Vaadin Spring integration
I lately became interested in Vaadin, another web framework but where everything is done on the server side: no need for developers to learn HTML, CSS nor JavaScript. Since Vaadin adress my remarks about web applications being to expensive because of a constant need of well-rounded developers, I dug a little deeper: it will probably be the subject of another post.
Anyway, i became a little disappointed when I wanted to use my favourite Dependency Injection framework, namely Spring, in Vaadin. After a little Google research, I found the Vaadin Wiki and more precisely the page talking about Vaadin Spring Integration. It exposes two ways to integrate Spring in Vaadin.
The first one uses the Helper “pattern”, a class with static method that has access to the Spring application context. IMHO, those Helper classes should be forgotten now we have DI since they completely defeat its purpose. If you need to explicitly call the Helper static method in order to get the bean, where’s the Inversion of Control?
The second solution uses Spring proprietary annotation @Autowired in order to use DI. Since IoC is all about decoupling, I’m vehemently opposed to coupling my code to the Spring framework.
Since neither option seemed viable to me, let me present you the one I imagined: it is very simple and consists of subclassing the Vaadin’s AbstractApplicationServlet and using it instead of the classical ApplicationServlet.
public class SpringVaadinServlet extends AbstractApplicationServlet {
/** Class serial version unique identifier. */
private static final long serialVersionUID = 1L;
private Class clazz;
@Override
public void init(ServletConfig config) throws ServletException {
super.init(config);
WebApplicationContext wac = WebApplicationContextUtils.getRequiredWebApplicationContext(
config.getServletContext());
Application application = (Application) wac.getBean("application", Application.class);
clazz = application.getClass();
}
/**
* Gets the application from the Spring context.
*
* @return The Spring bean named 'application'
*/
@Override
protected Application getNewApplication(HttpServletRequest request)
throws ServletException {
WebApplicationContext wac = WebApplicationContextUtils.getRequiredWebApplicationContext(
request.getSession().getServletContext());
return (Application) wac.getBean("application", Application.class);
}
/**
* @see com.vaadin.terminal.gwt.server.AbstractApplicationServlet#getApplicationClass()
*/
@Override
protected Class getApplicationClass()
throws ClassNotFoundException {
return clazz;
}
}
This solution is concise and elegant (according to me). Its only drawback is that it couples the servlet to Spring. But a class-localized coupling is of no consequesence and perfectly acceptable. Morevoer, this lets you use Spring autowiring mechanism, JSR 250 autowiring or plain old XML explicit wiring.
Hi there,
Thank you for your post, it sounds interesting. But I’m such a newbie on these technologies and I have some problem to imagine your solution in a project.
Do you have somewhere a simple example which could easily show us how it is working ?
Thank you again !!!
Regards,
Guillaume
Just replace Vaadin servlet declaration in your web.xml deployment descriptor by the following snippet:
<?xml version="1.0" encoding="UTF-8"?> <web-app...> ... <servlet> <servlet-name>Vaadin servlet</servlet-name> <servlet-class>ch.frankel.blog.vaadin.SpringVaadinServlet </servlet-class> <init-param> <param-name>application</param-name> <param-value>ch.frankel.blog.vaadin.Application</param-value> </init-param> </servlet> <servlet-mapping> <servlet-name>Vaadin servlet</servlet-name> <url-pattern>/*</url-pattern> </servlet-mapping> </web-app>“Its only drawback is that it couples the servlet to Spring”. That’s kinda the point
You gotta tie the know somewhere.
@Brian
know=knot
Hi Nicolas,
Is the … section above required at all?
Should the “application” bean be defined in a/the spring applicationcontext.xml file?
Thanks,
Matt
Sorry, there’s a problem with my last post, it should be:
Is the init-param section above required at all?
Should the “application” bean be defined in a/the spring
applicationcontext.xmlfile?Thanks,
Matt
I have the exact same questions as asked by Matt just above. Plus, are your UI components like form, window, textbox… so on are also managed by spring? for example, my forms need a service bean set to them so that they can persist when the form is populated.
@Matt
Matt, the init-param is not used per se but could be so that the Application bean could be named differently. Good remark.
@kunal
All my components are managed by Spring so that I can inject them services, like you need them to.
Surely, the Vaadin components (including the application) would have to be be scoped on “prototype” in order not to share state across sessions?!
Please more updates , examples and files to download
HI I m using Vaadin frame work assume that i have table inside the panel . I m getting spring Service from BackSide .(Server) which is best way to populate the data for the gride if you give me example it would be great
Hi,
I use 13.5.2. Setup from http://www.blackbeltfactory.com/ui#CoursePage/15593452/EN
to allow @Autowire and others Spring tools because @Autowire and others things worked only on the class that extends Application.
Don’t know why it’s happen , but it’s working , its using AspectJ , could be a ‘fix’ for not using it?
Hi,
BlackBelt Factory’s solution is on a whole different integration level than what I propose.
According to me, AOP is a kind of heavy artillery that’s very powerful: so, I’m very wary about it. In Vaadin’s case, it’s not my first choice because I can do without it easily. Choose your libraries carefully, since with luck you will have to maintain your software on a long period.
I cant avoid use AspectJ as I mentioned . I would if it was possible. ( other classes get nulls when trying autowired )
You wrote :
“Spring Integration is an add-on for Vaadin that let you use Spring and its dependency injection mechanism in Vaadin painlessly.”
but it doesn’t work , except on the class which extends Application , any solution?
Thanks
@Zakos
I would suggest you use their method and not the Vaadin add-on I provide. I can’t imagine them being compatible.
i’m chinese,my english is not good.
I had downloaded Spring Integration is an add-on for Vaadin,but is doesn’t work.
the readme.txt of zip file have some errors and less than description for applicationContext.xml of spring.
my configuration is
web.xml
Vaadin servlet
cn.zuoguodang.vaadin.SpringVaadinServlet
application
cn.zuoguuodang.vaadin.DemoApplication
Vaadin servlet
/*
applicationContext.xml
it works ordinary.if you have question then send email to zuoguodang@163.com,Look forward to learning together.
thx.
I’m afraid I’m not getting it. Can you explain why it is a good idea to use Spring with the Vaadin UI Code?
Hello Sebastian,
I didn’t state it was a good idea to use Spring to glue together your UI components, just that it was possible. Anyway, you’ll probably need to inject your components with services to load the data to display and this article tells you how to integrate Spring and Vaadin.
Don’t understand me wrong, I really like your article and I appreciate your Vaadin tutorials in general but from your point of view what would be the way to go? Would it be worth the effort to integrate Spring with Vaadin (I don’t know much about the benefits you get from Spring besides DI) or wouldn’t it be the easier and better documented way to go straight on without an DI framework for the view?
My answer cannot be as black-and-white as you want it to be: it depends on your context, including (and surely not limited to) your enterprise, your skills, your co-workers skills, your willingness to unit test, and so on.