Getting error while creating rest service using apache camel

Question

Since i am prety much new to Apache camel and especially Rest DSL, I thought of trying a sample of Rest DSL.

So i created a camel-config.xml as:

<?xml version="1.0" encoding="UTF-8"?>

<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:camel="http://camel.apache.org/schema/spring"
       xsi:schemaLocation="
         http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
         http://camel.apache.org/schema/spring http://camel.apache.org/schema/spring/camel-spring.xsd">

  <!-- use camel-metrics route policy to gather metrics for all routes -->
  <!-- bean id="metricsRoutePolicyFactory" class="org.apache.camel.component.metrics.routepolicy.MetricsRoutePolicyFactory"/-->

  <!-- a rest service which uses binding to/from pojos -->
  <bean id="userRoutes" class="org.apache.camel.example.rest.UserRouteBuilder"/>

  <!-- a bean for user services -->
  <bean id="userService" class="org.apache.camel.example.rest.UserService"/>

  <camelContext id="myCamel" xmlns="http://camel.apache.org/schema/spring">
    <routeBuilder ref="userRoutes"/>
  </camelContext>

</beans>

and my route class is :

package org.apache.camel.example.rest;

import org.apache.camel.builder.RouteBuilder;

/**
 * Define REST services using the Camel REST DSL
 */
public class UserRouteBuilder extends RouteBuilder {

    public void configure() throws Exception {
        rest("/say").get("/hello").to("direct:hello").get("/bye")
                .consumes("application/json").to("direct:bye").post("/bye")
                .to("mock:update");
        from("direct:hello").transform().constant("Hello World");
        from("direct:bye").transform().constant("Bye World");
    }

}

and my web.xml is :

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" id="WebApp_ID" version="2.5">
  <display-name>My Camel Rest Application</display-name>

  <!-- location of Camel Spring xml files -->
  <context-param>
    <param-name>contextConfigLocation</param-name>

    <!-- to use Java DSL -->
    <param-value>classpath:camel-config.xml</param-value>

    <!-- to use XML DSL, then enable me, and disable Java DSL above
    <param-value>classpath:camel-config-xml.xml</param-value>
    -->
  </context-param>

  <!-- the listener that kick-starts Spring -->
  <listener>
    <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
  </listener>

  <!-- to setup Camel Servlet -->
  <servlet>
    <display-name>Camel Http Transport Servlet</display-name>
    <servlet-name>CamelServlet</servlet-name>
    <servlet-class>org.apache.camel.component.servlet.CamelHttpTransportServlet</servlet-class>
    <load-on-startup>1</load-on-startup>
  </servlet>

  <!-- START SNIPPET: e1 -->
  <!-- to setup Camel Swagger api servlet -->
  <servlet>
    <servlet-name>ApiDeclarationServlet</servlet-name>
    <servlet-class>org.apache.camel.component.swagger.DefaultCamelSwaggerServlet</servlet-class>
    <init-param>
      <!-- we specify the base.path using relative notation, that means the actual path will be calculated at runtime as
           http://server:port/contextpath/rest -->
      <param-name>base.path</param-name>
      <param-value>rest</param-value>
    </init-param>
    <init-param>
      <!-- we specify the api.path using relative notation, that means the actual path will be calculated at runtime as
           http://server:port/contextpath/api-docs -->
      <param-name>api.path</param-name>
      <param-value>api-docs</param-value>
    </init-param>
    <init-param>
      <param-name>api.version</param-name>
      <param-value>1.2.3</param-value>
    </init-param>
    <init-param>
      <param-name>api.title</param-name>
      <param-value>User Services</param-value>
    </init-param>
    <init-param>
      <param-name>api.description</param-name>
      <param-value>Camel Rest Example with Swagger that provides an User REST service</param-value>
    </init-param>
    <load-on-startup>2</load-on-startup>
  </servlet>

  <!-- swagger api declaration -->
  <servlet-mapping>
    <servlet-name>ApiDeclarationServlet</servlet-name>
    <url-pattern>/api-docs/*</url-pattern>
  </servlet-mapping>
  <!-- END SNIPPET: e1 -->

  <!-- define that url path for the Camel Servlet to use -->
  <servlet-mapping>
    <servlet-name>CamelServlet</servlet-name>
    <url-pattern>/rest/*</url-pattern>
  </servlet-mapping>

  <!-- START SNIPPET: e2 -->
  <!-- enable CORS filter so people can use swagger ui to browse and test the apis -->
  <filter>
    <filter-name>RestSwaggerCorsFilter</filter-name>
    <filter-class>org.apache.camel.component.swagger.RestSwaggerCorsFilter</filter-class>
  </filter>

  <filter-mapping>
    <filter-name>RestSwaggerCorsFilter</filter-name>
    <url-pattern>/api-docs/*</url-pattern>
    <url-pattern>/rest/*</url-pattern>
  </filter-mapping>
  <!-- END SNIPPET: e2 -->

  <welcome-file-list>
      <welcome-file>home.html</welcome-file>
  </welcome-file-list>

</web-app>

Now i have created a war file of my restProject and i deployed it on tomcat. Provided all the neccessary jars in the lib folder of tomcat. I am using camel 2.14.

Now when i start my tomcat, During startup i get error as :

SEVERE: Context initialization failed
org.apache.camel.RuntimeCamelException: java.lang.IllegalStateException: Cannot find RestConsumerFactory in Registry or
as a Component to use
        at org.apache.camel.util.ObjectHelper.wrapRuntimeCamelException(ObjectHelper.java:1364)
        at org.apache.camel.spring.SpringCamelContext.onApplicationEvent(SpringCamelContext.java:122)
        at org.apache.camel.spring.CamelContextFactoryBean.onApplicationEvent(CamelContextFactoryBean.java:327)
        at org.springframework.context.event.SimpleApplicationEventMulticaster.multicastEvent(SimpleApplicationEventMult
icaster.java:96)
        at org.springframework.context.support.AbstractApplicationContext.publishEvent(AbstractApplicationContext.java:3
34)
        at org.springframework.context.support.AbstractApplicationContext.finishRefresh(AbstractApplicationContext.java:
948)
        at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:482)
        at org.springframework.web.context.ContextLoader.configureAndRefreshWebApplicationContext(ContextLoader.java:389
)
        at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:294)
        at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:112)
        at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4791)
        at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5285)
        at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
        at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:901)
        at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:877)
        at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:618)
        at org.apache.catalina.startup.HostConfig.deployDirectory(HostConfig.java:1100)
        at org.apache.catalina.startup.HostConfig$DeployDirectory.run(HostConfig.java:1618)
        at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:471)
        at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:334)
        at java.util.concurrent.FutureTask.run(FutureTask.java:166)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603)
        at java.lang.Thread.run(Thread.java:722)
Caused by: java.lang.IllegalStateException: Cannot find RestConsumerFactory in Registry or as a Component to use
        at org.apache.camel.component.rest.RestEndpoint.createConsumer(RestEndpoint.java:238)
        at org.apache.camel.impl.EventDrivenConsumerRoute.addServices(EventDrivenConsumerRoute.java:65)
        at org.apache.camel.impl.DefaultRoute.onStartingServices(DefaultRoute.java:80)
        at org.apache.camel.impl.RouteService.warmUp(RouteService.java:134)
        at org.apache.camel.impl.DefaultCamelContext.doWarmUpRoutes(DefaultCamelContext.java:2379)
        at org.apache.camel.impl.DefaultCamelContext.safelyStartRouteServices(DefaultCamelContext.java:2309)
        at org.apache.camel.impl.DefaultCamelContext.doStartOrResumeRoutes(DefaultCamelContext.java:2091)
        at org.apache.camel.impl.DefaultCamelContext.doStartCamel(DefaultCamelContext.java:1951)
        at org.apache.camel.impl.DefaultCamelContext.doStart(DefaultCamelContext.java:1777)
        at org.apache.camel.support.ServiceSupport.start(ServiceSupport.java:61)
        at org.apache.camel.impl.DefaultCamelContext.start(DefaultCamelContext.java:1745)
        at org.apache.camel.spring.SpringCamelContext.maybeStart(SpringCamelContext.java:254)
        at org.apache.camel.spring.SpringCamelContext.onApplicationEvent(SpringCamelContext.java:120)
        ... 22 more

I am trying to figure out for the past two days, Why i am getting this error. Really looking forward to your solutions. Thanks in advance..

Answer 1

If you are running a Camel-Spring Boot application, you can solve the issue by adding the following dependency in your pom.xml:

<dependency>
  <groupId>org.apache.camel.springboot</groupId>
  <artifactId>camel-http-starter</artifactId>
</dependency>

Answer 2

You need an additional configuration for the rest DSL. 4 components as described in http://camel.apache.org/rest-dsl.html are supporting rest DSL.Take a look at the Section [Components supporting Rest DSL].For the configuration take a look at [Configuring Rest DSL] section

What you need actually is 2 more additions.

1) In your route builder a rest configuration part. For servlet component that could be restConfiguration().component("servlet") ->more options here.

Find the full configuration in this example

2) Add a dependency in pom.xml.

<dependency>
   <groupId>org.apache.camel</groupId>
   <artifactId>camel-servlet</artifactId>
</dependency>

For a spark-rest configuration take a look at the code here