We are migrating our App from JBoss Seam to CDI (JEE6), so we are changing some anotations like #In and #Out, there's a lot of information that we have found helpful, but we have some troubles trying to find out how to replace anotations with particular patterns:
For #In anotation
#Name("comprobantes")//context name
...
#In(create=false,value="autenticadoPOJO",required=false)
private UsuarioPOJO autenticadoPOJO;
We can use #Inject from CDI, but how to set the name of the context variable for this case?.
For the #Out anotation
#Out(scope = ScopeType.SESSION, value = "autenticadoPOJO", required = false)
I have read some blogs and they say that I can use #Produces in CDI, how we can set the scope, before or after adding this anotation?
I appreciate any help or any helpful documentation.
I'm afraid there is no such thing like a 1:1 compatibility for #Out.
Technically, #Out in Seam 2 was realized by an interceptor for all method invocations - this turned out to be quite a performance bottleneck.
In CDI, most managed beans are proxied, this makes it technically impossible to implement outjection in the Seam 2 way.
What you can do (well, what you actually have to do) is going through all usages of #Out and replace it individually with some #Producer logic. Have a look at this official example here. In Seam 2, you would have outjected the authenticated user to the session-scope, in CDI a little producer method does (almost) the same.
That should hopefully give you a good start, feel free to ask further questions :)
http://docs.jboss.org/weld/reference/1.0.0/en-US/html/producermethods.html
8.1. Scope of a producer method
The scope of the producer method defaults to #Dependent, and so it will be called every time the container injects this field or any other field that resolves to the same producer method. Thus, there could be multiple instances of the PaymentStrategy object for each user session.
To change this behavior, we can add a #SessionScoped annotation to the method.
#Produces #Preferred #SessionScoped
public PaymentStrategy getPaymentStrategy() {
...
}
Related
I'm trying to add a RESTful web service with RESTeasy to our application running on JBoss 7.x, using Seam2.
I wanted to use as little Seam as possible, but I need it for Dependancy Injection.
My REST endpoints are as follows:
#Name("myEndpoint")
#Stateless
#Path("/path")
#Produces(MediaType.APPLICATION_JSON+"; charset=UTF-8")
public class MyEndpoint {
#In private FooService fooService;
#GET
#Path("/foo/{bar}")
public Response foobar(#CookieParam("sessionId") String sessionId,
#PathParam("bar") String bar)
{ ... }
}
I'm using a class extending Application. There is no XML config.
I can use the web service methods and they work, but I always get an IllegalStateException:
Exception processing transaction Synchronization after completion: java.lang.IllegalStateException: No event context active
Complete StackTrace
I did try everything in the documentation, but I can't get it away. If I leave out the #Stateless annotation, I don't get any Injection done. Adding #Scope doesn't do jack. Accessing the service via seam/resource/ doesn't even work (even without the Application class with #ApplicationPath).
It goes away if I don't use Dep. Injection, but instead add to each and every method
fooService = Component.getInstance("fooService");
Lifecycle.beginCall();
...
Lifecycle.endCall();
which isn't really a good solution. Nah, doesn't work either...
I have resolved the issue. For some reason (still not sure why, maybe because I tried to use Annotations and code exclusivly and no XML config), my REST service was availiable under a "non-standard" URL.
Usually it'd be something like "/seam/resources/rest".
Anyway, if you have a "custom" path, Seam doesn't know it should inject a context. You need to add <web:context-filter url-pattern="something" /> to your component.xml.
Specifically we already had this tag, but with the attribute regex-url-pattern and I extended it to match the REST URL.
I'd like to know what the best practices are for Eclipse 4 dependency injection.
After reading about this subject on the internet, I came up with the following strategy.
requirements
Share the data model of the application (e.g. company, employee, customer, ...) so that framework objects (view parts, handlers, listeners, ...) can access it with as little coupling as possible.
proposed strategy
I've used the lifeCycleURI plugin property to register a handler which is triggered at application startup. Such handler creates an "empty" top-level data model container object and place it into the EclipseContext. It is also discarded when application stops.
All Eclipse framework classes (view parts, handlers) use the classic DI to get such data model object injected.
Button listeners created with the class constructor can't have the data model object injected in them. So I thought they could be created with ContextInjectionFactory.make() to have injection performed. This would couple the class which creates the listener with CIF, but the great advantage is that injection works out of the box.
This is the best solution I've found yet to leverage E4 DI with as little coupling as possible. The weak spot is in my opinion this coupling with CIF. My question would be whether any strategy exist to remove even this coupling, or alternate solutions for the same requirements.
You can create a service class in your project, let's say ModelService.
Add #creatable and #singleton annotations to that class :
#creatable
#singleton
class ModelService{
}
And let DI do its job using following syntax in your parts/handlers/etc ..
#Inject ModelService modelService;
Then you can implement methods in your service like 'createBaseModel()', updateModel() and so on.
This creates a low coupling solution : you can also implement ModelService in a separate plugin and define it as a OSGi service.
for that solution, you can read this Lars Vogel article.
I'm building an extension in Extbase (latest version, latest typo3) and am having repositories injected into my models.
This simply does not work. No errors, no clues, nothing. The inject* Method simply does not get called. The exact same Injection works in the controller.
Is it possible to inject Repositories into models in Extbase? In general, injection to models is possible since 1.4.
How can I debug this? Where do I have to look?
This is a common misconception:
Not every class you use in TYPO3 CMS uses dependency injection by default - and it's a good thing.
What is true, is that every object that has been instantiated by the ObjectManager can benefit from it.
In short: if you new Thing() some object, it won't benefit from dependency injection. If you use the ObjectManager to get an instance of something, the whole dependency injection gallore will rain down on your new instance:
constructor injection [Example: How can I use an injected object in the constructor?
annotations are read and field injections are done
setter injection was done in the past (Remark: I think it's deprecated)
public method (if existent) initializeObject is called
Note that injected objects are being instantiated by the objectManager as well-so recursion is possible if injected ServiceA needs an injected ServiceB.
Singletons are possible as well if you implement the marker interface SingletonInterface.
Dependency injection only works if you get an instance of the object via the ObjectManager. If you are using the good ol'
t3lib_div::makeInstance('Tx_yourextension_domain_model_thing')
inject* methods are not being called.
There is a german blog entry explaining how it works.
Could someone help me understand the use of beanInterface parameter of #EJB annotation in JavaEE 6?
I have a situation in which I have an EJB and I want it to be accessed locally and remotely as well.
I have a MyBaseInterface and then both MyEJBLocalInterface and MyEJBRemoteInterface extending MyBaseInterface. Now I have MyEJB which is implementing both MyEJBLocalInterface and MyEJBRemoteInterface.
Now I have a situation in which I want only to access MyEJB locally.
Could I achieve the same with the following?
#EJB(beanInterface=MyEJBLocalInterface.class)
private MyBaseInterface instanceOfLocallyAccessedMyEJB;
Could someone help me understand the use of beanInterface parameter of #EJB attribute?
Thanks.
the beanInterface attribute of the #EJB annotation is used for different purposes depending on the EJB version you are using:
In EJB 3.X you can use it to specify whether you want to use the remote of local reference of the EJB you are referring to, which is your case.
In EJB 2.X it is used to specify the Home/LocalHome interface of the session/entity bean
To sum up, yes. You should be able to use it to inject the desired interface.
This might not be supported in older versions of JBoss though.
I am investigating the use of Autofac in our web application having previously used Castle Windsor in the past.
The thing that I really like with Autofac is being able to express dynamic component construction through lamda expressions, as opposed to creating DependancyResolvers etc. in Windsor.
One scenario I have is that I want a particular component to be registered at ASP.NET session level scope. With Windsor I would create/source a new LifestyleManager, however with Autofac I came up with this:
//Register SessionContext at HTTP Session Level
builder.Register(c =>
{
HttpContext current = HttpContext.Current;
//HttpContext handes delivering the correct session
Pelagon.Violet.Core.Interfaces.SessionContext instance = current.Session["SessionContext"] as Pelagon.Violet.Core.Interfaces.SessionContext;
if (instance == null)
{
instance = c.Resolve<Pelagon.Violet.Core.Interfaces.SessionContext>();
current.Session["SessionContext"] = instance;
}
return instance;
})
.FactoryScoped();
Which at some point I might be able to turn into an extension method. I accept this implemtation will bomb if the HttpContext.Current.Session is null as it should only be used in a web app.
The question is:
What is the best practice for such a registration in Autofac. I have seen a lot of mention about the use of nested containers etc. but no concrete examples, and I am keen to understand what might be wrong with the above approach (only thing I can think of is the automatic disposal stuff).
Thanks.
This looks fine.
Marking the component 'ExternallyOwned()' will ensure that Autofac doesn't call Dispose() on it.
The only gotchas here are that your session-scoped component could resolve dependencies of its own via the current container, and thus hold references to things that may belong to the current request (for instance.) This should be easy to spot in testing though.