Spring Boot
Available as of Camel 2.15
Spring Boot component provides auto-configuration for Apache Camel. Our opinionated auto-configuration of the Camel context auto-detects Camel routes available in the Spring context and registers the key Camel utilities (like producer template, consumer template and the type converter) as beans.
Maven users will need to add the following dependency to their pom.xml
in order to use this component:
<dependency>
<groupId>org.apache.camel</groupId>
<artifactId>camel-spring-boot</artifactId>
<version>${camel.version}</version> <!-- use the same version as your Camel core version -->
</dependency>
camel-spring-boot
jar comes with the spring.factories
file, so as
soon as you add that dependency into your classpath, Spring Boot will
automatically auto-configure Camel for you.
Camel Spring Boot Starter
Available as of Camel 2.17
Apache Camel ships a https://github.com/spring-projects/spring-boot/tree/master/spring-boot-starters[Spring Boot Starter] module that allows you to develop Spring Boot applications using starters. There is a sample application in the source code also.
To use the starter, add the following to your spring boot pom.xml file:
<dependency>
<groupId>org.apache.camel</groupId>
<artifactId>camel-spring-boot-starter</artifactId>
<version>2.17.0</version>
</dependency>
Then you can just add classes with your Camel routes such as:
package com.example;
import org.apache.camel.builder.RouteBuilder;
import org.springframework.stereotype.Component;
@Component
public class MyRoute extends RouteBuilder {
@Override
public void configure() throws Exception {
from("timer:foo").to("log:bar");
}
}
Then these routes will be started automatically.
You can customize the Camel application in the application.properties
or application.yml
file.
Auto-configured Camel context
The most important piece of functionality provided by the Camel
auto-configuration is CamelContext
instance.
Camel auto-configuration creates a SpringCamelContext
for you and
takes care of the proper initialization and shutdown of that context.
The created Camel context is also registered in the Spring application
context (under camelContext
bean name), so you can access it just as
any other Spring bean.
@Configuration
public class MyAppConfig {
@Autowired
CamelContext camelContext;
@Bean
MyService myService() {
return new DefaultMyService(camelContext);
}
}
Auto-detecting Camel routes
Camel auto-configuration collects all the RouteBuilder
instances from
the Spring context and automatically injects them into the provided
CamelContext
. That means that creating new Camel route with the Spring
Boot starter is as simple as adding the @Component
annotated class to
your classpath:
@Component
public class MyRouter extends RouteBuilder {
@Override
public void configure() throws Exception {
from("jms:invoices").to("file:/invoices");
}
}
+ ...or creating a new route `RouteBuilder` bean in your `@Configuration` class:
@Configuration
public class MyRouterConfiguration {
@Bean
RoutesBuilder myRouter() {
return new RouteBuilder() {
@Override
public void configure() throws Exception {
from("jms:invoices").to("file:/invoices");
}
};
}
}
Camel properties
Spring Boot auto-configuration automatically connects
to http://docs.spring.io/spring-boot/docs/current/reference/html/boot-features-external-config.html#boot-features-external-config[Spring
Boot external configuration] (like properties placeholders, OS
environment variables or system properties) with
the Camel properties support. It basically means
that any property defined in application.properties
file:
route.from = jms:invoices
…or set via system property…
java -Droute.to=jms:processed.invoices -jar mySpringApp.jar
…can be used as placeholders in Camel route:
@Component
public class MyRouter extends RouteBuilder {
@Override
public void configure() throws Exception {
from("{{route.from}}").to("{{route.to}}");
}
}
Custom Camel context configuration
If you would like to perform some operations on CamelContext
bean
created by Camel auto-configuration,
register CamelContextConfiguration
instance in your Spring context:
@Configuration
public class MyAppConfig {
...
@Bean
CamelContextConfiguration contextConfiguration() {
return new CamelContextConfiguration() {
@Override
void beforeApplicationStart(CamelContext context) {
// your custom configuration goes here
}
};
}
}
Method
C`amelContextConfiguration#`beforeApplicationStart(CamelContext)
will
be called just before the Spring context is started, so the
CamelContext
instance passed to this callback is
fully auto-configured. You can add many instances of
C`amelContextConfiguration` into your Spring context - all of them will
be executed.
Disabling JMX
To disable JMX of the auto-configured CamelContext
use
camel.springboot.jmxEnabled
property (JMX is enabled by default). For
example you could add the following property to your
application.properties
file:
camel.springboot.jmxEnabled = false
Auto-configured consumer and producer templates
Camel auto-configuration provides pre-configured ConsumerTemplate
and
ProducerTemplate
instances. You can simply inject them into your
Spring-managed beans:
@Component
public class InvoiceProcessor {
@Autowired
private ProducerTemplate producerTemplate;
@Autowired
private ConsumerTemplate consumerTemplate;
public void processNextInvoice() {
Invoice invoice = consumerTemplate.receiveBody("jms:invoices", Invoice.class);
...
producerTemplate.sendBody("netty-http:http://invoicing.com/received/" + invoice.id());
}
}
By default consumer templates and producer templates come with the endpoint cache sizes set to 1000. You can change those values via the following Spring properties:
camel.springboot.consumerTemplateCacheSize = 100
camel.springboot.producerTemplateCacheSize = 200
Auto-configured TypeConverter
Camel auto-configuration registers a TypeConverter
instance named
typeConverter
in the Spring context.
@Component
public class InvoiceProcessor {
@Autowired
private TypeConverter typeConverter;
public long parseInvoiceValue(Invoice invoice) {
String invoiceValue = invoice.grossValue();
return typeConverter.convertTo(Long.class, invoiceValue);
}
}
Spring type conversion API bridge
Spring comes with
the powerful http://docs.spring.io/spring/docs/current/spring-framework-reference/html/validation.html#core-convert[type
conversion API]. Spring API happens to be very similar to the Camel
type converter API. As those APIs are so
similar, Camel Spring Boot automatically registers a bridge converter
(SpringTypeConverter
) that delegates to the Spring conversion API.That
means that out-of-the-box Camel will treat Spring Converters like Camel
ones. With this approach you can enjoy both Camel and Spring converters
accessed via Camel TypeConverter
API:
@Component
public class InvoiceProcessor {
@Autowired
private TypeConverter typeConverter;
public UUID parseInvoiceId(Invoice invoice) {
// Using Spring's StringToUUIDConverter
UUID id = invoice.typeConverter.convertTo(UUID.class, invoice.getId());
}
}
Under the hood Camel Spring Boot delegates conversion to the Spring’s
ConversionService
instances available in the application context. If
no ConversionService
instance is available, Camel Spring Boot
auto-configuration will create one for you.
Disabling type conversions features
If you don’t want Camel Spring Boot to register type-conversions related
features (like TypeConverter
instance or Spring bridge) set the
camel.springboot.typeConversion
property to false
.
camel.springboot.typeConversion = false
Blocking main thread
This feature is available starting from Camel 2.15.2. Camel
applications extending FatJarRouter by default block the main thread of
the application. It means that after you start your fat jar, your
application waits for Ctrl+C signal and does not exit immediately. If
you would like to achieve similar behavior for non-FatJarRouter
applications, retrieve CamelSpringBootApplicationController `bean from
your `ApplicationContext
and use the former to block the main thread of
your application using
CamelSpringBootApplicationController#blockMainThread()
method.
public static void main(String... args) {
ApplicationContext applicationContext = new SpringApplication(MyCamelApplication.class).run(args);
CamelSpringBootApplicationController applicationController =
applicationContext.getBean(CamelSpringBootApplicationController.class);
applicationController.blockMainThread();
}
Adding XML routes
By default you can put Camel XML routes in the classpath under the directory camel, which camel-spring-boot will auto detect and include. From Camel 2.17 onwards you can configure the directory name or turn this off using the configuration option
// turn off
camel.springboot.xmlRoutes = false
// scan in the com/foo/routes classpath
camel.springboot.xmlRoutes = classpath:com/foo/routes/*.xml
The XML files should be Camel XML routes (not CamelContext) such as
<routes xmlns="http://camel.apache.org/schema/spring">
<route id="test">
<from uri="timer://trigger"/>
<transform>
<simple>ref:myBean</simple>
</transform>
<to uri="log:out"/>
</route>
</routes>
Adding XML Rest-DSL
By default you can put Camel Rest-DSL XML routes in the classpath under the directory camel-rest, which camel-spring-boot will auto detect and include. You can configure the directory name or turn this off using the configuration option
// turn off
camel.springboot.xmlRests = false
// scan in the com/foo/routes classpath
camel.springboot.xmlRests = classpath:com/foo/rests/*.xml
The Rest-DSL XML files should be Camel XML rests (not CamelContext) such as
<rests xmlns="http://camel.apache.org/schema/spring">
<rest>
<post uri="/persons">
<to uri="direct:postPersons"/>
</post>
<get uri="/persons">
<to uri="direct:getPersons"/>
</get>
<get uri="/persons/{personId}">
<to uri="direct:getPersionId"/>
</get>
<put uri="/persons/{personId}">
<to uri="direct:putPersionId"/>
</put>
<delete uri="/persons/{personId}">
<to uri="direct:deletePersionId"/>
</delete>
</rest>
</rests>