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Mule ESB Interview Question And Answers

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If you're preparing for an interview for a Mulesoft developer or architect role, you might appreciate some guidance on the types of questions you might expect to be asked. Every company's integration environment will be unique. In order to be picked and trained further, interviewers want applicants to have at least 60% to 70% of basic knowledge in line with their organization’s environment.

Although each interview will be different, common questions will inevitably be asked. Mulesoft is a fantastic field and with that in mind, we have researched and organized top Mulesoft 4  Interview Questions from industry experts.

In This Mule ESB Interview Questions, You Will Learn

Basic Mulesoft Interview Questions

Advanced Mulesoft Interview Questions

Top 10 MuleSoft Interview Questions

1. What is MuleSoft?

2. What is Mule ESB?

3. Why is Mule ESB so popular?

4. What are the Features of Mule ESB?

5. What is the definition of Web Services?

6. How to select an ESB?

7. What is Transient Context

8. What is REST?

9. What is Mule Context?

10. What exactly is DataWeave?

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Basic Mulesoft Interview Questions

If you're a beginner in this field and this is supposed to be your first job, you'll be asked the questions listed below.

Q1. What is MuleSoft?

Ans. MuleSoft is a next-generation integration platform used for connecting Data, Applications, and APIs on-premises and over the cloud platform.

MuleSoft works on the AnyPoint Connectivity Model which helps in connecting any existing SaaS-based applications or set of APIs through one single API interface.

The architecture is service-oriented which gives the flexibility to access all the required applications through this integration.

MuleSoft owns the Programmable Web portal that is widely used by application developers to help them build web, mobile, and other user applications.

So Mule is the most popularly used application integration and communication platform for business needs.

Q2. What is Mule ESB?

Ans. ESB stands for enterprise service bus, Mule is a runtime engine of the Java-based ESB integration platform. It allows the development teams to connect and access flexibly and easily exchange data.

It helps to enable easy integrations between application platforms without creating fuzz about different technologies being used by the applications (such as HTTP, SaaS, Payment Gateways, Web services, JMS).

EBS can be implemented and deployed anywhere in the application network. It triggers events in real-time or in the batch system providing global connectivity.

Q3. Why is Mule ESB so popular?

Ans. MuleSoft is a lightweight technology that supports a high level of scalability, which means it allows you to start small and scale as per your requirement. You can connect N number of applications within a single environment which has zero restriction for Apps communication.

Mule ESB manages N number of application interactions with each other without restricting that application into the same VM interaction or other VM interaction.

It means even though the application is running into different VMs, they can interact with each other.  Its flexibility with transportation protocol enables the interactions easily. 

Though there are many ESBs available in the market, MuleSoft gives you the most flexible and reliable services.
Another EBs comes with the restriction of limited functionalities or access to an existing application server or a specific messaging server, they put restrictions for the use of a specific vendor.

Whereas, MuleSoft comes with a high level of accessibility and adaptability with vendor-neutral methods. You can easily plug and play any application through any vendor.

Q4. What are the Features of Mule ESB?

Ans. Mule ESB is equipped with the following features:

  • It has a simple drag-and-drop graphical design.
  • Visual data mapping and transformation are possible with Mule ESB.
  • Hundreds of pre-built approved connectors are available to the user.
  • Monitoring and management are centralized.
  • It has a strong security enforcement capability for the company.
  • API administration is a feature that it offers.
  • For cloud/on-premise connectivity, there is a safe Data Gateway.
  • It offers the service registry, which publishes and registers all of the services exposed by the ESB.
  • A web-based management console gives users access to the system.
  • The use of a service flow analyzer allows for quick debugging.

Q5. What are the different types of Primitives used in Mediation?

Ans. These are the different types of primitives in mediation:

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

Q6. What are various types of Exception Handling?

Ans.

  • Choice Exception Handling.
  • Catch Exception Handling.
  • Rollback Exception Handling.
  • Global Exception Handling.
  • Default Exception Handling.

Q7. What is Shared Resource in Mule and how have they been used?

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

Q8. What are the different ESBs in the market?

Ans. There are various ESB's available in the market. Some are open-source, some licensed:

  • Talend
  • Mule ESB
  • JBoss Fuse ESB

Q9. Mention the various types of variables in mule

Ans.

  • Flow Variable: This variable is used to set or remove variables associated with a specific message in the current flow.
  • Record Variable: Batch processing flows employ the Record Variable.
  • Session Variable: Throughout the lifecycle, this variable is used to set or remove variables associated with a certain message.

Q10. What is the definition of Web Services?

Ans. 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.
Any web service has a server-client relationship. Web services can be synchronous or asynchronous. Any web service can have multiple clients.

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Q11. How to find when the project needs ESB?

Ans. ESB implementation is not suitable for all projects. Proper analysis should be done if the use of ESB will really benefit the project.
Some of the points to be considered while analyzing the need of ESB are as follows:

  • If the project requires integrating 3 or more applications/services. If the need is to communicate between two applications, using point-to-point integration would suffice.
  • If the project would need to be scaled in the future where it might be needed to interact with more services in the future. Not all projects need this as they may perform not that big a task.
  • If the project needs message routing capabilities such as forking and aggregating message flows. Such features are not required by all projects.
  • Is the architecture of what is to be achieved clear. It's much better to do simple POCs integrating small parts to evaluate the benefits.
  • Most ESBs are a costly affair. Does the project budget allow the use of ESB.

Q12. What are the different types of Flow Processing Strategies?

Ans. There are six different types of Flow Processing Strategies. They are

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

Q13. How to create and consume SOAP service in Mule?

Ans.

  • Creating SOAP Service – We can create a SOAP service the 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.

Q14. Explain ESB Integration core principles?

Ans.

Transformation - Data transformation between canonical data formats and specific data formats required by each ESB connector. Transport protocol negotiation between multiple formats. Such as HTTP, JMS, JDBC.

Mediation - Providing multiple interfaces for the purpose of

  • Supporting multiple versions of a service for backward compatibility or alternatively.
  • Allowing for multiple channels to the same underlying component implementation. This second requirement may involve providing multiple interfaces to the same component, one legacy interface (flat file), and one standards-compliant (SOAP/XML) interface.

Non-functional consistency - For a typical ESB initiative, this can include consistency around the way security and monitoring policies are applied and implemented.

Q15. How to select an ESB?

Ans.

  • Usability: How complicated is the installation process? The learning curve of the ESB should not belong.
  • Maintainability: How to monitor the product? If any GUI terminal is available for monitoring the services.
  • Community: Is there an active community for the ESB. Various discussion forums, tutorials, etc. Enterprise Support- Is the product support reliable. What services are available.
  • Flexibility: Can the ESB be configured to meet the business requirements.
  • Reliability: The reliability of the ESB. Its current users and various case studies if available.
  • Cost: The cost of the ESB. Its Licence policies. Support costs. etc.

Q16. What does the statement “Any Point Platform '' mean to MuleSoft?

Ans.

MuleSoft is a secure, robust, and highly scalable communication network that allows the application to do self-services, it helps organizations to integrate applications, data, and multiple devices in a flexible environment.

It is a hybrid application integration platform that includes ESB, unified solutions for APIs management, iPaaS, application design, and publishing. 

MuleSoft allows using N number of software and tools which includes the below list 

  • API Designer- Any Time Design Center
  • Any Point Studio- Any Point Design Center 
  • API Manager-Any Point Management Center
  • API Analytics-Any Point Management Center 
  • API Portal-Any Time Exchange 
  • MCQs- Runtime Services 
  • Mule ESB-Mule Runtime Engine 
  • Any point Connectors 
  • CloudHub- Hybrid Cloud 
  • Mule Enterprise Management 
Related blog: Differences between Dell Boomi and MuleSoft

Q17. What are the advantages of using an ESB?

Ans

  • High level of operational control from the central web-based portal. 
  • Wide range of connectivity through more than 120 leading SaaS-based applications on-premises.
  • Ensuring zero message loss reliability and gives you high availability. 
  • Custom code out of data mapping with graphical integration and transformation 
  • Analytics and API Management 
  • Equipped with thousands of automated tests and bug fixing techniques.
  • EDI/B2B Integration 
  • Batch Integration with Real-Time Integration techniques 
  • Premium connectors for HL7, Oracle, Epic, and SAP. 

Q18. What is Transient Context?

Ans.

  • Transient Context is used to pass the required values within the existing flow either the requesting flow or the responding flow. The transient flow could not make it link requests or responses together, so it is not used across.
  • It is not being used if you want to save an input message before service gets invoked into the request or response flow. 
  • Transient is made to act as temporary storage of messages in general after the service invokes a call, the next primitive creates another message by combining the two, first the invoked response and second the original message that is stored in the Transient Context.  

Q19. What are the different types of messages in MuleSoft?

Ans.

  • Echo and Log messages- Echo and log messages move from inbound to outbound routers.
  • Bridge Message – Basically, a passed message from inbound to outbound routers.  
  • Build Message- Messages that are created from fixed or dynamic values.  

Q20. What is API? Define the most prominent features of API.

Ans. API (Application Programming Interface) is a software interface that allows two different applications to interact in one platform. 

  • API has N number of benefits in terms of user’s usability 
  • APIs have become modern and advanced over time, it adheres to many standards such as HTTP and REST. 
  • APIs are developer-friendly, easy to understand, and broadly acceptable.
  • APIs are mostly used as a product rather than a set of codes. They are specifically designed for a particular group of audiences such as application developers, and Mobile App developers.
  • Every API comes with detailed documentation with version-specific information and up-gradation details. 
  • APIs are highly secure application interfaces that allow you to operate within a robust environment. 
  • APIs similar to any software product have their own SDLC (software development lifecycle).

Q21. What is REST?

Ans. REST stands for Representational State Transfer or RESTful web service. REST is a client-server architecture which means each unique URL is a 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.

Q22. What is RAML and why do we use it?

Ans. RAML – RESTful API Modeling Language

  • RAML is similar to WSDL, it contains endpoint URL, request/response schema, HTTP methods, and query and URI parameters.
  • RAML helps the 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 purposes.

Q23. What are the Message Sources in Mule ESB?

Ans. Message sources in Mule are usually Anypoint Connectors, elements that provide connectivity to a specific external source, either via a standard protocol (such as HTTP, FTP, SMTP) or a third-party API (such as Salesforce.com, Twitter, or MongoDB).

Q24. What is the difference between ESB and JMS?

Ans.

  • ESB provides the middleware and interfaces that allow businesses to connect their applications without writing code.
  • JMS provides the messaging capability and facilitates communication between the modules/applications.

Q25. Why is Mulesoft preferred over other ESB implementations?

Ans. Mule is lightweight but highly scalable, allowing you to start small and connect more applications over time.

The ESB manages all the interactions between applications and components transparently, regardless of whether they exist in the same virtual machine or over the Internet, and regardless of the underlying transport

protocol used.

Several commercial ESB implementations provide limited functionality or are built on top of an existing application server or messaging server, locking you into that specific vendor.

Mule is vendor-neutral, so different vendor implementations can plug into it. You are never locked in to a specific vendor when you use Mule.

Q26. Define Payload In MuleSoft

Ans. The payload is a Mule Runtime Variable that stores arrays or objects. It is wrapped under an org. mule.api.MuleMessage helps you get the different means of accessing the payload under different forms.
Mule messages are similar to any other SOAP JMS message; it also containers properties, headers, and multiple names attached to them. The main content of the message is called Payload. 

Q27. Explain the concept of endpoint?

Ans. An endpoint is a destination shared by many other routers in the group. It also helps to create a global endpoint. A global endpoint is not similar to an inbound and outbound routing service, but it makes it useful in many different places in the configuration file.

The entire endpoint destination must be named to be specified during the services. These names identify the global endpoint in the group of routers. The global endpoint also offers to clarify the usage of a specific destination. 

Various types of Endpoints in Mulesoft are HTTP, JMS, IMAP, SMTP, and AJAX.

Q28. Explain Mule Transformer

Ans. Mule transfer is an event instance that belongs to org.mule.api.MuleEvent library. This object carries the actual context of the message with the context of the event.
The main purpose of the transformer is to translate the message from one form to another. It is also possible to create a chain of transformers. It transits the message from one medium to another while staging into different services. 

Q29. What is the Transport Service Descriptor (TSD) in Mule?

Ans. The Transport Service Descriptor (TSD) is a technical configuration of the connector. This is a hidden configuration that is used in each instance of the connector.
It gives definitions to the parameters such as the use of particular parameters, what classes are required for that particular message receiver, dispatchers, and requesters.
The definition is about default transformation to use inbound or outbound and utilizing the response of the router. 

Q30. What Router is MuleSoft?

Ans. The router is one of the most critical services of MuleSoft. The Router finalizes and assigns the running territory for the messages to move from one service to another.
Basically, routing is a process of controlling the transitory decided by the router for the moving message to transit from one source to another. It can be also called a gatekeeper of the endpoint services.
It keeps track of targeted successions to ensure the message gets to deliver to the right intended destination. Routers can also act as a bundle of classified tasks, such as it can split, sort, group, or regroup messages based on specified conditions or certain mappings. 

Q31. Define the use of Filter in Mule.

Ans. Filters are the most powerful capability given to the routers to make smart decisions on the message delivery or request and response environment.
It also gives sight to the router to decide what to do with the messages in the transit stage. Some filters go through intense analysis of the message to find out the actual value for the desired outputs.  

Q32. Define SDO and SMO.

Ans.

  • SDO stands for service data objects that are the representation of variables and objects. 
  • SMO stands for Service Model Object and it is a pattern for using SDO for messages.

Q33. Define the purpose of Endpoint in Mule.

Ans. Endpoint defines the specific usage of the transport protocol. Whether you are reading the message, writing it, listening, or polling to a targeted destination the endpoint directs the usability of the protocol.
Endpoint controls the underlined entity which ensures the usability of the connectors. The targeted destination is defined as URI. It depends on the connectors whether the destination will be treated as URI or URL or JMS destination itself. 

Q34. What is the difference between service invoke and Callout?

Ans.

Service Invoke:

Service invoke is an initial process of creating a service for either request or response flow. The service can be request, response, or both and One-way implementation.

Multiple instances of a service can be created and permitted into a flow, that allows a series of services to operate within the flow.  

CallOut:

The purpose of the CallOut method is to receive messages and request the required service and operation in a flow. There is a CallOut node always presented into the median flow for connected target operation.

  • If the call attempt is successful the callout node in the responses flows median will start receiving the message.
  • If the call attempt is unsuccessful the callout node will be set to retry service in the flow depending on the type of fault that occurred. 

Q35. What is Mule Context?

Ans. In general, the message context defines the overall purpose of the message but here the context defines the temporary area which is created along with the SMO(server message object) in the median flow while the transition of the message.

SMO contains the shared context in the message flow. This shared context usually gets used at the time of aggregation, which means if you are aggregating and need to iterate the BO for the specified time.

Aggregative context maintains data between FanOut and FanIn primitives. The data(context) present in the request flow cannot be persistent throughout the request and response flow because it only belongs to the request BO.  

Q36. How are the messages in Mule composed?

Ans. The four different parts of the composed message in Mule

  • Payload - It’s the main data context carried by a particular message
  • Properties - Contains the Meta information or header similar to the SOAP message.
  • Multiple Name Attachments - To provide support for multipart messages. Or an exceptional payload for holding errors that occur during the event processing. 

Q37. How to judge the need for ESB in a project?

Ans. Project applications need to be analyzed very carefully to avoid unnecessary arrangements. ESB benefits in several ways for projects which need to operate in a huge setup of multifunctional application support. 

Q38. The analysis depends on many factors such as.

Ans.

  • If the project requires a group of actions with additional applications and servers where the interaction is happening between two or more complex resources.
  • If the project needs a broad scale up in the future and requires multiple application communication over a single setup.
  • If the project requires to route the messages between one end to such as forking and aggregation of the routed messages.
  • If the project allows this huge investment in need of application support. 

Q39. Define Fileage properties in file connector in MuleSoft?

Ans. File age defines the waiting duration of the endpoint before starting to read the file again. Such as file age 60000 indicates that the endpoint should wait about 1 minute before starting the next processing.  

Q40. What is the streaming property in the file connector in MuleSoft?

Ans. Streaming properties in connectors represent the values in true and false format. If the streaming value is true, it means you are working on streaming data on the connector otherwise if it’s false you are working on the file system. 

Q41. What is the polling frequency in the file connector in MuleSoft?

Ans. If you want a new file inbound endpoints to poll direction to read the new content then you require to set the polling frequency to a few milliseconds to achieve this. Here polling frequency defines the value of the poll.

Q42. Explain what is Configuration builder is MuleSoft

Ans. Configuration builder in Mule helps to transfer the human authorized configuration file into a complex graph of objects that substitute a running node in ESB. Configuration builder can be defined into two types:

  • Spring Driven Builder: It works with XML files 
  • Script Builder: It accepts scripting language files. 

Q43. Explain the concept of the Auto-Delete feature in the file connector.

Ans. The auto-delete value of this feature is zero by default which means its inbound endpoint will automatically delete the file from the source directory.

In case the source directory file does not require to be auto-deleted then you need to set the value to false. 

Q44. Difference between ESB and JMS 

Ans.

  • ESB solves the business problem by providing middleware support for application integration and communication issues without writing code.
  • JMS helps you get equipped with messaging capability and solve the communication issues between modules and instances. 

Q45. Explain the working functionality of the service layer. 

Ans. Mule service is a set of all Mule entities that is required to support the processing request in an arranged manner. This service is defined by a particular configuration that defines the different elements from a different layer of services.

It mobilizes the request which is open to receiving a particular request. It depends on the service layer's input channels whether a service can or cannot be accessible outside in a public ESB. 

Q46. List of flow processing strategies in MuleSoft.

Ans. It represents six types of strategy for Flow Processing 

  • Asynchronous Flow Processing
  • Custom Flow Processing 
  • Tread Per Processing 
  • Queued Asynchronous Flow Processing 
  • Synchronous Flow Processing 
  • Non-blocking Flow Processing 
  • Queued Flow Processing 

Q47. Define the available resources used for modularizing configuration in mule?

Ans. There are many resources available for modularizing configuration in Mule as:

Independent Configuration

A Mule instance is capable of loading multiple independent configuration files one after another.

Inherited Configuration

As the term inheritance refers to the parent and child relationships between the instances this configuration also showcases the parent-child relationship between two configurations.
It strongly provides this dependency with the guarantee that no configuration file will be omitted at the time of application booting. It used the same name for the parent and child models. 
For ex: 

<model name=”myConfig”><model name=”myConfig” inherit=”true”>

Imported Configuration 

It supports spring configuration so that you can easily use your spring config file to Mule configuration files. 
For ex: you need to extend instance.xml then it will import the spring context file: 

<spring:beans>,<spring:import resources=”instance-beans.xml”/></spring:beans>

Heterogeneous configuration  

As the term, heterogeneous means you can configure many types of files using this configuration method. The instances can be created using the Groovy script method and Spring XML Configuration builders.

Q48. Explain Transport layer functionality in MuleSoft.

Ans. The main operating task for the transport layer is to send and receive messages through the inbound and outbound communication networks. The transport layer gets configured with connectors, endpoints, and transformers. 

Transport is also responsible for the message adapter where the responsibility of the adapter is to extract all the information from the particular request such as data, Meta information or header info, and attachments. It also stores the information available in it.

Q49. Explain the functionality of Fan-In and Fan-Out

Ans.

Fan-Out: you can use Fan-Out primitive to trigger the output terminal initially with the input message or many times as per need. Fan-Out can be used individually or as a combination of Fan-In and Fan-Out. 

Fan-In: FanIn in a combination with Fan-Out works as a decision point to identify when to continue flow execution in the connector.

It accepts “N” number of messages until the decision point is made. The last message received in the flow is represented as an output terminal. 

Q50. What configuration is required for JDBC Adaptor implementation?

Ans. JDBC adaptor configuration is not a complex task for those who have experience in connecting DB. You need a data source to be connected and configured with a database.

Also if your DB is having secure access then you need to create a security authentication program.  

Q51. Name the technique of implementing a loop in mediation?

Ans. Fan-In and FanOut is the method to implement a loop in the mediation.

Q52. Explain the concept of Correlation Context.

Ans. When the mediation primitive requires passing the value from the request flow to response flow the correlation context plays the role. 

Q53. List out the primitives used in Mediation.

Ans. Mediation has many primitive as below 

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

Q54. Define Mule UMO

Ans. UMO is Universal Message Object; UMO components are also referred to as service components. 

Q55. Explain Mule Data Integrator.

Ans. Data Integrator tool is launched by Mule, which is a data visualization mapping tool having support for flat files, XML Mapping, and Java objects.

It was a tedious task for the developer to code complex mapping functionalities so the Mule Data Integrator tool provides drag and drop features to make the coding process easier. 

The mapping process gets support from eclipse (where plug-in has to be done before the process) to run the Data Integrator which is part of top layer applications in Mule Architecture. 

Q56. Find out the path for class Abstract Mule TestCase?

Ans. The path for Abstract Mule TestCase is  <mulehome>/lib/mule/mule-core-<version>.jar

Q57. What are the advantages of using Mulesoft?

Ans. There are many advantages of the MuleSoft integration platform

  • Very lightweight but highly scalable. 
  • It allows you to connect over a large scale of applications so that you can expand large over time. 
  • ESB ensures that the communication stays uninterrupted and consistent between the applications. 
  • Despite using the same protocols for Virtual Machine it allows you to build and maintain communication between applications. 
  • Ability to integrate and connect over a vast range of application networks.
  • POJO integration support to connect other components in the network.
  • Reusability of Components 
  • You can use existing components without writing MuleSoft specific codes.
  • A wide variety of vendors can be plugged in as it is a vendor-neutral solution.
  • Eliminates vendor dependencies by reducing vendor restrictions.
  • Can be deployed into n numbers or topologies despite sticking to one ESB as per your business need.
  • The great adaptability of change for higher business support. 

     

    Advanced Mulesoft Interview Questions 

If you are an experienced professional in this field who wants to advance in your career, you should read the following interview questions.

Q58. What is the MuleSoft Anypoint platform?

Ans. MuleSoft Anypoint is a unified integration platform that takes a comprehensive approach to API design and implementation. MuleSoft has around 300 databases, a SaaS platform, storage resources, and network service connections.

Q59. Explain Mule Expression Language (MEL).

Ans. MEL is a Mule-specific expression language that is used to access and analyze data in a Mule message's payload, variables, and properties. MEL allows you to rapidly and elegantly filter, route, or otherwise operate on the distinct components of the Mule message object. It is accessible and usable from practically every message processor in Mule.

Q60. What is the use of RAML in Mulesoft?

Ans. From designing and deploying to sharing the API lifecycle in Mulesoft everything is managed by RESTful API Modeling Language (RAML).  The information needed to describe RESTful APIs is best expressed in RAML. It's similar to WSDL (Web Services Description Language). Request/response schema, endpoint URL, URI parameter, HTTP methods, and query are all included in RAML.

Q61. Describe Caching

Ans. In Mulesoft, the concept of caching is to store and reuse frequently called data. The scope of Cache is used to decrease the processing load on Mulesoft and to improve the message processing speed within a flow.

Q62. How do you implement caching in Mulesoft?

Ans. Using Cache scope or object-store, you can implement caching in Mulesoft. Internally cache scope uses Object store for data storage. Both Cache scope and Object store have their particular use cases whenever required effectively.

Q63. How may the Mule application's performance be improved?

Ans

  • Over VM endpoints, try using flow references.
  • Connectors should ideally employ connection pooling.
  • Transforms can be done with Dataweave.
  • In apps, try to stay away from session variables. Performance is harmed by serialization and deserialization of session variables.

Q64. What are MuleSoft's integration patterns?

Ans. The patterns serve as a framework for developing, implementing, and integrating messaging and integration systems, as well as a common language for teams to use when developing solutions. Mule minimizes the time it takes to build integrations by using the patterns you use to create solutions.

Q65. Explain Mule Errors.

Ans. Errors occur when Mule executes a command. When a Mule app is operating, the Mule runtime engine as well as the module and connector activities set in the app might throw errors, which are represented by a Mule error object and are associated with a Mule event. With On-Error components, you can handle error objects and track them down in the logs.

Mule errors are classified into error kinds, which are organized in a hierarchical sequence and have a naming standard to assist you to identify the cause of the error and treat it at the appropriate level. Custom error types can also be created and mapped to these errors. The mappings might assist you in better distinguishing and grouping errors in your program.

Mule errors can be classified into two groups:

System Errors: When a system error occurs and no Mule event is involved, Mule throws a system error.

Messaging Errors: Whenever an issue arises within a Mule app's flow when Mule events and the messages they contain are handled, Mule throws a messaging error (a Mule error).

Q66. Describe MUnit in-detail

Ans. MUnit is an application testing framework of Mule that lets you create automated tests for your APIs and integrations quickly and effectively. It comes with a full set of integration and unit testing tools, as well as a Maven and Surefire interface for seamless integration with your continuous deployment infrastructure.

Since Mule 4.0, MUnit version 2.3 has been compatible with all Mule releases. You may use MUnit to:

  • Using Mule code, create your test.
  • Processors that act as dummies
  • Any processor can be seen.
  • Check processor calls for accuracy.
  • Tests can be enabled or disabled.
  • Tests with labels
  • The studio provides visual coverage.
  • Produce reports on coverage

MUnit is tightly linked with Anypoint Studio, allowing you to create, design, and run MUnit tests in the same way that Mule applications are.

Q67. Define AnyPoint Exchange 

Ans. The ability to explore, distribute, and incorporate assets and resources into your apps is one of the benefits of Anypoint Exchange. Build API developer portals, test and view APIs, build assets, simulate data to APIs (Mocking Service), and utilize API Notebooks to describe and test API functionality using Anypoint Exchange.

Q68. What services and tools does Mulesoft provide?

Ans. MuleSoft provides rigorous and effective assistance with data integration. MuleSoft provides the following services and tools:

  • API Designer is a web-based tool for JavaScript development that includes a console and a scripting notepad.
  • API Manager is a management solution that helps firms manage users, traffic, and SLAs.
  • Anypoint Studio is a graphical interface for creating and editing APIs and integrations.
  • API Portal provides developers with a variety of API-related documentation, tutorials, and code samples.
  • API Analytics is an analytics tool that lets users track an API's parameters. Its performance, functionality, and dependability are all factors to consider. A dashboard and charts are also included.

Q69. In MuleSoft, what exactly is a batch job?

Ans. Mule processes a message payload as a batch of records in a batch job, which is the scope element of an application. All three phases of processing are included in the phrase batch job: load and dispatch, process, and completion.

Q70. In MuleSoft, what precisely is a batch aggregator?

Ans. A Batch Aggregator populates a collection with data until it reaches the Nth record, which is equal to the Batch Aggregator's size attribute. The payload of the Mule Message that is processed by the Batch Aggregator processors is then the collection, which contains all records.

Q71. What are the benefits of batch processing?

Ans. Batch processing is a method for automating and processing a large number of transactions at once. Batch processing is useful for processes such as payroll, month-end reconciliation, and overnight trade settlement.

Q72. What are connectors in MuleSoft?

Ans. A connector is software that links a Mule flow to an external resource. The resource can be any content source, such as a database, protocol, or API. You can create a connector using the Anypoint Connector DevKit and the Anypoint Studio IDE. To make a connector, you'll need Java 6 or 7.

Q73. What are Anypoint connectors, and how do you use them?

Ans. Anypoint Connectors are reusable Mule runtime engine (Mule) extensions that allow you to connect Mule apps to third-party APIs, databases, and standard integration protocols. The connector configuration can be changed without requiring other elements of the program to be updated.

Q74. In Mulesoft, what is a Flow?

Ans. A flow is a series of Mule components that are linked together. An inbound endpoint component (from where the communication originates) and an outbound endpoint component are typically included in flow. As a result, the flow is in charge of all of the message's processing phases.

Q75. What’s the difference between flow and subflow?

Ans. 

  • Exception handling is handled differently in a private flow. Despite the fact that a sublow handles messages synchronously, the caller flow provides the processing strategy and exception handling.
  • Flows can be triggered by sources. No event sources exist in subflows. 
  • When compared to subflows, referring flows have a lower performance. 
  • Error management can be customized for each flow. Error handling is absent in subflows. 

Q76. What is MuleSoft's CloudHub?

Ans. CloudHub is a platform as a service (PaaS) component of Anypoint PlatformTM, which is a global, fully managed, multi-tenanted, secure, and highly available API and integration platform. You'll get regular software upgrades, and you won't have to worry about complicated hardware upkeep.

Q77. What is MuleSoft's API Notebook?

Ans. API Notebook is a web-based tool for creating interactive Javascript tutorials and demonstrations.

Q78. What MuleSoft deployment options are available?

Ans

  • On-premise 
  • Runtime Fabric (RTF)
  • Anypoint PCF (Anypoint Platform for Pivotal Cloud Foundry)
  • Anypoint PCE (Anypoint Public Cloud Edition) 

Q79.  What is PCE?

Ans. In Mulesoft, PCE is an acronym for Platform Cloud Edition. Mule apps are managed and executed on your local servers with Anypoint Platform Private Cloud Edition (Anypoint Platform PCE). High availability and scalability are built-in to the Anypoint Platform PCE thanks to Docker and Kubernetes. Without knowing Docker or Kubernetes, you can install the platform.

Q80. What is Runtime Fabric (RTF) in Mulesoft?

Ans. In Mulesoft, Runtime Fabric is a container service used for deploying mule runtime on the data center or on the cloud. All the benefits of the cloud such as high availability, rolling upgrade, automatic failover, etc., are all supported by Runtime Fabric. Additionally, you can even deploy multiple versions of mule runtime using Runtime Fabric.
Runtime Fabric Architecture is a set of VM work together to form a cluster. And each VM serves as either “worker” or “controller” mode in the cluster.
The controller node manages load balancing, distributed database, and orchestration service. Workers node manage mule applications and API gateways.

Q81. Describe Mule Maven Plugin

Ans.

Mulesoft application deployment and undeployment are managed by Mule Maven Plugin. With Enterprise Mule Runtime engine and Community Mule Kernel, you can utilize it. You can automatically deploy applications to the cloud, on-premise, and Anypoint Runtime Fabric Manager.
Mule Maven Plugin supports the following tasks:

Package: Used to execute a file or generate jar to Mule application.

  • mvn package

Deploy: Used to upload, deploy, and run the application on the target system.

  • mvn deploy -DmuleDeploy

Undeploy: Used to delete applications from the target system.

  • mvn mule:undeploy

Q82. What is watermarking in Mule 4?

Ans. Mulesoft Watermarking is a technique associated with duplicating processes while synchronizing data. Watermarking is the most common use of the object store.

Q83. In which time zone MuleSoft scheduler operates?

Ans. Schedulers use the same time as the machine on which Mule is operating. Mulesoft Schedulers always operate in UTC/GMT timezone.

Q84. Can you brief me about Anypoint MQ?

Ans. Anypoint MQ is a cloud messaging, multi-tenant service that allows users to achieve advanced asynchronous messaging scenarios between their applications.
Permits role-based access control, connectors, and client management by fully integrating with the Anypoint Platform.

With Anypoint MQ Connector, you can connect Mule Apps to ANypoint MQ. Through this, you can post and receive messages, acknowledge and delete messages from queues and exchanges. 

Q85. What are the 4 different ways to connect Anypoint VPC to a private network?

Ans. Using the following methods, you can connect Anypoint VPC (Virtual Private Cloud) to a private network:

  • Transit gateway attachment.
  • AWS Direct Connect.
  • IPsec tunnel.
  • VPC peering. 

Q86. Do peering connections have any bandwidth restrictions?

Ans. Bandwidth between instances in peering VPCs is the same as bandwidth inside the same VPC.

Q87. Is it possible to connect two VPCs with IP addresses that are identical?

Ans. No, the IP ranges of peering VPCs must not overlap.

Q88. Can I connect to a VPC in a different area using peering?

Ans. Peering between regions is currently unavailable. Both VPCs must be in the same region.

Q89. Explain about Dedicated Load Balancers (DLB).

Ans. CloudHub dedicated load balancers (DLBs) are an optional component of Anypoint Platform that allows you to route external HTTP and HTTPS traffic to various Mule apps running on CloudHub workers in a Virtual Private Cloud (VPC).

You can do the following using dedicated load balancers:

  • Handle load balancing between the CloudHub workers that operate your project.
  • Create SSL setups to give bespoke certificates and enforce two-way SSL client authentication if desired.
  • Set up proxy rules to link your applications to specific domains.
  • This allows you to host all of your apps on a single domain.

A dedicated load balancer for your Anypoint VPC can be created and configured in three ways:

  • The Anypoint Platform's Runtime Manager
  • Using the Anypoint Platform CLI's cloudhub load-balancer build command
  • These endpoints allow you to access the CloudHub REST API:

anypoint.mulesoft.com/cloudhub/api/organizations/{orgid}/loadbalancers

anypoint.mulesoft.com/cloudhub/api/organizations/{orgid}/vpcs


Q90. In MuleSoft, what exactly is an API manager?

Ans. API Manager is a component of the Anypoint Platform that allows you to manage, control, and secure APIs. API Gateway and Anypoint Service Mesh, both of which enforce policies, collect and track data of analytics, handle proxies, offer encryption and authentication, and manage applications, are used in the runtime.

Q91. What is the difference between an API manager and an API gateway?

Ans. While API gateways and API management are often used interchangeably, API management refers to the overall solution for managing APIs in production, which may include a cluster of API gateways, an administrative UI, and even add items like a developer portal for customers to sign up and generate new API keys.

Q92. Throttling vs. Rate Limiting: What's the Difference?

Ans. API Policies such as Rate Limiting and Throttling are available in MuleSoft, and you may use API Manager to implement them.

Rate Limiting: This policy restricts the number of requests an API can take in a certain period of time. Requests that exceed the limit will be rejected by the API.

Throttling: The Throttling policy puts requests that exceed their limitations in a queue to be processed later. If the processing fails after a specific number of attempts, the API will eventually refuse the request. You can set a retry delay and a retry limit.

Q93. What is the benefit of using MuleSoft Design Center?

Ans. Anypoint Design Center gives you the tools you need to create connectors, implement data and application flows, and make API design, reuse, and testing much easier.

Q94. What is Mule Runtime Manager, and what does it do?

Ans. Runtime Manager is an Anypoint Platform tool that lets you deploy and manage all of your Mule applications in one place, whether they're in the cloud or on-premises.
Anypoint Platform now has the ability to manage Scheduled flows from Mule Runtime 3.9.0 onwards.

Q95. What is a vCore MuleSoft?

Ans. On Cloudhub, it is a unit of computing capability for processing. A maximum of 10 apps can be deployed on a single vCore, with each mule program consuming 0.1 vCore.

Q96. What exactly is DataWeave?

Ans. DataWeave is a functional programming language that focuses on data transformation. It's MuleSoft's main data transformation language, as well as the expression language for configuring components and connectors. DataWeave, on the other hand, can be used in different ways, such as as a command-line tool.

Q97. How can you get access to Dataweave's secure properties?

Ans. You can access the secure property defined as part of the secure property file in the mule application by using p('secure::property name>').

Q98. What is the best way to call Flow from within a data weave?

Ans. To call flow from inside a data weave, you can use the data weave lookup function. It's compatible with Mule programs that run on Mule Runtime 4.1.4 or later. It accepts two parameters: the name of the flow and the input payload. For example, Lookup("flow name", payload").

Q99. In MuleSoft, what exactly is a batch aggregator?

Ans. A Batch Aggregator populates a collection with data until it reaches the Nth record, which is equal to the Batch Aggregator's size attribute. The payload of the Mule Message that is processed by the Batch Aggregator processors is then the collection, which contains all records.

Q100. What is distributed file polling, and how does it work?

Ans. Distributed file polling is used in Mule 4 to poll files across cluster nodes. This feature is enabled by default in only a few connectors.

  • File Connector
  • FTP Connector
  • SFTP Connector

Connectors can be configured to poll exclusively from the primary node @primaryNode Only, overriding the mule runtime engine's default setting.

Q101. How can we use mule flow to process only one message at a time?

Ans. We can create a flow that runs in a single thread; there is an option to set the Max Concurrency to 1, which will process only one message at a time.

Q102. How can you use a Dataweave to call a Custom Java Class?

Ans. The following is an example.

%dw 2.0
Import java!com.
mycompany::classname
output application/json
---
{
  a: classname::methodName("myString")
}

Q103. In Dataweave, how do I log a message?

Ans. In Dataweave, use the log(" Current Timestamp ",now()) function.

Q104. In Dataweave, how do you merge two Arrays?

Ans. To combine two arrays into one, use the flatten operator.

Q105. What is the purpose of identity management?

Ans. Users can be set up for single sign-on using identity management.
The SSO Standard is listed below.

  • Open ID connect
  • Open AM
  • OKTA
  • PingFederate
  • SAML 2.0
  • Salesforce

Q106. How does Mulesoft use OAuth 2.0?

Ans. In an OAuth2 Dance, the OAuth2 Provider Module lets a Mule Application be set up as an Authentication Manager (OAuth provider). During the execution of a flow, the application will be able to authenticate registered clients, issue tokens, validate tokens, or register and delete clients with this role.

Q107. What are the different types of grants in OAUTH 2.0?

Ans. 

  • AUTHORIZATION_CODE
  • RESOURCE_OWNER_PASSWORD_CREDENTIALS
  • CLIENT_CREDENTIALS
  • IMPLICIT

Q108. What are the requirements for building a DLB (Dedicated Load Balancer)?

Ans. 

By adding the Cloudhub Network Administrator permission to the profile of the organization where you're creating the load balancer, your profile is authorized to conduct this activity.
In the organization where you wish to establish a load balancer, create an Anypoint Virtual Private Cloud (Anypoint VPC).
Make at least one certificate and a private key for it.

Q109. What exactly is the EU Control Plane?

Ans. MuleSoft hosts an EU-only version of the Anypoint Platform control plane (Frankfurt or Dublin data centers). This allows you to install and manage your APIs, apps, and data exclusively within the European Union. This covers MuleSoft-related data and metadata. The EU control plane assures that all MuleSoft data is stored on the EU.

Q110. What is the purpose of the Anypoint runtime Plane?

Ans. Anypoint runtime plane deploys the mule runtime application and runs the mule runtime engine; in the case of Cloudhub, MuleSoft will maintain the runtime plane, while on-premise and RTF runtime planes will be controlled by the customer.


Conclusion

Thank you for taking the time to read the above article. I hope you found it useful. This “Mulesoft Interview Questions” blog is updated on a regular basis to keep you current with the latest Mulesoft developments. 

If you have any questions, please leave a comment. We'd also be happy to look into your recommendations if you're interested in learning more about any specific topic.

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Last updated: 27 Dec 2021
About Author
Remy Sharp
Ravindra Savaram

Ravindra Savaram is a Content Lead at Mindmajix.com. His passion lies in writing articles on the most popular IT platforms including Machine learning, DevOps, Data Science, Artificial Intelligence, RPA, Deep Learning, and so on. You can stay up to date on all these technologies by following him on LinkedIn and Twitter.

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