Jun 7, 2016

Using Apache Camel in Grails 3

Grails 2 has a plugin for Apache Camel called Routing but that plugin hasn’t been upgraded to Grails 3 yet. Luckily, Grails 3 is just Spring Boot so we can use the Camel Spring Boot component…. with some caveats.

After you add the Camel component and a domain object or two, and do a grails run-app you will see something like this:

Field error in object 'Foo' on field 'version': rejected value [2.15.5]; codes [Foo.version.typeMismatch.error,Foo.version.typeMismatch,foo.version.typeMismatch.error,foo.version.typeMismatch,typeMismatch.Foo.version,typeMismatch.version,typeMismatch.java.lang.Long,typeMismatch]; arguments [version]; default message [Unable to parse number [2.15.5]

… and I was using Camel 2.15.5 in my project. Oh no… well it seems that Camel uses version in it’s Exchange metadata and it sees version in the domain objects and just inserts it’s version number there. No cool. To stop this, you need to add the following to your Grails 3 config:

grails:
   gorm:
      autowire: false

This will disable injecting beans into your domain classes… this is not something I do very often so I’m fine with it, but your use cases may vary.

After this, it’s pretty easy. I create a service with grails create-service Route then put the following in:

import org.apache.camel.builder.RouteBuilder;

public class RouteService extends RouteBuilder {
    @Override
    public void configure() throws Exception {
        from("timer://foo?delay=1").to("log:bar?level=ERROR");
    }
}

And when you now run grails run-app you see that the route is running because you see these log messages.

ERROR bar - Exchange[ExchangePattern: InOnly, BodyType: null, Body: [Body is null]]
ERROR bar - Exchange[ExchangePattern: InOnly, BodyType: null, Body: [Body is null]]
ERROR bar - Exchange[ExchangePattern: InOnly, BodyType: null, Body: [Body is null]]
ERROR bar - Exchange[ExchangePattern: InOnly, BodyType: null, Body: [Body is null]]

About the Author

Mike Hostetler profile.

Mike Hostetler

Principal Technologist

Mike has almost 20 years of experience in technology. He started in networking and Unix administration, and grew into technical support and QA testing. But he has always done some development on the side and decided a few years ago to pursue it full-time. His history of working with users gives Mike a unique perspective on writing software.

One thought on “Using Apache Camel in Grails 3

  1. KP says:

    It has been ported to Grails 3. See here – https://github.com/padcom/grails-routing
    It’s just not been officially published to the repo – https://github.com/padcom/grails-routing/issues/53

  2. Andrey Volkov says:

    I spent a few hours to find and understand the issue with Camel and Grails! It looks like epic fail in integration of these 2 big whales.
    Thank you for this simple workaround.

Leave a Reply

Your email address will not be published. Required fields are marked *

Related Blog Posts
Android Development for iOS Developers
Android development has greatly improved since the early days. Maybe you tried it out when Android development was done in Eclipse, emulators were slow and buggy, and Java was the required language. Things have changed […]
Add a custom object to your Liquibase diff
Adding a custom object to your liquibase diff is a pretty simple two step process. Create an implementation of DatabaseObject Create an implementation of SnapshotGenerator In my case I wanted to add tracking of Stored […]
Keeping Secrets Out of Terraform State
There are many instances where you will want to create resources via Terraform with secrets that you just don’t want anyone to see. These could be IAM credentials, certificates, RDS DB credentials, etc. One problem […]
Validating Terraform Plans using Open Policy Agent
When developing infrastructure as code using terraform, it can be difficult to test and validate changes without executing the code against a real environment. The feedback loop between writing a line of code and understanding […]