I got the following code:
using (var client = new HttpClient(new NativeMessageHandler()))
{
client.Timeout = TimeSpan.FromSeconds(30.0);
var response = await client.PostAsync(requestString, content);
json = await response.Content.ReadAsStringAsync();
var tk = JObject.Parse(json);
if ((string)tk.GetValue("Ident") == "Message" && (int)tk.GetValue("Status") == 401)
throw new AuthenticationException();
return tk;
}
This is the base for calling a webservice for the app I'm working on. The thing is: Every time I step over this one line:
var response = await client.PostAsync(requestString, content);
I get an error message from Visual Studio saying "The network connection to {IP:PORT} has been lost. Debugging will be aborted."
And so I get disconnected (happens with Emulator and WP device). This is really annoying since I would like to debug the result, but no chance. As I just have noticed the connection breaks even if you continue. Once it hit's it, the connection get lost.
This is a very weird behavior. Any clues why this happens or what could trigger connection loss?
FYI I'm using Newtonsoft.Json for that.
Related
I'm facing a behavior in Minimal API that I can't understand.Consider the following simple Minimal API:
var builder = WebApplication.CreateBuilder(args);
var app = builder.Build();
app.UseExceptionHandler((exceptionApp) =>
{
exceptionApp.Run(async context =>
{
context.Response.ContentType = MediaTypeNames.Text.Plain;
var feature = context.Features.Get<IExceptionHandlerPathFeature>();
if (feature?.Error is BadHttpRequestException ex)
{
context.Response.StatusCode = 400;
var message =
(ex.InnerException is JsonException)
? "The request body is an invalid JSON"
: "Bad Request";
await context.Response.WriteAsync(message);
}
else
{
context.Response.StatusCode = 500;
await context.Response.WriteAsync("There is a problem occured");
}
});
});
app.MapPost("/models", (Model model) => Results.Created(string.Empty, model));
app.Run();
public record Model(int Value, string Title);
When I run the application in the Development environment, and pass an invalid JSON like
{
"value": 1,
"Title": Model #1
}
the custom exception handler is called and I have to control the behavior of the API. But whenever
I run the application in the Production environment, the framework automatically returns a
"bad request" response without letting me control the response.
Could anyone explain this behavior to me? I really need my exception handler to handle invalid input
JSON exceptions.
Thanks
After digging into ASP.Net Core source code for a while, I found that the following line resolves the issue.
builder.Services.Configure<RouteHandlerOptions>(o => o.ThrowOnBadRequest = true);
I'm trying to get some custom columns values (longitude,latitude) from ASPNetUsers Table from the DB , When I send a Get request throw browser I get a 200 ok with the requested json .. but when I try to use GetStringAsync to deserialize the response in my xamarin app I don't get any response .
In AccountController class
// POST api/Account/GetUserPostion
[Route("GetUserPostion")]
public LocationDataToPostAsync GetUserPostion()
{
var store = new UserStore<ApplicationUser>(new ApplicationDbContext());
var manager = new ApplicationUserManager(store);
LocationDataToPostAsync locationData = new LocationDataToPostAsync();
var model = manager.FindById(User.Identity.GetUserId());
locationData.UserId = User.Identity.GetUserId();
if (model.Longitude != null) locationData.Longitude = (double) model.Longitude;
if (model.Latitude != null) locationData.Latitude = (double) model.Latitude;
return locationData;
}
In ApiService class in xamarin forms app
public async Task<LocationDataToPostAsync> GetUserLocationAsync(string accessToken)
{
HttpClient client = new HttpClient();
client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", accessToken);
var json = await client.GetStringAsync("http://10.0.2.2:45455/api/Account/GetUserPostion");
var location = JsonConvert.DeserializeObject<LocationDataToPostAsync>(json);
return location;
}
It is unclear from your code if the Task is awaited or you are calling .Result or .GetAwaiter().GetResult() on the Task. However, as we found out in the comments adding .ConfigureAwait(false) fixed your issue.
This indicates that the code cannot return to the context it came from, so adding .ConfigureAwait(false) the code doesn't return to the context.
In your case the context is probably the UI thread and when it tries to return the UI thread is blocked.
The most likely scenario why the UI Thread is block is because you called your Task in a wrong manner. If you call it with .Result on the UI thread you are synchronously blocking the UI thread, hence anything that tries to return to the UI thread, will deadlock, since you are blocking that.
The easy fix here is to just add .ConfigureAwait(false) in your code. The better solution would be not to block the UI thread by awaiting the Task.
i have simple web sockets html5 , when the server is up every thing is working fine
the problem is when i close the server ( for testing )
im getting :
WebSocket connection to 'ws://127.0.0.1:7777/api' failed: Error in connection establishment: net::ERR_CONNECTION_REFUSED
which i unable to catch its never jumps to onerror or onclose in case of this error
init: function () {
this.m_wsiSendBinary = new WebSocket("ws://127.0.0.1:7681/wsapi");
this.m_wsiSendBinary.onopen = function(evt) {
cc.log("Send Binary WS was opened.");
};
this.m_wsiSendBinary.onmessage = (function(evt) {
this.handleServerResponse(yStr);
this.m_wsiSendBinary.onerror = function(evt) {
};
this.m_wsiSendBinary.onclose = function(evt) {
cc.log("m_wsiSendBinary websocket instance closed.");
self.m_wsiSendBinary = null;
};
}).bind(this);
I do not have full answer, however I dealt with similar issue and have a partial and not so elegant solution (but may help someone). Unfortunately without the elimination of the error message.
Two business requirements:
BR1 - Handle state in initialization when the server is not available.
BR2 - Handle state when the server stops.
Solution for BR1
var global_connection_openned=null;//Here you have the result
init: function () {
global_connection_openned=false;
this.m_wsiSendBinary = new WebSocket("ws://127.0.0.1:7681/wsapi");
this.m_wsiSendBinary.onopen = function(evt)
{
global_connection_openned=true;
};
Solution for BR2 (assumes the BR1)
//somewhere in your project called by setInterval(..) which will detect the connection is lost (and tries to reestablish/reopen the connetion.
{
if (this.m_wsiSendBinary==null || this.m_wsiSendBinary.readyState==3)
this.init();
if (!global_connection_openned)
this.m_wsiSendBinary=null;
}
Anyway, I would be really curious if there is solid and proper solution of this use case.
I am developing an iOS Application using MonoTouch. The application collects its data from a web service, using this code:
private static string getResult (string url)
{
string result;
var request = HttpWebRequest.Create (url);
request.ContentType = "application/json";
request.Method = "POST";
using (HttpWebResponse response = request.GetResponse() as HttpWebResponse)
{
if (response.StatusCode != HttpStatusCode.OK)
Console.Out.WriteLine("Error fetching data. Server returned status code: {0}", response.StatusCode);
using (StreamReader reader = new StreamReader(response.GetResponseStream()))
{
result = reader.ReadToEnd();
}
}
return result;
}
And this works fine, BUT when the json string returned from the Web Service reaches a certain size, the request returns with Internal server error 500. I have tried to invoke the service method directly in a web browser, and this returns a json string as expected. Why will it not work with my code, and is there a way to fix this?
Update:
I think this might solve my problem: http://forums.iis.net/t/1176077.aspx/1
Try Increasing Time Out for your service request. Your service must be timing out resulting 500 error
Also check this http://www.checkupdown.com/status/E500.html
I've got a node.js app that I want to use to check if a particular site is up and returning the proper response code. I want to be able to catch any errors that come up as the domain name isn't resolving or the request is timing out. The problem is is that those errors cause Node to crap out. I'm new to this whole asynchronous programming methodology, so I'm not sure where to put my try/catch statements.
I have an ajax call that goes to something like /check/site1. Server side that calls a function which attempts to make a connection and then return the statusCode. It's a very simple function, and I've wrapped each line in a try/catch and it never catches anything. Here it is:
function checkSite(url){
var site = http.createClient(80, url);
var request = site.request('GET', '/', {'host': url});
request.end();
return request;
}
Even with each of those lines wrapped in a try/catch, I will still get uncaught exceptions like EHOSTUNREACH and so on. I want to be able to catch those and return that to the ajax call.
Any recommendations on what to try next?
http.createClient has been deprecated.
Here is a quick example of how to handle errors using the new http.request:
var http = require("http");
var options = {
host : "www.example.com"
};
var request = http.request(options, function(req) {
...
});
request.on('error', function(err) {
// Handle error
});
request.end();
Unfortunately, at the moment there's no way to catch these exceptions directly, since all the stuff happens asynchronously in the background.
All you can do is to catch the uncaughtException's on your own:
var http = require('http');
function checkSite(url){
var site = http.createClient(800, url);
var request = site.request('GET', '/', {'host': url});
request.end();
return request;
}
process.on('uncaughtException', function (err) {
console.log(err);
});
checkSite('http://127.0.0.1');
Which in this case (notice port 800) logs:
{ message: 'ECONNREFUSED, Connection refused',
stack: [Getter/Setter],
errno: 111,
syscall: 'connect' }
Node.js is still under heavy development and there sure will be a lot of progress in the next couple of months, right now focus seem to be on fixing performance bugs for 3.x and making the API somewhat stable, because after all Node.js is mainly a server so throughput matters.
You can file a bug though, but be warned crashes etc. have way higher priority than features, and most new features make it in via fork pull requests.
Also for the current Roadmap of Node.js watch this talk by Ryan Dahl (Node's Creator):
http://developer.yahoo.com/yui/theater/video.php?v=yuiconf2010-dahl
I stumbled across another solution while I was researching a similar problem. http.Client emits an 'error' event if a connection can't be established for any reason. If you handle this event then the exception won't be thrown:
var http = require('http');
var sys = require('sys');
function checkSite(url) {
var site = http.createClient(80, url);
site.on('error', function(err) {
sys.debug('unable to connect to ' + url);
});
var request = site.request('GET', '/', {'host': url});
request.end();
request.on('response', function(res) {
sys.debug('status code: ' + res.statusCode);
});
}
checkSite("www.google.com");
checkSite("foo.bar.blrfl.org");
Of course, the connection error and the response to the request both arrive asynchronously, meaning that simply returning the request won't work. Instead, you'd have to notify the caller of the results from within the event handlers.
Actually it's even easier that the accepted answer:
function checkSite(url){
var http = require('http');
var request = http.get(url,r=>{console.log("OK",r)}).on("error",e=>{
console.log("ERROR",e)
})
}