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MuleSoft or Mule ESB interview Questions

Here are the 18 most important and common mulesoft or mule esb interview questions and answers which are bound to be asked in any Mule ESB interview. Whether it’s Mulesoft or Mule ESB interview with Accenture, Cognizant, Infosys, Deloitte or any company below Mule ESB interview questions are always always been asked. You can easily clear any Mulesoft or Mule ESB interview questions if you learn answers to these Mule ESB questions.

1. What are Web Services?

Web service is a function or program in any language that can be accessed over HTTP. Message format can be XML or JSON or any other program as long as the other programs can understand and communicate. Web services can be synchronous or asynchronous. Any web service has server-client relationship. Any web service can have multiple clients. Eg: When a travel portal is selling tickets of an airliner, Portal is client and the Airline is the server as it is selling its service.

3. What is REST?

REST stands for Representaional State Transfer or RESTful web service. REST is a client-server architecture which means each unique URL is representation of some object or resource. Any REST API developed uses HTTP methods explicitly and in a way that’s consistent with the protocol definition. This basic REST design principle establishes a one-to-one mapping between create, read, update, and delete (CRUD) operations and HTTP methods. According to this mapping:

  • To create a resource on the server, use POST.
  • To retrieve a resource, use GET.
  • To change the state of a resource or to update it, use PUT.
  • To remove or delete a resource, use DELETE.

If we want to create a REST service that fetchs the record of a customer then our URI will be:
– GET{customerID}
where HTTP method is GET,
Resource is customer
And URI parameter is customerID which dipicts
for which resource we want to fetch the records.

4. What’s the difference between SOAP and REST?

REST is almost always going to be faster. The main advantage of SOAP is that it provides a mechanism for services to describe themselves to clients, and to advertise their existence.

REST is much more lightweight and can be implemented using almost any tool, leading to lower bandwidth and shorter learning curve. However, the clients have to know what to send and what to expect.

In general, When you’re publishing an API to the outside world that is either complex or likely to change, SOAP will be more useful. Other than that, REST is usually the better option.

6. What is RAML and why we use it?

RAML – RESTful API Modeling Language
RAML is similar to WSDL, it contains endpoint URL, request/response schema, HTTP methods and query and URI parameter.
RAML helps client (a consumer of the service) know, what the service is and what/how all operations can be invoked.
RAML helps the developer in creating the initial structure of this API. RAML can also be used for documentation purpose.

7. What are the different types of flow

Subflow – A subflow is always synchronous. It is similar to a synchronous flow, subflow executes in the same thread of the calling process. Calling process triggers the sub-flow and waits for it to complete and resumes once the sub-flow has completed.
Synchronous Flow– Same as sub-flow, the only difference is that in synchronous flows you need to separately define an exception strategy to it, it does not inherit the exception strategy of its calling flow.
Asynchronous Flow – As in sub-flow and synchronous flow, calling process triggers the sub-flow and waits for it to complete; for asynchronous flow the flow, calling process triggers an asynchronous flow and moves ahead to its next activity. An asynchronous flow executes in parallel to its calling/parent flow in a different thread. An asynchronous flow does not return its output it its parent/calling flow.
Private Flow – flow that does not have an inbound connector in the source. Means a private flow cannot start of its own on receiving the inbound message as it does not have any inbound connector, A private flow can only be called using flow-ref same as sub-flow.

8. What are the different types of variables in mule?

Flow Variable
Session Variable
Record Variable

9. Various types of Exception Handling?

Default Exception Handling
Global Exception Handling
Catch Exception Handling
Choice Exception Handling
Rollback Exception Handling

10. What are Flow Processing Strategies?

Synchronous Flow Processing Strategy
Queued Flow Processing Strategy
Asynchronous Flow Processing Strategy
Thread Per Processing Strategy
Queued Asynchronous Flow Processing Strategy
Non-blocking Flow Processing Strategy
Custom Processing Strategy

11. What are the different ways to connect a database with Mule DB connector?

Read from here Mule Tutorial: Connecting with Database

12. What all storage type can be configured in Mule Cache Scope?

Read from here Mule Tutorial – Caching In Mule | Cache Scope

13. How can we create and consume SOAP service in Mule?

Creating SOAP Service – We can create a SOAP service same as we create Mule Project With RAML, the only change is instead of RAML we need to import Concert WSDL.
Consuming SOAP Service – We can use Web Service Consumer or CXF component in our mule flow to access/consume SOAP service.

14. What are Shared Resources in Mule and how are they been used?

We can make connectors as an reusable component by defining them as common resources and expose them to all applications deployed under a same domain, these resources are known as shared resources. These shared resource needs to be defined inside Mule Domain Project and then referred to each of the projects that are meant to use the elements in it.

15. What is and why use API Gateway?


16. What and how to use transaction management in Mule?


17. How can we deploy Mule API on different environment without changing the code or configuration details?


18. What are policy in Mule and how to implement custom policy?


Varun Goel

About Varun Goel

Varun Goel is a technology enthusiast with 6+ years exp in IT industry. In fact, he is been developing application after schooling as freelancer. Currently working with one of the Fortune’s 100 Companies having vast experience Mule ESB, Tibco, HTML5, CSS, JSS, Android, Core Java, JSP, PHP, MySQL, AutoCAD, Maya, ZBrush, Photoshop, Flash CS and many more.


  1. anonymous

    Hi Sir,
    I have 3 year experience in Tibco BW 5.13. I am planing to switch my career in mulesoft,
    But I am confused to switch in mulesoft so could you please guide me?

    1. Varun GoelVarun Goel Post author

      Hi Sir,
      I too have worked on Tibco 5.11, 3 years back and then switched to MuleSoft. With Tibco 6 out in the market couple of years back Tibco 5 has less value and opening. And when you already know 1 technology its always good to learn new. Mulesoft is very similar to tibco and you wont face any problem learning it. Mulesoft is currently a hot skill in the market. All the best.

    1. Varun GoelVarun Goel Post author

      Hi Sudheer,
      Yes Mule is currently in big demand and there are lots of opening for it. If you have core java knowledge as well then its a big plus.
      For freshers though its very difficult to get a job no matter how much technical knowledge they have.
      I would definitely recommend you to learn Mule and Java. All the best.

  2. MaxMule

    Guys if your well versed in mule then why you need interview questions…… @Admin there is a chance fake candidate can misuse this

    Post only basic interview questions not real time


    1. Varun GoelVarun Goel Post author

      Hi MaxMule,
      Agreed, there can be that chances as well, but if candidates have to fake they will even if I post or not.

  3. Ravindar


    Could you please write some more questions ,which frequently asking in interview.


  4. Shrikant Joshi

    Please elaborate more on server startup property “-Dmule.verbose.exceptions=true and accessing exception tree using #[exception.Info.get(‘Payload’)]. what are different options available for accessing exception payload mule.

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