Jonathan Lalou's Blog

Abstract

How to set dynamically the URL used by a HttpInvokerProxyFactoryBean in a Spring-deployed WAR?

Detailed Case

I have to deploy a GWT/GXT application, calling two distant services:
a remote EJB
a service accessed through Spring Remoting

Here is the Spring configuration file I firstly used:

[xml]
<util:properties id="jndiProperties" location="classpath:jndi.properties"/>
<jee:remote-slsb id="myRemoteEJBService" jndi-name="ejb.remote.myRemoteService"
business-interface="lalou.jonathan.myRemoteEJBService"
environment-ref="jndiProperties" cache-home="false"
lookup-home-on-startup="false" refresh-home-on-connect-failure="true" />

<bean id="mySpringRemoteService"
class="org.springframework.remoting.httpinvoker.HttpInvokerProxyFactoryBean">
<property name="serviceInterface"
value="lalou.jonathan.services.mySpringRemoteService" />
<property name="serviceUrl" value="${spring.remote.service.url}"/>
</bean>
[/xml]

Unhappily, even though the remote EJB is retrieved (which proves that the jndi file is available in the classpath and rightly loaded), the Spring Remote service is not. I had to write the URL in hard in the configuration file… This is not very efficient when you work in a large team, with different production and testings environments!

This is the log when myRemoteEJBService bean is loaded:
[java]2010-08-17 16:05:42,937 DEBUG support.DefaultListableBeanFactory – Creating shared instance of singleton bean ‘myRemoteEJBService’
2010-08-17 16:05:42,937 DEBUG support.DefaultListableBeanFactory – Creating instance of bean ‘myRemoteEJBService’
2010-08-17 16:05:42,937 DEBUG support.DefaultListableBeanFactory – Eagerly caching bean ‘myRemoteEJBService’ to allow for resolving potential circular references
2010-08-17 16:05:42,937 DEBUG support.DefaultListableBeanFactory – Returning cached instance of singleton bean ‘jndiProperties’
2010-08-17 16:05:42,937 DEBUG support.DefaultListableBeanFactory – Invoking afterPropertiesSet() on bean with name ‘myRemoteEJBService’
2010-08-17 16:05:42,937 DEBUG framework.JdkDynamicAopProxy – Creating JDK dynamic proxy: target source is EmptyTargetSource: no target class, static
2010-08-17 16:05:42,953 DEBUG support.DefaultListableBeanFactory – Finished creating instance of bean ‘myRemoteEJBService'[/java]

That is the log when mySpringRemoteService is loaded:
[java]2010-08-17 16:05:42,968 DEBUG support.DefaultListableBeanFactory – Creating shared instance of singleton bean ‘mySpringRemoteService’
2010-08-17 16:05:42,968 DEBUG support.DefaultListableBeanFactory – Creating instance of bean ‘mySpringRemoteService’
2010-08-17 16:05:42,984 DEBUG support.DefaultListableBeanFactory – Eagerly caching bean ‘mySpringRemoteService’ to allow for resolving potential circular references
2010-08-17 16:05:43,234 DEBUG support.DefaultListableBeanFactory – Invoking afterPropertiesSet() on bean with name ‘mySpringRemoteService’
2010-08-17 16:05:43,250 DEBUG framework.JdkDynamicAopProxy – Creating JDK dynamic proxy: target source is EmptyTargetSource: no target class, static
2010-08-17 16:05:43,250 DEBUG support.DefaultListableBeanFactory – Finished creating instance of bean ‘mySpringRemoteService'[/java]

You can notice that no mention to jndiProperties appears. Here is the key of the problem: jndiProperties is considered as a bean among others, which cannot be accessed easyly from the HttpInvokerProxyFactoryBean.

Fix

To fix the issue, you have to add an actual property holder in Spring XML configuration file, ie after:

[xml]<util:properties id="jndiProperties" location="classpath:jndi.properties"/>[/xml]

add an instanciation of PropertyPlaceholderConfigurer:

[xml]<bean id="propertyConfigurer" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
<property name="location" value="classpath:jndi.properties"/>
</bean>[/xml]