How to use properties with the SimpleRegistry in Apache Camel (Spring XML) - apache-camel

Question

I want to use a SimpleRegistry to store properties (as global variables). The property is changed with setProperty in a route with a jms endpoint. The camel documentation changed last week and has many dead links, also the Registry page. I did not found any samples that describe the use of the simpleRegistry.
I used the camel-example-servlet-tomcat as base. I do not use Fuse or the patched camel wildfly, because is to huge for our simple module.
<beans .... >
.
.
.
<bean id="simpleRegistry" class="org.apache.camel.support.SimpleRegistry" />
<camelContext xmlns="http://camel.apache.org/schema/spring">
<propertyPlaceholder id="properties" location="ref:simpleRegistry" />
<route id="storeConfig">
<from id="myTopic" uri="jms:topic:myTopic?selector=Configuration %3D 'xyz'" />
<log id="printHeader2" message="Received header: ${headers}" />
<log id="logToken" message="Received token: ${headers[myToken]}" />
<setProperty id="setMyToken" name="myProperty">
<simple>${headers[myToken]}</simple>
</setProperty>
</route>
<route id="externalIncomingDataRoute">
<from uri="servlet:hello" />
<transform>
<simple>The Token is: {{myProperty}}</simple>
</transform>
</route>
</camelContext>
</beans>
With the camel context deined like above, I got a java.io.FileNotFoundException Properties simpleRegistry not found in registry.
When I use <propertyPlaceholder id="properties" location="classpath:test.properties" /> and create a test.properties file, everything works fine but I cannot change the property. The operation in the setProperty tag is ignored.
The reason why I need a global variable is, I send a dynamic configuration (the myToken) via a jms topic to the camel context. A single route should store this configuration globaly. If an other route is called via an rest component, this route need the token to make a choice.

Answer 1

Alternatively you can achieve the same result following the below approach which uses the PropertiesComponent
<bean id="applicationProperties" class="java.util.Properties"/>
<bean id="properties" class="org.apache.camel.component.properties.PropertiesComponent">
<property name="location" value="classpath:application.properties"/>
<property name="overrideProperties" ref="applicationProperties" />
</bean>
Define the property place holder in the camel context:
<propertyPlaceholder id="propertiesRef" location="ref:applicationProperties" />
Set a property as shown below :
<bean ref="applicationProperties" method="setProperty(token, 'Test'})" />
And to fetch the property : ${properties:token}

Answer 2

OK, there are multiple subjects in your question.
You write you want to use Camel SimpleRegistry, but you obviously have a Spring application.
If you got Spring available, the Camel Registry automatically uses the Spring bean registry. The Camel Registry is just a thin wrapper or provider interface that uses whenever possible an available registry of another framework.
The Camel SimpleRegistry is only used when nothing else is available. This is basically an in-memory registry based on a Map.
You want to set an application property with <setProperty>.
<setProperty> sets an Exchange property, NOT an application property. With this you can save values in the Exchange of a message.
You want to use "global variables".
You could perhaps use a Spring singleton bean that is a Map. You could then autowire it where you need it, it would be like an application wide available map.
However, think twice why you need this kind of variable. This could also be a symptom of a design problem.