Registry

The org.apache.camel.spi.Registry API is a common API to lookup beans in any kind of runtime platform, whether you run Camel on Spring Boot, Quarkus, CDI, Standalone, Kafka or something else.

Camel uses the DefaultRegistry that based on which runtime used (Spring Boot, Quarkus, CDI, etc) will first lookup beans from the runtime platform, and fallback to Camel’s own SimpleRegistry.

Registry API

The registry has two sets of APIs:

  • binding

  • lookup

The binding API is used to add new beans into the registry. The lookup is used for looking up existing beans from the registry.

Binding API

The binding API is as follows:

public interface Registry extends BeanRepository {

    /**
     * Binds the bean to the repository (if possible).
     * If the bean is CamelContextAware then the registry will automatic inject the context if possible.
     *
     * @param  id    the id of the bean
     * @param  bean  the bean
     */
    void bind(String id, Object bean);

    /**
     * Binds the bean to the repository (if possible).
     * Binding by id and type allows to bind multiple entries with the same id but with different type.
     * If the bean is CamelContextAware then the registry will automatic inject the context if possible.
     *
     * @param  id    the id of the bean
     * @param  type  the type of the bean to associate the binding
     * @param  bean  the bean
     */
    void bind(String id, Class<?> type, Object bean);

}

If you for example need to add a bean to the Registry then you can easily do this from Java as follows:

Object myFoo = ...
camelContext.getRegistry().bind("foo", myFoo);

Then you can access the bean by the id, such as from a Camel route:

from("jms:cheese").bean("foo");

Binding in Spring XML

If you use Spring XML file, then any <bean> is automatic handled by Spring itself, and registered into Spring bean container; which means there is no need to bind the bean from Camel also.

<bean id="foo" class="com.foo.MyFoo"/>

Binding in Spring Boot

When using Spring Boot, then you can also use annotations to declare beans such as with the @Bean annotation on the method that creates the bean:

@Bean
public MyFoo foo() {
    return new MyFoo();
}

This is common functionality of Spring Boot, and you can find information about this in the Spring Boot project documentation.

Binding in Quarkus

Quarkus has similar functionality like Spring Boot to declare beans, which can be done with the javax.inject.enterprise.Produces and javax.inject.Named annotations:

@Produces @Named("foo")
public MyFoo foo() {
    return new MyFoo();
}

Lookup API

Registry is mostly used for looking up beans by their IDs, or by type. This is heavily used during startup of Camel where Camel is wiring up all components, endpoints, routes, processors, beans and so forth.

The lookup API is the following methods:

public interface BeanRepository {

    /**
     * Looks up a bean in the registry based purely on name, returning the bean or null if it could not be found.
     *
     * Important: Multiple beans of different types may be bound with the same name, and its encouraged to use the
     * lookupByNameAndType(String, Class) to lookup the bean with a specific type, or to use any of the
     * find methods.
     *
     * @param  name the name of the bean
     * @return      the bean from the registry or null if it could not be found
     */
    Object lookupByName(String name);

    /**
     * Looks up a bean in the registry, returning the bean or null if it could not be found.
     *
     * @param  name the name of the bean
     * @param  type the type of the required bean
     * @return      the bean from the registry or null if it could not be found
     */
    <T> T lookupByNameAndType(String name, Class<T> type);

    /**
     * Finds beans in the registry by their type.
     *
     * @param  type the type of the beans
     * @return      the types found, with their bean ids as the key. Returns an empty Map if none found.
     */
    <T> Map<String, T> findByTypeWithName(Class<T> type);

    /**
     * Finds beans in the registry by their type.
     *
     * @param  type the type of the beans
     * @return      the types found. Returns an empty Set if none found.
     */
    <T> Set<T> findByType(Class<T> type);

}

You can lookup beans from Java code as shown:

// lookup by id only
Object foo = camelContext.getRegistry().lookupByName("foo");

// lookup by type so there is no need for type casting
MyFoo foo2 = camelContext.getRegistry().lookupByNameAndType("foo", MyFoo.class);

Looking up beans

You can also use dependency injection that will lookup the bean via the Camel registry. If you use a runtime platform such as Spring Boot or Quarkus then they come with their own functionality for this. Camel also has its own bean injection annotation @BeanInject which can be used when running Camel standalone.

You can also use @BeanInject from Camel in Spring Boot or Quarkus; but this requires the class with the bean injection is managed by Camel (such as a RouteBuilder class); which may not always be the case. Therefore, it is best to only use the Spring Boot or Quarkus annotations.

Lookup in Spring Boot

When using Spring Boot you can use Spring annotations such as @Autowired or @Inject for dependency injection.

Lookup in Quarkus

When using Quarkus you can use CDI annotations such as @Inject and @Named for dependency injection.

More Information

See Bean Injection and Bean Integration for more details on working with Beans in Camel.

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