book

Apache Camel Developer's Cookbook

Name: Apache Camel Developer's Cookbook
ISBN: 9781782170303

by Scott Cranton, Jakub Korab

December 2013

Intermediate to advanced

424 pages

9h 7m

English

Packt Publishing

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Apache Camel Developer's Cookbook
Table of Contents
Apache Camel Developer's Cookbook
Credits
About the Authors
Acknowledgments
About the Reviewers
www.PacktPub.com
Support files, eBooks, discount offers and moreWhy Subscribe?Free Access for Packt account holdersInstant Updates on New Packt Books
Preface
What is Camel?
Camel Concepts

The Camel DSL
What this book covers
What you need for this book
Who this book is for
Conventions
Reader feedback
Customer support
Downloading the example codeErrataPiracyQuestions
1. Structuring Routes
Introduction
Using Camel in a Java application
Getting readyHow to do it...How it works...There's more...See also
Embedding Camel in a Spring application
Getting readyHow to do it...How it works...There's more...See also
Using Camel components
Getting readyHow to do it...How it works...There's more...See also
Reusing routing logic by connecting routes
Getting readyHow to do it...How it works...There's more...See also
Asynchronously connecting routes
Getting readyHow to do it...How it works...There's more...See also
Spanning Camel contexts within a single Java process
Getting readyHow to do it...How it works...See also
Using external properties in Camel routes
Getting readyHow to do it...How it works...There's more...See also
Reusing endpoints
Getting readyHow to do it...
Reusing routing logic through template routes
Getting readyHow to do it...How it works...See also
Controlling route startup and shutdown
Getting readyHow to do it...How it works...There's more...See also
2. Message Routing
Introduction
Content Based Routing
Getting readyHow to do it...How it works...There's more...See also
Filtering out unwanted messages
Getting readyHow to do it...How it works...There's more...See also
Wire Tap – sending a copy of the message elsewhere
Getting readyHow to do it...How it works...Deep copying of the exchangeThere's more...See also
Multicast – routing the same message to many endpoints
Getting readyHow to do it...How it works...There's more...See also
Recipient List – routing a message to a list of endpoints
Getting readyHow to do it...How it works...There's more...See also
Throttler – restricting the number of messages flowing to an endpoint
Getting readyHow to do it...How it works...There's more...See also
Request-response route sending a one-way message
Getting readyHow to do it...How it works...There's more...See also
One-way route waiting on a request-response endpoint
Getting readyHow to do it...How it works...There's more...See also
Dynamic Routing – making routing decisions at runtime
Getting readyHow to do it...How it works...There's more...See also
Load balancing across a number of endpoints
Getting readyHow to do it...How it works...There's more...See also
Routing Slip – routing a message to a fixed list of endpoints
Getting readyHow to do it...How it works...There's more...See also
3. Routing to Your Code
Introduction
Routing messages directly to a Java method
Getting readyHow to do it...How it works...There's more...See also
Sending messages directly to a Camel endpoint
Getting readyHow to do it...How it works...There's more...See also
Using a Java method as a Predicate
Getting readyHow to do it...How it works...There's more...See also
Writing a custom Camel Processor
Getting readyHow to do it...How it works...There's more...See also
Mapping the message to method parameters
Getting readyHow to do it...How it works...There's more...See also
Writing a custom data marshaller
Getting readyHow to do it...How it works...There's more...See also
Writing a custom data type converter
Getting readyHow to do it...How it works...There's more...See also
4. Transformation
Introduction
Transforming using a Simple Expression
Getting readyHow to do it...How it works...There's more...See also
Transforming inline with XQuery
Getting readyHow to do it...How it works...There's more...See also
Transforming with XSLT
Getting readyHow to do it...How it works...There's more...See also
Transforming from Java to XML with JAXB
Getting readyHow to do it...How it works...There's more...See also
Transforming from Java to JSON
Getting readyHow to do it...How it works...There's more...See also
Transforming from XML to JSON
Getting readyHow to do it...How it works...There's more...See also
Parsing comma-separated values (CSV)
Getting readyHow to do it...How it works...There's more...See also
Enriching your content with some help from other endpoints
Getting readyHow to do it...How it works...There's more...See also
Normalizing messages into a common XML format
Getting readyHow to do it...How it works...There's more...See also
5. Splitting and Aggregating
Introduction
Splitting a message into fragments
Getting readyHow to do it...How it works...There's more...See also
Splitting XML messages
Getting readyHow to do it...How it works...There's more...See also
Processing split messages in parallel
Getting readyHow to do it...How it works...There's more...See also
Aggregating related messages
Getting readyHow to do it...How it works...There's more...See also
Aggregating with timeouts
Getting readyHow to do it...How it works...See also
Aggregating with intervals
Getting readyHow to do it...How it works...See also
Processing aggregated messages in parallel
Getting readyHow to do it...How it works...There's more...See also
Splitting a message, and processing and gathering responses
Getting readyHow to do it...How it works...There's more...See also
Splitting messages and re-aggregating them using different criteria
Getting readyHow to do it...How it works...There's more...See also
6. Parallel Processing
Introduction
Increasing message consumption through multiple endpoint consumers
Getting readyHow to do it...How it works...There's more...See also
Spreading the load within a route using a set of threads
Getting readyHow to do it...How it works...There's more...See also
Routing a request asynchronously
Getting readyHow to do it...How it works...There's more...See also
Using custom thread pools
Getting readyHow to do it...How it works...There's more...See also
Using thread pool profiles
Getting readyHow to do it...How it works...There's more...See also
Working with asynchronous APIs
Getting readyHow to do it...How it works...There's more...See also
7. Error Handling and Compensation
Introduction
Logging errors
Getting readyHow to do it...How it works...There's more...See also
Dead Letter Channel – handling errors later
Getting readyHow to do it...How it works...There's more...See also
Retrying an operation
Getting readyHow to do it...How it works...There's more...See also
Conditional retry
Getting readyHow to do it...How it works...There's more...See also
Customizing each redelivery attempt
Getting readyHow to do it...How it works...There's more...See also
Catching exceptions
Getting readyHow to do it...How it works...There's more...See also
Marking exceptions as handled
Getting readyHow to do it...How it works...There's more...See also
Fine-grained error handling using doTry…doCatch
Getting readyHow to do it...How it works...There's more...See also
Defining completion actions
Getting readyHow to do it...How it works...There's more...See also
Defining completion actions dynamically
Getting readyHow to do it...How it works...There's more...See also
8. Transactions and Idempotency
Introduction
Preventing duplicate invocation of routing logic
Getting readyHow to do it...How it works...There's more...See also
Transactional file consumption
Getting readyHow to do it...How it works...There's more...See also
Using transactions with a database
Getting readyHow to do it...How it works...There's more...See also
Limiting the scope of a transaction
Getting readyHow to do it...How it works...There's more...
Rolling back a transaction
Getting readyHow to do it...How it works...There's more...
Using transactions with messaging
Getting readyHow to do it...How it works...There's more...See also
Idempotency inside transactions
Getting readyHow to do it...How it works...There's more...See also
Setting up XA transactions over multiple transactional resources
Getting readyHow to do it...How it works...There's more...See also
9. Testing
Introduction
Testing routes defined in Java
Getting readyHow to do it...How it works...There's more...See also
Using mock endpoints to verify routing logic
Getting readyHow to do it...How it works...There's more...See also
Replying from mock endpoints
Getting readyHow to do it...How it works...See also
Testing routes defined in Spring
Getting readyHow to do it...How it works...There's more...See also
Testing routes defined in OSGi Blueprint
Getting readyHow to do it...How it works...There's more...See also
Auto-mocking of endpoints
Getting readyHow to do it...How it works...There's more...
Validating route behavior under heavy load
Getting readyHow to do it...How it works...There's more...See also
Unit testing processors and Bean Bindings
Getting readyHow to do it...How it works...There's more...See also
Testing routes with fixed endpoints using AOP
Getting readyHow to do it...How it works...There's more...See also
Testing routes with fixed endpoints using conditional events
Getting readyHow to do it...How it works...There's more...See also
10. Monitoring and Debugging
Introduction
Logging meaningful steps within your route
Getting readyHow to do it...How it works...There's more...See also
Debugging using logging
Getting readyHow to do it...How it works...There's more...See also
Throughput logging
Getting readyHow to do it...How it works...There's more...See also
Enabling step-by-step tracing in code
Getting readyHow to do it...How it works...There's more...See also
Disabling JMX
Getting readyHow to do it...How it works...There's more...See also
Configuring JMX
Getting readyHow to do it...How it works...There's more...See also
Naming your routes to make it easier to monitor
Getting readyHow to do it...How it works...There's more...See also
Adding JMX attributes and operations
Getting readyHow to do it...How it works...There's more...See also
Monitoring other systems using the Camel JMX Component
Getting readyHow to do it...How it works...There's more...See also
Setting breakpoints in your routes
Getting readyHow to do it...How it works...There's more...See also
11. Security
Introduction
Encrypting configuration properties
Getting readyHow to do it...How it works...There's more...See also
Digitally signing and verifying messages
Getting readyHow to do it...How it works...There's more...See also
Encrypting and decrypting a message
Getting readyHow to do it...How it works...There's more...See also
Encrypting all or parts of an XML message
Getting readyHow to do it...How it works...There's more...See also
Authentication and authorization using Spring Security
Getting readyHow to do it...How it works...There's more...See also
12. Web Services
Introduction
Generating the service stubs from a WSDL
Getting readyHow to do it...How it works...There's more...See also
Invoking a remote web service from Camel
Getting readyHow to do it...How it works...There's more...See also
Implementing a web service with a Camel route
Getting readyHow to do it...How it works...There's more...See also
Providing multiple web service operations within a single route
Getting readyHow to do it...How it works...There's more...See also
Handling web service faults
Getting readyHow to do it...How it works...There's more...See also
Web service proxying
Getting readyHow to do it...How it works...There's more...See also
Index

Content preview from Apache Camel Developer's Cookbook

Rolling back a transaction

So far we have seen transaction success or failure determined naturally—that is, by whether an exchange was successfully processed, or if an exception was thrown during its processing. This recipe will provide you with a number of additional options around controlling transaction rollback.

Getting ready

The Java code for this recipe is located in the org.camelcookbook.transactions.rollback package. The Spring XML files are located under src/main/resources/META-INF/spring and prefixed with rollback.

How to do it...

You can use the rollback DSL statement to throw an exception with an optional message.

In the XML DSL, we use the following code:

<from uri="direct:transacted"/> <transacted/> <setHeader headerName="message"> <simple>${body}</simple> ...

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