While calling Rest services(remote machine) from local machine i am getting httprequest exception,I found that this exception is coming while we are making asynchronous call using httpclient in the code.
var httpresponse = await _httpClient.SendAsync(httpClientRequests);
Sometimes i am able to get response from services but it is happening intermittently.
I have cross checked the request url also,it's correct.
Also i am getting data only in debug mode not in release.
Is this server side issue or client side?
Related
I have a XML-RPC server (using XML-RPC.net) running as a .NET console application. I'm trying to connect to it via my ASP.NET Core (2.1.1) web app but the client keeps timing out. Postman also returns a response immediately without issues.
Here is how I'm calling it:
HttpClient client = _clientFactory.CreateClient();
client.Timeout = TimeSpan.FromSeconds(10);
var httpRequest = new HttpRequestMessage(HttpMethod.Post, instance.ServiceUrl);
var stringContent = new ByteArrayContent(Encoding.UTF8.GetBytes(request.ToString()));
httpRequest.Content = stringContent;
httpRequest.Content.Headers.ContentType = MediaTypeHeaderValue.Parse("text/xml");
var httpResponse = await client.SendAsync(httpRequest);
var response = await httpResponse.Content.ReadAsByteArrayAsync();
I can see that the request was made successfully as the console app returns a response. Fiddler shows there was a 200 response but await client.SendAsync(httpRequest); times-out!
The request usually completes in under 10ms so the timeout value is just for debugging, if I leave it out it would take 60s. The response returns XML.
I've tried rewriting this to use StringContent and using PostAsync, same issue. I also attempted to rewrite this using WebClient but it returned The remote server returned an error: (100) Continue. not sure if that's relevant.
Been stuck on this for a whie, anyone know what could be happening?
OK I did some googling and it looks like I needed this line:
client.DefaultRequestHeaders.ExpectContinue = true;
It was definitely related to 100 status code returned not being handled properly.
Found it here:
https://social.msdn.microsoft.com/Forums/en-US/042016f0-d70e-42f9-9924-5febeb2bea86/excluding-the-quotexpect-100continuequot-header-from-httpwebrequest-posts?forum=winappswithcsharp
I'm trying to connect to our wordpress api in our asp.net mvc application, using the following code
public static string GetLifespeakBlogListings()
{
WebClient client = new WebClient();
string url = "https://lifespeak.com/wp-json/wp/v2/posts?categories=6";
string listings = client.DownloadString(url);
return listings;
}
however I'm getting the following exception :
System.Security.SecurityException Failed to negotiate HTTPS connection with server.fiddler.network.https> HTTPS handshake to lifespeak.com (for #1) failed. System.IO.IOException Unable to read data from the transport connection: An existing connection was forcibly closed by the remote host.
If I access this feed from a browser, it works fine https://lifespeak.com/wp-json/wp/v2/posts?categories=6
However, if I try from fiddler, I get the same exception:
I'm assuming that something on our wordpress site is blocking this request for some reason. Is there something I can configure to prevent this? How can I determine the cause?
The issue was that the version of System.Net I was using in my application was attempting to make the request to the wordpress API using TLS 1.0, and was getting rejected, similar to the issue with fiddler that dave pointed out above. I fixed this by adding the following line of code in the method, as specified in How to specify SSL protocol to use for WebClient class
ServicePointManager.SecurityProtocol = (SecurityProtocolType)3072;
Note that the value has to be added manually and cast as a SecurityProtocolType, as .net 4.0 (the version I was using) doesn't support tls1.2
Using SignalR for ASP.NET Core 2.0, Client side (1.0.0-alpha2-final), C# VS2017.
To connect the code is:
await hubConnection.StartAsync();
since this is an await for a void how can we test if the client did manage to connect ? In my tests I have a breakpoint on the server side in public override async Task OnConnectedAsync() but that breakpoint is not always hit therefore I know that sometimes the client does not connect. Or perhaps it did connect but OnConnectedAsync() was not triggered?
How can the client knows it succeeded in establishing the connection?
Thanks
Edit: More info. It does fire OnConnectedAsync() when using localhost (debugging in VS); it does not fire OnConnectedAsync() when connecting through ngrok. Maybe this is something to do with proxy/CORS, I am not familiar with.
Edit: It appears that the Client does indeed connect because if I change the URL to a non existing one it gives a 404. So it appears that the problem is that OnConnectedAsync() does not fire when the client connects through ngrok but does fire when connected directly to localhost.
StartAsync is not a void method but returns a Task. If the client does not connect StartAsync throws (returns a faulted task) otherwise the async call will complete without an error (returns a completed task) after the client is successfully connected.
I have a .Net 4.5.2 WebApp that is calling my API. When I point my web app to the LocalHost version of my API, it gets the data, and comes back just fine. I published that API, and confirm that the API is working correctly with PostMan.
Then I run the exact same WebApp code, changing only the URI from localhost to live api, and I get a multiple exception error consisting of the following:
An existing connection was forcibly closed by the remote host
Unable to read data from the transport connection: An existing connection was forcibly closed by the remote host.
The underlying connection was closed: An unexpected error occurred on a send.
An error occurred while sending the request.
Here's my calling code
using (HttpClient client = new HttpClient())
{
client.DefaultRequestHeaders.Accept.Clear();
client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
client.DefaultRequestHeaders.Add("user", serializedUser);
response = null;
try
{
//Uri uri = new Uri("https://jsonplaceholder.typicode.com/posts/1");//https works
Uri uri = new Uri("https://api.acme.com/values/test");
//Uri uri = new Uri("http://localhost/5000/values/test"); //http localhost works
response = client.GetAsync(uri).Result;
}
catch (Exception e)
{
string er = e.Message;
}
}
EDIT 1: I created a .NET Core app from scratch, and my original code works perfectly calling my live API. My original code also work in .NET 4.5.2 calling a different "https" API.
EDIT 2:
So this is where I'm at now, I have created two generic apps from VS 2015, one is a .NET Core Web App, the other a .NET Framework Web App. I have used the above code exactly the same in both apps to call the API. In both apps, I can call a generic "https" api I found online (jsonplaceholder). I can also call the localhost version of my app at "http" from both. In the .NET Core version of the app, I can call my "https" live API and get the results I'm looking for. In the .NET Framework app I still get the same errors.
I can't figure out what the difference is between my Core and Framework requests that is getting one shut down when the other isn't.
It seems you are hosting the application on secured http environment (https). Are you using SSL certificate on the server where you are hosting your Web API? If not, It might be throwing the certificate related exceptions.
Just add the following line before the call to GetAsync and This will ignore the SSL errors.
ServicePointManager.ServerCertificateValidationCallback = delegate { return true; };
This is only recommended in an intranet environment or other closed network where server identities can't be forged.
C# Ignore certificate errors?
Adding the following line before my API call fixed the issue, but I'd love to hear an explanation of what this line does, and any security risks this might impose using it in my web app.
System.Net.ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12 | SecurityProtocolType.Tls11 | SecurityProtocolType.Tls;
Props to this answer!
I have the following method which is returning an incorrect response to the browser before the method is even complete. This is in Spring 3.2.
#RequestMapping(value="/process1/createEditContract/validate", method=RequestMethod.POST)
public #ResponseBody StatusResponse validateProcess1(#ModelAttribute("contractEditForm") #Valid Process1CreateEditContractDTO dto, BindingResult bindingResult) {
StatusResponse response = new StatusResponse();
response.setSuccess(true);
if (bindingResult.hasErrors()) {
log.debug("Errors found. Processing status response");
response.setSuccess(false);
List<FieldError> fieldErrors = bindingResult.getFieldErrors();
for (FieldError fe: fieldErrors) {
response.getMessages().add(messageSource.getMessage(fe, null));
}
}
return response;
}
StatusResponse is a simple object that a javascript function in the JSP reads to generate a Javascript alert stating whether the action was successful or errors occurred. The method makes it all the way through, but as soon as it tries to write the response, I get this:
java.net.SocketException: Software caused connection abort: socket write error
I've been stuck for a day now, any help would be appreciated.
UPDATE
I rolled back from Spring 3.2 to Spring 3.1, and the wording of the error message changed enough to give me more information.
Basically, I'm getting now seeing this:
IllegalStateException: Response already committed
What I don't see is what is causing the response to commit so quickly. Maybe a conflict with the OpenSessionInViewFilter?
This error can occur when the local network system aborts a connection, such as when WinSock closes an established connection after data retransmission fails (receiver never acknowledges data sent on a datastream socket).". See this MSDN article. See also Some information about 'Software caused connection abort.
To prove which component fails I would monitor the TCP/IP communication using wireshark and look who is actaully closing the port, also timeouts could be relevant.
The javascript runs in browser, and your controller runs on server. You cannot pass a complex object from the controller to the javascript without converting it to a textual format such as xml or json.
So you should :
choose a format (say json)
add a produces="application/json" in your RequestMapping annotation
do generate json in your controller method