Camel Components for Google App Engine
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This component is deprecated and will be removed form Camel 2.18 onwards. |
The Camel components for Google App Engine (GAE) are part of the camel-gae
project and provide connectivity to GAE's cloud computing services. They make the GAE cloud computing environment accessible to applications via Camel interfaces. Following this pattern for other cloud computing environments could make it easier to port Camel applications from one cloud computing provider to another. The following table lists the cloud computing services provided by Google and the supporting Camel components. The documentation of each component can be found by following the link in the Camel Component column.
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glogin | These components interact with the Google |
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Accounts API for authentication and authorization. Google Accounts is not specific to Google App Engine but is often used by GAE applications for implementing security. The gauth component is used by web applications to implement a Google-specific OAuth consumer. This component can also be used to OAuth-enable non-GAE web applications. The glogin component is used by Java clients (outside GAE) for programmatic login to GAE applications. For instructions how to protect GAE applications against unauthorized access refer to the Security for Camel GAE applications page. |
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Camel context
Setting up a SpringCamelContext
on Google App Engine differs between Camel 2.1 and Camel 2.2higher versions. The problem is that usage of the Camel-specific Spring configuration XML schema from the http://camel.apache.org/schema/spring
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namespace requires JAXB and Camel 2.1 depends on a Google App Engine SDK version that doesn't support JAXB yet.
- Camel 2.1 depends on the Google App Engine SDK 1.2.6 which doesn't support JAXB. Refer to the #Camel 2.1 subsection for instructions how to set up a
SpringCamelContext
with Camel 2.1 on GAE. - Camel 2.2 depends on the Google App Engine SDK 1.2.8, the first version that introduces support for JAXB. Refer to the #Camel 2.2 subsection for instructions how to set up a
SpringCamelContext
with Camel 2.2 on GAE.
This limitation has been removed since Camel 2.2.
JMX must be disabled in any case With both versions, JMX must be disabled because the javax.management
package isn't on the App Engine JRE whitelist.
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<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="
http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-2.5.xsd">
<bean id="camelContext"
class="org.apache.camel.component.gae.context.GaeSpringCamelContext">
<property name="routeBuilder" ref="myRouteBuilder" />
</bean>
<bean id="myRouteBuilder"
class="org.example.MyRouteBuilder">
</bean>
</beans>
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Alternatively, use the routeBuilders
property of the GaeSpringCamelContext
for setting a list of route builders. Using this approach, a SpringCamelContext
can be configured on GAE without the need for JAXB.
Camel 2.2 or higher
With Camel 2.2 or higher, applications can use the http://camel.apache.org/schema/spring
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namespace for configuring a SpringCamelContext
but still need to disable JMX. Here's an example.
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<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-2.5.xsd
http://camel.apache.org/schema/spring
http://camel.apache.org/schema/spring/camel-spring.xsd">
<camel:camelContext id="camelContext">
<camel:jmxAgent id="agent" disabled="true" />
<camel:routeBuilder ref="myRouteBuilder"/>
</camel:camelContext>
<bean id="myRouteBuilder"
class="org.example.MyRouteBuilder">
</bean>
</beans>
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<web-app
xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
xsi:schemaLocation="
http://java.sun.com/xml/ns/javaee
http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" version="2.5">
<servlet>
<servlet-name>CamelServlet</servlet-name>
<servlet-class>org.apache.camel.component.servlet.CamelHttpTransportServlet</servlet-class>
<init-param>
<param-name>contextConfigLocation</param-name>
<param-value>appctx.xml</param-value>
</init-param>
</servlet>
<!--
Mapping used for external requests
-->
<servlet-mapping>
<servlet-name>CamelServlet</servlet-name>
<url-pattern>/camel/*</url-pattern>
</servlet-mapping>
<!--
Mapping used for web hooks accessed by task queueing service.
-->
<servlet-mapping>
<servlet-name>CamelServlet</servlet-name>
<url-pattern>/worker/*</url-pattern>
</servlet-mapping>
</web-app>
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The location of the Spring application context XML file is given by the contextConfigLocation
init parameter. The appctx.xml
file must be on the classpath. The servlet mapping makes the Camel application accessible under http://<appname>.appspot.com/camel/...
when deployed to Google App Engine where <appname>
must be replaced by a real GAE application name. The second servlet mapping is used internally by the task queueing service for background processing via web hooks. This mapping is relevant for the gtask component and is explained there in more detail.
Security
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