Mulesoft Interview Questions and Answers (Mule 4)

1.       What is Mulesoft and Why to use Mulesoft?

·       Integration platform to help businesses connect data, applications and devices across on-premises and cloud computing environments.

·       API tools to implement API, micro services and API Management.

      2.       What is Mule message/event – what it contains.

Mule Message: (Mule 3)                                      Mule Event: (Mule 4)

3.       Different type of variables in Mule 3? How these are going to work in Mule 4?

Variables: (Mule 3)

·       Flow Variables - Flow Variables can pass from one Flow to another only when using a flow reference component.

·       Session Variables - Session Variables cannot cross HTTP CONNECTOR but they can cross VM CONNECTOR.

·       Record Variables - They can persist across multiple batch steps but not in the source (Load and Dispatch) or the On Complete phase.

In Mule 4 there is no such variables, there is only one variable. Mule runtime will take care of how the variable to act. If we define inside for, batch it will work as record variable, if we define inside flow it will act as flow variable. 

     4.       Different type of flow processing strategies?

·       The Synchronous Flow Processing Strategy: Mule processes messages in a single thread.

·       The Queued-Asynchronous Flow Processing Strategy: Mule uses a queue to decouple the receiver thread from the rest of the flow.

·       Asynchronous-processing-strategy: Same as queued-asynchronous processing strategy except that it doesn’t use a queue.

·       Queued-thread-per-processor-processing-strategy:  Writes messages to a queue, then every processor in the scope runs sequentially in a different thread.

·       Thread-per-processor-processing-strategy: Every processor in the scope runs sequentially in a different thread.

     5.       Different types of exception handling in Mule 3/Mule 4?

In Mule 3:

·       Default Exception Strategy

·       Rollback Exception Strategy

·       Catch Exception Strategy

·       Choice Exception Strategy

·       Reference Exception Strategy

In Mule 4:

·       On Error Continue

·       On Error Propagate

     6.       What is RAML and why to use it?

RESTful API Modeling Language is a YAML-based language for describing RESTful APIs. It provides all the information necessary to describe RESTful or practically RESTful APIs.

We use RAML to Design an API.

     7.       I have below RAML, how many flows will it generates?

Three

    8.       What is Fragment and how to use it?

An API fragment is a RAML document that has a version and an identifier. A way to create APIs more efficiently is to get reuse by reusing portions or fragments of APIs into specs.

    9.       What is the different between fragment and a library?

Fragment: Is a kind usable project which can contain different RAML files for Data types, examples, resource types etc.

Library: Is a single RAML file, in which we can define Data Types, examples, resource etc.

    10.   What is Trait? What is Resource Type? Difference between Trait and Resource Type?

Trait: Traits is like function and is used to define common attributes for HTTP method (GET, PUT, POST, PATCH, DELETE, etc) such as whether or not they are filterable, searchable, or pageable.

ResourceTypes: Is like resource in that it can specify the descriptions, methods, and its parameters.

Difference: Trait can be used for methods, errors, examples etc. But Resource Type can be used for define resources only.

     11.   What is API Route Kit how it works? On what basis routing is going to happen?

APIkit Route Kit is a tool for building Mule REST API flows. By using this we can route to appropriate flow based on method name and resource.

Based on Method name and Resource name its going to route the request to particular flow.

     12.   What is SOAP Route Kit? How the routing works in SOAP Route Kit?

SOAP Route Kit is a tool for building Mule SOAPAPI flows.

Based on Method name it’s going to route the request to particular flow.

     13.   I hope you worked on MySQL connector right. I am using select operation with id 123, but there is no id with 123 in database table. What will happen to your flow? Will it throw error or not?

It will return empty array.

    14.   What is the security mechanism your using to integrate Salesforce? How you got the token?

You have to explain how its implemented in your project.

    15.   Difference between Object Store and VM connector and when to use what?

Object Store: An Object Store is a Mule component that allows for simple key-value storage. Although it can serve a wide variety of use cases, it is mainly design for:

·       Storing synchronization information, such as watermarks.

·       Storing temporal information such as access tokens.

·       Storing user information.

Virtual Machine: Virtual Machine (VM) (VM Connector) handles intra-app and inter-app communication through asynchronous queues that can be transient or persistent.

·       Transient queues are faster than persistent queues, but they are not reliable in the case of a system crash.

·       Persistent queues are slower but reliable.

     16.   What is the security mechanism used in your project and how its implemented?

You have to explain how its implemented in your project.

     17.   Different between SOAP and Rest?

     18.   Different between PATCH, PUT and POST?

POST is used to create a new entity.

PATCH is used to update an existing entity with new information. You can’t patch an entity that doesn’t exist.

PUT is used to set an entity’s information completely. PUTting is similar to POSTing, except that it will overwrite the entity if already exists or create it otherwise.

     19.   Can I use POST method to fetch the details? (When to use it?)

Yes, we can. If we have more query parameters in uri, it best practice to use POST method to fetch the details. There is a URI length limit, so if it’s more query parameters URL length will be more, so in that case we should use POST method.

     20.   What is Reliability? How it can be achievable?

Zero tolerance for message loss. We should not loss the transactions due to some technical issues. We can achieve this by using ESB solution messaging like MQ.

     21.   Difference between Map, flatMap and MapObject?

Map: Iterates over items in an array and outputs the results into a new array.

FlatMap: Iterates over each item in an array and flattens the results.

MapObject: Iterates over an object using a mapper that acts on keys, values, or indices of that object.

     22.   How to convert an Object into Array using Data weave?

Pluck - Iterates over an object and returns an array of keys, values, or indices from the object 

     23.   I have array within it I have nested array of data, how can I make simple array?

Flatten - Turns a nested array into a simple array

     24.   Difference between flatMap and flatten?

flatMap: Iterates over each item in an array and flattens the results, can act on values and indices of items in the array.

Flatten - Turns a nested array into a simple array. only acts on the values of the arrays

    25.   What are the different ways we can create API Manager instance?

·       Creating from RAML,

·       Creating from WSDL,

·       Importing from another environment.

·       Creating based on URL.

    26.   Difference between Rating Limit and SLA Based policies?

Rating Limit: Selecting a limit in API Manager defines the quota per time window.

SLA-based rate limiting: Restricts the number of requests by application to your API based on the configuration of an SLA tier.

    27.   What is Throttling and when to use?

Throttling is intended to smooth spikes, Mule Runtime can delay requests and retry the requests later. delay the number of requests to process later.

    28.   What is worker? How to scale application in Runtime manager?

Worker is an instance of Mule that runs your integration applications. Each worker has 2 GB of storage for applications to use.

By vertically (adding more vCcore) and by horizontally(adding more workers) to the application.

    29.   What is the logging management used in your project?

    30.   I am using scatter-gather and calling 2 services parallelly. One got success response and one got failed with connectivity error. What will happen in scatter-gather?

The complete flow gets failed and will raise error. Based on error handing implementation it will go to error flow.

     31.   Difference between MMC and CloudHub?

MMC: MMC is an enterprise management and monitoring tool designed specifically for Mule ESB instances. MMC provides a comprehensive set of functionality for managing and monitoring running Mule instances, Mule clusters, applications within Mule instances, and the flows within those applications.

CloudHub: CloudHub is an integration platform as a service (iPaaS) where you can deploy sophisticated cross-cloud integration applications in the cloud, create new APIs on top of existing data sources, integrate on-premises applications with cloud services, and much more.