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.
Related
I am looking into Microsoft Orleans. I have setup a cluster in docker, tt is working perfectly. I am trying to read the documentation on message delivery, but I can't seem to find anything on retry. If I have a grain calling a grain, like this:
public class HelloGrain : Orleans.Grain, IHello
{
private readonly ILogger logger;
private IOtherGrain otherGrain;
public HelloGrain(ILogger<HelloGrain> logger)
{
this.logger = logger;
}
public override async Task OnActivateAsync()
{
otherGrain = GrainFactory.GetGrain(this.GetPrimaryKeyString());
await base.OnActivateAsync();
}
Task<string> IHello.SayHello(string greeting)
{
string otherGrainReturn = await this.otherGrain.MethodAsync();
return Task.FromResult($"\n Client said: '{greeting}', so HelloGrain says: Hello!");
}
}
Is the string otherGrainReturn = await this.otherGrain.MethodAsync(); getting retried, on failure, somehow? Is it only a timeout that decide when the call fails? Is this to be handled as a basic HTTP call, and should i therefore be retrying myself?
It could be awesome with som link to documentation that say something more on the subject (at-least-once retry etc).
You can see here that by design, Orleans doesn't have any kind of retry policy.
But you can add it by yourself with a simple try catch block (Or with a specific library like Polly).
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 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.
Below I present a part of an Azure Web App that handles a device notification logic. What I'm doing is invoking the code shown below from a ASP MVC Controller.
But when I run it I get an hung (ever-pending) request from the browser.
I thought I've found a workaround by wrapping the SendAsync call in a BackgroundWorker thread. It's better, but I doesn't work right. For first couple of times (one or two) it works ok, but then it happens again, the wrapped thread hangs.
The code is not far different from the one on MSDN for a console application. What am I missing?
using System.Web.Configuration;
using Microsoft.Azure.Devices;
namespace MyTest
{
public class Sender
{
private readonly string connectionString;
private readonly Microsoft.Azure.Devices.ServiceClient serviceClient;
public Sender()
{
connectionString = WebConfigurationManager.AppSettings["ConnectionString"];
serviceClient = ServiceClient.CreateFromConnectionString(connectionString);
}
public async void SendRequest(string deviceId, string msgText)
{
var message = new Message();
message.Properties.Add("text", msgText));
await serviceClient.SendAsync(deviceId, message);
}
}
}
The problem was caused by inappropriate usage of ASP MVC framework.
It turned out that AsyncController has to be used instead of just Controller when a long running async\await is utilized. The pipeline must be async all the way.
I have a need to use a .net client to connect to a Signalr enabled application.
The client class needs to be a singleton and loaded for use globally.
I want to know what is the best technique for using singletons globally within an MVC application.
I have been looking into using the application start to get the singleton, where I keep it is a mystery to me.
The HUB cant be a singleton by design SignalR creates a instance for each incoming request.
On the client I would use a IoC framework and register the client as a Singleton, this way eachb module that tries to get it will get the same instance.
I have made a little lib that takes care of all this for you, install server like
Install-Package SignalR.EventAggregatorProxy
Read here for the few steps to hook it up, it needs a back plate service bus or event aggregator to be able to pickup your events
https://github.com/AndersMalmgren/SignalR.EventAggregatorProxy/wiki
Once configured install the .NET client in your client project with
Install-Package SignalR.EventAggregatorProxy.Client.DotNet
See here how to set it up
https://github.com/AndersMalmgren/SignalR.EventAggregatorProxy/wiki/.NET-Client
Once configured any class can register itself as a listener like
public class MyViewModel : IHandle<MyEvent>
{
public MyViewModel(IEventAggregator eventAggregator)
{
eventAggregator.Subscribe(this);
}
public void Handle(MyEvent message)
{
//Act on MyEvent
}
}
On the server you can send a message from outside the hub to all connected clients using the GetClients() method like this:
public MyHub : Hub
{
// (Your hub methods)
public static IHubConnectionContext GetClients()
{
return GlobalHost.ConnectionManager.GetHubContext<MyHub>().Clients;
}
}
You can use it like this:
MyHub.GetClients().All.SomeMethod();