API return failed using webrequest

Question

I trying to connect an api in my application, this connection works before but now stopped.

If i use any browser or postman application the result is correct, but when i use a webrequest, webclient or any method in Visual Studio i received a timeout error.

I put the User Agent, set timeout, use ssl and the result is the same every time.

The end points tested is:

https://bittrex.com/api/v1.1/public/getmarkets

https://api.coinmarketcap.com/v1/ticker/?limit=1

When i use a site to test like a google this response works.

Any idea?

Update using WebRequestHelper

Imports System
Imports System.IO
Imports System.Net
Imports System.Net.Security
Imports System.Security.Cryptography.X509Certificates
Imports System.Text

Public Class WebRequestHelper
    Private m_ResponseUri As Uri
    Private m_StatusCode As HttpStatusCode
    Private m_StatusDescription As String
    Private m_ContentSize As Long
    Private m_WebException As WebExceptionStatus
    Public Property SiteCookies As CookieContainer
    Public Property UserAgent As String = "Mozilla / 5.0(Windows NT 6.1; WOW32; Trident / 7.0; rv: 11.0) like Gecko"
    Public Property Timeout As Integer = 30000
    Public ReadOnly Property ContentSize As Long
        Get
            Return m_ContentSize
        End Get
    End Property

    Public ReadOnly Property ResponseUri As Uri
        Get
            Return m_ResponseUri
        End Get
    End Property

    Public ReadOnly Property StatusCode As Integer
        Get
            Return m_StatusCode
        End Get
    End Property

    Public ReadOnly Property StatusDescription As String
        Get
            Return m_StatusDescription
        End Get
    End Property

    Public ReadOnly Property WebException As Integer
        Get
            Return m_WebException
        End Get
    End Property


    Sub New()
        SiteCookies = New CookieContainer()
    End Sub

    Public Function GetSiteResponse(ByVal siteUri As Uri) As String
        Dim response As String = String.Empty

        ServicePointManager.DefaultConnectionLimit = 50
        Dim maxFWValue As SecurityProtocolType = System.Enum.GetValues(GetType(SecurityProtocolType)).OfType(Of SecurityProtocolType)().Max()
        ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls11 Or SecurityProtocolType.Tls12 Or maxFWValue
        ServicePointManager.ServerCertificateValidationCallback = AddressOf TlsValidationCallback

        Dim Http As HttpWebRequest = WebRequest.CreateHttp(siteUri.ToString)
        With Http
            .Accept = "ext/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8"
            .AllowAutoRedirect = True
            .AutomaticDecompression = DecompressionMethods.GZip Or DecompressionMethods.Deflate
            .CookieContainer = Me.SiteCookies
            .Headers.Add(HttpRequestHeader.AcceptEncoding, "gzip, deflate")
            .Headers.Add(HttpRequestHeader.AcceptLanguage, "en-US,en;q=0.7")
            .Headers.Add(HttpRequestHeader.CacheControl, "no-cache")
            .KeepAlive = True
            .MaximumAutomaticRedirections = 50
            .ServicePoint.Expect100Continue = False
            .ServicePoint.MaxIdleTime = Me.Timeout
            .Timeout = Me.Timeout
            .UserAgent = Me.UserAgent
        End With

        Try
            Using webResponse As HttpWebResponse = DirectCast(Http.GetResponse, HttpWebResponse)
                Me.m_ResponseUri = webResponse.ResponseUri
                Me.m_StatusCode = webResponse.StatusCode
                Me.m_StatusDescription = webResponse.StatusDescription
                Dim contentLength As String = webResponse.Headers.Get("Content-Length")
                Me.m_ContentSize = If(String.IsNullOrEmpty(contentLength), 0, Convert.ToInt64(contentLength))

                Using responseStream As Stream = webResponse.GetResponseStream()
                    If webResponse.StatusCode = HttpStatusCode.OK Then
                        Dim reader As StreamReader = New StreamReader(responseStream, Encoding.Default)
                        Me.m_ContentSize = webResponse.ContentLength
                        response = reader.ReadToEnd()
                        Me.m_ContentSize = If(Me.m_ContentSize = -1, response.Length, Me.m_ContentSize)
                    End If
                End Using
            End Using
        Catch exW As WebException
            If exW.Response IsNot Nothing Then
                Me.m_StatusCode = CType(exW.Response, HttpWebResponse).StatusCode
            End If
            Me.m_StatusDescription = "WebException: " & exW.Message
            Me.m_WebException = exW.Status
        End Try
        Return response
    End Function

    Private Function TlsValidationCallback(sender As Object, CACert As X509Certificate, CAChain As X509Chain, SslPolicyErrors As SslPolicyErrors) As Boolean
        If SslPolicyErrors = SslPolicyErrors.None Then Return True
        Dim Certificate As New X509Certificate2(CACert)

        CAChain.Build(Certificate)
        For Each CACStatus As X509ChainStatus In CAChain.ChainStatus
            If (CACStatus.Status <> X509ChainStatusFlags.NoError) And
                (CACStatus.Status <> X509ChainStatusFlags.UntrustedRoot) Then
                Return False
            End If
        Next
        Return True
    End Function

End Class

And use this to call the class

Dim url As String = "https://bittrex.com/api/v1.1/public/getmarkets"
    Dim uri As New Uri(url)
    Dim wr As New WebRequestHelper
    Dim resp = wr.GetSiteResponse(uri)

Answer 1

This is an example of how I connect to API.

First, create APIJSONViewModel based on your JSON result to store value of id, name, symbol, rank, price_usd, price_btc and etc..

        Dim limitnumber as integer = 1
        Dim apiurl As String = "https://api.coinmarketcap.com" 'base url
        Dim apirequesturi As String = "/v1/ticker/?limit=" & limitnumber 'request uri

        Dim resultresponse As List(Of APIJSONViewModel) = New List(Of APIJSONViewModel)

        Try
            Using client As HttpClient = New HttpClient

                ' set url
                client.BaseAddress = New Uri(apiurl)

                ' set json
                client.DefaultRequestHeaders.Accept.Clear()
                client.DefaultRequestHeaders.Accept.Add(New MediaTypeWithQualityHeaderValue("application/json"))

                ' post model as json
                Dim response As HttpResponseMessage = Await client.GetAsync(apirequesturi)

                If response.IsSuccessStatusCode Then

                    ' result get!
                    resultresponse = Await response.Content.ReadAsAsync(Of List(Of APIJSONViewModel))()

                Else
                    r.Errors.Add(response.ReasonPhrase)
                End If

            End Using
        Catch ex As Exception
            r.Errors.Add(ex.Message)
        End Try