THIS IS A TEST INSTANCE. ALL YOUR CHANGES WILL BE LOST!!!!
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ServletListener
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Component
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Available
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as
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of
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Camel
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2.11
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This
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component
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is
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used
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for
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bootstrapping
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Camel
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applications
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in
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web
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applications.
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For
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example
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beforehand
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people
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would
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have
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to
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find
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their
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own
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way
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of
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bootstrapping
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Camel,
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or
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rely
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on
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3rd
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party
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frameworks
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such
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as
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Spring
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to
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do
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it.
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This component supports Servlet 2.x
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onwards,
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which
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mean
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it
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works
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also
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in
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older
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web
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containers;
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which
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is
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the
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goal
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of
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this
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component.
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Though
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Servlet
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2.x
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requires
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to
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use
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a
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web.xml
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file
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as
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configuration.
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For
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Servlet
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3.x
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containers
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you
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can
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use
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annotation
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driven
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configuration
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to
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boostrap
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Camel
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using
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the
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@WebListener,
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and
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implement
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your
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own
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class,
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where
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you
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boostrap
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Camel.
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Doing
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this
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still
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puts
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the
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challenge
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how
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to
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let
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end
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users
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easily
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configure
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Camel,
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which
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you
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get
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for
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free
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with
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the
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old
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school
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web.xml
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file.
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Maven users will need to add the following dependency to their pom.xml for this component:
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Using
You would need to chose one of the following implementations of the abstract class org.apache.camel.component.servletlistener.CamelServletContextListener
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.
JndiCamelServletContextListenerwhich uses theJndiRegistryto leverage JNDI for its registry.SimpleCamelServletContextListenerwhich uses theSimpleRegistryto leverage ajava.util.Map
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- as
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- its
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- registry.
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To
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use
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this
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you
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need
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to
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configure
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the
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org.apache.camel.component.servletlistener.CamelServletContextListener
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in
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the
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WEB-INF/web.xml
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file
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as
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shown
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below:
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Options
The org.apache.camel.component.servletlistener.CamelServletContextListener
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supports
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the
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following
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options
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which
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can
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be
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configured
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as
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context-param
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in
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the
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web.xml
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file.
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Option | Type | Description |
|---|---|---|
propertyPlaceholder.XXX |
| To configure property placeholders in Camel. You should prefix the option with "propertyPlaceholder.", |
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for |
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example |
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to |
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configure |
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the |
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location, |
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use |
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propertyPlaceholder.location |
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as |
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name. |
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You |
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can |
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configure |
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all |
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the |
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options |
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from |
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the |
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component. |
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jmx.XXX |
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| To configure JMX. You should prefix the option with "jmx.", |
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for |
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example |
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to |
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disable |
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JMX, |
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use |
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jmx.disabled |
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as |
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name. |
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You |
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can |
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configure |
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all |
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the |
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options |
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from |
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|
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. |
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As |
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well |
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the |
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options |
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mentioned |
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on |
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the |
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page. |
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name |
| To configure the name of the CamelContext. |
messageHistory |
| Camel 2.12.2: Whether to enable or disable Message History (enabled by default). |
streamCache |
| Whether to enable Stream caching. |
trace |
| Whether to enable Tracer. |
delayer |
| To set a delay value for Delay Interceptor. |
handleFault |
| Whether to enable handle fault. |
errorHandlerRef |
| Refers to a context scoped Error Handler to be used. |
autoStartup |
| Whether to start all routes when starting Camel. |
useMDCLogging |
| Whether to use MDC logging. |
useBreadcrumb |
| Whether to use breadcrumb. |
managementNamePattern |
| To set a custom naming pattern for JMX MBeans. |
threadNamePattern |
| To set a custom naming pattern for threads. |
properties.XXX |
| To set custom properties on |
routebuilder.XXX |
| To configure routes to be used. See below for more details. |
CamelContextLifecycle |
| Refers to a FQN classname of an implementation of |
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. |
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Which |
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allows |
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to |
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execute |
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custom |
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code |
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before |
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and |
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after |
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has |
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been |
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started |
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or |
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stopped. |
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See |
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below |
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for |
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further |
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details. |
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XXX |
| To set any option on CamelContext. |
Examples
See Servlet Tomcat No Spring Example.
Accessing the created CamelContext
Available as of Camel 2.14/2.13.3/2.12.5
The created CamelContext is stored on the ServletContext as an attribute with the key "CamelContext". You can get hold of the CamelContext if you can get hold of the ServletContext as shown below:
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Configuring routes
You need to configure which routes to use in the web.xml file. You can do this in a number of ways, though all the parameters must be prefixed with "routeBuilder".
Using a RouteBuilder class
By default Camel will assume the param-value is a FQN classname for a Camel RouteBuilder class, as shown below:
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You can specify multiple classes in the same param-value
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as
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shown
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below:
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The name of the parameter does not have a meaning at runtime. It just need to be unique and start with "routeBuilder".
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In
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the
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example
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above
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we
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have
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"routeBuilder-routes".
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But
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you
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could
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just
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as
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well
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have
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named
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it
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"routeBuilder.foo".
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Using
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package
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scanning
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You
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can
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also
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tell
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Camel
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to
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use
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package
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scanning,
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which
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mean
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it
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will
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look
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in
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the
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given
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package
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for
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all
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classes
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of
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types
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and
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automatic
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adding
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them
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as
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Camel
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routes.
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To
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do
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that
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you
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need
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to
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prefix
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the
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value
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with
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"packagescan:"
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as
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shown
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below:
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Using a XML file
You can also define Camel routes using XML DSL, though as we are not using Spring or Blueprint the XML file can only contain Camel route(s).
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In
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the
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web.xml
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you
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refer
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to
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the
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XML
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file
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which
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can
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be
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from
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"classpath",
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"file"
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or
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a
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"http"
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url,
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as
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shown
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below:
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And the XML file is:
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Notice that in the XML file the root tag is <routes> which must use the namespace "http://camel.apache.org/schema/spring".
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This
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namespace
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is
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having
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the
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spring
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in
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the
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name,
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but
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that
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is
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because
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of
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historical
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reasons,
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as
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Spring
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was
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the
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first
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and
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only
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XML
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DSL
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back
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in
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the
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time.
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At
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runtime
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no
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Spring
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JARs
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is
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needed.
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Maybe
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in
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Camel
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3.0
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the
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namespace
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can
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be
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renamed
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to
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a
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generic
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name.
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Configuring propert placeholders
Here is a snippet of a web.xml
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configuration
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for
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setting
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up
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property
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placeholders
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to
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load
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myproperties.properties
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from
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the
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classpath
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Configuring JMX
Here is a snippet of a web.xml
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configuration
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for
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configuring
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JMX,
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such
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as
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disabling
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JMX.
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JNDI or Simple as Camel Registry
This component uses either JNDI or Simple as the Registry.
This allows you to lookup Beans and other services in JNDI, and as well to bind and unbind your own Beans.
This is done from Java code by implementing the org.apache.camel.component.servletlistener.CamelContextLifecycle
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.
Using custom CamelContextLifecycle
In the code below we use the callbacks beforeStart and afterStop to enlist our custom bean in the Simple Registry, and as well to cleanup when we stop.
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Then
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we
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need
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to
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register
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this
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class
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in
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the
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web.xml
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file
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as
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shown
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below,
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using
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the
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parameter
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name
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"CamelContextLifecycle".
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The
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value
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must
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be
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a
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FQN
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which
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refers
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to
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the
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class
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implementing
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the
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org.apache.camel.component.servletlistener.CamelContextLifecycle
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interface.
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As we enlisted our HelloBean Bean using the name "myBean"
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we
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can
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refer
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to
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this
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in
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the
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Camel
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routes
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as
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shown
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below:
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Important:
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If
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you
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use
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org.apache.camel.component.servletlistener.JndiCamelServletContextListener
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then
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the
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CamelContextLifecycle
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must
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use
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the
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JndiRegistry
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as
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well.
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And
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likewise
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if
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the
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servlet
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is
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org.apache.camel.component.servletlistener.SimpleCamelServletContextListener
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then
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the
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CamelContextLifecycle
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must
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use
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the
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SimpleRegistry