DZone
Thanks for visiting DZone today,
Edit Profile
  • Manage Email Subscriptions
  • How to Post to DZone
  • Article Submission Guidelines
Sign Out View Profile
  • Post an Article
  • Manage My Drafts
Over 2 million developers have joined DZone.
Log In / Join
Refcards Trend Reports
Events Video Library
Refcards
Trend Reports

Events

View Events Video Library

Zones

Culture and Methodologies Agile Career Development Methodologies Team Management
Data Engineering AI/ML Big Data Data Databases IoT
Software Design and Architecture Cloud Architecture Containers Integration Microservices Performance Security
Coding Frameworks Java JavaScript Languages Tools
Testing, Deployment, and Maintenance Deployment DevOps and CI/CD Maintenance Monitoring and Observability Testing, Tools, and Frameworks
Culture and Methodologies
Agile Career Development Methodologies Team Management
Data Engineering
AI/ML Big Data Data Databases IoT
Software Design and Architecture
Cloud Architecture Containers Integration Microservices Performance Security
Coding
Frameworks Java JavaScript Languages Tools
Testing, Deployment, and Maintenance
Deployment DevOps and CI/CD Maintenance Monitoring and Observability Testing, Tools, and Frameworks

Last call! Secure your stack and shape the future! Help dev teams across the globe navigate their software supply chain security challenges.

Modernize your data layer. Learn how to design cloud-native database architectures to meet the evolving demands of AI and GenAI workloads.

Releasing software shouldn't be stressful or risky. Learn how to leverage progressive delivery techniques to ensure safer deployments.

Avoid machine learning mistakes and boost model performance! Discover key ML patterns, anti-patterns, data strategies, and more.

Related

  • Finally, an ORM That Matches Modern Architectural Patterns!
  • How Stalactite ORM Implements Its Fluent DSL
  • Implementing PEG in Java
  • Why "Polyglot Programming" or "Do It Yourself Programming Languages" or "Language Oriented Programming" sucks?

Trending

  • Breaking Bottlenecks: Applying the Theory of Constraints to Software Development
  • Cookies Revisited: A Networking Solution for Third-Party Cookies
  • How to Configure and Customize the Go SDK for Azure Cosmos DB
  • Contextual AI Integration for Agile Product Teams
  1. DZone
  2. Coding
  3. Java
  4. Camel Exception Handling Overview for a Java DSL

Camel Exception Handling Overview for a Java DSL

By 
Ben O'Day user avatar
Ben O'Day
·
Apr. 25, 12 · Interview
Likes (2)
Comment
Save
Tweet
Share
65.9K Views

Join the DZone community and get the full member experience.

Join For Free
Here are some notes on adding Camel (from v2.3+) exception handling to a JavaDSL route.  There are various approaches/options available.  These notes cover the important distinctions between approaches...

Default handling
The default mode uses the DefaultErrorHandler strategy which simply propagates any exception back to the caller and ends the route immediately.  This is rarely the desired behavior, at the very least, you should define a generic/global exception handler to log the errors and put them on a queue for further analysis (during development, testing, etc).

onException(Exception)
    .to("log:GeneralError?level=ERROR")
    .to("activemq:queue:GeneralErrorQueue");


Try-catch-finally
This approach mimics the Java for exception handling and is designed to be very readable and easy to implement.  It inlines the try/catch/finally blocks directly in the route and is useful for route specific error handling.

from("direct:start")
    .doTry()
        .process(new MyProcessor())
    .doCatch(Exception.class)
        .to("mock:error");
    .doFinally()
        .to("mock:end");

onException
This approach defines the exception clause separately from the route.  This makes the route and exception handling code more readable and reusable.  Also, the exception handling will apply to any routes defined in its CamelContext.

onException(Exception.class)
    .to("mock:error");

from("direct:start") .process(new MyProcessor()) .to("mock:end");

 

Handled/Continued
These APIs provide valuable control over the flow.   Adding handled(true) tells Camel to not propagate the error back to the caller (should almost always be used).  The continued(true) tells Camel to resume the route where it left off (rarely used, but powerful).  These can both be used to control the flow of the route in interesting ways, for example...

from("direct:start")
    .process(new MyProcessor())
    .to("mock:end");

//send the exception back to the client (rarely used, clients need a meaningful response)
onException(ClientException.class)
    .handled(false)    //default
    .log("error sent back to the client");

//send a readable error message back to the client and handle the error internally
onException(HandledException.class)
    .handled(true)
    .setBody(constant("error"))
    .to("mock:error");

//ignore the exception and continue the route (can be dangerous, use wisely)
onException(ContinuedException.class)
    .continued(true);


Using a processor for more control
If you need more control of the handler code, you can use an inline Processor to get a handle to the exception that was thrown and write your own handler code...

onException(Exception.class)
.handled(true) .process(new Processor() { public void process(Exchange exchange) throws Exception { Exception exception = (Exception) exchange.getProperty(Exchange.EXCEPTION_CAUGHT); //log, email, reroute, etc. } });


Summary
Overall, the exception handling is very flexible and can meet almost any scenario you can come up with.  For the sake of focusing on the basics, many advanced features haven't been covered here.
  
For more details, see these pages on Camel's site...

http://camel.apache.org/error-handling-in-camel.html
http://camel.apache.org/try-catch-finally.html
http://camel.apache.org/exception-clause.html
Domain-Specific Language Java (programming language)

Published at DZone with permission of Ben O'Day, DZone MVB. See the original article here.

Opinions expressed by DZone contributors are their own.

Related

  • Finally, an ORM That Matches Modern Architectural Patterns!
  • How Stalactite ORM Implements Its Fluent DSL
  • Implementing PEG in Java
  • Why "Polyglot Programming" or "Do It Yourself Programming Languages" or "Language Oriented Programming" sucks?

Partner Resources

×

Comments

The likes didn't load as expected. Please refresh the page and try again.

ABOUT US

  • About DZone
  • Support and feedback
  • Community research
  • Sitemap

ADVERTISE

  • Advertise with DZone

CONTRIBUTE ON DZONE

  • Article Submission Guidelines
  • Become a Contributor
  • Core Program
  • Visit the Writers' Zone

LEGAL

  • Terms of Service
  • Privacy Policy

CONTACT US

  • 3343 Perimeter Hill Drive
  • Suite 100
  • Nashville, TN 37211
  • support@dzone.com

Let's be friends: