I have a full engine that relies on abstractions based on user interactions. This works great with WPF/Xamarin app, cause I can implements this abstractions with window/form.
I have a little problem for porting this engine into ASP MVC.
A simple example can be show as this.
Abstraction interface (simplified)
public interface IQuestionBox
{
Task<bool> ShowYesNoQuestionBox(string message);
}
For WPF, it's really simple, I implement this interface as return the result of a window by calling ShowDialog().
In a simple business class, I can have this kind of calls (simplified) :
public async Task<string> GetValue(IQuestionBox qbox)
{
if(await qbox.ShowYesNoQuestionBox("Question ?"))
{
return "Ok";
}
return "NOk";
}
I really don't see how can I implement this kind of behavior in ASP, due to stateless of HTTP, knowing that this kind of call can be as various as domain/business need. The way I think it should be done is by returning a PartialView to inject into popup, but I don't see how to do this without breaking all the process ...
Anyone has ever done this ?
as I've said, I strongly doesn't recommend this pratice, but its possible, bellow the code that allows to do it, let's go:
To become it's possible I abused the use from TaskCompletionSource, this class allow us to set manually result in a task.
First we need to create a structure to encapsulate the process:
public class Process
{
// this dictionary store the current process running status, you will use it to define the future answer from the user interaction
private static Dictionary<string, Answare> StatusReport = new Dictionary<string, Answare>();
// this property is the secret to allow us wait for the ShowYesNoQuestion call, because til this happen the server doesn't send a response for the client.
TaskCompletionSource<bool> AwaitableResult { get; } = new TaskCompletionSource<bool>(true);
// here we have the question to interact with the user
IQuestionBox QuestionBox { get; set; }
// this method, receive your bussiness logical the receive your question as a parameter
public IQuestionBox Run(Action<IQuestionBox> action)
{
QuestionBox = new QuestionBox(this);
// here we create a task to execute your bussiness logical processment
Task.Factory.StartNew(() =>
{
action(QuestionBox);
});
// and as I said we wait the result from the processment
Task.WaitAll(AwaitableResult.Task);
// and return the question box to show the messages for the users
return QuestionBox;
}
// this method is responsable to register a question to receive future answers, as you can see, we are using our static dictionary to register them
public void RegisterForAnsware(string id)
{
if (StatusReport.ContainsKey(id))
return;
StatusReport.Add(id, new Answare()
{
});
}
// this method will deliver an answer for this correct context based on the id
public Answare GetAnsware(string id)
{
if (!StatusReport.ContainsKey(id))
return Answare.Empty;
return StatusReport[id];
}
// this method Releases the processment
public void Release()
{
AwaitableResult.SetResult(true);
}
// this method end the process delivering the response for the user
public void End(object userResponse)
{
if (!StatusReport.ContainsKey(QuestionBox.Id))
return;
StatusReport[QuestionBox.Id].UserResponse(userResponse);
}
// this method define the answer based on the user interaction, that allows the process continuing from where it left off
public static Task<object> DefineAnsware(string id, bool result)
{
if (!StatusReport.ContainsKey(id))
return Task.FromResult((object)"Success on the operation");
// here I create a taskcompletaionsource to allow get the result of the process, and send for the user, without it would be impossible to do it
TaskCompletionSource<object> completedTask = new TaskCompletionSource<object>();
StatusReport[id] = new Answare(completedTask)
{
HasAnswared = true,
Value = result
};
return completedTask.Task;
}
}
After that the question implementation
public interface IQuestionBox
{
string Id { get; }
Task<bool> ShowYesNoQuestionBox(string question);
HtmlString ShowMessage();
}
class QuestionBox : IQuestionBox
{
Process CurrentProcess { get; set; }
public string Id { get; } = Guid.NewGuid().ToString();
private string Question { get; set; }
public QuestionBox(Process currentProcess)
{
CurrentProcess = currentProcess;
CurrentProcess.RegisterForAnswer(this.Id);
}
public Task<bool> ShowYesNoQuestionBox(string question)
{
Question = question;
CurrentProcess.Release();
return AwaitForAnswer();
}
public HtmlString ShowMessage()
{
HtmlString htm = new HtmlString(
$"<script>showMessage('{Question}', '{Id}');</script>"
);
return htm;
}
private Task<bool> AwaitForAnswer()
{
TaskCompletionSource<bool> awaitableResult = new TaskCompletionSource<bool>(true);
Task.Factory.StartNew(() =>
{
while (true)
{
Thread.Sleep(2000);
var answare = CurrentProcess.GetAnswer(this.Id);
if (!answare.HasAnswered)
continue;
awaitableResult.SetResult(answare.Value);
break;
}
});
return awaitableResult.Task;
}
}
The differences for yours implementaion are:
1 - I create an Identifier to know for who I have to send the aswer, or just to stop the process.
2 - I receive a Process as parameter, because this allows us to call the method
CurrentProcess.Release(); in ShowYesNoQuestion, here in specific, releases the process to send the response responsable to interact with the user.
3 - I create the method AwaitForAnswer, here one more time we use from the TaskCompletionSource class. As you can see in this method we have a loop, this loop is responsable to wait for the user interaction, and til receive a response it doesn't release the process.
4 - I create the method ShowMessage that create a simple html script alert to simulate the user interaction.
Then a simple process class as you should be in your bussiness logical:
public class SaleService
{
public async Task<string> GetValue(IQuestionBox qbox)
{
if (await qbox.ShowYesNoQuestionBox("Do you think Edney is the big guy ?"))
{
return "I knew, Edney is the big guy";
}
return "No I disagree";
}
}
And then the class to represent the user answer
public class Answer
{
// just a sugar to represent empty responses
public static Answer Empty { get; } = new Answer { Value = true, HasAnswered = true };
public Answer()
{
}
// one more time abusing from TaskCompletionSource<object>, because with this guy we are abble to send the result from the process to the user
public Answer(TaskCompletionSource<object> completedTask)
{
CompletedTask = completedTask;
}
private TaskCompletionSource<object> CompletedTask { get; set; }
public bool Value { get; set; }
public bool HasAnswered { get; set; }
// this method as you can see, will set the result and release the task for the user
public void UserResponse(object response)
{
CompletedTask.SetResult(response);
}
}
Now we use all the entire structure create for this:
[HttpPost]
public IActionResult Index(string parametro)
{
// create your process an run it, passing what you want to do
Process process = new Process();
var question = process.Run(async (questionBox) =>
{
// we start the service
SaleService service = new SaleService();
// wait for the result
var result = await service.GetValue(questionBox);
// and close the process with the result from the process
process.End(result);
});
return View(question);
}
// here we have the method that deliver us the user response interaction
[HttpPost]
public async Task<JsonResult> Answer(bool result, string id)
{
// we define the result for an Id on the process
var response = await Process.DefineAnswer(id, result);
// get the response from process.End used bellow
// and return to the user
return Json(response);
}
and in your view
<!-- Use the question as the model page -->
#model InjetandoInteracaoComUsuario.Controllers.IQuestionBox
<form asp-controller="Home" asp-action="Index">
<!-- create a simple form with a simple button to submit the home -->
<input type="submit" name="btnDoSomething" value="All about Edney" />
</form>
<!-- in the scripts section we create the function that we call on the method ShowMessage, remember?-->
<!-- this method request the action answer passing the questionbox id, and the result from a simple confirm -->
<!-- And to finalize, it just show an alert with the process result -->
#section scripts{
<script>
function showMessage(message, id) {
var confirm = window.confirm(message);
$.post("/Home/Answer", { result: confirm, id: id }, function (e) {
alert(e);
})
}
</script>
#Model?.ShowMessage()
}
As I've said, I realy disagree with this pratices, the correct should to write a new dll, to support the web enviroment, but I hope it help you.
I put the project on github to you can download an understand all the solution
I realy hope it can help you
You can create a web socket connection from client side to server side. And work with front-end content with web socket request. It could be implemented as following:
Client side:
$app = {
uiEventsSocket : null,
initUIEventsConnection : function(url) {
//create a web socket connection
if (typeof (WebSocket) !== 'undefined') {
this.uiEventsSocket = new WebSocket(url);
} else if (typeof (MozWebSocket) !== 'undefined') {
this.uiEventsSocket = new MozWebSocket(url);
} else {
console.error('WebSockets unavailable.');
}
//notify if there is an web socket error
this.uiEventsSocket.onerror = function () {
console.error('WebSocket raised error.');
}
this.uiEventsSocket.onopen = function () {
console.log("Connection to " + url + " established");
}
//handling message from server side
this.uiEventsSocket.onmessage = function (msg) {
this._handleMessage(msg.data);
};
},
_handleMessage : function(data){
//the message should be in json format
//the next line fails if it is not
var command = JSON.parse(data);
//here is handling the request to show prompt
if (command.CommandType == 'yesNo') {
var message = command.Message;
var result = confirm(message);
//not sure that bool value will be successfully converted
this.uiEventsSocket.send(result ? "true" : "false");
}
}
}
And init it from ready or load event:
window.onload = function() { $app.initUIEventsConnection(yourUrl); }
Note that you url should begin with ws:// instead of http:// and wss:// instead of https:// (Web Sockets and Web Sockets Secure).
Server side.
Here is a good article for how to setup web sockets at asp.net core application or you could find another one. Note that you should group web socket connections from single user and if you want to send a message to the concrete user, you should send message for every connection from this user.
Every web socket you should accept with AcceptWebSocketAsync() method call and then add instance of this web socket to singleton, which contains a set of web sockets connection groupped by user.
The following class will be used to operate commands:
public class UICommand
{
public string CommandType { get; set; }
public string Message { get; set; }
public Type ReturnType { get; set; }
}
And a full code of singleton for handling sockets
public class WebSocketsSingleton
{
private static WebSocketsSingleton _instance = null;
//here stored web sockets groupped by user
//you could use user Id or another marker to exactly determine the user
private Dictionary<string, List<WebSocket>> _connectedSockets;
//for a thread-safety usage
private static readonly ReaderWriterLockSlim Locker = new ReaderWriterLockSlim();
public static WebSocketsSingleton Instance {
get {
if (this._instance == null)
{
this._instance = new WebSocketsSingleton();
}
return this._instance;
}
}
private WebSocketsSingleton()
{
this._connectedSockets = new Dictionary<string, List<WebSocket>>();
}
/// <summary>
/// Adds a socket into the required collection
/// </summary>
public void AddSocket(string userName, WebSocket ws)
{
if (!this._connectedSockets.ContainsKey(userName))
{
Locker.EnterWriteLock();
try
{
this._connectedSockets.Add(userName, new List<WebSocket>());
}
finally
{
Locker.ExitWriteLock();
}
}
Locker.EnterWriteLock();
try
{
this._connectedSockets[userName].Add(ws);
}
finally
{
Locker.ExitWriteLock();
}
}
/// <summary>
/// Sends a UI command to required user
/// </summary>
public async Task<string> SendAsync(string userName, UICommand command)
{
if (this._connectedSockets.ContainsKey(userName))
{
var sendData = Encoding.UTF8.GetBytes(JsonConvert.SerializeObject(command));
foreach(var item in this._connectedSockets[userName])
{
try
{
await item.SendAsync(new ArraySegment<byte>(sendData), WebSocketMessageType.Text, true, CancellationToken.None);
}
catch (ObjectDisposedException)
{
//socket removed from front end side
}
}
var buffer = new ArraySegment<byte>(new byte[1024]);
var token = CancellationToken.None;
foreach(var item in this._connectedSockets[userName])
{
await Task.Run(async () => {
var tempResult = await item.ReceiveAsync(buffer, token);
//result received
token = new CancellationToken(true);
});
}
var resultStr = Encoding.Utf8.GetString(buffer.Array);
if (command.ReturnType == typeof(bool))
{
return resultStr.ToLower() == "true";
}
//other methods to convert result into required type
return resultStr;
}
return null;
}
}
Explanation:
on establishing connection from web socket it will be added with
AddSocket method
on sending request to show a message, the required command will be passed into SendAsync method
the command will be serialized to JSON (using Json.Net, however you could serialize in your way) and send to all sockets, related to the required user
after the command sent, application will wait for respond from front end side
the result will be converted to required type and sent back to your IQuestionBox
In the web socket handling your should add some kind of the following code:
app.Use(async (http, next) =>
{
if (http.WebSockets.IsWebSocketRequest)
{
var webSocket = await http.WebSockets.AcceptWebSocketAsync();
var userName = HttpContext.Current.User.Identity.Name;
WebSocketsSingleton.Instance.AddSocket(userName, webSocket);
while(webSocket.State == WebSocketState.Open)
{
//waiting till it is not closed
}
//removing this web socket from the collection
}
});
And your method implementation of ShowYesNoQuestionBox should be kind of following:
public async Task<bool> ShowYesNoQuestionBox(string userName, string text)
{
var command = new UICommand
{
CommandType = "yesNo",
Message = text,
ReturnType = typeof(bool)
};
return await WebSocketsSingleton.Instance.SendAsync(string userName, command);
}
Note that there should be added userName to prevent sending the same message to all of the connected users.
WebSocket should create the persistent connection between server and client sides, so you could simply send commands in two ways.
I am kindly new to Asp.Net Core, so the final implementation could be a bit different from this.
It's actually much the same, except your UI is sort of disconnected and proxied with the HTTP protocol for the most part.
you essentially need to build the same code as your WPF code but then in the browser construct ajax calls in to the controller actions to apply your logic.
To clarify ...
so lets say you are building up a process over a series of questions that based on the users answer you put different steps in to the process.
You can either ...
build the process in the database
build it in session on the server
build it on the client as a js object
then do a post for execution ofthe constructed process.
think of the "statelessness" as a series of short interactions, but the state you keep between them can be done either on the client, in a db or in the users logged in session on the web server.
In your controller you can add an ActionResult that will give you the html response to your jquery modal popup request. Here is an example
public class MController : Controller {
public ActionResult doWork(requirement IQuestionBox)
{
// model is already modelBound/IOC resolved
return PartialView("_doWork", requirement );
}
}
//scripts
$(function(){
$.ajax({
url:"/m/doWork",
type:"get",
success:function(data){
$modal.html(data); // bind to modal
}
});
});
Apologies for not fully understanding the question.
hope this helps!
Related
I have like that scenario:
I have an endpoint and this endpoint will save the requests in List or Queue in memory and it will return immediately success response to the consumer. This requirement is critical, the consumer should not wait for the responses, it will get responses from a different endpoint if it needs. So, this endpoint must return as quickly as possible after saving the request message in memory.
Another thread will distribute these requests to other endpoints and save the responses in memory as well.
What I did till now:
I created a controller api to save these requests in the memory. I saved them in a static request List like below:
public static class RequestList
{
public static event EventHandler<RequestEventArgs> RequestReceived;
private static List<DistributionRequest> Requests { get; set; } = new List<DistributionRequest>();
public static int RequestCount { get => RequestList.Requests.Count; }
public static DistributionRequest Add(DistributionRequest request)
{
request.RequestId = Guid.NewGuid().ToString();
RequestList.Requests.Add(request);
OnRequestReceived(new RequestEventArgs { Request = request });
return request;
}
public static bool Remove(DistributionRequest request) => Requests.Remove(request);
private static void OnRequestReceived(RequestEventArgs e)
{
RequestReceived?.Invoke(null, e);
}
}
public class RequestEventArgs : EventArgs
{
public DistributionRequest Request { get; set; }
}
And another class is subscribed to that event that exists in that static class and I am creating a new thread to make some background web requests to be able to achieve 2. item which I stated above.
private void RequestList_RequestReceived(object sender, RequestEventArgs e)
{
_logger.LogInformation($"Request Id: {e.Request.RequestId}, New request received");
Task.Factory.StartNew(() => Distribute(e.Request));
_logger.LogInformation($"Request Id: {e.Request.RequestId}, New task created for the new request");
//await Distribute(e.Request);
}
public async Task<bool> Distribute(DistributionRequest request)
{
//Some logic running here to send post request to different endpoints
//and to save results in memory
}
And here is my controller method:
[HttpPost]
public IActionResult Post([FromForm] DistributionRequest request)
{
var response = RequestList.Add(request);
return Ok(new DistributionResponse { Succeeded = true, RequestId = response.RequestId });
}
I tried that approach but it did not work as I expected, it should return within milliseconds since I am not waiting for responses but it seems to wait for something, and after every single request waiting time is increasing as below:
What am I doing wrong? Or Do you have a better idea? How can I achieve my goal?
Based on you example code I tried to implement it without "eventing". Therefore I get much better request times. I cannot say if this is related to your implementation or the eventing itself for this you have to do profiling.
I did it this way
RequestsController
Just like you had it in your example. Take the request and add it to the requests list.
[Route("requests")]
public class RequestsController : ControllerBase
{
private readonly RequestManager _mgr;
public RequestsController(RequestManager mgr)
{
_mgr = mgr;
}
[HttpPost]
public IActionResult AddRequest([FromBody] DistributionRequest request)
{
var item = _mgr.Add(request);
return Accepted(new { Succeeded = true, RequestId = item.RequestId });
}
}
RequestManager
Manage the request list and forward them to some distribor.
public class RequestManager
{
private readonly ILogger _logger;
private readonly RequestDistributor _distributor;
public IList<DistributionRequest> Requests { get; } = new List<DistributionRequest>();
public RequestManager(RequestDistributor distributor, ILogger<RequestManager> logger)
{
_distributor = distributor;
_logger = logger;
}
public DistributionRequest Add(DistributionRequest request)
{
_logger.LogInformation($"Request Id: {request.RequestId}, New request received");
/// Just add to the list of requests
Requests.Add(request);
/// Create and start a new task to distribute the request
/// forward it to the distributor.
/// Be sure to not add "await" here
Task.Factory.StartNew(() => _distributor.DistributeAsync(request));
_logger.LogInformation($"Request Id: {request.RequestId}, New task created for the new request");
return request;
}
}
RequestDistributor
Distribution logic can be implemented here
public class RequestDistributor
{
public async Task DistributeAsync(DistributionRequest request)
{
/// do your distribution here
/// currently just a mocked time range
await Task.Delay(5);
}
}
Wire up
... add all these things to your dependency injection configuration
public void ConfigureServices(IServiceCollection services)
{
services.AddControllers();
services.AddSingleton<RequestDistributor>();
services.AddSingleton<RequestManager>();
}
Tests
With the here provided code pieces I received all the requests back in less than 10 ms.
Note
This is just an example try to always add interfaces to your services to make them testable ;).
I'm working on c# project.
I'd like to send API request via websocketsharp library in some sort of synchronous way.
I've been trying to do it following way:
Before we send any WS request , we create new SynchronousRequest() object with unique ID and add the newly created object to some sort of waiting list
We send WS request adding unique ID to the payload, on the response - the server will return the same id.
We start waiting for the event to be signaled (signaling happens once we receive response)
On the response handler:
Once WS response arrives, I try to match the context by the unique ID
Once it's matched, we signal event that the response has been received and add the response payload to the the synchronousRequest() object
Problem is step 3, once i use WaitOne() on the event the entire websocket client hangs and no further responses will be received - resulting in complete deadlock.
How can i do some sort of WaitOne() call in seperate thread or perhaps completely better solution exists for my problem, so the entire client does not hang and we match the contexts?
public class SynchronousRequest
{
public long requestId;
public ManualResetEvent resetEvent = new ManualResetEvent(false);
public dynamic response;
public SynchronousRequest()
{
var random = new Random();
requestId = random.Next();
}
}
public class APIWebSocket: BaseAPIWebSocket
{
private List<SynchronousRequest> waitingSyncRequests = new List<SynchronousRequest>();
public APIWebSocket()
{
ws = new WebSocket("wss://www.someserver.com");
registerConnectionEvents(); //Registers onOpen(), onMessage() handlers and similar
}
public void SendSyncTest()
{
var sr = new SynchronousRequest();
waitingSyncRequests.Add(sr);
//some data to send
var msg = new
{
jsonrpc = "2.0",
method = "public/ticker",
id = sr.requestId, //Response should contain the same ID
#params = new
{
instrument_name = "ETH"
}
};
ws.Send(JsonConvert.SerializeObject(msg));
//Below WaitOne() causes the entire websocket connection/thread to block
// No further messages will be received by HandleMessage() once we call WaitOne()
sr.resetEvent.WaitOne(); //Wait until we receive notification that response has been received
//do some processing on response here...
//Synchronous request completed, remove it from list
waitingSyncRequests.Remove(sr);
}
protected override void OnReceivedMessage(System.Object sender, WebSocketSharp.MessageEventArgs e)
{
dynamic message = JsonConvert.DeserializeObject(e.Data);
if (message.id != null )
{
//Find a resetEvent for given message.id
var matchingSyncRequest = waitingSyncRequests.First(r => r.requestId == message.id);
if (matchingSyncRequest != null)
{
matchingSyncRequest.response = message;
matchingSyncRequest.resetEvent.Set(); //Notify that response has been received
}
}
}
}
From what i understand you need to await on some event that will be set at some future time.
You could consider using TaskCompletionSource.
1.Whenever you send a message that you need its result , you could create a TaskCompletionSource (tcs) , add it to a Dictionary and send
the message over the socket.
2.You await tcs.Task or tcs.Task.Result on that tcs.
3.On another Thread/Task you could process your incoming responses ( in your case you have your received message handler. Whenever you receive a response of a target type or
id , you could just fetch the tcs from the dictionary based on the id, and
Task.SetResult(response) it.In that moment the caller (the one you are
awaiting gets unblocked).
public class Message
{
public string ID{get;set;}
}
public class Response
{
public string Id{get;set;}
}
public void MyClass
{
private ConcurrentDictionary<string,TaskCompletionSource<Response>>map=new ConcurrentDictionary<string,TaskCompletionSource<Response>>();
private Websocket socket;
public void SomeEventTrigger()
{
var msg=new Message{ Id="somespecialID" };
var tcs=new TaskCompletionSource<Response>();
ws.Send(JsonConvert.SerializeObject(msg));
if(!this.map.TryAdd(msg.Id,tcs))
{
return;
}
var result=tcs.Result; //this gets blocked until you use `tcs.SetResult`- > that would happen in your OnReceivedMessage
this.map.TryRemove(msg.Id,out TaskCompletionSource<Response>resp);
}
protected override void OnReceivedMessage(System.Object sender, WebSocketSharp.MessageEventArgs e)
{
Response message = JsonConvert.DeserializeObject<Response>(e.Data);
if (message.id != null )
{
if(this.map.TryGetValue(message.id),out TaskCompletionSource<Response> tcs)
{
tcs.SetResult(message); //this unblocks the method that wrote the message to the socket (above)
}
}
}
}
P.S
You need to make sure that you use Task.SetResult on the correct tcs so that the correct call to SomeEventTrigger method stops waiting.
I am new to Azure Event Grid and Webhooks.
How can I bind my .net mvc web api application to Microsoft Azure Event Grid?
In short I want, whenever a new file is added to blob storage, Azure Event grid should notify my web api application.
I tried following article but no luck
https://learn.microsoft.com/en-us/azure/storage/blobs/storage-blob-event-quickstart
How can I bind my .net mvc web api application to Microsoft Azure Event Grid?
In short I want, whenever a new file is added to blob storage, Azure Event grid should notify my web api application.
I do a demo for that, it works correctly on my side. You could refer to the following steps:
1.Create a demo RestAPI project just with function
public string Post([FromBody] object value) //Post
{
return $"value:{value}";
}
2.If we want to intergrate azure storage with Azure Event Grid, we need to create a blob storage account in location West US2 or West Central US. More details could refer to the screen shot.
2.Create Storage Accounts type Event Subscriptions and bind the custom API endpoint
3.Upload the blob to the blob storage and check from the Rest API.
You can accomplish this by creating an custom endpoint that will subscribe to the events published from Event Grid. The documentation you referenced uses Request Bin as a subscriber. Instead create a Web API endpoint in your MVC application to receive the notification. You'll have to support the validation request just to make you have a valid subscriber and then you are off and running.
Example:
public async Task<HttpResponseMessage> Post()
{
if (HttpContext.Request.Headers["aeg-event-type"].FirstOrDefault() == "SubscriptionValidation")
{
using (var reader = new StreamReader(Request.Body, Encoding.UTF8))
{
var result = await reader.ReadToEndAsync();
var validationRequest = JsonConvert.DeserializeObject<GridEvent[]>(result);
var validationCode = validationRequest[0].Data["validationCode"];
var validationResponse = JsonConvert.SerializeObject(new {validationResponse = validationCode});
return new HttpResponseMessage
{
StatusCode = HttpStatusCode.OK,
Content = new StringContent(validationResponse)
};
}
}
// Handle normal blob event here
return new HttpResponseMessage { StatusCode = HttpStatusCode.OK };
}
Below is an up-to-date sample of how you would handle it with a Web API. You can also review and deploy a working sample from here: https://github.com/dbarkol/azure-event-grid-viewer
[HttpPost]
public async Task<IActionResult> Post()
{
using (var reader = new StreamReader(Request.Body, Encoding.UTF8))
{
var jsonContent = await reader.ReadToEndAsync();
// Check the event type.
// Return the validation code if it's
// a subscription validation request.
if (EventTypeSubcriptionValidation)
{
var gridEvent =
JsonConvert.DeserializeObject<List<GridEvent<Dictionary<string, string>>>>(jsonContent)
.First();
// Retrieve the validation code and echo back.
var validationCode = gridEvent.Data["validationCode"];
return new JsonResult(new{
validationResponse = validationCode
});
}
else if (EventTypeNotification)
{
// Do more here...
return Ok();
}
else
{
return BadRequest();
}
}
}
public class GridEvent<T> where T: class
{
public string Id { get; set;}
public string EventType { get; set;}
public string Subject {get; set;}
public DateTime EventTime { get; set; }
public T Data { get; set; }
public string Topic { get; set; }
}
You can also use the Microsoft.Azure.EventGrid nuget package.
From the following article (credit to gldraphael): https://gldraphael.com/blog/creating-an-azure-eventgrid-webhook-in-asp-net-core/
[Route("/api/webhooks"), AllowAnonymous]
public class WebhooksController : Controller
{
// POST: /api/webhooks/handle_ams_jobchanged
[HttpPost("handle_ams_jobchanged")] // <-- Must be an HTTP POST action
public IActionResult ProcessAMSEvent(
[FromBody]EventGridEvent[] ev, // 1. Bind the request
[FromServices]ILogger<WebhooksController> logger)
{
var amsEvent = ev.FirstOrDefault(); // TODO: handle all of them!
if(amsEvent == null) return BadRequest();
// 2. Check the eventType field
if (amsEvent.EventType == EventTypes.MediaJobStateChangeEvent)
{
// 3. Cast the data to the expected type
var data = (amsEvent.Data as JObject).ToObject<MediaJobStateChangeEventData>();
// TODO: do your thing; eg:
logger.LogInformation(JsonConvert.SerializeObject(data, Formatting.Indented));
}
// 4. Respond with a SubscriptionValidationResponse to complete the
// event subscription handshake.
if(amsEvent.EventType == EventTypes.EventGridSubscriptionValidationEvent)
{
var data = (amsEvent.Data as JObject).ToObject<SubscriptionValidationEventData>();
var response = new SubscriptionValidationResponse(data.ValidationCode);
return Ok(response);
}
return BadRequest();
}
}
I have been doing a lot of research on finding a working example of SignalR implementation where status updates are sent only to an instance of a browser tab. My application extracts web data, and that process takes a lot of time.
I have been able to send status updates, but only to all users that have the webpage open.
//Server side (works just fine)
public class SendCustomText : Hub
{
public string myStatus;
public void CurrentStatus()
{
var context = GlobalHost.ConnectionManager.GetHubContext<SendCustomText>();
context.Clients.All.setStatus(myStatus);
}
}
//Client side
<script type="text/javascript">
$(function () {
//Declare a proxy to the reference hub
var currentStatus = $.connection.sendCustomText;
currentStatus.client.setStatus = function (value) {
$('#signalr_french_status').text(value.toString());
}
$.connection.hub.start().done(function () {
$('pandora_french_panel_extract_button').click(function () {
currentStatus.server.send();
})
})
$.connection.hub.disconnected(function () {
$.connection.hub.start();
})
})
What I, however, need is a way to update progress only in a tab that is open. The logged-in user may open another tab and process another job, and that new tab should display its own progress.
I did try successfully getting the connection ID client side and then passing it through AJAX to the server code. I need your help with an example where connection ID is used in the hub.
context.Clients.Client(connectionID).setStatus();
I could solve the problem myself. (I had made a very basic error initially. The first time, I used public string myConnectionID, that is, without the static keyword.)
public class SendCustomText : Hub
{
public string myStatus;
public static string myConnectionID;
public void CurrentStatus()
{
var context = GlobalHost.ConnectionManager.GetHubContext<SendCustomText>();
context.Clients.Client(myConnectionID).setStatus(myStatus);
}
public override System.Threading.Tasks.Task OnConnected()
{
myConnectionID = Context.ConnectionId;
return base.OnConnected();
}
}
Background:
I'm working on Cache warmup functionality to increase the performance on ASP.NET MVC Web by pre-loading the object in Cache before it's been requested.
I'm using Azure In-Role cache, which provided AddItemLevelCallback function when Cache is updated/removed/added etc. I've shared the code logic below.
Problem:
The AddItemLevelCallback on NotifyOnceCacheIsUpdated shown in the code snippet below doesn't get invoked straight away until Item is added/updated. The request will need to wait. But the problem is the the AddItemLevelCallback is async and KickOffWarmUpCache on DAL may return before the actual item is added/updated.
What would be the elegant way to handle this scenario where KickOffWarmUpCache only returns the result to the caller only after AddItemLevelCallback is triggered.
Technology: MVC3, .NET Framework 4.5
Code Sample:
CONTROLLER
public void WarmUpCache(string id)
{
var userInfo = BLL.KickOffWarmUpCache(string id);
}
BLL
public UserInfo KickOffWarmUpCache(string id)
{
return DAL.KickOffWarmUpCache(string id)
}
DAL
public UserInfo KickOffWarmUpCache(string id)
{
UserInfo userInfo = new UserInfo();
//If Status = Progress
if (cache.Get(id).Status == "Progress")
{
NotifyOnceCacheIsUpdated(id,(result)=>
{
userInfo=result.userInfo;
});
}else{
userInfo=Cache.Get(id);
}
//This needs to wait for until callback is triggered and userInfo is populated
return userInfo;
}
UTIL
public void NotifyOnceCacheIsUpdated(string cacheKey, Action<T> callback)
{
DataCacheOperations allCacheOperations = DataCacheOperations.ReplaceItem | DataCacheOperations.AddItem ;
_ndItemLvlAllOps = cache.AddItemLevelCallback(cacheKey, allCacheOperations,
(CacheName, cacheRegion, cacheKey, itemVersion, OperationId, nd) =>
{
cachedData = cache.Get(cacheKey);
callback(cachedData);
});
}
public Task<UserInfo> KickOffWarmUpCache(string id)
{
//If Status = Progress
if (cache.Get(id).Status == "Progress")
{
var ret = new TaskCompletionSource<UserInfo>();
NotifyOnceCacheIsUpdated(id,(result)=>
{
//complete the task.
ret.SetResult(result.userInfo);
});
//return a Task...which the SetResult will complete.
return ret.Task;
}
//Return a result synchronously
return Task.FromResult(Cache.Get(id));
}