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 onwards, which mean it works also in older web containers; which is the goal of this component.
Servlet 2.x requires to use a web.xml file as configuration. For Servlet 3.x containers you can use annotation driven configuration to boostrap Camel using the @WebListener, and implement your own class, where you boostrap Camel. Doing this still puts the challenge how to let end users easily configure Camel, which you get for free with the old school web.xml file. |
Maven users will need to add the following dependency to their pom.xml for this component:
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{note} Maven users will need to add the following dependency to their {{pom.xml}} for this component: {code:xml} <dependency> <groupId>org.apache.camel</groupId> <artifactId>camel-servletlistener</artifactId> <version>x.x.x</version> <!-- use the same version as your Camel core version --> </dependency> {code} h3. Using You would need to chose one of the following implementations of the abstract class {{ |
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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{snippet:id=web|lang=xml|url=camel/trunk/components/camel-servletlistener/src/test/resources/myweb.xml} h3. Options The {{ |
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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{div:class=confluenceTableSmall} || Option || Type || Description || | propertyPlaceholder.XXX | | To configure [property placeholders|Using PropertyPlaceholder] in Camel. You should prefix the option with "propertyPlaceholder.", for example to configure the location, use propertyPlaceholder.location as name. You can configure all the options from the [Properties] component. | | jmx.XXX | | To configure [JMX|Camel JMX]. You should prefix the option with "jmx.", for example to disable JMX, use jmx.disabled as name. You can configure all the options from {{org.apache.camel.spi.ManagementAgent}}. As well the options mentioned on the [JMX|Camel JMX] page. | | name | {{String}} | To configure the name of the [CamelContext]. | | messageHistory | {{Boolean}} | *Camel 2.12.2:* Whether to enable or disable [Message History] (enabled by default). | | streamCache | {{Boolean}} | Whether to enable [Stream Caching]. | | trace | {{Boolean}} | Whether to enable [Tracer]. | | delayer | {{Long}} | To set a delay value for [Delay Interceptor]. | | handleFault | {{Boolean}} | Whether to enable handle fault. | | errorHandlerRef | {{String}} | Refers to a context scoped [Error Handler] to be used. | | autoStartup | {{Boolean}} | Whether to start all routes when starting Camel. | | useMDCLogging | {{Boolean}} | Whether to use [MDC Logging]. | | useBreadcrumb | {{Boolean}} | Whether to use [breadcrumb|MDC Logging]. | | managementNamePattern | {{String}} | To set a custom naming pattern for JMX MBeans. | | threadNamePattern | {{String}} | To set a custom naming pattern for threads. | | properties.XXX | | To set custom properties on {{CamelContext.getProperties}}. This is seldom in use. | | routebuilder.XXX | | To configure routes to be used. See below for more details. | | CamelContextLifecycle | | Refers to a FQN classname of an implementation of {{org.apache.camel.component.servletlistener.CamelContextLifecycle}}. Which allows to execute custom code before and after [CamelContext] has been started or stopped. See below for further details. | | XXX | | To set any option on [CamelContext]. | {div} h3. Examples See [Servlet Tomcat No Spring Example]. h3. 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". h4. Using a RouteBuilder class By default Camel will assume the param-value is a FQN classname for a Camel [RouteBuilder] class, as shown below: {code:xml} |
Examples
See Servlet Tomcat No Spring Example.
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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<context-param>
<param-name>routeBuilder-MyRoute</param-name>
<param-value>org.apache.camel.component.servletlistener.MyRoute</param-value>
</context-param>
{code}
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You
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can
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specify
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multiple
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classes
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in
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the
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same
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param-value
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as
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shown
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below:
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{code:xml} <context-param> <param-name>routeBuilder-routes</param-name> <!-- we can define multiple values separated by comma --> <param-value> org.apache.camel.component.servletlistener.MyRoute, org.apache.camel.component.servletlistener.routes.BarRouteBuilder </param-value> </context-param> {code} |
The
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name
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of
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the
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parameter
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does
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not
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have
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a
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meaning
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at
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runtime.
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It
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just
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need
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to
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be
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unique
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and
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start
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with
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"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".
Using package scanning
You can also tell Camel to use package scanning, which mean it will look in the given package for all classes of RouteBuilder types and automatic adding them as Camel routes. To do that you need to prefix the value with "packagescan:" as shown below:
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h4. Using package scanning You can also tell Camel to use package scanning, which mean it will look in the given package for all classes of [RouteBuilder] types and automatic adding them as Camel routes. To do that you need to prefix the value with "packagescan:" as shown below: {code:xml} <context-param> <param-name>routeBuilder-MyRoute</param-name> <!-- define the routes using package scanning by prefixing with packagescan: --> <param-value>packagescan:org.apache.camel.component.servletlistener.routes</param-value> </context-param> {code} h4. 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 |
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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{code:xml} <context-param> <param-name>routeBuilder-MyRoute</param-name> <param-value>classpath:routes/myRoutes.xml</param-value> </context-param> {code} |
And
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the
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XML
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file
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is:
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} <?xml version="1.0" encoding="UTF-8"?> <!-- the xmlns="http://camel.apache.org/schema/spring" is needed --> <routes xmlns="http://camel.apache.org/schema/spring"> <route id="foo"> <from uri="direct:foo"/> <to uri="mock:foo"/> </route> <route id="bar"> <from uri="direct:bar"/> <to uri="mock:bar"/> </route> </routes> {code} |
Notice
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that
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in
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the
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XML
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file
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the
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root
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tag
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is
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<routes>
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which
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must
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use
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the
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namespace
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"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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{code:xml} <!-- setup property placeholder to load properties from classpath --> <!-- we do this by setting the param-name with propertyPlaceholder. as prefix and then any options such as location, cache etc --> <context-param> <param-name>propertyPlaceholder.location</param-name> <param-value>classpath:myproperties.properties</param-value> </context-param> <!-- for example to disable cache on properties component, you do --> <context-param> <param-name>propertyPlaceholder.cache</param-name> <param-value>false</param-value> </context-param> {code} h4. Configuring JMX Here is a snippet of a |
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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{code:xml} <!-- configure JMX by using names that is prefixed with jmx. --> <!-- in this example we disable JMX --> <context-param> <param-name>jmx.disabled</param-name> <param-value>true</param-value> </context-param> {code} h3. JNDI or Simple as Camel [Registry] This component uses either JNDI or Simple as the [Registry]. This allows you to lookup [Bean]s and other services in JNDI, and as well to bind and unbind your own [Bean]s. This is done from Java code by implementing the {{ |
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.
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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}}. h4. 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. {snippet:id=e1|lang=java|url=camel/trunk/components/camel-servletlistener/src/test/java/org/apache/camel/component/servletlistener/MyLifecycle.java} |
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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{code:xml} <context-param> <param-name>CamelContextLifecycle</param-name> <param-value>org.apache.camel.component.servletlistener.MyLifecycle</param-value> </context-param> {code} |
As
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we
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enlisted
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our
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HelloBean
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using
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the
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name
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"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:
| Code Block |
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} public class MyBeanRoute extends RouteBuilder { @Override public void configure() throws Exception { from("seda:foo").routeId("foo") .to("bean:myBean") .to("mock:foo"); } } {code} * |
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
...
well.
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And
...
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
...
use
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the
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SimpleRegistry