Apache Camel Interview Questions For Freshers & Experienced

  • Question 1) What is Apache Camel?
  • Question 2) What are routes in Apache Camel?
  • Question 3) What are components in Apache Camel?
  • Question 4) How to pass data between the routes in Apache Camel?
  • Question 5) What is a camel context?
  • Question 6) What is RouterContext?
  • Question 7) How does Apache Camel work with ActiveMQ?
  • Question 8) How do I disable JMX in Apache Camel?
  • Question 9) How to restart CamelContext?
  • Question 10) How to enable debug logging in Apache Camel?
  • Sharad Jaiswal
  • 25th Dec, 2019
  • 749 Followers

Apache Camel Interview Questions
Updated ON

25th Dec, 2019

No. of Questions

10

Posted In

Java

Author

Sharad Jaiswal

What is Apache Camel?

Apache Camel is used for a message-orientated interface and an open-sourced structure with a command-based meditation mechanism and routing that offers a Java entity-based execution of the enterprise combination pattern utilizing Java domain-specific language or an implementation programming interface to configure mediation and routing rules. Hence, the domain-specific language portrays the fact that Apache Camel can aid smart fulfillment of routing regulations in a unified development environment utilizing methodical Java code sans huge sum volumes of XML arrangement files, but XML arrangements within Spring framework is also braced.

Thus, through Apache Camel, developers can easily access and create easily the integration by offering concrete execution of totally and widely utilized enterprise integration patterns associated with the huge types of APIs and transports.

Key Features of Apache Camel

Below are few major features of Apache Camel

Open source framework

Pluggable data formats

POJO model

Message-oriented middleware

Ease of testing

Eclipse based tooling

Type converters for marshaling and unmarshalling

100+ Components

Message Exchange Patterns

Apache Camel Interview Questions

Q1. What is Apache Camel?

Apache Camel is an open-source framework for defining routing and mediation rules in different domain-specific languages like Java-based Fluent API, Spring, etc. It focuses on making integration easier and more accessible to developers. The Camel framework provides concrete implementations for all widely used EIP (Enterprise Integration Patterns). It also provides support for Bean Binding and integration with other popular frameworks like CDI, Spring, and Blueprint.

Apache Camel is used with other services like Apache ServiceMix, Apache ActiveMix, and Apache CXF. Apache Camel is a cross-platform developed by Apache Foundation and stored in Camel Repository.

Q2. What are routes in Apache Camel?

The Route in the Apache Camel is one of the main building blocks that is used to contain flow and integration logic. You can specify sources and the endpoint of the route using the DSL. The transformations that need to be taken place during the routing can also be defined in the route. The URI’s to receive data from different sources can also be denied in the route.

The route can be configured by extending the RouteBuilder class and overriding the configure() method. The from() and to() method is used inside the configure() method to define the sources and endpoint of the routing.

//example of routing using RouteBuilder class
Public class MyRouteBuilder extends RouteBuilder{ @Override Public void configure() throws Exception { //define your route } }

Q3. What are components in Apache Camel?

The component in Apache Camel is the factory that is used to model the endpoint of the message channels that either consume or send a message. The component can be created by implementing the org.apache.camel.Component by a class.

Some of the pre-built components in the Camel are,

  • Bean – It invokes Java bean in the registry.
  • Direct – It is used to synchronously call other endpoints.
  • File – It is used to read or write to a file.
  • Log – It is used to log messages.
  • Mock – It tests the messages that flow through the route.
  • SEDA – It is used to asynchronously call another endpoint.
  • Timer – It sends a message at regular intervals in the route.

Q4. How to pass data between the routes in Apache Camel?

The data can be passed between thee endpoints using the routes. You need to define the from and to location and use RouteBuilder to define the route in Java DSL. The source of the route starts at one point and ends at one or more points. Between the two endpoints, you need to define the processing logic using the configure method.

//example of route creation with the source and endpoints for passing data
context.addRoutes(new RouteBuilder() {
  @Override
  public void configure() throws Exception {
     from("direct:DistributeOrderDSL")
     .to("stream:out");
  }
}

Q5. What is a camel context?

The Camel context in the Apache camel is the loading container of all the resources that are required for the execution of the routing. It is the runtime system. It provides all the resources and access to all other services in the Apache camel. The different resources in the camel context are type converters, registry, components, endpoints, routes, data formats, and languages.

These resources in the context allow the user to execute the routing logic. It is described by org.apache.camel.CamelContext interface.

Q6. What is RouterContext?

The router context is the tag that is used to define routes outside the <camelcontext/> tag in XML. A new route can be defined by the <routeContext/> tag. The definition of the route that is created in the <routeContext/> tag can be reused by different <camelContext/>. But at runtime, the camel context will create its own route instance based on the definition.

Q7. How does Apache Camel work with ActiveMQ?

The ActiveMQ component is used to embed Apache Camel inside the ActiveMQ broker. It provides good flexibility in extending the message broker. The ActiveMQ component also avoids the serialization and network cost of connecting to ActiveMQ remotely.

This component is based on the JMS component and allows the messages to be sent or consumed using the JMS Queue.

Q8. How do I disable JMX in Apache Camel?

The JMX instrumentation agent is enabled in Camel by default. To disable the JMX instrumentation agent, set the following property in the Java VM system property,

Dorg.apache.camel.jmx.disabled=true

Another way of disabling is by adding the JMX agent element inside the camel context element in the Spring configuration,

<camelContext id="camel" xmlns="http://camel.apache.org/schema/spring">
 <jmxAgent id="agent" disabled="true"/>
   ...
</camelContext>

Q9. How to restart CamelContext?

The camel context provides different methods like start, stop, suspend, resume to control the camel lifecycle. Restarting a service can be achieved by using two different methods. One is using stop the context and then starting the context. It is called cold restart and it makes all the endpoints obsolete by clearing the internal state, cache, etc. Another method is by using suspend and resume operations. It keeps all the endpoints, so you can use them after restarting.

Q10. How to enable debug logging in Apache Camel?

To enable the debug logging, the log4j is used. Then, enable the DEBUG level logging in the log4j property file for the org.apache.camel package. To enable the debugging in the log4j.properties file add the following line.

log4j.logger.org.apache.camel = DEBUG

About Author :

  • Author of Apache Camel Interview Questions

    Sharad Jaiswal

    Sharad Jaiswal is Sr. Web Developer from Noida area. He have rich experience in PHP, Angular Js, React, javascript and Node .If you any query or project on these programming you can drop your enquiry in comment section.

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