Apache camel interview questions.

2. What is Apache Camel ?
Apache Camel is a rule-based routing and
provides a Java object-based implementation of
Integration Patterns using an API (or declarative
Specific Language) to configure routing and
better understand what is apache camel, lets first
are Enterprise Applications and Enterprise

4. How to implement Error Handling using Apache Camel ?
•Error handling in Camel can roughly be separated into two
transactional
•Transactional
What is a Message in Apache Camel ?
•Message implements the Message pattern and represents an
message as part of an Exchange.It contains the data being
consists of the following fields-Unique Identifier
•Headers
•Body
•Fault Flag

5. What is an exchange in Apache Camel ?
•Camel Exchange represents an abstraction for an exchange of messages
•which involves a request
•message and its corresponding reply or an exception message.
•It consists of-Exchange ID
•Message Exchange Pattern
•InOnly message
•InOut message
•Exception
•Properties
How to read data from queues using Apache Camel ?
We make use of Apache Camel JMS Component. We will be reading from one
JMS Queue and sending the message to another jms queue. Also we will be
making use of ActiveMQ queues.

6. What are Components in Apache Camel ?
Component act as an endpoint factory using which we can interact with
external systems. Camel provides a large number of components using
externals systems.
For example here we have to transfer files from one folder to another, so
component at both the end of the message channel.
What is CamelContext ?
We cannot run our Camel Application only using the route. We also need
acts as a runtime system that runs and manages the routes. It is
aspects of a route.
What is Quartz Library? How to use it with Apache Camel
Quartz is a richly featured, open source job scheduling library that can be
any Java application - from the smallest stand-alone application to the

7. How to implement Exception Handling in Apache Camel ?
•Using Apache Camel Exception Handling can be implemented
Block
•Using OnException Block
Enlist few good uses for Apache Camel?
Apache Camel is a good choice when you want to integrate several applications with
different protocols and technologies. You can use it with Java, Scala, Groovy or Spring
XML.
What is Processor in Apache Camel?
Processor is Apache Camel is an interface that is used to implement consumers of
message exchanges or Message Translator.

8. What are Components in Apache Camel?
A Component in Apache Camel is a factory or collection of Endpoint instances. We
can configure Component instances explicitly and add them to a CamelContext in an
IoC container like Spring or Guice. Components can be auto-discovered using URIs.
Apache Camel provides numerous pre-built components. Below we have listed some
important Camel components from the core module.
•Bean
•Direct
•File
•Log
•SEDA
•Timer

9. What are routes in Apache Camel?
Routes plays a critical role in Apache Camel. The application flow and logic are specified here.In
Camel we can define routing rules using a Java DSL.
How to rollback transaction in Apache Camel DSL?
To rollback transaction in Apache Camel DSL, you can perform the following steps:
•Remove Spring transaction manager.
•Remove Spring transaction policy.
•Remove transacted() from Camel route.
What Are Eips In Apache Camel?
EIPS (ENTERPRISE INTEGRATION PATTERNS) is an architectural design pattern that defines code-
agnostic workflows for common business tasks.

10. What is Messaging?
Messaging is a communication mechanism used for
system interactions. In software development messaging
enables distributed communication that is loosely
coupled. A messaging client can send messages to, and
receive messages from, any other client.
What is Advanced Message Queuing Protocol (AMQP)
?
The Advanced Message Queuing Protocol (AMQP) is an
open standard application layer protocol for message-
oriented middleware. AMQP 0-9-1 is a binary messaging
protocol and semantic framework for microservices and
enterprise messaging.

11. How to start the execution of routes Apache Camel?
To start the execution of routes Apache Camel, you can perform the following steps:
•Create a CamelContext.
•Optionally, configure components or endpoints.
•Add whatever routing rules you wish using the DSL and RouteBuilder or using XML DSL.
•Start the Camel context.
What are DSLs and which DSLs have you used?
Routes in a variety of domain-specific languages (DSL).The most popular ones are Java DSL -
A Java based DSL using the fluent builder style. Spring XML - A XML based DSL in Spring XML
files
What is an ESB? Have you deployed camel on any ESB?
ESB stands for Enterprise Service Bus. It can be defined as a tool designed to help implement
an application using SOA principles Not for all projects projects is the use of ESB an optimum
solution ESB should be used when projects involve integrating a number of Endpoints like
Webservices, JMS, FTP etc. Have deployed JBoss Fuse ESB for Apache Camel Deployement.

12. Apache camel Kafka
It is basically an open-source framework. It
basically or mainly focuses on making things
easier. Also, they make the integration
process very simple and sorted for the
developers.
It has a very unique design messaging
system. It is a log service that is distributed
and partitioned.
It basically focuses on enterprise integration
patterns. Also, it is really and highly
configurable.
It has a very high and reliable performance
efficiency. Also, it is really scalable.
What is basic differences between Apache Camel and Kafka?

13. What are endpoints in apache camel?
Camel supports the Message Endpoint pattern using the Endpoint
interface. Endpoints are usually created by a Component and Endpoints
are usually referred to in the DSL via their URIs.
What are various components in apache camel? Which ones have you
used?
Apache camel provides us with a number of components. These
components make interacting create endpoints with which a system can
interact with other external systems. For example using an ActiveMQ
component we expose an ActiveMQ endpoint for interaction with external
system. There are more than 100 components provided by Apache
Camel. Some of them are FTP,JMX, Webservices, HTTP. Apache camel
also allows users to create custom components.

14. How are exception handled using Apache Camel?
Exception can be handled using the <try>
<catch> block, <OnException> block or the
<errorHandler> block.
The errorHandler is used to handle any uncaught
Exception that gets thrown during the routing and
processing of a message. Conversely,
onException is used to handle specific Exception
types when they are thrown.

15. What is Redelivery policy in Apache Camel?
A redelivery policy defines rules when Camel Error Handler perform
redelivery attempts. For example you can setup rules that state how
many times to try redelivery, and the delay in between attempts, and so
forth.
What is RouterContext?
It is now possible to define routes outside <camelContext/> which you do
in a new <routeContext/> tag. The routes defined in <routeContext/> can
be reused by multiple <camelContext/>. However its only the definition
which is reused. At runtime each CamelContext will create its own
instance of the route based on the definition.

16. What is Apache Camel Idempotent Consumer pattern?
In Apache Camel we use the Idempotent Consumer pattern to filter out
duplicate messages. Consider a scenario where we have to process files
only once. If there are any duplicates they should be skipped. Using
Apache Camel we can use Idempotent Consumer directly within the
component so it will skip files that are processed once. This feature is be
enabled by setting the idempotent=true option. In order to achieve this
Apache Camel keeps track of the consumed files using a message id
which is stored in the repository called Idempotent Repository. Apache
Camel provides the following types of IdempotentRepository.

17. THANK YOU
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