I would like to use ASP.NET Core's default DI container to setup DI for my Service Fabric project.
//This is what I've got so far, and it works great
ServiceRuntime.RegisterServiceAsync(
"MyServiceType",
context => new MyService(context, new MyMonitor()
).GetAwaiter().GetResult();
//This is how I use it
public MyService(StatefulServiceContext context, IMonitor myMonitor)
: base(context)
{
this._myMonitor = myMonitor;
}
How would I set up DI, if MyMonitor class has a dependency on a ConfigProvider class, like this:
public MyMonitor(IConfigProvider configProvider)
{
this._configProvider = configProvider;
}
I think this question will give you some light: Why does ServiceRuntime.RegisterServiceAsync return before the serviceFactory func completes?
Technically, the ServiceRuntime.RegisterServiceAsync() is a dependency registration, it requires you to pass the serviceTypeName and the factory method responsible for creating the services Func<StatelessServiceContext, StatelessService> serviceFactory
The factory method receives the context and returns a service (Stateful or stateless).
For DI, you should register all dependencies in advance and call resolve services to create the constructor, something like:
var provider = new ServiceCollection()
.AddLogging()
.AddSingleton<IFooService, FooService>()
.AddSingleton<IMonitor, MyMonitor>()
.BuildServiceProvider();
ServiceRuntime.RegisterServiceAsync("MyServiceType",
context => new MyService(context, provider.GetService<IMonitor>());
}).GetAwaiter().GetResult();
PS:
Never Register the context (StatelessServiceContext\StatefulServiceContext) in the DI, in a shared process approach, multiple partitions might be hosted on same process and will have multiple contexts.
This code snippet is not tested, I've used in the past, don't have access to validate if matches the same code, but is very close to the approach used, might need some tweaks.
Hi #OscarCabreraRodríguez
I am working on the project that simplifies development of Service Fabric Reliable Services and it has great built-in support for dependency injection scenarios.
You can find general information project page, wiki and specific information about dependency injection here.
The idea is that project abstracts you from working with Service instance directly instead providing you with a set of more concrete objects.
Here is a simple example for ASP.NET Core application:
public static void Main(string[] args)
{
new HostBuilder()
.DefineStatefulService(
serviceBuilder =>
{
serviceBuilder
.UseServiceType("ServiceType")
.DefineAspNetCoreListener(
listenerBuilder =>
{
listenerBuilder
.UseEndpoint("ServiceEndpoint")
.UseUniqueServiceUrlIntegration()
.ConfigureWebHost(
webHostBuilder =>
{
webHostBuilder
.ConfigureServices(
services =>
{
// You can configure as usual.
services.AddTransient<IMyService, MyService>();
})
.UseStartup<Startup>();
});
});
})
.Build()
.Run();
[Route("api")]
public class ApiController : Controller
{
public ApiController(IMyService service) { }
[HttpGet]
[Route("value")]
public string GetValue()
{
return $"Value from {nameof(ApiController)}";
}
}
Hope I understand your use case correctly and this information is relevant.
Related
I use Unity in an MVC5 project (.net461) for DI and I want to register a service with multiple lifetimes.
With the classic core DI I would use RegisterScoped and that's it. Whenever the service is resolved within an Http Request I would reuse the same instance for the duration of the request. If I want to fire a background task, that background task should open a service scope, and I would resolve a new instance for the service for the duration of that scope. No need to have different registrations for the service. In the first case, the scope is created by the runtime, and in the second it is manually created by the developer. In both cases, the service provider only knows that the service is scoped, it doesn't care about where and how the scope has opened.
With Unity the first case is solved with PerRequestLifetimeManager. The second case is solved with a HierarchicalLifetimeManager.
But how should I have a combination of the two?
Whenever a service is resolved within an HttpRequest (in a controller constructor for instace) it should use the PerRequestLifetimeManager and wherever it is resolved in a child container (within the constructor of another service that is instantiated in the child container) it should use HierarchicalLifetimeManager.
How can I register the service with both managers?
At the end of the day, I had to implement my own solution which is based on (but not using) Unity.Mvc, Unity.WebApi packages, and the HierarchicalLifetimeManager.
None of the solutions I found online worked for my case. Most of them covered only the per request part, but not the per custom user scope part.
The key of the solution is not the lifetime manager but the dependency resolver. The lifetime manager for my requirements should always be HierarchicalLifetimeManager because that is what I truly need. A new container for each scope, which is covered by child containers and HierarchicalLifetimeManager.
Using Integrating ASP.NET Core Dependency Injection in MVC 4 as an example on how to implement your own dependency resolver, I came up with the solution below.
What I had to do, is to make sure a new scope is created on the beginning of the Http Request, and Disposed at the end of the Http Request. This part is covered by implementing a simple HttpModule. This part is similar to the HttpModule used by the official Unity Per Request Lifetime implementation.
Per Http Request Module
This is the module implementation
internal class UnityPerHttpRequestModule : IHttpModule
{
private static IUnityContainer _rootContainer;
public void Init(HttpApplication context)
{
context.BeginRequest += (s, e) =>
((HttpApplication)s).Context.Items[typeof(UnityPerHttpRequestModule)]
= _rootContainer.CreateChildContainer();
context.EndRequest += (s, e) =>
(((HttpApplication)s).Context.Items[typeof(UnityPerHttpRequestModule)]
as IUnityContainer)?.Dispose();
}
public static void SetRootContainer(IUnityContainer rootContainer)
{
_rootContainer = rootContainer ?? throw new ArgumentNullException(nameof(rootContainer));
}
public void Dispose() { }
}
On Beginning the request we create a new child container and place it in the HttpRequest Items dictionary.
On Ending the request we retrieve the child container from the Items dictionary and dispose it.
The static method SetRootContainer should be called once at the startup of the application to pass in the initial root Unity container, the one that services are registered on.
public class Global : HttpApplication
{
void Application_Start(object sender, EventArgs e)
{
UnityPerHttpRequestModule.SetRootContainer(UnityConfig.Container); // pass here the root container instance
...
}
}
We also need to register the module with owin.
using Microsoft.Owin;
using Microsoft.Web.Infrastructure.DynamicModuleHelper;
using Owin;
[assembly: OwinStartup(typeof(MyApp.Startup))]
[assembly: WebActivatorEx.PreApplicationStartMethod(typeof(MyApp.Startup), nameof(MyApp.Startup.InitScopedServicesModule))]
namespace MyApp
{
public partial class Startup
{
public static void InitScopedServicesModule()
{
DynamicModuleUtility.RegisterModule(typeof(UnityPerHttpRequestModule));
}
public void Configuration(IAppBuilder app)
{
}
}
}
MVC Dependency Resolver
Now the http module is registered and we have a new scope created on each request. Now we need to instruct MVC and WebApi to use that scope. For this, we need to create the appropriate dependency resolvers. I created one dependency resolver for MVC and one for WebApi since they need to implement different interfaces (I could have implemented both in the same class though).
The dependency resolver for MVC is this:
internal class UnityMvcPerHttpRequestDependencyResolver : IDependencyResolver
{
private readonly IUnityContainer rootContainer;
internal UnityMvcPerHttpRequestDependencyResolver(IUnityContainer rootContainer)
{
this.rootContainer = rootContainer;
}
internal IUnityContainer Current => (HttpContext.Current?.Items[typeof(UnityPerHttpRequestModule)] as IUnityContainer) ?? this.rootContainer;
public void Dispose() { }
public object GetService(Type serviceType)
{
try
{
return Current.Resolve(serviceType);
}
catch (ResolutionFailedException)
{
return null;
}
}
public IEnumerable<object> GetServices(Type serviceType)
{
try
{
return Current.ResolveAll(serviceType);
}
catch (ResolutionFailedException)
{
return null;
}
}
}
What the resolver does is that it checks for an HTTP Context and gets the unity container in the Context's item dictionary and uses this container to resolve the services. So effectively, if the service requested is registered with a Hierarchical Lifetime, a new instance of that service will be created within the child container (aka within the context of the request). Since the child container is disposed at the end of the request by the http module, any services instantiated in the child container are also disposed.
Things to notice here:
The IDependencyResolver interface here is the System.Web.Mvc.IDependencyResolver. This is the interface expected by the MVC. The WebApi expects a difference IDependencyResolver (same name, different namespaces)
Catching ResolutionFailedException. If you don't catch those exceptions, the application will crash.
Now that we have the MVC dependecy resolver, we need to instruct MVC to use this resolver.
public static class UnityMvcActivator
{
public static void Start()
{
FilterProviders.Providers.Remove(FilterProviders.Providers.OfType<FilterAttributeFilterProvider>().First());
FilterProviders.Providers.Add(new UnityFilterAttributeFilterProvider(UnityConfig.Container));
//DependencyResolver.SetResolver(new UnityDependencyResolver(UnityConfig.Container));
DependencyResolver.SetResolver(new UnityMvcPerHttpRequestDependencyResolver(UnityConfig.Container));
// TODO: Uncomment if you want to use PerRequestLifetimeManager
//Microsoft.Web.Infrastructure.DynamicModuleHelper.DynamicModuleUtility.RegisterModule(typeof(UnityPerRequestHttpModule));
}
}
Things to notice here:
Do not register the official UnityPerRequestHttpModule since we implement our own. ( I could probably use that module but my implementation would depend on the inner implementation of the official module and I don't want that, since it may change later)
Web Api Dependency Resolver
Simlilar to MVC dependency resolver, we need to implement one for the Web Api
internal class UnityWebApiPerHttpRequestDependencyResolver : IDependencyResolver
{
private readonly IUnityContainer rootContainer;
internal UnityWebApiPerHttpRequestDependencyResolver(IUnityContainer rootContainer)
{
this.rootContainer = rootContainer;
}
internal IUnityContainer Current => (HttpContext.Current?.Items[typeof(UnityPerHttpRequestModule)] as IUnityContainer) ?? this.rootContainer;
public IDependencyScope BeginScope() => this;
// Dispose, GetService and GetServices are the same as MVC dependency resolver
}
Things to notice here:
IDependencyResolver here is of type System.Web.Http.Dependencies.IDependencyResolver. It is not the same as MVC's IDependencyResolver.
This Dependency resolver interface implements one more method: BeginScope. This is important here. WebApi pipeline is different that MVC pipeline. WebApi engine, by default, calls BeginScope to open a new scope for each web api request, and uses that scope to resolve controllers and services. So, Web api has already a scoped mechanism. BUT we have already created a scope ourselves with our per request module and we want to use that scope. So what we have to do here is to not create a new scope again. It already exists. So calling BeginScope on our resolver should return the same resolver scope, thus we return this.
Now that we have created the WebApi resolver, we have to also register it to web api.
using System.Web.Http;
[assembly: WebActivatorEx.PreApplicationStartMethod(typeof(MyApp.UnityWebApiActivator), nameof(MyApp.UnityWebApiActivator.Start))]
namespace MyApp
{
/// <summary>
/// Provides the bootstrapping for integrating Unity with WebApi when it is hosted in ASP.NET.
/// </summary>
public static class UnityWebApiActivator
{
/// <summary>
/// Integrates Unity when the application starts.
/// </summary>
public static void Start()
{
// Use UnityHierarchicalDependencyResolver if you want to use
// a new child container for each IHttpController resolution.
// var resolver = new UnityHierarchicalDependencyResolver(UnityConfig.Container);
var resolver = new UnityWebApiPerHttpRequestDependencyResolver(UnityConfig.Container);
GlobalConfiguration.Configuration.DependencyResolver = resolver;
}
}
}
Registering services
Now that we have set up and registered all our Resolvers and modules, the last thing to do is to remember to register each scoped service with HierarchicalLifetimeManager. Since our scoped solution depends on child containers, registering our scoped services that way will suffice.
Conclusion
And with that, I managed to implement a working scoped DI solution with Unity. The example below did not work with the official Per Request Lifetime solution, but worked with my custom implementation.
class TestController{
private readonly IMyScopedService service;
private readonly IUnityContainer container;
public TestController(IUnityContainer container, IMyScopedService service){
this.service = service;
this.container = container;
}
public ActionResult Post( ... ){
var childContainer = this.container.CreateChildContainer();
var scopedService = childContainer.GetService<IMyScopedService>()
HostingEnviroment.QueueBackgroundWorkItem(() => {
using(childContainer){
scopedService.DoWork();
}
});
}
}
With the official PerRequestLifetimeManager solution, this.service and scopedService were the same instance. The scoped service was instantiated in the http context, then the same instance was fetched again from the child container (since it was registerd with PerRequestLifetimeManager and not HierarchicalLifetimeManager) and passed to the background Job. The background job outlives the http request. The instance is disposed when the Http requests ends, but it is still being used in the background job which probably runs in another thread. Concurrency issues (and more) arise. For instance you can't use the same instance of an EF DbContext in multiple threads.
With the custom implementation above, the example works. scopedService is a different instance since it is registered with a HierarchicalLifetimeManager. this.services is disposed when the http request ends but scopedService lives during the whole execution of the background Job.
What we effectively do is control the lifetime of the services by controlling the lifetime of child containers. And I have the impression that this is the solution for every scoped service scenario.
Register all scoped services with HierarchicalLifetimeManager
Control the lifetime of services by controlling the lifetime of the child containers.
I am very new with orleans and trying to grasp everything with grains and so forth.
What i got is that in my startup.cs file i add the SignalR like this
public IServiceProvider ConfigureServices(IServiceCollection services)
{
Program.WriteConsole("Adding singletons");
services
.AddSingleton(achievementManager)
.AddMvc();
services.AddSingleton(SignalRClient);
return services.BuildServiceProvider();
}
So far everything is fine i can start my host/application and it connects to SignalR as it should. But what i cant wrap my head around is how do i get this down to my grain? if i had a controller i would simply send it down in the constructor on startup but how do i do this with a grain? Or can i even do it like this. Any guidance is appreciated.
In the grain then i want to do something like this
[StatelessWorker]
[Reentrant]
public class NotifierGrain : Grain, INotifierGrain
{
private HubConnection SignalRClient { get; }
public NotifierGrain(HubConnection signalRClient)
{
SignalRClient = signalRClient;
SignalRClient.SendAsync(Methods.RegisterService, Constants.ServiceName);
}
public Task NotifyClients(object message, MessageType type)
{
var registerUserNotification = (RegisterUserNotificationModel)message;
SignalRClient.SendAsync(Methods.RegisterUserToMultipleGroups, registerUserNotification.UserId, registerUserNotification.InfoIds);
}
return Task.CompletedTask;
}
Then i try to call the Notify method from another grain like this
var notifier = GrainFactory.GetGrain<INotifierGrain>(Constants.NotifierGrain);
await notifier.NotifyClients(notification, MessageType.RegisterUser);
But trying to do this ends up with an error like this
InvalidOperationException: Unable to resolve service for type 'Microsoft.AspNetCore.SignalR.Client.HubConnection' while attempting to activate 'User.Implementation.Grains.NotifierGrain'.
Orleans supports constructor injection, so you can inject the SignalRClient into your grain constructor. In your code you are already correctly registering the client using services.AddSingleton(SignalRClient), so I will focus on how to inject the type into your grain.
I do not know what the type the SignalR client object is, but in this example I assume that the type is "SignalRClient":
[StatelessWorker]
[Reentrant]
public class NotifierGrain : Grain, INotifierGrain
{
private readonly SignalRClient signalRClient;
public NotifierGrain(SignalRClient signalRClient)
{
this.signalRClient = signalRClient;
}
public async Task NotifyClients(object message, MessageType type)
{
var registerUserNotification = (RegisterUserNotificationModel)message;
await this.signalRClient.SendAsync(
MessageMethods.RegisterUserToMultipleGroups,
registerUserNotification.UserId,
registerUserNotification.infoIds);
}
}
Depends how you're thinking to use SignalR Server, if you're going to host your SignalR server with Microsoft Orleans for sure you need to have backplane to handle the Orleans cluster communications.
You can use SignalR Orleans which has everything done out of the box for you :)
Also if you need a reactive SignalR library for the frontend, you can use Sketch7 SignalR Client
PS I m one of the authors of both libraries.
In ASP.NET 5, I have an IRepository interface that I used to access some databases, like this:
public interface IRepository {
IQueryable<T> QueryItems(string sql);
}
public class Repository : IRepository {
private readonly string ConnectionString;
public Repository(string connStr) {
// Save the injected connection string
this.ConnectionString = connStr;
}
public IQueryable<T> QueryItems(string sql) {
// Implementation ignored here
}
}
In my Startup.cs class, I am registering the IoC/DI like this:
services.AddTransient<IRepository>(s => new Repository("DUMMY_CONNSTR"));
That all works fine if I only have one connection string. However, how can I register and subsequently inject the correct IRepository if I use the Repository to connect to 2+ different databases with different connection strings?
services.AddTransient<IRepository>(s => new Repository("DUMMY_CONNSTR"));
services.AddTransient<IRepository>(s => new Repository("DIFFERENT_CONNSTR"));
In older IoC/DI systems, I would have use "named" implementations that could be resolved with something like a [Dependency("DUMMY")] attribute on the constructor parameter.
Any help would be appreciated.
There are a few approach that you can take one is to inject a factory and base on the specific criteria you can produce a repository, the other approach is use a Dispatcher that also produce the repository base on the criteria, below is a question that I ask with the same problem. The question below have both approach but they were codding a beta version of .net core
See this question for reference and code
You can substitute StructureMap or Autofac for the default DI container (see my blog post for detailed instructions). Both support "named" interface registration (StructureMap named instances and Autofac named and keyed services).
Additionally, if you target dnx451, you can use Autofac's WithKey attribute. Using the Visual Studio sample project from the blog post, add the following dependency in project.json:
"frameworks": {
"dnx451": {
"dependencies": {
"Autofac.Extras.AttributeMetadata": "4.0.0"
}
}
},
Given a test class with the following constructor:
public MyClass([WithKey("logging")] IRepository repository)
{
Repository = repository;
}
you would register everything in ConfigureServices (note the use of WithAttributeFilter():
containerBuilder.Register(c => new Repository("DEFAULT_CONNSTR")).Keyed<IRepository>("default");
containerBuilder.Register(c => new Repository("LOGGING_CONNSTR")).Keyed<IRepository>("logging");
containerBuilder.RegisterType<MyClass>().WithAttributeFilter();
The definition of my interface is as follows:
public interface IApplicationSettings
{
string LoggerName { get; }
string NumberOfResultsPerPage { get; }
string EmailAddress { get; }
string Credential { get; }
}
The implementation of this interface is given below:
public class WebConfigApplicationSettings : IApplicationSettings
{
public string LoggerName
{
get { return ConfigurationManager.AppSettings["LoggerName"]; }
}
public string NumberOfResultsPerPage
{
get { return ConfigurationManager.AppSettings["NumberOfResultsPerPage"]; }
}
public string EmailAddress
{
get { return ConfigurationManager.AppSettings["EmailAddress"]; }
}
public string Credential
{
get { return ConfigurationManager.AppSettings["Credential"]; }
}
}
I also created a factory class to obtain the instance of the concrete implementation of WebConfigSettings as follows:
public class ApplicationSettingsFactory
{
private static IApplicationSettings _applicationSettings;
public static void InitializeApplicationSettingsFactory(
IApplicationSettings applicationSettings)
{
_applicationSettings = applicationSettings;
}
public static IApplicationSettings GetApplicationSettings()
{
return _applicationSettings;
}
}
Then I resolved dependency as follows:
public class DefaultRegistry : Registry {
public DefaultRegistry() {
Scan(
scan => {
scan.TheCallingAssembly();
scan.WithDefaultConventions();
scan.With(new ControllerConvention());
});
For<IApplicationSettings>().Use<WebConfigApplicationSettings>();
ApplicationSettingsFactory.InitializeApplicationSettingsFactory
(ObjectFactory.GetInstance<IApplicationSettings>());
}
}
Now when i running my application it throw me following exception:
Exception has been thrown by the target of an invocation.
and the Inner Exception is
No default Instance is registered and cannot be automatically determined for type 'Shoppingcart.Infrastructure.Configuration.IApplicationSettings'\r\n\r\nThere is no configuration specified for Shoppingcart.Infrastructure.Configuration.IApplicationSettings\r\n\r\n1.) Container.GetInstance(Shoppingcart.Infrastructure.Configuration.IApplicationSettings)\r\n
I am using StructureMap for MVC5
The reason your code isn't working is because when you call ObjectFactory.GetInstance<IApplicationSettings>(), your registry hasn't been registered and thus, StructureMap's configuration is incomplete.
I believe what you're trying to do is the following (tested and works):
public class ApplicationSettingsFactory
{
public ApplicationSettingsFactory(WebConfigApplicationSettings applicationSettings)
{
_applicationSettings = applicationSettings;
}
private static IApplicationSettings _applicationSettings;
public IApplicationSettings GetApplicationSettings()
{
return _applicationSettings;
}
}
With your registry configured like this:
public DefaultRegistry() {
Scan(scan => {
scan.TheCallingAssembly();
scan.WithDefaultConventions();
scan.With(new ControllerConvention());
});
this.For<IApplicationSettings>().Use(ctx => ctx.GetInstance<ApplicationSettingsFactory>().GetApplicationSettings());
}
I can't really tell you why your registration fails in StructureMap, but if you allow me, I would like to feedback on your design.
Your design and code violates a few basic principles:
You are violating the Interface Segregation Princple (ISP).
The ISP describes that interfaces should be narrow (role interfaces) and should not contain more members than a consumer uses. You however defined an application wide IApplicationSettings interface and your intention is to inject into any consumer that needs some configuration settings. Changes are really slim however that there is a consumer that actually needs all settings. This forces the consumer to depend on all members, it makes the API more complex, while it just needs one.
You are violating the Open/Closed Principle (OCP).
The OCP describes that it should be possible to add new features without making changes to existing classes in the code base. You will however find yourself updating the IApplicationSettings interface and its implementations (you will probably have a fake/mock implementation as well) every time a new setting is added.
Configuration values aren't read at startup, which makes it harder to verify the application's configuration.
When a consumer makes a call to a property of your IApplicationSettings abstraction, you are forwarding the call to the ConfigurationManager.AppSettings. This means that if the value isn't available or incorrectly formatted, the application will fail at runtime. Since some of your configuration values will only be used in certain cases, this forces you to test every such case after you deployed the application to find out whether the system is configured correctly.
Solution
The solution to these problems is actually quite simple:
Load configuration values at start-up.
Inject configuration values directly into a component that needs that exact value.
Loading the configuration values directly at start-up, allows the application to fail fast in case of a configuration error, and prevents the configuration from being read over and over again needlessly.
Injecting configuration values directly into a component, prevents that component from having to depend on an ever-changing interface. It makes it really clear what a component is depending upon, and bakes this information in during application start-up.
This doesn't mean though that you can't use some sort of ApplicationSettings DTO. Such DTO is exactly what I use in my applications. This basically looks as follows:
public static Container Bootstrap() {
return Bootstrap(new ApplicationSettings
{
LoggerName = ConfigurationManager.AppSettings["LoggerName"],
NumberOfResultsPerPage = int.Parse(
ConfigurationManager.AppSettings["NumberOfResultsPerPage"]),
EmailAddress = new MailAddres(
ConfigurationManager.AppSettings["EmailAddress"]),
Credential = ConfigurationManager.AppSettings["Credential"],
});
}
public static Container Bootstrap(ApplicationSettings settings) {
var container = new Container();
container.RegisterSingle<ILogger>(
new SmtpLogger(settings.LoggerName, settings.EmailAddress));
container.RegisterSingle<IPagingProvider>(
new PagingProvider(settings.NumberOfResultsPerPage));
// Etc
return container;
}
In the code above you'll see that the creation of the ApplicationSettings DTO is split from the configuration of the container. This way I can test my DI configuration inside an integration test, where the start-up projects configuration file is not available.
Also note that I supply the configuration values directly to the constructors of components that require it.
You might be skeptic, because it might seem to pollute your DI configuration, because you have dozens of objects that require to be set with the same configuration value. For instance, your application might have dozens of repositories and each repository needs a connection string.
But my experience is that is you have many components that need the same configuration value; you are missing an abstraction. But don't create an IConnectionStringSettings class, because that would recreate the same problem again and in this case you aren't really making an abstraction. Instead, abstract the behavior that uses this configuration value! In the case of the connection string, create an IConnectionFactory or IDbContextFactory abstraction that allows creation of SqlConnection's or DbContext classes. This completely hides the fact that there is a connection string from any consumer, and allows them to call connectionFactory.CreateConnection() instead of having to fiddle around with the connection and the connection string.
My experience is that makes the application code much cleaner, and improves the verifiability of the application.
Thanks every one for responses. I found my solution. The solution is instead of using Default Registry I created another class for resolve the dependencies. Inside the class I used
ObjectFactory.Initialize(x =>
{
x.AddRegistry<ControllerRegistry>();
});
instead of
IContainer Initialize() {
return new Container(c => c.AddRegistry<ControllerRegistry>());
}
Then inside ControllerRegistry I resolved dependencies as follows:
// Application Settings
For<IApplicationSettings>().Use<WebConfigApplicationSettings>();
Then I called that class inside Global.asax as follows:
Bootstrap.ConfigureDependencies();
Finally inside Global.asax I resolved dependency for Factory class as follows:
ApplicationSettingsFactory.InitializeApplicationSettingsFactory
(ObjectFactory.GetInstance<IApplicationSettings>());
My entire code is given below:
Bootstrap class (newly created)
public class Bootstrap
{
public static void ConfigureDependencies()
{
ObjectFactory.Initialize(x =>
{
x.AddRegistry<ControllerRegistry>();
});
}
public class ControllerRegistry : Registry
{
public ControllerRegistry()
{
// Application Settings
For<IApplicationSettings>().Use<WebConfigApplicationSettings>();
}
}
}
Global.asax
Bootstrap.ConfigureDependencies();
ApplicationSettingsFactory.InitializeApplicationSettingsFactory
(ObjectFactory.GetInstance<IApplicationSettings>());
I have an existing MVC application that is using Dependency Injection with Ninject. I installed the Ninject.MVC3 nuget package and it creates a class called NinjectWebCommon in my App_Start, which completely isolates the kernel and registers all of my bindings:
public static void Start()
{
DynamicModuleUtility.RegisterModule(typeof(OnePerRequestHttpModule));
DynamicModuleUtility.RegisterModule(typeof(NinjectHttpModule));
bootstrapper.Initialize(CreateKernel);
}
private static IKernel CreateKernel()
{
var kernel = new StandardKernel();
kernel.Bind<Func<IKernel>>().ToMethod(ctx => () => new Bootstrapper().Kernel);
kernel.Bind<IHttpModule>().To<HttpApplicationInitializationHttpModule>();
RegisterServices(kernel);
return kernel;
}
private static void RegisterServices(IKernel kernel)
{
kernel.Bind<IFoo>().To<Foo>();
}
We have a new requirement that we thought SignalR would be able to satisfy, so we installed SignalR 2 nuget package into the project. I created a Hub and did some searching on how to implement Dependency Injection into the project and found an article that suggests creating a SignalRDependencyResolver. http://www.asp.net/signalr/overview/signalr-20/extensibility/dependency-injection
The article has you creating a kernel in the Startup.cs file that is used for registering SignalR in OWIN:
public class Startup
{
public void Configuration(IAppBuilder app)
{
var kernel = new StandardKernel();
var resolver = new NinjectSignalRDependencyResolver(kernel);
kernel.Bind<IStockTicker>()
.To<Microsoft.AspNet.SignalR.StockTicker.StockTicker>() // Bind to StockTicker.
.InSingletonScope(); // Make it a singleton object.
kernel.Bind<IHubConnectionContext>().ToMethod(context =>
resolver.Resolve<IConnectionManager>().GetHubContext<StockTickerHub>().Clients
).WhenInjectedInto<IStockTicker>();
var config = new HubConfiguration()
{
Resolver = resolver
};
app.MapSignalR(config);
}
}
The problem is that this approach has me creating two different kernels and they seem to have their own set of dependencies that they know how to resolve. If I have a dependency defined in NinjectWebCommon, the Hub doesn't know how to resolve that dependency. Without exposing my kernel in NinjectWebCommon, what is the proper way to add DI into SignalR using the Ninject.MVC3 package?
None of the current answers directly answer your question. Also achieving the result you are after is very straightforward once you know exactly what to do. The "proper" way to do this is to set SignalR's dependency resolver in the CreateKernel method of the NinjectWebCommon class.
Assuming you have created a NinjectSignalRDependencyResolver class as you mention, no other code needs to be added anywhere except for the line highlighted in the code snippet below:
private static IKernel CreateKernel()
{
var kernel = new StandardKernel();
kernel.Bind<Func<IKernel>>().ToMethod(ctx => () => new Bootstrapper().Kernel);
kernel.Bind<IHttpModule>().To<HttpApplicationInitializationHttpModule>();
// THIS LINE DOES IT!!! Set our Ninject-based SignalRDependencyResolver as the SignalR resolver
GlobalHost.DependencyResolver = new NinjectSignalRDependencyResolver(kernel);
RegisterServices(kernel);
return kernel;
}
Apart from the above, nothing more needs to be done except declaring your bindings in the RegisterServices method of NinjectWebCommon. In your example this would look like:
private static void RegisterServices(IKernel kernel)
{
kernel.Bind<IStockTicker>()
.To<Microsoft.AspNet.SignalR.StockTicker.StockTicker>() // Bind to StockTicker.
.InSingletonScope(); // Make it a singleton object.
kernel.Bind<IHubConnectionContext>().ToMethod(context =>
resolver.Resolve<IConnectionManager>().GetHubContext<StockTickerHub>().Clients
).WhenInjectedInto<IStockTicker>();
}
Except for the NinjectSignalRDependencyResolver class you created, no other code needs to be added. Importanly, the OwinStartup class remains unmodified, as follows:
public class Startup
{
public void Configuration(IAppBuilder app)
{
app.MapSignalR();
}
}
The above example achieves the following important outcomes which were what you asked in your question:
You only have a single Ninject Kernel created
The kernel and all binding configurations remain confined to NinjectWebCommon
The default SignalR resolver is your NinjectSignalRDependencyResolver
Dependency Injection into all SignalR hubs is achieved
Hopefully this helps people out.
Have you tried adding the StockTickerHub itself to your kernel?
By default, SignalR uses Activator.CreateInstance to construct Hubs without any constructor arguments. If you want to inject your own dependencies into a Hub, you can do so by registering the Hub with SignalR's dependency resolver.
https://github.com/SignalR/SignalR/blob/2.0.1/src/Microsoft.AspNet.SignalR.Core/Hubs/DefaultHubActivator.cs#L28
If you want to get really creative, you can register your own IHubActivator instead of registering all of Hubs individually.
I go into more detail in how Hubs are created by default in this answer: SignalR with IoC (Castle Windsor) - which lifetime for hubs?
There is a problem with the singleton scope. I don´t know who should get the blame here (Ninject, SignalR, MVC, etc...), but it works if you use ToConstant:
var binding = Bind<IMustBeSingleton>().ToConstant(new MustBeSingleton());
I had the same problem, and I found the solution: SignalR, WebAPI and MVC sharing the same dependency resolver kernel
I shared a complete solution with MVC, WebAPI and SignalR using the same Ninject kernel: https://drive.google.com/file/d/0B52OsuSSsroNX0I5aWFFb1VrRm8/edit?usp=sharing
That example web app, contains a single page that shows the AppDomain and GetHashCode of an object that is supposed to be unique across the three frameworks, giving a result similar to:
Dependency Test
Framework IMySingletonService instance
MVC AppDomainId:2 / HashCode:5109846
WebAPI AppDomainId:2 / HashCode:5109846
SignalR AppDomainId:2 / HashCode:5109846
I hope this helps.