Develop Reference

xamarin android : httpclient PostAsync

we have an app under xamarin android build with visual studio 2017.
this app works since three years without any problems.
since two weeks and I don't know why actually some device can't sync with our back end.
It's really strange because nothing has change in this part .
this error does not appear on all devices but on one or two from time to time
we use the dll httpClient for to sync the datas with our backend.
If i put a break point inside the postAsync I have an exception with this -> Cannot access a disposed object. Object name: 'System.Net.Sockets.NetworkStream
Any one has an idea about how to solve this ? also what does it meam ?
Here is it the code of the postAsync method :
thanks for our time and comment guys
public override HttpResult ExecutePost(Uri target, string body)
{
var client = new HttpClient();
client.MaxResponseContentBufferSize = MaxHttpResponseBufferSize;
try
{
var requestContent = new StringContent(body, RequestContentEncoding, RequestContentType);
var response = client.PostAsync(target, requestContent).Result;
if (response.IsSuccessStatusCode)
{
var content = response.Content.ReadAsStringAsync().Result;
return new HttpResult(content, null, null);
}
return new HttpResult(null, "Response is empty", response.StatusCode.ToString());
}
catch (Exception e)
{
return new HttpResult(null, "Problem with the HttpPost", e.Message);
}
}

I experienced the same issue. Have been battling for 6 hours on this issue.
If you read the error, I was getting (Failed to connect to localhost/127.0.0.1:7113). If you put localhost in your browser or swagger tool it will work but if you put https://127.0.0.1:7113/api/weatherforecast in your browser it will not work. It will give you a certificate problem.
So I think you have to resolve 127.0.0.1 to localhost with https certificate on your local dev machine.
I'm building a MAUI app with Visual Studio 2022 Preview.
So I solved this issue by deploying my API to AZURE.
Then update to the azure url for example:
string apiUrl = "https://weatherforecast.azurewebsites.net/api/weatherforecast";
and then it worked brilliantly. Like super brilliantly.
Here is my code:
public void LoginAsync()
{
HttpClient client = new HttpClient();
string apiUrl = "https://weatherforecast.azurewebsites.net/api/weatherforecast";
UserCredentials.EmailAddress = LoginUIEntity.EmailAddress;
UserCredentials.Password = LoginUIEntity.Password;
string serialized = JsonConvert.SerializeObject(UserCredentials);
var inputMessage = new HttpRequestMessage
{
Content = new StringContent(serialized, Encoding.UTF8, "application/json")
};
inputMessage.Headers.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
try
{
var message = client.PostAsync(apiUrl, inputMessage.Content).Result;
if (message.IsSuccessStatusCode)
{
var apiResponse = message.Content.ReadAsStringAsync();
UserCredentials = JsonConvert.DeserializeObject<UserCredentials>(apiResponse.Result);
if (UserCredentials.IsValid)
{
UserCredentials.IsLoggedIn = true;
}
else
{
ErrorMessage = "Invalid credentials supplied.";
}
}
}
catch (Exception ex)
{
ErrorMessage = "An error has occurred. Please contact support if the error persists.";
}
}
}

thanks for the link your provide.
I've try up the buffer on the postasync / try to sync in wifi OR 3G / delete special character in json / ...
but nothing work
we have move the prod database to the test and try to sync the data to the test database with postman. with postman the result was ENTITY TOO LARGE !
Json is size > 1.2 mega and the default value inside IIS is set to 1 mega
Here is it the problem ...
thanks problem solve

I cannot established connection with WCF services in Xamarin

I have a WPF application in VB.NET that already developed by my old colleagues. Now, my superior want to replace current platform by implementing the same concept to be run on the Android system. So, I've decided to use Xamarin Android .NET Standard.
I have searched for a way to consume WCF and the error throw before I'm asking but I'm still stuck at the same error.
I have set up the service references WCF on the android class. Given on solution, I have 2 projects:- MyProject and MyProject.Android
===========================================================================
WPF
Private Function EstablishConnect() As Boolean
Try
Dim context As InstanceContext = New InstanceContext(Me)
svrobj = New DisplayServicesClient(context, "DisplayTcpBinding")
Dim endpointAddress As New EndpointAddress(modUtility.ServerEndPointAddress)
svrobj.Endpoint.Address = endpointAddress
svrobj.Open()
SecondDiffFromServer = DateDiff(DateInterval.Second, Now, svrobj.GetDateTime)
Return True
Catch ex As Exception
WriteLog.Log(ex.ToString, True)
Return False
End Try
End Function
modUtility.ServerEndPointAddress get from INI:
net.tcp://localhost:8002/AppServ/WCFServices/Display
===========================================================================
XAMARIN FORMS
private async Task<bool> EstablishConnectAsync()
{
try
{
InstanceContext context = new InstanceContext(this);
svrobj = new DisplayServicesClient(DisplayServicesClientBase.EndpointConfiguration.DisplayTcpBinding); //, DisplayServicesClientBase.EndpointConfiguration.DisplayTcpBinding
EndpointAddress endpointAddress = new EndpointAddress(modUtility.ServerEndPointAddress);
svrobj.Endpoint.Address = endpointAddress;
await svrobj.OpenAsync();
modUtility.SecondDiffFromServer = (int)(DateTime.Now - await svrobj.GetDateTimeAsync()).TotalSeconds;
return true;
}
catch (Exception ex)
{
Device.BeginInvokeOnMainThread(() =>
{
ResultText.Text = "Unable to established connection with endpoint service. Ex-" + ex.Message;
});
return false;
}
}
modUtility.ServerEndPointAddress get from settings:
net.tcp://10.0.2.2:8002/AppServ/WCFServices/Display
I'm currently run android on emulator.
My code throw exception on any call to svrobj function. Below are the error that throw:-
The communication object System.ServiceModel.DuplexChannelFactory`1[AppServ.IDisplayServices] is not at created state but at Opening state.
The method or operation is not implemented.
Do I missing something or do I have implement wrong way?

Cookies not working on mobile browsers (using ASP.NET MVC )

I have an ASP.NET C# MVC4 Web site that I have working wonderfully for the most part. However, when we tested on mobile, the cookies that I am using for authentication would not work. I set the Auth cookie in my controller action but when trying to access them on the next call they are not there. Once again this is ONLY A PROBLEM ON MOBILE. Works fine in desktop versions of IE, Chrome and Firefox. Does not work with Chrome on Android.
Code to write cookie (in controller action):
//Set information into object that can be read out of the cookie later
FormsAuthModel UserDataObj = new FormsAuthModel
{
UserID = dmUser.ID,
PasswordChange = dmUser.PasswordChange
};
string UserData = Convert.ToBase64String(clsShared.Serialize(UserDataObj));
//Create the ticket
FormsAuthenticationTicket ticket = new FormsAuthenticationTicket(1, dmUser.UserName, DateTime.Now, DateTime.Now.AddDays(1), false, UserData, FormsAuthentication.FormsCookiePath);
// Encrypt the ticket
string encTicket = FormsAuthentication.Encrypt(ticket);
// Create the cookie
HttpCookie cookie = new HttpCookie(FormsAuthentication.FormsCookieName, encTicket);
System.Web.HttpContext.Current.Response.Cookies.Add(cookie);
Code to read cookie (in Global.asax.cs - Application_PostAuthenticateRequest):
HttpCookie authCookie = HttpContext.Current.Request.Cookies[FormsAuthentication.FormsCookieName];
if (authCookie != null)
{
try
{
FormsAuthenticationTicket authTicket = FormsAuthentication.Decrypt(authCookie.Value);
UserDataObj = (FormsAuthModel)clsShared.Deserialize(Convert.FromBase64String(authTicket.UserData), typeof(FormsAuthModel));
}
catch (Exception ex)
{
Console.WriteLine(ex.Message);
//WriteEvent(string.Format("Error deserializing auth ticket - {0}", ex.Message), EventLogEntryType.Error);
}
}
The AuthCookie is always null on the subsequent requests. What the user sees is a login screen, they fill it out and they get redirected right back to the login screen.
I could not find anything in my searches that helped explain why all the mobile requests (my phone, my tablet and other users' phones) would act differently than the desktop browsers.
Any help would be greatly appreciated.
Thanks!!

OK I found a solution although I am not sure why. I changed the cookie creation code as follows and it worked.
//Set information into object that can be read out of the cookie later
FormsAuthModel UserDataObj = new FormsAuthModel
{
UserID = dmUser.ID,
PasswordChange = dmUser.PasswordChange
};
string UserData = Convert.ToBase64String(clsShared.Serialize(UserDataObj));
//Create the ticket
FormsAuthenticationTicket ticket = new FormsAuthenticationTicket(1, dmUser.UserName, DateTime.Now, DateTime.Now.AddDays(1), false, UserData, FormsAuthentication.FormsCookiePath);
// Encrypt the ticket
string encTicket = FormsAuthentication.Encrypt(ticket);
// Create the cookie - FIX IS HERE!!!
Response.Cookies[FormsAuthentication.FormsCookieName].Value = encTicket;
//HttpCookie cookie = new HttpCookie(FormsAuthentication.FormsCookieName, encTicket);
//Response.Cookies.Add(cookie);
Notice that the only change is in adding the cookie by setting the value directly instead of creating a cookie object and adding that to the collection.
i.e. - Response.Cookies["Name"] = Value;
I got the idea from this MS article: https://msdn.microsoft.com/en-us/library/ms178194.aspx.
So does anyone know why this would make a difference? I have used the cookie instance method several times before and never had this problem.

What does Device Id mean Azure Push Notifications in Xamarin Android? How to get it?

We are using Azure Mobile Services to Push notifications to a Xamarin Android and a Xamarin iOS and a Windows Universal App. The Windows Universal App has plenty of documentation around what we need, although we haven’t had a chance to implement it yet. However, both Xamarin Android and iOS are missing all documentation around Push Notifications. If you go to http://azure.microsoft.com/en-us/documentation/services/mobile-services/ and select Xamarin Android or Xamarin iOS and .NET Backend there are zero links for documentation around these APIs. After digging around a ton yesterday I found this: http://azure.microsoft.com/en-us/documentation/articles/mobile-services-dotnet-backend-xamarin-android-get-started-push/ and http://azure.microsoft.com/en-us/documentation/articles/mobile-services-dotnet-backend-xamarin-ios-get-started-push/ both which were last updated in September of last year. The documentation was promised to be updated over 5 months ago.
When I use the Xamarin Component from Microsoft for Azure Mobile Services: http://components.xamarin.com/view/azure-mobile-services/ I am able to get the MobileServiceClient up and running, but not the Push notifications.
The API:
Push pushManager = MobileService.GetPush();
string deviceId = "what is this???";
//Option 1:
pushManager.RegisterNativeAsync(deviceId);
//Option 2:
GcmRegistration googleNotificationRegistration = new GcmRegistration(deviceId);
pushManager.RegisterAsync(googleNotificationRegistration);
Documentation I’m using:
Push.RegisterAsync:
https://msdn.microsoft.com/en-us/library/microsoft.windowsazure.mobileservices.push.registerasync.aspx
GcmRegistration: I can’t find any documentation for this class
Registration (Base class for GcmRegistration):
https://msdn.microsoft.com/en-us/library/microsoft.windowsazure.mobileservices.registration.aspx
Note: the parameter for Registration is not named deviceId it is named channelUri
Push.RegisterNativeAsync:
https://msdn.microsoft.com/en-us/library/dn643553.aspx
Note: the parameter of RegisterNativeAsync is not named deviceId it is named channelUri
My question is simple:
What is deviceId supposed to be? And how do I get it?
All the documentation above is for Winodws Universal Apps not for Xamarin Apps on Mono.
In the writing up of this question I have found articles about "Get Started with Notification Hubs":
Xamarin iOS - http://azure.microsoft.com/en-us/documentation/articles/partner-xamarin-notification-hubs-ios-get-started/
Xamarin Android - http://azure.microsoft.com/en-us/documentation/articles/partner-xamarin-notification-hubs-android-get-started/
Are these the example I should be using? They look old and the Android one mentions nothing about Azure Mobile Services. Should I not even be using the Azure Mobile Services Xamarin Component for Android?

tl;dr
deviceId should be just the GCMRegistrationId.
I looked into the source code of the implementations of the component DLLs and also Android SDKs.
Firstly, let's take a look to your option 1 and option 2 behind the scene. Basically both eventually do the same job of creating a GcmRegistration and passing it the internal RegistrationManager.
public Task RegisterAsync (Registration registration)
{
if (registration == null) {
throw new ArgumentNullException ("registration");
}
if (string.IsNullOrWhiteSpace (registration.PushHandle)) {
throw new ArgumentNullException ("registration.deviceId");
}
return this.RegistrationManager.RegisterAsync (registration);
}
public Task RegisterNativeAsync (string deviceId, IEnumerable<string> tags)
{
if (string.IsNullOrWhiteSpace (deviceId)) {
throw new ArgumentNullException ("deviceId");
}
GcmRegistration registration = new GcmRegistration (deviceId, tags);
return this.RegistrationManager.RegisterAsync (registration);
}
Then, one of the API calls that I can find involving the Registration.PushHandle (which is the deviceId you passed) is as below
public async Task<IEnumerable<Registration>> ListRegistrationsAsync (string deviceId)
{
MobileServiceHttpResponse mobileServiceHttpResponse = await this.client.HttpClient.RequestAsync (HttpMethod.Get, string.Format ("/push/registrations?deviceId={0}&platform={1}", new object[] {
Uri.EscapeUriString (deviceId),
Uri.EscapeUriString (Platform.Instance.PushUtility.GetPlatform ())
}), this.client.CurrentUser, null, true, null, MobileServiceFeatures.None);
return JsonConvert.DeserializeObject<IEnumerable<Registration>> (mobileServiceHttpResponse.Content, new JsonConverter[] {
new RegistrationConverter ()
});
}
I have then switched to Android Mobile Services SDK to look for similar code to find some hints. Sadly, it is found called pnsHandle in android but still no hints what it is.
/**
* Registers the client for native notifications with the specified tags
* #param pnsHandle PNS specific identifier
* #param tags Tags to use in the registration
* #return The created registration
* #throws Exception
*/
public Registration register(String pnsHandle, String... tags) throws Exception {
if (isNullOrWhiteSpace(pnsHandle)) {
throw new IllegalArgumentException("pnsHandle");
}
Registration registration = PnsSpecificRegistrationFactory.getInstance().createNativeRegistration(mNotificationHubPath);
registration.setPNSHandle(pnsHandle);
registration.setName(Registration.DEFAULT_REGISTRATION_NAME);
registration.addTags(tags);
return registerInternal(registration);
}
Finally, I guess the below example code from http://azure.microsoft.com/en-us/documentation/articles/mobile-services-dotnet-backend-android-get-started-push/#update-app should be calling the same API which now explain everything, i.e. deviceId is just the GCMRegistrationId.
#Override
public void onRegistered(Context context, final String gcmRegistrationId) {
super.onRegistered(context, gcmRegistrationId);
new AsyncTask<Void, Void, Void>() {
protected Void doInBackground(Void... params) {
try {
ToDoActivity.mClient.getPush().register(gcmRegistrationId, null);
return null;
}
catch(Exception e) {
// handle error
}
return null;
}
}.execute();
}

ASP.Net MVC HttpContext.User.Identity is getting lost

I have a really weird scenario that I'm stuck on. I have a ASP.Net MVC 4 app where I'm authenticating a user and creating an authCookie and adding it to the response's cookies then redirecting them to the target page:
if (ModelState.IsValid)
{
var userAuthenticated = UserInfo.AuthenticateUser(model.UserName, model.Password);
if (userAuthenticated)
{
var userInfo = UserInfo.FindByUserName(model.UserName);
//SERIALIZE AUTHENTICATED USER
var serializer = new JavaScriptSerializer();
var serializedUser = serializer.Serialize(userInfo);
var ticket = new FormsAuthenticationTicket(1, model.UserName, DateTime.Now, DateTime.Now.AddMinutes(30), false, serializedUser);
var hash = FormsAuthentication.Encrypt(ticket);
var authCookie = new HttpCookie(FormsAuthentication.FormsCookieName, hash) {Expires = ticket.Expiration};
Response.Cookies.Add(authCookie);
if (Url.IsLocalUrl(model.ReturnUrl) && model.ReturnUrl.Length > 1 && model.ReturnUrl.StartsWith("/") && !model.ReturnUrl.StartsWith("//") && !model.ReturnUrl.StartsWith("/\\"))
{
return Redirect(model.ReturnUrl);
}
var url = Url.Action("Index", "Course");
return Redirect(url);
}
ModelState.AddModelError("", "The user name or password provided is incorrect.");
}
This is working just fine in all browsers. I can login and access the secure pages in my app.
My client is requesting an android version of this app. So, I'm trying to figure out how to convert this app into an APK file. My first attempt is to create a simple index.html page with an iframe that targets the application. This works just fine in Firefox and IE 9. However, when accessing the index.html page that contains the iframe that points to the app via Chrome, I get past the login code above and the user gets redirected to the secure controller, but the secure controller has a custom attribute to make sure the user is authenticated:
public class RequiresAuthenticationAttribute : ActionFilterAttribute
{
public override void OnActionExecuting(ActionExecutingContext filterContext)
{
if (filterContext.HttpContext.User.Identity.IsAuthenticated) return;
if (filterContext.HttpContext.Request.Url == null) return;
var returnUrl = filterContext.HttpContext.Request.Url.AbsolutePath;
if (!filterContext.HttpContext.Request.Browser.IsMobileDevice)
{
filterContext.HttpContext.Response.Redirect(FormsAuthentication.LoginUrl + string.Format("?ReturnUrl={0}", returnUrl), true);
}
else
{
filterContext.HttpContext.Response.Redirect("/Home/Home", true);
}
}
}
My app is failing on: filterContext.HttpContext.User.Identity.IsAuthenticated. IsAuthenticated is always false, even though the user was authenticated in the code above.
Keep in mind this only happens when accessing the app via iframe in Chrome. If I access the app directly instead of via iframe, then everything works just fine.
Any ideas?
UPDATE:
My controller extends SecureController. In the constructor of SecureController I have the code that deserializes the user:
public SecureController()
{
var context = new HttpContextWrapper(System.Web.HttpContext.Current);
if (context.Request.Cookies[FormsAuthentication.FormsCookieName] != null)
{
var serializer = new JavaScriptSerializer();
var cookie = context.Request.Cookies[FormsAuthentication.FormsCookieName].Value;
var ticket = FormsAuthentication.Decrypt(cookie);
CurrentUser = serializer.Deserialize<UserInfo>(ticket.UserData);
}
else
{
CurrentUser = new UserInfo();
}
//if ajax request and session has expired, then force re-login
if (context.Request.IsAjaxRequest() && context.Request.IsAuthenticated == false)
{
context.Response.Clear();
context.Response.StatusCode = 401;
context.Response.Flush();
}
}

First, you should be deriving from AuthorizeAttribute, not an ActionFilterAttribute. Authorization attributes execute before the method is even called at a higher level of the pipeline, while ActionFilters execute much further down, and other attributes can execute before yours.
Secondly, you aren't showing the code you use to decrypt the ticket and set the IPrincipal and IIdentity. Since that's where the problem is, it's odd that you didn't include it.