I know I can subscribe to different lifetime events: http://docs.autofac.org/en/latest/lifetime/events.html
but does Autofac provide an event that is raised upon registration?
i.e. OnRegistered
it would be very handy on Assembly Scanning.
I should mention I use Autofac 3.5.2
Like the OnRegistered event?
builder.RegisterAssemblyTypes(Assembly.GetCallingAssembly()).OnRegistered(e =>
{
// Your code here
});
Related
I want to subscribe an global event which is invoked after a registration has been added.
I don't want to manually subscribe to an event for every registered service/component, because that's boilerplate code and it's easy to forget it when adding new registrations.
When the event fires I want do some checks on the already registered registrations and if a condition is met, e.q it's a named registration and it's a reference type then I want to add additional/new registrations, this should happen before the container is built.
What's the right way to achieve this?
Can I do it in a CustomModule that derives from Module?
Br
Autofac doesn't support "registration events" or anything like that - only resolution events. What you might be able to do is:
Use the OnlyIf extensions for conditional registration (here are the unit tests showing examples)
Register your conditional thing last so everything else is registered and OnlyIf will work.
Possibly use the Properties dictionary on the ContainerBuilder to your advantage, such that when the important things get registered they add something to the properties dictionary that you can check for.
I think some combination of those things should get you what you're looking for. But, unfortunately, there's no event. The reason is that registrations aren't just a simple collection of objects the way they are in Microsoft.Extensions.DependencyInjection - registrations are all callback methods that don't actually execute until you call Build. The final set of registrations is only really available then; and when Build is called, you can't modify that list of callbacks post-facto to add or change registrations.
That architecture is not likely to change because it's pretty baked into the core of the builder syntax for registrations. The above options are about it.
I am using Axon 3.1.1 and wanted to know,
How can I get a list of eventprocessor in my configuration file,
I went through the springAmQPmessageSource file but still not sure how to exactly do it.
So that I can pass my event to appropriate eventhandler on Query side.
List<Consumer<List<? extends EventMessage<?>>>> eventProcessors = new CopyOnWriteArrayList<>();
Updated
I was retrieving message from kafka topic and wanted to wire them to specific eventhandler but since I am not able to get evenprocessors, I am not able to do that.
Can you please tell me how to do it, if I am using Axon 3.0.5
If you're using the SpringAmqpMessageSource, you will not need to retrieve the list of eventProcessors you've shared, as Axon will automatically subscribe all the event handling components to it for you.
Subsequently, the events the Message Source receives will automatically be pushed to all the listeners in your query side.
As this is all covered as Axon infrastructure under the hood, there is no one-off way to pull them out of it for your own use (other than potentially wiring them yourself).
Hence, you shouldn't have to do this yourself.
But, maybe I'm missing an obvious point here.
Could you elaborate a little more why you need the list of handlers in the first place?
I am very new to Autofac dependency injection and I got these questions related to my project. I have gone through many articles but I am not getting a clear picture on some of the questions I have. Mine is a service application on .Net REST API. I am doing instance registration in App_Start module as shown below.
private static IContainer RegisterServices(ContainerBuilder builder)
{
builder.RegisterApiControllers(Assembly.GetExecutingAssembly());
builder.RegisterType<DCLMessengerContext>()
.As<DbContext>()
.ExternallyOwned()
.InstancePerLifetimeScope();
builder.RegisterType<DbFactory>()
.As<IDbFactory>()
.ExternallyOwned()
.InstancePerLifetimeScope();
builder.RegisterType<UnitOfWork>()
.As<IUnitOfWork>()
.InstancePerLifetimeScope();
builder.RegisterGeneric(typeof(EntityBaseRepository<>))
.As(typeof(IEntityBaseRepository<>))
.InstancePerLifetimeScope();
builder.RegisterType<PersonServiceClient>()
.As<IPerfService>()
.InstancePerLifetimeScope();
builder.RegisterType<PagingServiceContractClient>()
.As<PagingServiceContract>()
.InstancePerLifetimeScope();
builder.RegisterType<MessageService>()
.As<IMessageService>()
.InstancePerLifetimeScope();
Container = builder.Build();
return Container;
}
My service layer is "MessageService" and there I am performing all the DB and other integration operations and getting the instances through constructor injection. These are the questions I have around this implementation.
I am using InstancePerLifeTimeScope for all my registrations. Is this is the right approach? After the life cycle of each controller request (http request), will these instances will be automatically disposed?
Do we need to manually implement any Dispose operation on any of these instances? ( I don’t have any unmanaged objects in my code)
From the service method, I need to create a fire&forget thread as well using Task.Run(). What is the best approach to supply instances to this fire&forget thread? If I use InstancePerLifeTimeScope, I can see that new thread also getting the same instances that available through the service class so I am just confused when these instances will be disposed?
When you resolve the instance per lifetime scope component, you get a
single instance per nested scope
So if you are using them in controllers. You will have one object for per request and they will be disposed. But if you resolve them in a singleton object they wil live with this object.
Is this is the right approach?
It depends what you need. If you need singleton object, it's not. If you just want to use this service in request scope use instanceperrequest it's better.
Autofac automatically calls dispose for IDisposable objects. If you
need dispose method, implement it. It's not related with autofac.
If you use another thread resolve objects in this thread. Otherwise when request disposed your objects will be disposed and your thread will be fail. Check this.
I am explicitly declaring my registerations as per web request lifecycle but they are still singletons.
this is a problem because my command handlers depend on an IDbConnection which is also registered per web request.
here is my registration code:
container.Register(
Classes
.FromAssemblyContaining<EcruiterCommands>()
.BasedOn(typeof (ICommandHandler<>))
.WithService.AllInterfaces()
.LifestylePerWebRequest());
I found the issue, the culprit is this line:
.BasedOn(typeof (ICommandHandler<>))
it resets the registration.
Does the Zend 2 event manager have the ability to fire listeners in classes that are not loaded?
If I understand you correctly, then I believe that you can register listeners using the StaticEventManager (see Event Manager Quick Start).
In this case, you do not need to have an instance of the target class (just the name), but you can register listeners for events (typically methods) on future instances of that target class that may occur.
Of course, in order to be useful, the target class should actually compose an EventManager instance (probably via an events() method, as described on the same Quick Start page) and actually fire the events.
I confess that I am still trying to wrap my own head around the ZF2 EventManager, so if I have totally boned it up here, please feel free to correct me.