MuleSoft Interview Questions and Answers covered in this article aim to help you crack Interview for MuleSoft Developer and related jobs. MuleSoft Developers and MuleSoft Architects are high in demand in the market due to growing popularity of MuleSoft in the integration world.

MuleSoft Interview Questions and Answers for MuleSoft Related Job Interviews

In this post, I will cover some of the important basic as well as intermediate and to an extent; advanced level interview questions related to MuleSoft. It is highly recommended to go through various tutorials about MuleSoft on TutorialsPedia YouTube Channel, Mule ESB category on this blog and of course; official MuleSoft Documentation to equip yourself with necessary knowledge. Just reading Interview Questions alone won’t help you succeeding interviews and subsequently in the industry.

Top 15 MuleSoft Interview Questions and Answers

1. Explain different features & capabilities of MuleSoft as an Integration Platform

MuleSoft AnyPoint is a leading integration platform which enables organizations to achieve integration of heterogeneous systems & applications.

Mulesoft is an API-led connectivity platform that enables organizations to integrate applications, data, and devices across on-premises and cloud environments. Its key features include:

Anypoint Studio:  An eclipse based visual design environment for building integrations and APIs through its drag & drop support.
Anypoint Exchange: A marketplace for discovering, sharing, and reusing APIs and integration assets.
Anypoint Platform:  A cloud-based platform for managing, monitoring, and deploying integrations and APIs.
Mule Runtime Engine: A lightweight integration runtime for processing messages and events.

Design Center: A browser based designer to help creating API Specifications & a flow designer to design Mule Flows.

2. What is the difference between flow and sub-flow in Mulesoft?

In Mulesoft, a flow is a sequence of processing steps that handles a single message or event. A sub-flow is a reusable sequence of processing steps that can be called from multiple flows. The main differences between the two are:

• Main Flows have a defined trigger which acts as a process starter to start the flow, while sub-flows are always called from another flow.
• Main Flows can contain error handling and exception strategies, while sub-flows cannot.
• Main Flows can define global elements such as connectors and transformers, while sub-flows cannot.

3. What is the difference between On-Error-Propagate and On-Error-Continue?

On Error Propagate and On Error Continue are two error handling mechanism used in Mule Applications. On Error Propagate propagates the error to the higher level after executing any message processors within On Error Propagate Block. On the other hand, On Error Continue returns a success back to the higher level after executing the processors within on error continue block.

In case of On Error Propagate, no further success path message processors will be processed on the higher level (e.g. inside calling flow) but in case of On Error  Continue, any subsequent message processors in the higher flow will be executed.

4. What is the difference between object store and caching in MuleSoft?

In Mulesoft, object store and caching are both used to store and retrieve data during integration processing, but they serve different purposes:

Object store: MuleSoft Object Store is a facility to store data and state  in and across Mule Applications, Batch Processes and Components. It stores data between flows and sub-flows, and allows you to share data across multiple flows. It is designed for short-term storage and is not optimized for performance.

Recommended : MuleSoft Object Store V2 Tutorial : Object Store Connector Operations in Mule 4

Caching: Caching feature in MuleSoft is used to store data in memory for quick access to improve performance by avoiding the need to make repeated calls to external systems. It is designed for longer-term storage and can be configured for different eviction policies.

5. How do you achieve API Security in Mulesoft?

Mulesoft provides several ways to secure APIs, including:

HTTPS: To Secure data transmission with encrypted. Both One Way SSL and Mutual SSL are supported.
OAuth2: To control access to your API by requiring authentication and authorization using OAuth2 standards.
API Gateway: To secure APIs using MuleSoft API Manager secure policies like throttling, rate-limiting, IP white-listing, IP black-listing etc.

6. What are the different types of connectors available in Mulesoft?

Mulesoft provides a wide range of connectors for integrating with different systems and applications. Some examples are:

JMS Connector (for JMS based messaging operations)

Salesforce Connector

SFTP Connector

Database connectors (e.g., MySQL, Oracle, SQL Server)

Messaging connectors (e.g., JMS, AMQP, Kafka)

Web services connectors (e.g., SOAP, REST)

File connectors (e.g., FTP, SFTP, Dropbox)

Social media connectors (e.g., Twitter, LinkedIn, Facebook)

7. What is the difference between synchronous and asynchronous processing in Mulesoft?

In Mulesoft, synchronous processing means that a message is processed immediately and the response is sent back to the calling party in the same flow. On the other hand,  Asynchronous processing means that the message is processed in a separate thread or flow, and the response is sent back at a later time. The main differences between the two are:

Synchronous processing is faster but it is blocking in nature and can result in slower overall performance if there are long-running operations, while asynchronous processing can improve performance by allowing parallel processing.

8. What is the Mule Message structure in Mulesoft?

Mule message consists of:

Message Payload: the actual data being processed, such as a message or file.
Message Attributes: metadata associated with the payload, such as headers and properties.
Variables: temporary data holders used to store, retrieve data during the processing of the message.
Exceptions: information about any errors or exceptions that occur during processing.

9. What are different deployment options available in MuleSoft?

Mule Applications can be deployed to on-prem or cloud infrastructure in various ways. E.g. you can use CI/CD pipelines to deploy Mule Applications in an automated manner or deploying using Runtime Manager. You can also deploy directly to cloudhub from AnyPoint Studio as well.

Recommended: MuleSoft CI/CD: Deployment Automation Using Jenkins for Mule 4 Applications

10. How We can enable reusability of  integration assets like APIs, Connectors, templates  in Mulesoft?

For this purpose we can get benefit from MuleSoft AnyPoint Exchange which is a central hub for discovering, sharing, and reusing APIs, connectors, templates, and other integration assets. Its main role is to promote collaboration and reduce duplication of effort by allowing developers and teams to:

• Search for and discover existing integration assets (e.g. connectors, APIs)
• Publish and share their own integration assets.
• Collaborate with other developers and teams on integration projects.
• Reuse integration assets across different projects and environments.

11. What is the difference between flow variables and session variables in Mulesoft?

Flow variables are temporary variables that are only available within the context of a single flow or sub-flow. They are generally used to store & retrieve data that is needed for a short period of time during processing.

On the other hand, Session variables share data across different flows within the same session. They are typically used to store data that needs to persist across different flows or sub-flows in a single session.

12. What is the role of DataWeave in Mulesoft?

DataWeave is a functional data transformation language used in Mulesoft to transform data from one format to another. It provides a rich set of functions that can be used to achieve required transformations.

DataWeave provides a simple syntax for accessing, filtering, and manipulating data, and it also supports complex operations such as aggregation, grouping, and sorting.

13. What are different layers of  API-led connectivity?

MuleSoft API Led Connectivity is based on following three API layers:

System API layer: This layer exposes core system functionality as a set of reusable APIs. E.g. we can expose some of SAP core functionality through System APIs.
Process API layer: This layer APIs work as orchestration APIs as they orchestrates multiple system APIs to perform a specific business process.
Experience API layer:  This layer is used to expose APIs for external consumers. Internally this layer utilizes the exposed APIs from other two layers to serve the required purpose.

14. What is the use of RAML in MuleSoft?

RAML (Restful API Modeling Language)  is used to describe REST APIs. In MuleSoft RAML is used to create API Specifications. Using RAML, we can define API blue-prints.

15. How Automated Unit Testing can be done in MuleSoft?

For unit testing, MuleSoft provides MUnit framework. This framework can be used by developers to create and execute automated tests for their integration applications. MUnit framework helps in unit testing, integration testing and functional testing.