What is the difference between SEDA, VM and direct in Apache Camel?

Question

I had worked with both SEDA and direct, and I\'ve also read the documentation.

But I still cannot visualize the usage of SEDA and direct. Vm is new to me.

Pleas

Answer 1

The difference between direct: and seda: components is that the first is synchronous and the second is asynchronous, with a queue.

The practical difference is that for sending synchronous messages, you must wait for the route to complete, whereas with asynchronous messages, its "fire and forget" - you put them onto a queue and presume a consumer will process them. You can also have multiple consumers (parallelisation).

The last example, vm: is also asynchronous, but it can also call routes in different camel contexts within the same JVM. Imagine application 1 has a camel context, and application 2 has a camel context, in this way they can communicate with each other.

edit:

In relation to "what to use when" :

• use direct: for calling normally between endpoints in a camel context
• use seda: when you need parallelisation or queues, but dont want to use jms:
• use vm: when calling between applications.

There are of course many other use cases but those are the common ones (subjective to my own experience)