Error while consuming API into .NET 3.5 with VS2008 into Console App

Praveen Kumar

Note:

The same code when I am execution on dotnetfiddle.net where framework version is v4.7. It is working perfectly. While the code I have written is compatible with v3.5

I am consuming an API into .NET 3.5 using Visual Studio 2008 using WebRequest. Following are the details of API:

Method:POST

ConetntType:application/x-www-form-urlencoded

With Three Parameters.

Key Value

ApiKey string

ApiOwner string

RequestBody json string

I am using the following code pattern.

WebRequest request = WebRequest.Create("https://hostname/RestWS/api/v1/order/orderPull");
request.Method = "POST";
string postData = "ApiOwner=sa&ApiKey=d564078......9530dec&RequestBody=";
postData = postData + "{ \"orderNo\":\"o81075084\",\n \"statuses\":[],\n \"fromDate\":\"\",\n \"toDate\":\"\",\n \"pageNumber\":\"\",\n \"order_Location\":\"\",\n \"IsReplacementOrder\":\"\",\n \"orderSource\":\"\",\n \"paymentType\":[\"Prepaid\",\"COD\"]\n }";
byte[] byteArray = Encoding.UTF8.GetBytes(postData);
request.ContentType = "application/x-www-form-urlencoded";
request.ContentLength = byteArray.Length;
Stream dataStream = request.GetRequestStream(); //Error at this line
dataStream.Write(byteArray, 0, byteArray.Length);
dataStream.Close();
WebResponse response = request.GetResponse();
Console.WriteLine(((HttpWebResponse)response).StatusDescription);
dataStream = response.GetResponseStream();
StreamReader reader = new StreamReader(dataStream);
string responseFromServer = reader.ReadToEnd();
Console.WriteLine(responseFromServer);
reader.Close();
dataStream.Close();
response.Close();

Exception

Inner Exception:

Unable to read data from the transport connection: An existing connection was forcibly closed by the remote host.

5 Replies

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Praveen Kumar5y ago
Hi Sachin,

I have got Tls12 fix for .NET 3.5 from my colleague. Here is the code snippet for the same.
public const SslProtocols _Tls12 = (SslProtocols)0x00000C00;
public const SecurityProtocolType Tls12 = (SecurityProtocolType)_Tls12;

static void Main(string[] args)
{

    WebRequest request = WebRequest.Create("/RestWS/api/eretail/v1/order/orderPull");
    request.Method = "POST";
    string postData = "ApiOwner=s..a&ApiKey=4bcd98.......0789530dec&RequestBody=";
    postData = postData + "{ \"orderNo\":\"o81075084\",\n \"statuses\":[],\n \"fromDate\":\"\",\n \"toDate\":\"\",\n \"pageNumber\":\"\",\n \"order_Location\":\"\",\n \"IsReplacementOrder\":\"\",\n \"orderSource\":\"\",\n  \"paymentType\":[\"Prepaid\",\"COD\"]\n }";
    byte[] byteArray = Encoding.UTF8.GetBytes(postData);
    request.ContentType = "application/x-www-form-urlencoded";
    request.ContentLength = byteArray.Length;

    ServicePointManager.SecurityProtocol = Tls12;
    Stream dataStream = request.GetRequestStream();  //Error at this line
    dataStream.Write(byteArray, 0, byteArray.Length);
    dataStream.Close();
    WebResponse response = request.GetResponse();
    Console.WriteLine(((HttpWebResponse)response).StatusDescription);
    dataStream = response.GetResponseStream();
    StreamReader reader = new StreamReader(dataStream);
    string responseFromServer = reader.ReadToEnd();
    Console.WriteLine(responseFromServer);
    reader.Close();
    dataStream.Close();
    response.Close();

    Console.ReadLine();

}
Praveen Kumar5y ago
Hi Sachin,

I had tried the same but it is not working into .NET 3.5

TLS12 is not available in this framework.

Kindly suggest to me, the way of passing multiple parameters for content type form-urlencode is correct or not.
Sachin Singh5y ago
then use tls 12 (use pipe symbol)
System.Net.ServicePointManager.SecurityProtocol |= SecurityProtocolType.Tls12;
Praveen Kumar5y ago
For the time, I have to use .NET 3.5

SecurityProtocolType.Tls12; it is not available into this framework.

So, I have tried the following setting which is compatible for 3.5 but it is not working. In 3.5.

System.Net.ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls;

Note:

I have an existing application, where I have consumed so many APIs and those are working perfectly. But the content type of those API is application/json while here I am using application/x-www-form-urlencoded.
Sachin Singh5y ago
this is a TLS issue , .Net <4.5 uses TLS 1.0 which causes this error ,

Method1)kindly use later version like .Net 4.5/+ which is smart enough to use both TLS 1.1 and 1.2.
method 2)Add the following code before you instantiate your web service client:

System.Net.ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12;