In Mulesoft, a shared resource is a common resource that is exposed to all applications deployed under the same domain. The biggest advantage of using the shared resource is that it allows different development teams to work parallel.

For example, Connector configurations can be used as a reusable resource, sharing them among all applications deployed.

The shared resources should be defined in the Mulesoft Domain Project and referred to each of the projects eligible to use the elements within it.

32) What are the different types of flow processing strategies in Mulesoft?

Following are the different six types of strategy Mulesoft has for flow processing:

A queued asynchronous flow processing.
Custom flow processing.
Tread per processing.
Queued flow processing.
Non-blocking flow processing.
Synchronous flow processing.
Asynchronous flow processing.

33) What are Connectors in Mulesoft?

In Mulesoft, connectors are Mule’s abstraction used for sending and receiving data and interacting with various APIs. There are generally two types of connectors in Mule:

Transport: Transport is the most common form of connector used in Mule. Like HTTP, transport is used to provide an adaptation layer for a protocol.

Cloud connectors: Cloud connectors are generally used to interact with an API. They don’t give endpoints. Instead, they have message processors that map to the operations provided in the API. These cloud connectors combine the operations of an API.

34) What are the different types of ESPs used in the market?

Following are the different types of ESPs used in the market:

Mule ESB
JBoss fuse ESB
Talend

35) What are the Workers in Mulesoft?

In Mulesoft, Workers are the dedicated instance of Mule hosted on AWS. They are used to run the integration applications.

Following is the list of some important features of the workers:

Capacity: It is used for data processing. Every worker has a certain amount of capacity.
Isolation: Isolation means that every worker runs in a separate container from every other application.
Manageability: It specifies that the deployment and management of each worker are done independently.
Locality: This feature specifies that every worker that runs is located on a specific worker cloud.

36) What does the model layer of Mulesoft represent?

The model layer is the first logical layer of Mulesoft. It is used to represent the runtime environment that hosts services and describe the behavior of Mule when processing requests that are handled by services. It provides services with default values to simplify configuration.

37) What is a runtime manager in Mulesoft?

In Mulesoft, the runtime manager is used to deploy and manage Mule applications. This is done on the Mule runtime engine where Mule is running. We can change the runtime version of the application at a given time and also deploy or pause the mule application by using runtime manager. We can also increase or decrease the worker size as well.

38) What is a connector in MuleSoft?

In Mulesoft, a connector is used to control the particularly used protocols, and it can be configured with parameters specific to that protocol. The connector also holds state context, which we can share with any entity in charge of actual communications.

39) What are the ways to improve the performance of the Mule Application in MuleSoft?

Following are some ways that can be used to improve the performance of the Mule Application in MuleSoft:

By putting the data validation at the start of the flow.
Use the streaming to process data.
Save the results of the application and reuse them later.
Process data asynchronously wherever is possible.

40) What is the use of Outbound Endpoint in MuleSoft?

The Outbound Endpoint in MuleSoft is used to perform the following things:

Send SOAP messages
Write to file streams
Send email messages

41) What is the concept of Correlation Context?

The Correlation Context is a primitive used to pass values from request flow to response flow.

42) What do you understand by Endpoints in Mule?

In Mule, Endpoints are used to specify a particular usage of a protocol. It is used for polling, reading from, or writing to a destination.

It is also used to control what underlying entities would be used with a dependent connector.

43) How can we achieve reliability in Mulesoft?

In Mulesoft, reliability means zero message loss. So, if you want to achieve reliability, then your application must be designed to capture the state of a running process/instance, which another running node in the cluster can pick up.

Reliable messaging is achieved by the built-in support of transactions in transport if the application uses a transactional transport such as Java Message Service (JMS), Virtual Machine (VM), Database (DB), etc. A reliable messaging pattern is mandatory if we are dealing with non-transactional endpoints.

44) What is a component in Mule?

Components are used to perform an important role in Mulesoft services. Every service in Mulesoft consists of core components and core and inbound and outbound routers. Components are also used to implement behavior in service. They can be very simple, like logging messages or invoking other services.

45) What do you understand by Flow and Subflow in Mule?

Flow: In Mule, flow occurs when we combine multiple individual processors to handle a receipt, processing, and the eventual routing of a message. We can connect several flows to build one complete application. Then, we can deploy this application on Mule, on-premise, another app server, or on the cloud. A message entering a flow can pass through a large variety of processors. After receiving the message through a request-response inbound endpoint, Mule transforms the content into a new format. The business logic is then processed in a component before returning a response through the message source.

Subflow: We can call the subflow by using the flow-reference element of Mule. When the subflow is called using a flow-reference element by the main flow, the entire message structure, i.e., attachments, payload, properties, etc., are passed along with the context. Subflows are very useful when adding re-usable logic, as we can call sub-flows multiple times. It can also enhance performance in comparison to flow.

46) What is the full form of TSD in Mule?

TSD is an acronym that stands for Transport Service Descriptor. It is a connector used for technical configuration. It is used to define classes name used for message receivers, dispatchers, and requesters. Its default value may be changed according to the behavior of transport.

47) What are the main differences between Flow and Subflow in Mule?

Following is a list of main differences between Flow and Subflow in Mule?

Flow	Subflow
A flow follows its strategy for exception handling, and it also does not have a source defined.	A subflow is used to process messages synchronously, and it follows the strategy of processing and exception handling from the calling flow.
Flows can have sources such as HTTP Listener that can impact the flow execution.	Subflows don’t support event sources. For example, you can’t place an HTTP Listener in the subflow.
Each flow can have its error handling.	Subflow doesn’t support error handling, and it inherits the error handling strategy from parent flow.
The performance of referring flows is not as good as compared to subflow.	Referring subflow gives better performance as compared to flow.

48) What are the main characteristics of the global endpoint?

Following is the list of main characteristics of global endpoint:

The global endpoint can be used in different places of configuration files.
It is not typified or outbound routing.
It must apply the global service name so that it can reference the endpoint.
It also helps to clarify the usage of a particular destination.

49) Which are the supported languages by Mulesoft?

Following are the main supported languages of Mulesoft:

Python
Ruby
Groovy
JavaScript

50) What are the different types of configuration builders in Mulesoft?

There are mainly two types of configuration builders in Mulesoft:

Spring-driven builder
Script builder

51) What is a multicasting router in Mule?

In Mulesoft, multicasting routers send messages to more than one endpoint over different transports, and it also facilitates users to move the same messages across different endpoints.

Top 50+ Most Asked Mulesoft Interview Questions and Answers (2022)