Develop Reference

How to Post a web request and receive a file from web API response?

I have an Infopath Form Template on Sharepoint, I want to add a button there so when the user clicks on it, it will POST an string to the following Web API. The following web API is tested and returns an excel file as shown:
I want to Post the FileName of the excel file using post request and it is important for me the request method to be POST type. and then the user will download a file with the specified 'FileName'.
Actually i want to use post method because at the next stage i will send the content of the excel file too.
Important Note: I only can use .Net FrameWork 3.5 because this is the only framework supported in InfoPath Form Templates.
[HttpPost]
public HttpResponseMessage Post([FromBody]string FileName)
{
string reqBook = "c:\somefile.xlsx";
//converting Excel(xlsx) file into bytes array
var dataBytes = File.ReadAllBytes(reqBook);
//adding bytes to memory stream
var dataStream = new MemoryStream(dataBytes);
HttpResponseMessage httpResponseMessage = Request.CreateResponse(HttpStatusCode.OK);
httpResponseMessage.Content = new StreamContent(dataStream);
httpResponseMessage.Content.Headers.ContentDisposition = new System.Net.Http.Headers.ContentDispositionHeaderValue("attachment");
httpResponseMessage.Content.Headers.ContentDisposition.FileName = FileName;
httpResponseMessage.Content.Headers.ContentType = new System.Net.Http.Headers.MediaTypeHeaderValue("application/octet-stream");
return httpResponseMessage;
}

When you perform the HttpPost on the client side, you will want to read the HttpResponseStream to get the byte data of the response stream.
Once you have the response stream data, you can then deserialize it to the type of object in C# you want, or you could alternatively just write it to the disk as
File.WriteAllBytes("someexcel.xlsx",data);
An easy way to do it would be with the HttpClient class.
HttpClient client = new HttpClient();
var response = client.PostAsync("", null).Result;
var content = response.Content.ReadAsByteArrayAsync().Result;
File.WriteAllBytes("excel.xlsx", content);
Just fill in the PostAsync bit with the Url and the content you wish to post.
I am using .Result to keep everything synchronous - but you can use 'await' if you prefer.
If you are working with HttpWebRequests - then the process becomes more complicated, as you need to manage the streams yourself.
The HttpClient will manage and handle it all for you - so I recommend it, unless there is something special it needs to do that it currently does not.
Due to your .Net 3.5 requirement:
private static HttpWebResponse MakeRequest(string url, string postArgument)
{
HttpWebRequest request = (HttpWebRequest)WebRequest.Create(url);
request.Method = "POST";
request.ContentType = "multipart/form-data;";
Stream stream = request.GetRequestStream();
string result = string.Format("arg1={0}", postArgument);
byte[] value = Encoding.UTF8.GetBytes(result);
stream.Write(value, 0, value.Length);
stream.Close();
return (HttpWebResponse)request.GetResponse();
}
You can then do:
var response = MakeRequest("http://mywebsite.com/ProcessExcel", "accounts.xlsx");
And then do
Stream objStream = response .GetResponseStream();
BinaryReader breader = new BinaryReader(objStream);
byte[] data= breader.ReadBytes((int)webresponse.ContentLength);
File.WriteAllBytes("excel.xlsx",data);

Proper Way to open this URL in a C# app

I have a URL that I want to open in my C# app. This URL is used to talk to a communications device, not an internet web site. I have gotten by (I think) all the cert stuff. But the text I get back in the program IS NOT the same thing that CORRECTLY displays when I use a web browser.
Here's the code.
using System;
using System.IO;
using System.Net;
using System.Text;
using System.Net.Security;
using System.Security.Cryptography.X509Certificates;
using System.Web;
namespace VMLConnStatus
{
class Program
{
static void Main(string[] args)
{
System.Net.ServicePointManager.CertificatePolicy = new MyPolicy();
// Create a request for the URL: https://192.168.30.15/cgi-bin/connstatus?202
String url = "https://192.168.30.15/cgi-bin/";
String data = "connstatus?202";
// Create a request using a URL that can receive a post.
WebRequest request = WebRequest.Create(url);
// Set the Method property of the request to POST.
request.Method = "POST";
// Create POST data and convert it to a byte array.
string postData = data;
byte[] byteArray = Encoding.UTF8.GetBytes(postData);
// Set the ContentType property of the WebRequest.
request.ContentType = "application/x-www-form-urlencoded";
// Set the ContentLength property of the WebRequest.
request.ContentLength = byteArray.Length;
// Get the request stream.
Stream dataStream = request.GetRequestStream();
// Write the data to the request stream.
dataStream.Write(byteArray, 0, byteArray.Length);
// Close the Stream object.
dataStream.Close();
// Get the response.
WebResponse response = request.GetResponse();
// Display the status.
Console.WriteLine(((HttpWebResponse)response).StatusDescription);
// Get the stream containing content returned by the server.
dataStream = response.GetResponseStream();
// Open the stream using a StreamReader for easy access.
StreamReader reader = new StreamReader(dataStream);
// Read the content.
string responseFromServer = reader.ReadToEnd();
// Display the content.
Console.WriteLine(responseFromServer);
// Clean up the streams.
reader.Close();
dataStream.Close();
response.Close();
Console.ReadLine();
}
}
public class MyPolicy : ICertificatePolicy
{
public bool CheckValidationResult(ServicePoint srvPoint,
X509Certificate certificate, WebRequest request,
int certificateProblem)
{
//Return True to force the certificate to be accepted.
return true;
}
}
}
The result, though not perfectly displayed in Chrome, should be:
NA NA NA NA 4c:cc:34:02:6d:26 00:23:A7:24:A3:B6
But the text I get in the console window is:
Ok
<HTML>
<HEAD><TITLE>Index of cgi-bin/</TITLE></HEAD>
<BODY BGCOLOR="#99cc99" TEXT="#000000" LINK="#2020ff" VLINK="#4040cc">
<H4>Index of cgi-bin/</H4>
<PRE>
. 15Jun2014 09:48
0
.. 15Jun2014 09:48
0
connstatus 15Jun2014 09:48
19580
firmwarecfg 15Jun2014 09:48
45736
webcm 15Jun2014 09:48
23836
</PRE>
<HR>
<ADDRESS><A HREF="http://www.acme.com/software/mini_httpd/">mini_httpd/1.19 19de
c2003</A></ADDRESS>
</BODY>
</HTML>
Not EVEN close to the same thing.
What am I doing wrong?
Chuck
UPDATE: Code changed. URL, GET, and request writing (presuming I understood the directions). New code is:
static void Main(string[] args)
{
System.Net.ServicePointManager.CertificatePolicy = new MyPolicy();
// Create a request for the URL: https://192.168.30.15/cgi-bin/connstatus?202
String url = "https://192.168.30.15/cgi-bin/connstatus?202";
// Create a request using a URL that can receive a post.
WebRequest request = WebRequest.Create(url);
// Set the Method property of the request to POST.
request.Method = "GET";
// Set the ContentType property of the WebRequest.
request.ContentType = "application/x-www-form-urlencoded";
// Get the request stream.
//Now it throws an exception here--------------------------------
//"Cannot send a content-body with this verb-type."
Stream dataStream = request.GetRequestStream();
// Close the Stream object.
dataStream.Close();
// Get the response.
WebResponse response = request.GetResponse();
// Display the status.
Console.WriteLine(((HttpWebResponse)response).StatusDescription);
// Get the stream containing content returned by the server.
dataStream = response.GetResponseStream();
// Open the stream using a StreamReader for easy access.
StreamReader reader = new StreamReader(dataStream);
// Read the content.
string responseFromServer = reader.ReadToEnd();
// Display the content.
Console.WriteLine(responseFromServer);
// Clean up the streams.
reader.Close();
dataStream.Close();
response.Close();
Console.ReadLine();
}

You are using http method POST but the url you have in the comment looks more like GET so then you probably need WebRequest.Create(url + data).
The incorrect response is the index page for https://192.168.30.15/cgi-bin/ which if you put into Chrome will give you the same "wrong" response.
You might not need to write any data to the request stream and can change the Method and ContentType for the request.

The solution required two parts.
First, doing the proper things, thus a total code rework.
I had the dreaded "The server committed a protocol violation. Section=ResponseHeader Detail=Header name is invalid". I tried to make the programatic solution for this work, but it is a .NET 2.0 solution and I was not able to figure it out in .NET4+. So, I edited the .config file and went on.
Here's the final code:
//Initialization
HttpWebRequest WebReq = (HttpWebRequest)WebRequest.Create(#"https://192.168.30.15/cgi-bin/connstatus?202");
//method is GET.
WebReq.Method = "GET";
//Get the response handle
HttpWebResponse WebResp = (HttpWebResponse)WebReq.GetResponse();
//read the response
Stream Answer = WebResp.GetResponseStream();
StreamReader _Answer = new StreamReader(Answer);
//display it
Console.WriteLine(_Answer.ReadToEnd());
//pause for the ENTER key
Console.ReadLine();
This was added to the .config file in the debug folder (and would be added in the Release folder also..... using VS2013)
<system.net>
<settings>
<httpWebRequest useUnsafeHeaderParsing = "true"/>
</settings>
</system.net>
Thank-you to everyone that replied. The inspiration helped me get to the solution.

how to display the content of given url in window application with c#

I want to get the http request header and also the post data from a given URL.... how to do that?.... I have to display http request header, http response header, content of a given url and post data...
Below is my code for that....
private void button1_Click(object sender, EventArgs e)
{
try
{
string url = txtUrl.Text;
HttpWebRequest WebRequestObject = (HttpWebRequest)HttpWebRequest.Create(url);
HttpWebResponse Response = (HttpWebResponse)WebRequestObject.GetResponse();
HttpStatusCode code = Response.StatusCode;
txtStatus.Text = code.ToString();
txtResponse.Text = Response.Headers.ToString();
// Open data stream:
Stream WebStream = Response.GetResponseStream();
// Create reader object:
StreamReader Reader = new StreamReader(WebStream);
// Read the entire stream content:
string PageContent = Reader.ReadToEnd();
// Cleanup
Reader.Close();
WebStream.Close();
Response.Close();
txtContent.Text = PageContent;
// var request = WebRequest.Create("http://www.livescore.com ");
//var response = request.GetResponse();
}
catch(Exception ex)
{
MessageBox.Show(ex.ToString());
}
}
But how to get post data and http request header that i dont know...pls help

It's not very clear what you are trying to accomplish with mixed references to GET, POST, and request and response headers.
If you can make the request you want in a browser and use Fiddler to intercept it, you can use the Fiddler add-on Request-To-Code to generate C# code that will perform the request. The generated code would probably be a good place for you to start - from something that works and with which you can further tinker.
Fiddler is a great way to learn more about HTTP.

Copy a PDF Stream to File

I'm calling a routine in PHP (TCPDF) from C# via WebRequest using StreamReader. The PDF file is returned as a stream and stored in a string (obv). I know the data being returned to the string is actually a PDF file, as I've tested it in PHP. I'm having a hard time writing the string to a file and actually getting a valid PDF in C#. I know it has something to do with the way I'm trying to encode the file, but the several things I've tried have resulted in 'Not today, Padre' (i.e. they didn't work)
Here's the class I'm using to perform the request (thanks to user 'Paramiliar' for the example I'm using/borrowed/stole):
public class httpPostData
{
WebRequest request;
WebResponse response;
public string senddata(string url, string postdata)
{
// create the request to the url passed in the paramaters
request = (WebRequest)WebRequest.Create(url);
// set the method to POST
request.Method = "POST";
// set the content type and the content length
request.ContentType = "application/x-www-form-urlencoded";
request.ContentLength = postdata.Length;
// convert the post data into a byte array
byte[] byteData = Encoding.UTF8.GetBytes(postdata);
// get the request stream and write the data to it
Stream dataStream = request.GetRequestStream();
dataStream.Write(byteData, 0, byteData.Length);
dataStream.Close();
// get the response
response = request.GetResponse();
dataStream = response.GetResponseStream();
StreamReader reader = new StreamReader(dataStream);
// read the response
string serverresponse = reader.ReadToEnd();
//Console.WriteLine(serverresponse);
reader.Close();
dataStream.Close();
response.Close();
return serverresponse;
}
} // end class httpPostData
...and my call to it
httpPostData myPost = new httpPostData();
// postData defined (not shown)
string response = myPost.senddata("http://www.example.com/pdf.php", postData);
In case it isn't clear, I'm stuck writing string response to a valid .pdf file. I've tried this (Thanks to user Adrian):
static public void SaveStreamToFile(string fileFullPath, Stream stream)
{
if (stream.Length == 0) return;
// Create a FileStream object to write a stream to a file
using (FileStream fileStream = System.IO.File.Create(fileFullPath, (int)stream.Length))
{
// Fill the bytes[] array with the stream data
byte[] bytesInStream = new byte[stream.Length];
stream.Read(bytesInStream, 0, (int)bytesInStream.Length);
// Use FileStream object to write to the specified file
fileStream.Write(bytesInStream, 0, bytesInStream.Length);
}
}
..and the call to it:
string location = "C:\\myLocation\\";
SaveStreamToFile(location, response); // <<-- this throws an error b/c 'response' is a string, not a stream. New to C# and having some basic issues with things like this
I think I'm close...a nudge in the right direction would be greatly appreciated.

You can use WebClient. Use the method DownloadFile, or the async ones.
Have fun!
Fernando.-
Sorry, I haven't read your comments till now.
I guess you have already done this...
But this may help you (just replace urls and paths) (from: http://msdn.microsoft.com/en-us/library/ez801hhe.aspx )
string remoteUri = "http://www.contoso.com/library/homepage/images/";
string fileName = "ms-banner.gif", myStringWebResource = null;
// Create a new WebClient instance.
WebClient myWebClient = new WebClient();
// Concatenate the domain with the Web resource filename.
myStringWebResource = remoteUri + fileName;
Console.WriteLine("Downloading File \"{0}\" from \"{1}\" .......\n\n", fileName, myStringWebResource);
// Download the Web resource and save it into the current filesystem folder.
myWebClient.DownloadFile(myStringWebResource,fileName);
Console.WriteLine("Successfully Downloaded File \"{0}\" from \"{1}\"", fileName, myStringWebResource);
Console.WriteLine("\nDownloaded file saved in the following file system folder:\n\t" + Application.StartupPath);

How do you login to a webpage and retrieve its content in C#?

How do you login to a webpage and retrieve its content in C#?

That depends on what's required to log in. You could use a webclient to send the login credentials to the server's login page (via whatever method is required, GET or POST), but that wouldn't persist a cookie. There is a way to get a webclient to handle cookies, so you could just POST the login info to the server, then request the page you want with the same webclient, then do whatever you want with the page.

Look at System.Net.WebClient, or for more advanced requirements System.Net.HttpWebRequest/System.Net.HttpWebResponse.
As for actually applying these: you'll have to study the html source of each page you want to scrape in order to learn exactly what Http requests it's expecting.

How do you mean "login"?
If the subfolder is protected on the OS level, and the browser pops of a login dialog when you go there, you will need to set the Credentials property on the HttpWebRequest.
If the website has it's own cookie-based membership/login system, you will have to use HttpWebRequest to first response to the login form.

string postData = "userid=ducon";
postData += "&username=camarche" ;
byte[] data = Encoding.ASCII.GetBytes(postData);
WebRequest req = WebRequest.Create(
URL);
req.Method = "POST";
req.ContentType = "application/x-www-form-urlencoded";
req.ContentLength = data.Length;
Stream newStream = req.GetRequestStream();
newStream.Write(data, 0, data.Length);
newStream.Close();
StreamReader reader = new StreamReader(req.GetResponse().GetResponseStream(), System.Text.Encoding.GetEncoding("iso-8859-1"));
string coco = reader.ReadToEnd();

Use the WebClient class.
Dim Html As String
Using Client As New System.Net.WebClient()
Html = Client.DownloadString("http://www.google.com")
End Using

You can use the build in WebClient Object instead of crating the request yourself.
WebClient wc = new WebClient();
wc.Credentials = new NetworkCredential("username", "password");
string url = "http://foo.com";
try
{
using (Stream stream = wc.OpenRead(new Uri(url)))
{
using (StreamReader reader = new StreamReader(stream))
{
return reader.ReadToEnd();
}
}
}
catch (WebException e)
{
//Error handeling
}

Try this:
public string GetContent(string url)
{
using (System.Net.WebClient client =new System.Net.WebClient())
{
return client.DownloadString(url);
}
}