When to use Spring Integration vs. Camel?
We choose Camel over Spring-Integration because the fluent API is really nice. We actually use it in Spring projects and use Spring to configure part of it. The programming API's are clear and there is a large set of sensible components.
We did a small scale shootout and basically at that time for our requirement Camel won. We use it mainly to transfer internal datafiles to/from external parties which usually requires format conversions sending it using ftp/sftp/... or attaching it to an email and sending it out.
We found the edit-compile-debug cycle reduced. Using groovy to experiment setting up routes are added bonuses.
Spring-Integration is a great product too, and I am quite sure it would satisfy our needs too.
I only recommend Spring Integration if you already have got a Spring project and you have just to add some "basic" integration using File, FTP, JMS, JDBC, and so on.
Apache Camel has two main advantages:
- Many, many more technologies are supported.
- Besides, a (good) XML DSL, there are fluent APIs for Java, Groovy and Scala.
Because Apache Camel has very good integration with Spring, I would even use it instead of Spring Integration in most Spring projects.
If you need more details, you can read my experiences in my blog post: Spoilt for Choice: Which Integration Framework to use – Spring Integration, Mule ESB or Apache Camel?
I have recently conducted a Camel vs Spring Integration shoot-out with the aim to integrate Apache Kafka. Despite being an avid Spring developer, I sadly found my suspicion with Spring's ever-growing Project stack confirmed: Spring is awesome as IOC-Container to serve as glue for other framework, but it fails at providing viable alternatives to those frameworks. There might be exceptions to this, namely everything to do with MVC, where Spring came from and where it does a great job, but other attempts to provide new functionality on top of container features fall short for three reasons and the SI Kafka use case confirms all of them:
- Introduction of a long-winded difficult to use DSL for XML-configuration.
- Pages of xml-configuration code to get all framework components wired-up.
- Missing resources to provide functionality on par with dedicated frameworks.
Now, back to the results of my shoot-out: most importantly I am impressed by Camels overall concept of routes between endpoints. Kafka seamlessly integrates with this concept and three lines of configuration are enough to get everything up-and-running. Problems encountered during the process are neatly addressed by ample documentation from the project team as well as a lot of questions on Stackoverflow. Last but not least, there is a comprehensive integration into Spring that leaves no wishes unfulfilled.
With SI on the contrary, the documentation for the Kafka integration is quite intense and still fails to explain clearly how to integrate Kafka. The integration of Kafka is pressed into the SI-way of doing things, which adds extra complexity. Other documentation, e.g. on Stackoverflow is also less plentiful and less helpful than for Camel.
My conclusion: cobbler stick to your trade - use Spring as a container and Camel as system integration framework.