can someone please clarify for me, when im Autowiring Spring State Machine, and execute start() method, am i creating the instance of the state machine, similarly to lets say Activiti ProcessInstance or Camunda ProcessInstance.
If you let spring context to create a single machine you create one instance within a jvm, start/stop really doesn't matter. In a same way if you create a machine factory, you can ask that factory to create individual instances in a same jvm. Don't know activity/camunda so don't know how those relates to processes.
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We are constructing instance of CouchBase cluster in Spring singleton bean afterProperties() method by reading the configurations (like hosts, ports, connection time outs,..). This is working well.
We were using Apache hierarchical configuration for the configurations. Apache hierarchical configurations has reload strategy and does not require server restart after the configuration changed. New configurations will be reflected in 2 minutes.
Now we got requirement to update CouchBase configurations at run time. But since Spring #afterProperties is bean life cycle method and does not execute again, we could not able to achieve what we are looking for.
Right now, we need to restart the server(Tomcat) to reflect the new settings.
Is there any mechanism in Spring or any other better approach to fulfill our requirement ( singleton bean capable to handle configuration change at run time).
Thinking in better design perspective, please provide your thoughts.
Have one service named AccountService.5 instances are needed to support the traffic.all these instances run in docker container.Now I need to run a schedule task.this task should only run on a single AccountService instance.but not all the five instances.which one is not important
My question is how to configure to achieve this.Can eureka do this?and zookeeper seems have the ability to manage the cluster.Do I need to register the AccountService into Zookeeper?
Hope someone can share experience with me
Consider using a shared data store like Redis or, if you're already using a DB, a table in the DB, to have a task lock. The first instance to come up can grab the lock, run the task, and release the lock.
Include spring-cloud-task in your dependency (which is suitable for scheduled tasks).
Then enable this property - spring.cloud.task.single-instance-enabled=true
Add Spring Integration dependencies. Copy/paste from here - https://docs.spring.io/spring-cloud-task/docs/current/reference/#features-single-instance-enabled
Note:
Locks are created and stored under TASK_LOCK table. Make sure its clean, otherwise you will have problems restarting.
Use Spring Based task scheduling #Schedule
For more click here
I want to share a singleton bean across multiple war. I know sharing ApplicaitonContext using parentContextKey attribute(Example, http://blog.springsource.org/2007/06/11/using-a-shared-parent-application-context-in-a-multi-war-spring-application/)
But this way instance of bean created multiple (for 2 war, 2 instance). I want only 1 instance across 2 war.
Another way, If i set some value in any POJO, it should be accessible in another war.
Reason i need this is, there are some beans(like HibernateSessionFactory, Datasource etc which are expensive) which are created multiple times(n instance for n war). Whereas i want to utilize same instance instead of creating same in different war.
Can anyone provide me solution for this?
You could achieve this by binding the objects into the global JNDI tree. That means that both WARs would have references to an object looked up in JNDI.
Hibernate allows you to use the hibernate.session_factory_name property (this may well be a good starting point. Data sources should already be looked up from JNDI.
One thing, I would not class a session factory or a data source as expensive, so you may well be saving a miniscule amount of memory in exchange for a lot of additional complexity, so I would ask myself the question on whether this is worth the additional maintenance headaches.
Spring provide a way to expose any bean (service) and these bean can be access from any other web application or any standalone application.
please refer Remoting and Web Service using Spring to get more details.
I've gotten the basics of Spring more or less down (I think) and I'm trying out new things. Currently, I'm trying to figure out a way not to have explicitly write a service class for each entity/repository if that service is just going to be extending a generic service class.
What I'd like to be able to do is, after the Entity and Repository beans are loaded, loop through them, check to see if a bean named [Model Name]Service exists and, if it does not, create a new instance of my generic service class, pass in the Repository object, and then register this service in the applicationContext.
Is this possible and if so, what is the best way to do it? I've been trying to figure out the PostProcessors, but the one that I think would actual work (BeanPostProcessor) doesn't seem like the appropriate place to do this.
Thanks for your time
I have a web application that uses Struts2 + Spring for the resource injection, basically my DAO. Now I would like to create a thread that periodically polls the database and, if needed, send email notifications to users.
I would like to know how I can implement this in a way that this thread can use my DAO. I haven't been able to manage Spring to inject it the way I've done it. So I would like to hear suggestions and see if someone can point me to the right way.
Right now I have a thread started by a ServletContextListener, that just creates a timer and schedules an action every 5 minutes. But I can't get this action to use my DAO. I don't have any need to use this structure, I'm open to using whichever solution works.
Thanks for your help!
Edit: As axtavt suggested, I used Spring task Execution Scheduling and it works perfectly, the thing is that my task gets injected with the DAO but then I get LazyInitializationException every time I try to access a property of my fetched objects, any suggestion on how to solve that??
Perhaps the best option is to use Spring's own scheduling support, see 25. Task Execution and Scheduling (if necessary - with Quartz, see 25.6 Using the OpenSymphony Quartz Scheduler). This apporach allows you to configure your scheduled action as Spring beans, so you can wire them with other beans such as DAO.
Alternatively, you can use the following to obtain any Spring bean in web application (for example, to obtain DAO from your thread):
WebApplicationContextUtils.getWebApplicationContext(servletContext).getBean(...)