I am trying to get the gRPC C# example working inside WPF.
The same code which is working inside a Console Application is not working. What am I missing.
The minimal class which works in the Console App and does not work in WPF looks like this:
public class GrpcClientImpl
{
private GrpcService.GrpcService.GrpcServiceClient client;
public GrpcTestClientImpl()
{
var channel = new Channel("127.0.0.1:6980", ChannelCredentials.Insecure);
client = new GrpcService.GrpcService.GrpcServiceClient(channel);
ProcessFeed().Wait();
}
public async Task ProcessFeed()
{
try
{
using (var call = client.Feed(new FeedRequest()))
{
var responseStream = call.ResponseStream;
while (await responseStream.MoveNext())
{
var result = responseStream.Current;
Console.WriteLine("received result");
}
}
}
catch (RpcException e)
{
Console.WriteLine("RPC failed " + e);
throw;
}
}
}
The responseStream.MoveNext() is where it is hanging. It does not respond to sent items and it does also not trigger an exception if the gRPC server is not there. What have I missed?
The problem is the blocking call ProcessFeed().Wait(); within the constructor.
This post explains why:
http://blog.stephencleary.com/2012/07/dont-block-on-async-code.html
To solve the issue, call await ProcessFeed(); from outside (not in the costructor).
Related
using System;
using System.Text;
namespace ConsoleApp7
{
class Program
{
static void Main(string[] args)
{
YourClient client = new YourClient();
client.Put();
}
public class YourClient
{
private readonly HttpClient _client;
public YourClient()
{
_client = new HttpClient();
}
public async Task Put() // must be async
{
using (var request = new HttpRequestMessage(HttpMethod.Put, "https://api.minecraftservices.com/minecraft/profile/name/egg"))
{
request.Headers.Add("Authorization", "Bearer token");
request.Content = new StringContent("body", Encoding.UTF8, "content-type");
using (var response = await _client.SendAsync(request))
{
var data = await response.Content.ReadAsStringAsync();
var code = response.StatusCode;
Console.WriteLine(Convert.ToString(code));
// do something with data
}
}
}
}
}
}
I'm not getting any output and I don't know why. I'm trying to print the response code of the request but nothing is output, is it to do with my method?
I have tried printing hi after Client.Put() and it was printed, so I know that my code is actually running, I just don't know why it isn't printing the status code ...
The excellent comment by Prolog points out one of two issues. If your Console app is built on < C# 7.1 you will need a workaround to prevent the app from exiting (before the request has time to process) so in this case add Console.ReadKey() as the very last line. This will spin the message loop until you hit a key. But this is not the main issue and I would like to offer a couple of debugging tips.
The big issue is this:
If I run your code, your http request is failing and is throwing a System.FormatException
Usually this type of exception is not set to Break when Thrown. (You can verify this by looking in the Exception Settings window.) Unfortunately, this is giving you a silent failure in this case, so you must take matters into your own hands to observe it.
Suggestions for debugging your code
Use a try-catch block around any code that has any likelihood of failing.
Use System.Diagnostics.Debug.Assert which will cause your program to break on a line if any condition expression evaluates to false (but only when you're running in Debug mode not Release mode).
Add output statements to trace execution. Using Debug.WriteLine will send messages to the Output window (but again, only in Debug mode). Alternatively, since we have a Console app here, I'm using the main app window to output trace statements.
Example using 1-3:
public async Task Put() // must be async
{
Console.WriteLine("Begin Put()");
try
{
using (var request = new HttpRequestMessage(HttpMethod.Put, "https://api.minecraftservices.com/minecraft/profile/name/egg"))
{
request.Headers.Add("Authorization", "Bearer token");
request.Content = new StringContent("body", Encoding.UTF8, "content-type");
using (var response = await _client.SendAsync(request))
{
var data = await response.Content.ReadAsStringAsync();
var code = response.StatusCode;
Console.WriteLine(Convert.ToString(code));
// do something with data
}
}
}
catch (Exception ex)
{
System.Diagnostics.Debug.Assert(condition: false, message: ex.Message);
}
Console.WriteLine("End Put()");
}
Now, if I run the code it will break and show what the problem is.
Use the Exception Settings window to turn on all exceptions (if in doubt). Now the code will break on the exact line that is the problem.
Verify that you are Setting Authorization Header of HttpClient correctly as this may be part of the root cause of the exception.
Finally, if you continue after the Debug.Assert you will see the following text in your console which will confirm whether your Put method has had a chance to complete or not.
Hope these suggestions help you solve this problem and future ones!
// This workaround for C# versions below 7.1 attempts to
// mimic an `async Main` method.
static void Main(string[] args)
{
RunAsync();
Console.ReadKey();
}
private static async void RunAsync()
{
YourClient client = new YourClient();
// Put() should be awaited inside an async method
await client.Put();
}
I am trying to debug a request by GetFromJsonAsync which is supposed to fetch data from a Flask API and convert to JSON within a .NET Core cli app.
The issue I am having however is that after performing the request the cli app simply exits with no error. I have tried implementing try/catch block but nothing shows up there.
the Flask endpoint builds jsonifies a number of uuids and messages from Postgres and returns them to the client.
As GetFromJsonAsync is asynchronous I have tried making the Flask endpoint likewise but that has not seemed to help at all. The latter works fine and has been validated with curl.
I know the call executes as I can see it in my web server logs.
A similar call which simply returns plain javascript object {"foo": "bar"} works fine which is why I think this could by an async issue but I cannot see any errors etc to troubleshoot. I have placed a breakpoint on the foreach after the call but this is never hit.
What am I missing here?
public static async void GetMessages()
{
ConfigureHeaders();
try
{
var client = Client;
var res = await Client.GetFromJsonAsync<Received>(Url + "/api/chat/message"); // stops here
foreach (var c in res!.messages) // breakpoint here is never hit
Console.WriteLine(c);
}
catch (Exception e)
{
Console.WriteLine(e);
throw;
}
}
public class Received
{
public Dictionary<string,string> messages { get; set; }
}
Flask
#message.get("/api/chat/message")
#csrf.exempt
async def get_messages():
new_msgs = {}
msgs = await get_unreplied() # DB gets called from another function here
try:
for m in msgs:
new_msgs[m.id] = m.message
if len(new_msgs) != 0:
return jsonify(new_msgs)
else:
return jsonify("no messages")
except Exception as e:
print(str(e))
This returns...
{
"id_foo1": "message_bar1",
"id_foo2": "message_bar2"
}
Best guess: your Main function is not awaiting the call to GetMessages
public async Task<int> Main(string []args)
{
await GetMessages();
}
I'm working on a Winforms app that executes SQL Procedures through a SignalR client. I'm relatively new to using SignalR and am still wrapping my head around it.
I start off by running my connection method to establish a connection with my SignalR service. I have two addresses configured ready for when I puslish but the DEV configuration leads to the SignalR service I am hosting locally.
Connection to SignalR (ConnectHub)
private async Task ConnectHub()
{
string hubAddress = "";
#if DEBUG
HubAddress = ConfigurationManager.AppSettings["HubAddress_DEV"];
#else
HubAddress = ConfigurationManager.AppSettings["HubAddress_PROD"];
#endif
if (string.IsNullOrEmpty(hubAddress))
{
MessageBox.Show("Hub Address is missing from configuration.");
}
ConnectionHandler.Client = new HubClient(hubAddress, "MyHub");
ConnectionHandler.Client.MyAlert += ConnectionHandler.ClientOnMyAlert;
ConnectionHandler.Client.ServerErrorEvent += ConnectionHandler.ClientOnServerErrorEvent;
await ConnectionHandler.Client.Connect(new List<string>() {
VehicleInfo.ThisVehicle.WarehouseCode,
VehicleInfo.ThisVehicle.VehicleName
});
}
My client is stored globally in my ConnectionHandler class where my event handlers are also kept. (I have breakpoints on these as I have not implemented them yet)
ConnectionHandler Class
public static class ConnectionHandler
{
public static HubClient Client { get; set; }
public static void ClientOnServerErrorEvent(string error)
{
throw new NotImplementedException(); //Currently not implemented
}
public static async Task ClientOnMyAlert(EnumMyAlertType alerttype, string message, Exception exception)
{
await Task.Yield(); //Currently not implemented
}
}
When I call the code to Invoke the procedure in my SignalR client, it returns a DataTable to me which is the intended result.
Call to SignalR
await ConnectHub();
DataTable dt = await ConnectionHandler.Client.Connection.InvokeCoreAsync<DataTable>(
"FetchStatuses",
new object[0]); //This call works as intended and returns a populated DataTable
StatusInfo = new CStatuses();
All the above code is currently done on the main form, however I wanted to move this call to SignalR into a constructor to try and tidy things up.
The problem comes when I try to move this call into another method, the program hangs as I don't think it has received the return value from SignalR, I have placed a breakpoint beneath it and it is not reached. A TryCatch reveals nothing as it hangs within the "Try" with no exception.
Calling from contructor
public CStatuses()
{
Statuses = new List<CStatus>();
var dataTable = ConnectionHandler.Client.Connection.InvokeCoreAsync<DataTable>("FetchStatuses",
new object[0])
.Result; //My program hangs on this line and proceeds no further
I am at a loss as to why it is doing this when I can get a value from the client from the form and when other members of my team have tried to do the same thing they can make a call to SignalR also from a different method.
Does anyone have any ideas as to how I can make this work?
I realize this has gotten quite long but if I can elaborate on things please let me know
FIXED CODE THANKS TO SOLUTION:
I have moved the code from my CStatuses constructor into a new async method within the same class and called it after initialization. This removes the need for .Result and appears to solve the problem for me.
public async Task PopulateStatuses()
{
var dataTable = await ConnectionHandler.Client.Connection.InvokeCoreAsync<DataTable>("FetchStatuses",
new object[0]);
Statuses = new List<CStatus>();
foreach (DataRow row in dataTable.Rows)
{
var status = new CStatus
{
StatusId = Common.Utility.GetInt16Value(row["StatusID"]),
StatusCode = Common.Utility.GetStringValue(row["StatusCode"]),
Description = Common.Utility.GetStringValue(row["Description"])
};
Statuses.Add(status);
}
}
You are running into a deadlock with the .Result call, I would suggest creating an async method in the CStatuses class and after you initialize your CStatuses class call the websocket for data.
I have created a chatbot in web channel and direct line.
When i tested in bot emulator i get the right response and when i try to test the same intent in localhost ( webchat) i got different response.
I will show you and example :
call an agent
give me your customer number
( after custemer number was sended ) are you sure ?
if you click Yes ...the data are stored in database ( sql server )
If you do the save in localhost you get : You cancelled the form ( in fact i havent cancell any form
Here is the luisdialog here i call the form :
[LuisIntent("human")]
public async Task human(IDialogContext context, LuisResult result)
{
var form = new FormDialog<Human>(
new Human(),
Human.BuildForm,
FormOptions.PromptInStart,
result.Entities);
context.Call<Human>(form, LossFormCompleted)
}
private async Task LossFormCompleted(IDialogContext context,
IAwaitable<Human> result)
{
HumanCall form = null;
try
{
form = await result;
}
catch (OperationCanceledException)
{
}
if (form == null)
{
await context.PostAsync("You cancelled the form.");
}
else
{
//call the LossForm service to complete the form fill
var message = $"Your data are stored in database";
await context.PostAsync(message);
}
context.Wait(this.MessageReceived);
}
The form model is :
[Serializable]
public class Human
{
[Prompt("What is your contract number?")]
public string contract;
public static IForm<Human> BuildForm()
{
OnCompletionAsyncDelegate<HumanCall> wrapUpRequest = async (context, state) =>
{
using (BotModelDataContext BotDb = new BotModelDataContext())
{
tblBot bot = new tblBot();
bot = BotDb.tblBots.SingleOrDefault(q => q.Reference == state.contract);
if (bot != null)
{
using (bbbserviceSoapClient cws = new bbbserviceSoapClient())
{
viewc a= new viewc();
a.Lastname = bot.Lastname;
}
}
}
};
return new FormBuilder<Human>().Message
("can you send us some info ?")
.Field(nameof(contract))
.OnCompletion(wrapUpRequest)
.Confirm("Are you sure: Yes or No. ")
.Build();
}
}
}
Can someone help me where i'm wrong ? What can i do to retrieve the same response ? It's about timeout problem or what do you thing ?
I do a test based on the code that you provided and make slight modifications, and I find that if some exceptions occur in wrapUpRequest method, it would show "You cancelled the form" instead of the message "Your data are stored in database".
So I suspect that exceptions occurring in wrapUpRequest method (perhaps database query issue or request sent by bbbserviceSoapClient is timeout etc) when you do test via web chat, which causes the issue.
To troubleshoot the issue, you can try to implement/write custom log to detect if any exception occurs within wrapUpRequest method when you test via web chat.
I need to upgrade our service bus nuget package to 3.2.2 (think the evenprocessor host requires it) but I have always kept our service bus project lib at 2.8.2. This is mainly due to the fact that BeginReceive() and EndReceive() looks to have been removed. Is there any reason or anyway I can easily convert this
public void StartReceiving(RecieverCallback callback, TimeSpan waittime, object state = null)
{
this._recieverCallback = callback;
_queueClient = this.MessagingFactory.CreateQueueClient(QueueName, ReceiveMode);
// make initial async call
_asyncresult = _queueClient.BeginReceive(waittime, ReceiveDone, _queueClient);
}
public void ReceiveDone(IAsyncResult result)
{
if (result != null)
{
try
{
var tmpClient = result.AsyncState as QueueClient;
var brokeredMessage = tmpClient.EndReceive(result);
if (brokeredMessage != null)
{
if (ReceiveMode == ReceiveMode.PeekLock)
{
brokeredMessage.Complete();
}
var tmpMessage = brokeredMessage.GetBody<T>();
ProcessMessageProperties(tmpMessage, brokeredMessage);
_recieverCallback(tmpMessage);
}
}
catch (Exception ex)
{
_logger.Fatal("ReceiveDone: {0}", ex.Message);
Console.WriteLine(ex.Message);
}
}
// do recieve for next message
_asyncresult = _queueClient.BeginReceive(ReceiveDone, _queueClient);
}
Image showing the error
Following image shows what happens if I upgrade servicebus to 3.2.2 which I believe will solve the original error (program running 3.2.2, lib project running 2.8.x)
I figured it out see link
https://gist.github.com/sitereactor/8953583
If anyone has a similar issue, let me know and will post my code but its 95% the same as per the link.