THIS IS A TEST INSTANCE. ALL YOUR CHANGES WILL BE LOST!!!!
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Camel
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Components
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for
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App
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Engine
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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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=Tutorials} * A good starting point for using Camel on GAE is the [Tutorial for Camel on Google App Engine] * The [OAuth tutorial|Tutorial-OAuth] demonstrates how to implement [OAuth|http://oauth.net/] in web applications. {tip} The Camel components for [Google App Engine|http://code.google.com/appengine/] (GAE) are part of the {{camel-gae}} project and provide connectivity to GAE's [cloud computing services|http://code.google.com/appengine/docs/java/apis.html]. 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. {div:class=confluenceTableSmall} ||GAE service||Camel component||Component description|| |[URL fetch service|http://code.google.com/appengine/docs/java/urlfetch/]|[ghttp]|Provides connectivity to the GAE URL fetch service but can also be used to receive messages from servlets.| |[Task queueing service|http://code.google.com/appengine/docs/java/taskqueue/]|[gtask]|Supports asynchronous message processing on GAE by using the task queueing service as message queue.| |[Mail service|http://code.google.com/appengine/docs/java/mail/]|[gmail]|Supports sending of emails via the GAE mail service. Receiving mails is not supported yet but will be added later.| |[Memcache service|http://code.google.com/appengine/docs/java/memcache/]| |Not supported yet.| |[XMPP service|http://code.google.com/appengine/docs/java/xmpp/]| |Not supported yet.| |[Images service|http://code.google.com/appengine/docs/java/images/]| |Not supported yet.| |[Datastore service|http://code.google.com/appengine/docs/java/datastore/]| |Not supported yet.| |[Accounts service|http://code.google.com/apis/accounts/]|[gauth] \\ [glogin]|These components interact with the Google 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|http://code.google.com/apis/accounts/docs/OAuth.html] 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|gsec] page.| {div} h3. |
Camel
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context
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Setting
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up
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a
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SpringCamelContext
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on
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App
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Engine
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differs
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between
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Camel
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2.1
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and
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higher
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versions.
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The
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problem
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is
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that
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usage
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of
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the
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Camel-specific
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Spring
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configuration
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XML
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schema
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from
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the
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http://camel.apache.org/schema/spring
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namespace
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requires
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JAXB
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and
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Camel
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2.1
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depends
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on
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a
...
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App
...
Engine
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SDK
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version
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that
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doesn't
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support
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JAXB
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yet.
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This
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limitation
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has
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been
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removed
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since
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Camel
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2.2.
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JMX
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must
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be
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disabled
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in
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any
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case
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because
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the
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javax.management
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package
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isn't
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on
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the
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App
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Engine
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JRE
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whitelist.
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Camel
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2.1
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camel-gae
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2.1
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comes
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with
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the
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following
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CamelContext
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implementations.
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org.apache.camel.component.gae.context.GaeDefaultCamelContext
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- (extends
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org.apache.camel.impl.DefaultCamelContext
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- )
org.apache.camel.component.gae.context.GaeSpringCamelContext
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- (extends
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org.apache.camel.spring.SpringCamelContext
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- )
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Both
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disable
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JMX
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before
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startup.
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The
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GaeSpringCamelContext
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additionally
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provides
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setter
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methods
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adding
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route
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builders
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as
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shown
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in
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the
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next
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example.
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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> {code} |
Alternatively,
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use
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the
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routeBuilders
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property
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of
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the
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GaeSpringCamelContext
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for
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setting
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a
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list
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of
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route
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builders.
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Using
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this
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approach,
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a
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SpringCamelContext
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can
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be
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configured
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on
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GAE
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without
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the
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need
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for
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JAXB.
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Camel
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2.2
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or
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higher
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With
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Camel
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2.2
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or
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higher,
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applications
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can
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use
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the
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http://camel.apache.org/schema/spring
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namespace
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for
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configuring
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a
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SpringCamelContext
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but
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still
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need
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to
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disable
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JMX.
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Here's
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an
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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> {code} {anchor: |
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The
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web.xml
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Running
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Camel
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on
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GAE
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requires
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usage
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of
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the
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CamelHttpTransportServlet
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from
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camel-servlet
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.
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The
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following
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example
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shows
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how
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to
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configure
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this
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servlet
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together
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with
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a
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Spring
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application
...
context
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XML
...
file.
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{code:xml|title=web.xml} <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> {code} |
The
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location
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of
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the
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Spring
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application
...
context
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XML
...
file
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is
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given
...
by
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the
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contextConfigLocation
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init
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parameter.
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The
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appctx.xml
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file
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must
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be
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on
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the
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classpath.
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The
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servlet
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mapping
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makes
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the
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Camel
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application
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accessible
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under
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http://<appname>.appspot.com/camel/...
...
when
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deployed
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to
...
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App
...
Engine
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where
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<appname>
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must
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be
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replaced
...
by
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a
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real
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GAE
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application
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name.
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The
...
second
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servlet
...
mapping
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is
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used
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internally
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by
...
the
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task
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queueing
...
service
...
for
...
background
...
processing
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via
...
...
...
.
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This
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mapping
...
is
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relevant
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for
...
the
...
...
component
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and
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is
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explained
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there
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in
...
more
...
detail.
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