I'm sorry Mule doesn't support SpEL in the frequency
attribute so I had to build the horrible contraption shown below to implement your requirement using only configuration elements.
You could also create a custom class to parse the initial properties
bean instead of using the MethodInvokingFactoryBean
as I'm doing below.
<spring:beans>
<util:properties id="properties" location="classpath:appProperties.properties" />
<spring:bean id="giantsNewProperty"
class="org.springframework.beans.factory.config.MethodInvokingFactoryBean"
p:targetObject-ref="properties" p:targetMethod="setProperty">
<spring:property name="arguments">
<spring:list>
<spring:value>GiantsNewComputedPoll</spring:value>
<spring:value>#{ T(java.lang.Integer).valueOf(properties.getProperty("GiantsNew.poll")) * 5 }</spring:value>
</spring:list>
</spring:property>
</spring:bean>
<spring:bean id="computedProperties" factory-bean="properties"
factory-method="clone" depends-on="giantsNewProperty" />
<context:property-placeholder
properties-ref="computedProperties" />
</spring:beans>
...
<poll frequency="${GiantsNewComputedPoll}">