Apache Camel is designed to work nicely with the Spring Framework in a number of ways.
- Camel uses Spring Transactions as the default transaction handling in components like JMS and JPA
- Camel works with Spring 2 XML processing with the Xml Configuration
- Camel Spring XML Schema's is defined at Xml Reference
- Camel supports a powerful version of Spring Remoting which can use powerful routing between the client and server side along with using all of the available Components for the transport
- Camel provides powerful Bean Integration with any bean defined in a Spring
- Camel integrates with various Spring helper classes; such as providing Type Converter support for Spring Resources etc
- Allows Spring to dependency inject Component instances or the CamelContext instance itself and auto-expose Spring beans as components and endpoints.
- Allows you to reuse the Spring Testing framework to simplify your unit and integration testing using Enterprise Integration Patterns and Camel's powerful Mock and Test endpoints
- From Camel 2.15: Camel supports Spring Boot using the
- From Camel 2.17.1: Camel supports Spring Cache based Idempotent repository
Using Spring to configure the CamelContext
You can configure a
CamelContext inside any
spring.xml using the CamelContextFactoryBean. This will automatically start the CamelContext along with any referenced Routes along any referenced Component and Endpoint instances.
- Adding Camel schema
- Configure Routes in two ways:
- Using Java Code
- Using Spring XML
Adding Camel Schema
For Camel 1.x you need to use the following namespace:
with the following schema location:
You need to add Camel to the
So the XML file looks like this:
Or you can refer to the camel XSD in the XML declaration:
... so the declaration is:... and then use the
camel:namespace prefix, and you can omit the inline namespace declaration:
Advanced Configuration Using Spring
See more details at Advanced configuration of CamelContext using Spring
Using Java Code
You can use Java Code to define your RouteBuilder implementations. These can be defined as beans in spring and then referenced in your camel context e.g.
Camel also provides a powerful feature that allows for the automatic discovery and initialization of routes in given packages. This is configured by adding tags to the camel context in your spring context definition, specifying the packages to be recursively searched for RouteBuilder implementations. To use this feature in
1.X, requires a
<package></package> tag specifying a comma separated list of packages that should be searched e.g.
Use caution when specifying the package name as
org.apache.camel or a sub package of this. This causes Camel to search in its own packages for your routes which could cause problems.
Will ignore already instantiated classes
<packageScan> will skip any classes which has already been created by Spring etc. So if you define a route builder as a spring bean tag then that class will be skipped. You can include those beans using
<routeBuilder ref="theBeanId"/> or the
In Camel 2.0 this has been extended to allow selective inclusion and exclusion of discovered route classes using Ant like path matching. In spring this is specified by adding a
<packageScan/> tag. The tag must contain one or more
package elements (similar to
1.x), and optionally one or more
excludes elements specifying patterns to be applied to the fully qualified names of the discovered classes. e.g.,
Exclude patterns are applied before the include patterns. If no include or exclude patterns are defined then all the Route classes discovered in the packages will be returned.
In the above example, camel will scan all the
org.example.routes package and any subpackages for
RouteBuilder classes. Say the scan finds two
RouteBuilders, one in
MyRoute and another
MyExcludedRoute in a subpackage
excluded. The fully qualified names of each of the classes are extracted (
org.example.routes.excluded.MyExcludedRoute ) and the include and exclude patterns are applied.
The exclude pattern
**.*Excluded* is going to match the FQCN
org.example.routes.excluded.MyExcludedRoute and veto camel from initializing it.
Under the covers, this is using Spring's AntPatternMatcher implementation, which matches as follows
**.*Excluded* would match
**.??cluded* would match
org.simple.Excluded but not match
Available as of Camel 2.4
You can allow Camel to scan the container context, e.g. the Spring
ApplicationContext for route builder instances. This allow you to use the Spring
<component-scan> feature and have Camel pickup any
RouteBuilder instances which was created by Spring in its scan process.
@Componentand have those routes included by Camel:
You can also use the ANT style for inclusion and exclusion, as mentioned above in the
How do I import routes from other XML files
Available as of Camel 2.3
When defining routes in Camel using Xml Configuration you may want to define some routes in other XML files. For example you may have many routes and it may help to maintain the application if some of the routes are in separate XML files. You may also want to store common and reusable routes in other XML files, which you can simply import when needed.
In Camel 2.3 it is now possible to define routes outside
<camelContext/> which you do in a new
Notice: When you use
<routeContext> then they are separated, and cannot reuse existing
<dataFormats> and similar cross cutting functionality defined in the
<camelContext>. In other words the
<routeContext> is currently isolated. This may change in Camel 3.x.
For example we could have a file named
myCoolRoutes.xml which contains a couple of routes as shown:
myCoolRoute.xmlfile. And then inside
<camelContext/>you can refer to the
idas shown below: Also notice that you can mix and match, having routes inside
CamelContextand also externalized in
You can have as many
<routeContextRef/> as you like.
The routes defined in
<routeContext/> can be reused by multiple
<camelContext/>. However its only the definition which is reused. At runtime each
CamelContext will create its own instance of the route based on the definition.
Test Time Exclusion.
At test time it is often desirable to be able to selectively exclude matching routes from being initialized that are not applicable or useful to the test scenario. For instance you might a spring context file
routes-context.xml and three Route builders
RouteC in the
org.example.routes package. The
packageScan definition would discover all three of these routes and initialize them.
RouteC is not applicable to our test scenario and generates a lot of noise during test. It would be nice to be able to exclude this route from this specific test. The
SpringTestSupport class has been modified to allow this. It provides two methods (
excludedRoutes) that may be overridden to exclude a single class or an array of classes.
In order to hook into the
camelContext initialization by spring to exclude the
MyExcludedRouteBuilder.class we need to intercept the spring context creation. When overriding
createApplicationContext to create the spring context, we call the
getRouteExcludingApplicationContext() method to provide a special parent spring context that takes care of the exclusion.
RouteC will now be excluded from initialization. Similarly, in another test that is testing only
RouteC, we could exclude
RouteA by overriding:
Using Spring XML
Configuring Components and Endpoints
activemqin the above example), then you can refer to the component using
activemq:[queue:|topic:]destinationName. This works by the
SpringCamelContextlazily fetching components from the spring context for the scheme name you use for Endpoint URIs.
For more detail see Configuring Endpoints and Components.
Spring Cache Idempotent Repository
Available as of Camel 2.17.1
If you want to be injected with the CamelContext in your POJO just implement the CamelContextAware interface; then when Spring creates your POJO the
CamelContext will be injected into your POJO. Also see the Bean Integration for further injections.
To avoid a hung route when testing using Spring Transactions see the note about Spring Integration Testing under Transactional Client.