Say I have a Swing/Spring standalone application. I am wondering whether Spring does detect runtime changes to its configuration file such as this one (assuming the file is on the classpath):
Commenting second bean and adding first bean as below:
<beans>
<bean id="randonNumberGenerator" class="com.me.MyGenerator"/>
<!--
<bean id="randonNumberGenerator" class="com.someoneelse.ADifferentGenerator"/>
-->
</beans>
Will Spring change the implementation at runtime as expected?
I don't think Spring provides a way to reload the configuration on-the-fly. It could be possible by re-instantiating the entire ApplicationContext, but that would mean that all beans are recreated etc., and internal state of the software would probably fly out the window in the process.
I think you can use the "AbstractRefreshableApplicationContext" to refresh the context.
AbstractRefreshableApplicationContext refreshableContext = new ClassPathXmlApplicationContext ( "applicationContextRefreshable.xml" );
refreshableContext.refresh ( );
For details you can have a look here
Related
I have my KnowledgeAgent setup as
<drools:kagent kbase="kbase" id="knowledgeAgent" new-instance="false" >
<drools:resources>
<drools:resource source="classpath:change-set.xml" type="CHANGE_SET" />
</drools:resources>
</drools:kagent>
So it scans the change-set.xml from classpath for resources. And I have another component which will dynamially generate the change-set.xml based on rulefiles found on disk. The spring configuration for this is
<bean id="changesetHandler" class="ChangesetHandler" autowire="byName" lazy-init="true" />
The problem here is that the change-set.xml is generated by my custom component, but I cannot set the Drools KnowledgeAgent component to be dependant on it as it follows it's own schema which does not seem to have depends-on attribute.
Given that a knowledge agent listens for changes, it should reload the knowledge base as soon as your bean generates the change set. Why not load a default empty change set initially and then load the dynamic change set when it has been generated?
Personally I avoid the Drools-Spring components. I find it easier to create a service within my application, which holds my knowledge base. I can then define whatever dependencies I like within that service and ensure that any initialisation has been completed.
I'm looking for a way to conditionally set up jms:message-driven-channel-adapter in spring 3.0 & spring integration 2.2.
I would like to have an entry in a property file like: "create.message.driven.channel.adapter=true" for each environment and I would like spring to decide whether to set up the channel or not based solely on the entry from the property file.
Is there a way to accomplish this using only spring xml configuration and a property file?
You can't do it exactly the way you describe. With Spring 3.1, you could do it with Spring Profiles...
<beans>
...
<beans profile="foo">
<jms:message-driven-adapter ... />
</beans>
</beans>
Then run with ... -Dspring.profiles.active=foo.
You could do it with JavaConfig
#Bean
public Object foo() {
// if property set, return an MDA, otherwise a String
}
Or, probably the easiest, so long as you don't explicitly start() the context, you could use
<jms:message-driven-adapter ...
auto-startup="${start.message.driven.channel.adapter}" />
In which case, the bean would be defined, but it just wouldn't be started so it wouldn't even open a JMS connection. You would also need a property placeholder configurer pointed at your properties file.
But, auto-startup only applies to starting on refresh(), an explicit context.start() will still start it.
I have config xml based spring application for which I have moved proprties required at start up time in database. It was very difficult to manage hundreds in property file and that is why database is introduced. To read properties a spring restful service is developed to return a map of all properties required at start up time.
I want to know how to replace properties reading from a map to spring context file e.g. ${config.service.url} should be polulated from a map read via web service.
One option I considered is to upgrade to Annotation based and start using MapPropertySource and Environment interface as environment.getRequiredProperty("config.service.url"). However upgrading to Annotation based is a big impact on project and is no at this time.
Second option that I am looking forward is to have a customised PropertyPlaceholderConfigurer.
Any pointer/help on this will be great.
Cheers,
Amber
You could define a PropertyPlaceholderConfigurer, but instead of specifying a file location, you can pass the properties directly as returned by your restful service.
<bean class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
<property name="properties" .../>
</bean>
It seems like there's been a few iterations of property support in spring it's hard to tell what's best practice and the manuals are written from the point of view of someone who is familiar with every other iteration. I feel like this should be a simple and common requirement but given how hard it's been please correct me if there's a more idiomatic way.
What I want is to pass an additional properties file to my spring web app based on a context property which the client is setting using a tomcat descriptor like so
<Context path="/foo" reloadable="true">
<Parameter name="foo.config" value="file:${catalina.base}/conf/foo.properties"/>
</Context>
In spring for the live profile I have this
<beans profile="live">
<context:property-placeholder location="classpath:timetabling.live.properties,${timetabling.config}"
ignore-resource-not-found="true" />
</beans>
So I'd assumed this doesn;t work because I'm trying to configure placeholder suppport with a placeholder. If I use a system property however then this works fine. I know that spring 3.1 has baked in support for system and environment properties so I guess my question is how can I augment this support with something context aware before the placeholder is resolved?
--Update--
looking at http://blog.springsource.org/2011/02/15/spring-3-1-m1-unified-property-management/ particularly at footnote 1, I would expect to have a DefaultWebEnvironment which should already have aceess to context init params. Now I am more confused, can someone provide me with a concrete example of context property retrieval? At this point I feel like I've read every javadoc available and they are just not helpful.
<context:property-placeholder /> sets up a PropertyPlaceholderConfigurer which reads from .properties, system properties and environment variables. A Tomcat context.xml however sets up a servlet context init parameter. So what you need is a ServletContextPropertyPlaceholderConfigurer.
Seems like a simple task. I have a webapp which requires a database connection. I'd like to be able to drop an updated .war file on this app server and load a new version without having to re-edit an applicationConfig.xml file to specify the database connection parameters for production.
Is using the container to setup the data source and then referencing it from JNDI the preferred way to go? I think it is cleaner having it all defined in the spring .xml file, but I can't come up with a clean way to allow the production password to be set only once as we roll out new versions.
So, how do you specify your database connection information in a spring application so that you can upgrade it without having to re-edit the files?
If you use JNDI, how do you handle setting up of your tests since the JNDI is not going to be available outside of the container?
Thanks!
The typical way to externalize database connection properties is to store them in a .properties file and load using <context:property-placeholder .../> . Then you can have different .properties files for testing and production.
If you choose JNDI, you can use a Spring's mock JNDI support for testing.
One approach is for your Spring configuration file to be composed of fragments related to specific layers in your application.
One such fragment could contain your DataSource defintion. For production, this fragment would use a jee:jndi-lookup. And then for test, have a different fragment would use a DriverManagerDataSource ?
Update:
If you want to change the datasource after deployment, then you can use this technique, along with changing the which datasource is injected into your other beans using a PropertyPlaceholderConfigurer as explained in an old post I wrote
eg:
<bean class="foo.bar.SomeClassNeedingDataSource"">
<property name="dataSource" ref="${the.datasource.to.inject}" />
</bean>
<jee:jndi-lookup id="jndiDataSource" ... />
<bean id="driverManagerDataSource"
class="org.springframework.jdbc.datasource.DriverManagerDataSource">
...
</bean>
# the properties file
the.datasource.to.inject = jndiDataSource
#the.datasource.to.inject = driverManagerDataSource