Asynchronous Routing Engine
Available as of Camel 2.4
As of Camel 2.4 the asynchronous routing engine is back and kicking.
All the Enterprise Integration Patterns are supported as well a selected number of Components.
When we say a component is supported, that means, the component is leveraging the asynchronous model. For example Jetty uses continuations and the async http client to be fully asynchronous and non blocked. That means no threads will ever be blocked while waiting for a reply.
In the future additional Components will be supported as well where it's applicable.
Forcing to use synchronous processing
You can configure the endpoints with the option synchronous=true to force using synchronous processing. For example when sending a web service request using CXF, the caller will wait for the reply if synchronous=true was configured. Currently this option is supported by the all the producers. If you don't want to let the CXF consumer leverage the CXF continuation API to use the asynchronous processing, you can also use this option synchronous=true to disable it. The JBI and NMR component are always asynchronous and doesn't support this option.
Background information
See Asynchronous Processing for additional information and the concepts behind the asynchronous model.