I have a web api that gets realtime data from IoT device. My data is geographic coordinates (lon,lat)
public class DataController: ApiController{
public IHttpActionResult Post(Location loc){
// save loc to database.
}
}
in this first scenario, I am saving databse. So I have a client application that has a map. and I want to show incoming locations on my map as realtime.
But SignalR has a separated Hub class.
public class DataPublisherHub : Hub
{
public void PublishCoordinates()
{
// I want to send all clients incoming locations that web api action.
//????
Clients.All.sendAll();
}
}
Your client application should first of all subscribe itself to the server signalR Subscribe() method where you can add it to some group like below.
public void Subscribe(long clientId)
{
Groups.Add(Context.ConnectionId, clientId.ToString());
}
Then, after saving your coordinates to the database, call the PublishCordinates() method in the hub like:
public IHttpActionResult Post(Location loc)
{
// save loc to database.
DataPublisherHub.PublishCordinates(loc);
}
Change the PublishCordinates() method like:
public void PublishCoordinates(Location loc)
{
try
{
var context = GlobalHost.ConnectionManager.GetHubContext<DataPublisherHub>();
context.Clients.Group(clientId.ToString()).Recieve(loc);
}
catch(Exception ex)
{
return;
}
}
Maybe I misunderstood but you can create a static function in your hub like this :
public class DataPublisherHub : Hub
{
public static void PublishCoordinates(string lat, string long)
{
// I want to send all clients incoming locations that web api action.
//????
var context = GlobalHost.ConnectionManager.GetHubContext<DataPublisherHub>();
context.Clients.All.sendLatLong(lat,long);
}
}
and call it from your post function like this :
public class DataController: ApiController{
public IHttpActionResult Post(Location loc){
// save loc to database.
DataPublisherHub.PublishCoordinates(loc.lat,loc.long)
}
}
EDIT :
Dont forget to implements the OnConnected() function in your hub to get all existing data in the database :
public override Task OnConnected()
{
//Get all datas from db
foreach (var data in datas){
Clients.Caller.sendLatLong(data.lat,data.long);
}
return base.OnConnected();
}
Related
All my SignalR clients connect using a JWT bearer token. I utilize the [Authorize] attribute in my SignalR Hub.
This token contains a userId which can be used to check if a user has read access on the resource through the resource's users property which contains a List<PuppyUserPermission> that look like this:
public class PuppyUserPermission
{
public string userId { get; set; }
public bool read { get; set; }
public bool write { get; set; }
}
The question is: how do I connect the dots here? Ideally, instead of something like
[Authorize]
public class PuppyHub : Hub
{
public async Task SendPuppy(Puppy pup)
{
await Clients.All.SendAsync(pup);
}
}
I would so something like the following (this is more pseudo code than anything else, as I don't use valid methods):
[Authorize]
public class PuppyHub : Hub
{
public async Task SendPuppy(Puppy pup)
{
var clients = Puppy.users.Where(u => u.read == true);
await clients.SendAsync(pup);
}
}
Basically, I'd like to ensure that the clients recieving the Puppy object via SignalR would be authorized users on the resource. Problem is, Clients is just a list of string client IDs, and I'm not sure how to go about tying them to actual users on my Puppy resource.
How do I go about achieving this?
From the beginning, I had the feeling that the answer lay in IUserIdProvider, but I didn't see how that would work for multiple users.
I finally found the answer, but it'll definitely need some cleanup.
First, create your own implementation of IUserIdProvider as follows:
public class MyUserIdProvider : IUserIdProvider
{
public string GetUserId(HubConnectionContext connection)
{
var username = connection.User.Claims.Where(x => x.Type == "THE_CLAIM_YOU_WANT_TO_USE_TO_IDENTIFY_USERS").First().Value;
return username;
}
}
Next, register it using DI:
services.AddSingleton<IUserIdProvider, MyUserIdProvider >();
Now, when you want to send events from the server, use DI in your constructor to pull down an instance of your SignalR Hub as per usual:
private IHubContext<PuppyHub> puppyHub { get; }
public UsersController(IHubContext<PuppyHub> _puppyHub)
{
puppyHub = _puppyHub;
}
Then, where when you want to tell your clients about the new Puppy:
// ... typical controller code
// assume we have a var, puppy, with a list of authorized users
// use System.Linq to get a list of userIds where the user is authorized to read the puppy
var authorizedUsers = (IReadOnlyList<string>)puppy.users.Where(x => x.permissions.read == true).Select(i => i._id).ToList();
// send the new puppy to the authorized users
await puppyHub.Clients.Users(authorizedUsers).SendAsync("SendPuppy", puppy);
And viola! You have now done resource-based authorization with SignalR.
First of all, excuse my English, it's very bad. I am using MassTransit with Azure Service Bus for asynchronous communication between microservices. By their own definition, and to avoid generating dependencies between them, messages sent between different microservices are defined in each of them, that is, they are part of different namespaces. The automatic management of MassTransit causes queues and topics to be managed by the object type, which prevents the microservices that consume a message from receiving the messages sent by the microservice publisher. The same thing happens with two classes with the same properties in the same namespace but with a different class name.
Is there any way to solve this?
The options that have occurred to me are:
Remove the namespace from the endpoint of the destination address, naming it only with the name of the class.
That MassTransit can manage the creation of queues and topics based on the serialization of the object, instead of managing it based on the object type (perhaps through some type of wrapping object?)
I leave an example that I hope can help you in understanding the problem.
//FIRST PROGRAM - MESSAGE CONSUMER
namespace Consumer
{
public class Example
{
public string PropOne { get; set; }
public string PropTwo { get; set; }
}
public class ExampleConsumer :
IConsumer<Example>
{
public List<Example> ConsumedTestObjectList { get; } = new List<Example>();
//THIS METHOD NEVER CALL !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
public Task Consume(ConsumeContext<ExampleConsumer> context)
{
ConsumedTestObjectList.Add(context.Message);
return Task.CompletedTask;
}
}
public class ConsumerProgram
{
public static void Main()
{
var bus = Bus.Factory.CreateUsingAzureServiceBus(sbc =>
{
var host = sbc.Host("connectionString", h => {});
});
sbc.ReceiveEndpoint(host, e =>
{
e.Consumer<ConsumerProgram.Example>(context =>
{
return Console.Out.WriteLineAsync($"Message Received: {JsonConvert.SerializeObject(context.Message)}");
});
});
bus.Start(); // This is important!
Console.WriteLine("Press any key to exit");
Console.ReadKey();
bus.Stop();
}
}
}
//SECOND PROGRAM - MESSAGE PUBLISHER
namespace Publisher
{
public class Example
{
public string PropOne { get; set; }
public string PropTwo { get; set; }
}
public class PublisherProgram
{
public static void Main()
{
var bus = Bus.Factory.CreateUsingAzureServiceBus(sbc =>
{
var host = sbc.Host("connectionString", h => {});
});
bus.Start(); // This is important!
//send new instance of Publisher.Example
var example = new Example() { PropOne = "1", PropTwo = "2" };
bus.Publish(example);
Console.WriteLine("Press any key to exit");
Console.ReadKey();
bus.Stop();
}
}
}
Thank you very much.
regards
Borja
The message type, and the resulting name, are a key concept within MassTransit. If you want to avoid sharing assemblies between projects, that is fine, but you will need to match the entire interface (or class, in your case) name, including namespace, or it will not route properly.
Yes, you can override the entity name formatter to change how topics are named but it won't change the message type requirement for deserialization of the message (which happens, by type).
So the recommendation here is to use the same namespace for the contracts, even if they're in separate projects.
I want to populate an object using methods in a Controller class. So I've created the object in the Controller class and then tried to populate it using methods in the class. This does not work though, because everytime a method in a controller is called, the entire Controller class is reinitiated. So I get a brand new object everytime I try to populate the object. However, I don't know how else I can create an object and populate it. I've added the code below. The object I'm talking about is ProcessModel. Ignore the other objects I created at the top of the class.
Controller:
public class HomeController : Controller
{
ProcessModel pm = new ProcessModel();
RetrievePatterns pt = new RetrievePatterns();
RetrieveModel rm = new RetrieveModel();
public IActionResult Index()
{
FindPatterns fp = new FindPatterns(rm.pm, pt.KpiPatterns);
ViewData["KPIs"] = fp.passdata;
return View();
}
[HttpPost]
public IActionResult AddEvent([FromBody] Event data)
{
data.ID = pm.EventObjects.Count + 1;
pm.EventObjects.Add(data);
return Json(pm.EventObjects.Count);
}
[HttpPost]
public IActionResult AddProcessName(string data)
{
pm.ID = 1;
pm.Name = data;
return Json(new { title = pm.Name });
}
public IActionResult About()
{
ViewData["Message"] = "Your application description page.";
return View();
}
public IActionResult Contact()
{
ViewData["Message"] = "Your contact page.";
return View();
}
public ActionResult Error()
{
return View(new ErrorViewModel { RequestId = Activity.Current?.Id ?? HttpContext.TraceIdentifier });
}
}
Object:
public class ProcessModel
{
public List<Event> EventObjects = new List<Event>();
public List<Entity> EntityObjects = new List<Entity>();
public int ID { get; set; }
public string Name { get; set; }
}
You could create a Singleton class which is responsible to create only one instance from Process model;
public class ProcessModelSingleton
{
private static ProcessModel _processModel = new ProcessModel();
private ProcessModelSingleton()
{
}
public static ProcessModel Instance
{
get { return _processModel; }
}
}
Then assign it a global variable in the controller;
ProcessModel pm = ProcessModelSingleton.Instance;
EDIT
Created instance by singleton class shared by all users. So, if you want to make it user specific, using Session is the best option.
public ProcessModel pm {
get
{
if (Session["ProcessModel"] == null)
{
Session["ProcessModel"] = new ProcessModel();
}
return (ProcessModel)Session["ProcessModel"];
}
}
Keep in mind static variables are shared across all users for that web server. So data populated into a singleton class by one user's request can be read/overwritten by a different user's request. This may be what you are after, but if not you should look into Session State.
ASP.NET Session State Overview
As HTTP is stateless by nature, usage of sessions are discouraged my Microsoft for Asp.NET. By default they are only visible to the web server that creates them so if you are using a farm, you either need to look at server affinity (also called sticky sessions) with a load balancer or out of proc state (such as SQL Server or NCache).
Ideally your application design should avoid the need for sessions and carry only the necessary data between requests via cookies and/or query strings. For more complex applications however this is usually not possible and so Session State is used.
I am using SignalR 2 and I can not figure out how I can use my Hub methods e.g from inside a controller action.
I know I can do the following:
var hub = GlobalHost.ConnectionManager.GetHubContext<T>();
hub.Clients.All.clientSideMethod(param);
But that executes the method directly on the client side.
What if I have business logic inside my server side ClientSideMethod(param) method I want to call from my controller the same way as when it is called from the client side?
At the moment I use public static void ClientSideMethod(param) inside my hub and in that method I use the IHubContext from the ConnectionManager.
Is there no better was of doing this?
The following is not working (anymore in SignalR 2?):
var hubManager = new DefaultHubManager(GlobalHost.DependencyResolver);
instance = hubManager.ResolveHub(typeof(T).Name) as T;
instance.ClientSideMethod(param);
There I get a "Hub not created via Hub pipeline not supported" exception, when accessing the Clients.
It might work to create a "helper" class that implements your business rules and is called by both your Hub and your Controller:
public class MyHub : Hub
{
public void DoSomething()
{
var helper = new HubHelper(this);
helper.DoStuff("hub stuff");
}
}
public class MyController : Controller
{
public ActionResult Something()
{
var hub = GlobalHost.ConnectionManager.GetHubContext<MyHub>();
var helper = new HubHelper(hub);
helper.DoStuff("controller stuff");
}
}
public class HubHelper
{
private IHubConnectionContext hub;
public HubHelper(IHubConnectionContext hub)
{
this.hub = hub;
}
public DoStuff(string param)
{
//business rules ...
hub.Clients.All.clientSideMethod(param);
}
}
As I did not find a "good solution" I am using #michael.rp's solution with some improvements:
I did create the following base class:
public abstract class Hub<T> : Hub where T : Hub
{
private static IHubContext hubContext;
/// <summary>Gets the hub context.</summary>
/// <value>The hub context.</value>
public static IHubContext HubContext
{
get
{
if (hubContext == null)
hubContext = GlobalHost.ConnectionManager.GetHubContext<T>();
return hubContext;
}
}
}
And then in the actual Hub (e.g. public class AdminHub : Hub<AdminHub>) I have (static) methods like the following:
/// <summary>Tells the clients that some item has changed.</summary>
public async Task ItemHasChangedFromClient()
{
await ItemHasChangedAsync().ConfigureAwait(false);
}
/// <summary>Tells the clients that some item has changed.</summary>
public static async Task ItemHasChangedAsync()
{
// my custom logic
await HubContext.Clients.All.itemHasChanged();
}
Is there a good way to call methods in SignalR hub from a controller ?
Right now I have this:
public class StatsHub : Hub
{
private static readonly Lazy<StatsHub> instance = new Lazy<StatsHub>(() => new StatsHub());
public static StatsHub Instance { get { return instance.Value; } }
public StatsHub()
{
if (this.Clients == null)
{
var hubContext = SignalR.GlobalHost.ConnectionManager.GetHubContext<StatsHub>();
this.Clients = hubContext.Clients;
this.Groups = hubContext.Groups;
}
}
// methods here...
}
so in my controller actions I can just say, for example
StatsHub.Instance.SendMessage("blah");
and it's almost good, except that hubContext doesn't have Caller or Context properties of Hub - which are nice to have.
Hopefully, there's a better way to do this ?
If you want to broadcast over a hub from outside of the hub, you need GlobalHost.ConnectionManager.GetHubContext<MyHub>() to get ahold of the hub context. You can then use this context to broadcast via the .Clients property.
As indicated in your sample code you already get ahold of the hub context, but doing so inside the hub just doesn't feel right in my opinion. If you're only using the logic in SendMessage() from your controller actions, I'd move the code right into the controller action and use the hub context obtained via GetHubContext<T>() from there.
Please note that the Caller or Context property will always be null in this scenario, because SignalR wasn't involved when making a request to the server and therefore cannot provide the properties.
Found a DefaultHubManager, which is what I need, I think.
DefaultHubManager hd = new DefaultHubManager(GlobalHost.DependencyResolver);
var hub = hd.ResolveHub("AdminHub") as AdminHub;
hub.SendMessage("woohoo");
Works. If there's an even better/preferred way - please share.
As per the latest documentation, IHubContext can be injected by dependency injection.
documentation : https://learn.microsoft.com/en-us/aspnet/core/signalr/hubcontext?view=aspnetcore-6.0
In service you could do
public class NotificationService : INotificationService
{
private readonly IHubContext<NotificationHub> _hubContext;
public NotificationService(IHubContext<NotificationHub> hubContext)
{
_hubContext = hubContext;
}
}
In controller
public class HomeController : Controller
{
private readonly IHubContext<NotificationHub> _hubContext;
public HomeController(IHubContext<NotificationHub> hubContext)
{
_hubContext = hubContext;
}
}
Once you have HubContext you could send message to group/client etc.
public async Task SendMessage()
{
return await _hubContext.Clients.All.SendAsync("Notify", $"Hello world");
}