I have a aspx page that seems to be loading twice when I enter the Url to the page.
In this page's loading event, I'm making an connection to a server to retrieve a document and then I output the downloaded bytes to the output stream of the page.
This is causing the page to load twice for some strange reason. If I hard code a byte array without making this connection, the page loads once and all is well.
Here are the methods used to retrieve the external document. Maybe you can see something I can't.
public static byte[] GetDocument(string url)
{
HttpWebRequest myHttpWebRequest = (HttpWebRequest)WebRequest.Create(url);
HttpWebResponse myHttpWebResponse = (HttpWebResponse)myHttpWebRequest.GetResponse();
Stream stream = myHttpWebResponse.GetResponseStream();
byte[] _Data = StreamToBytes(stream);
return _Data;
}
private static byte[] StreamToBytes(System.IO.Stream theStream)
{
if (theStream == null)
throw new ArgumentException("URL null.");
int bytesRead = 0;
byte[] buffer = new byte[8096];
MemoryStream bufferStream = new MemoryStream();
try
{
do
{
bytesRead = theStream.Read(buffer, 0, 8096);
bufferStream.Write(buffer, 0, bytesRead);
} while (bytesRead > 0);
}
finally
{
bufferStream.Flush();
theStream.Close();
theStream.Dispose();
}
return bufferStream.ToArray();
}
The likely culprit is having the page directive of AutoEventWireup="true" in addition to OnInit() having this.Page_Load += Page_Load;
Auto Event Wireup does what it sounds like. If there is a method that follows the naming convention, the event is automatically wired up.
You also oftentimes see this on button handlers. The button handler will be set specifically, and the page will also create a button handler if the name follows the convention buttonname_OnClick(sender,args)
These kind of problems often happens due to img tags that have an empty src ...
Related
I'm trying to stream my own online radio on my site. I'm right now focusing on simply using an http handler and html5 to do so.
How can I keep IISHandler constantly running without ever ending for each user? Like a real online radio.
You have directly redirect to any url inside handler provided that url has audio content, you are are intended to put handler to <audio> src. So you can try this.
public void ProcessRequest(HttpContext context)
{
//context.Response.Redirect("http://api.soundcloud.com/tracks/148976759/stream?client_id=201b55a1a16e7c0a122d112590b32e4a");
// you can use above or else below
byte[] content = null;
string fileName = context.Server.MapPath(#"\mp3\") + context.Request["file_name"];
if (File.Exists(fileName))
{
using (FileStream stream = new FileStream(fileName, FileMode.Open))
{
content = new byte[System.Convert.ToInt32(stream.Length)];
stream.Read(content, 0, System.Convert.ToInt32(stream.Length));
context.Response.ContentType = "audio/mp3";
context.Response.OutputStream.Write(content, 0, content.Length);
}
}
}
<audio src="Handler1.ashx" controls></audio>
Regarding IISHandler constantly running? -- When you host this in IIS, any request to handler ( i.e. you will have a html page having audio's src= handler, so end-user hits that html page, handler will be invoked), it will process the request. The similar concept like aspx . They are hosted in IIS, any request to that will be process. Do you get my point here?
Sorry for my ignorance. You'll have to explain things to me, I'm treading in new waters. I have some background in JAVA but mostly php, javascript.
http://www.codeproject.com/Articles/19971/How-to-attach-to-Browser-Helper-Object-BHO-with-C
I followed this article with some of my own modifications and my question is specifically, how do I detect the "top level frame" of the webpage, ie the parent document. Any code I execute in OnDocumentComplete will run when any iframes on the page have also completed.
My function and the solution I implemented isn't actually producing the correct results.
public class BHO:IObjectWithSite
{
WebBrowser webBrowser;
HTMLDocument document;
public void OnDocumentComplete(object pDisp, ref object URL)
{
document = (HTMLDocument)webBrowser.Document;
string href = document.location.href;
//get top level page
if (href == URL.ToString())
{
HttpWebRequest WebReq = (HttpWebRequest)WebRequest.Create("http://mysite.com");
WebReq.Method = "POST";
WebReq.ContentType = "application/x-www-form-urlencoded";
byte[] buffer = Encoding.ASCII.GetBytes("string");
WebReq.ContentLength = buffer.Length;
Stream PostData = WebReq.GetRequestStream();
PostData.Write(buffer, 0, buffer.Length);
PostData.Close();
// Prepare web request and send the data.
HttpWebResponse WebResp = (HttpWebResponse)WebReq.GetResponse();
StreamReader streamResponse = new StreamReader(WebResp.GetResponseStream(), true);
string Response = streamResponse.ReadToEnd();
Newtonsoft.Json.Linq.JObject json = Newtonsoft.Json.Linq.JObject.Parse(Response);
string active = json["active"].ToString();
//print to screen
System.Windows.Forms.MessageBox.Show(active, "Title");
}
}
Checking if document.location.href matches URL works in most cases but is not guaranteed. So the result is I end up with multiple webrequests and popups on 1 page load.
The easiest way is to store the web browser object (IWebBrowser2) in an object property in the SetSite method (examples in C++ but should be straightforward to translate to C#):
CComQIPtr<IServiceProvider> pServiceProvider(pUnkSite);
if (!pServiceProvider) {
return E_FAIL;
}
pServiceProvider->QueryService(SID_SWebBrowserApp, IID_IWebBrowser2, (LPVOID*)&m_WebBrowser.p);
if (!m_WebBrowser) {
return E_FAIL;
}
This will store the browser pointer in the object member m_WebBrowser. Then you can compare with the pDisp parameter to OnDocumentComplete:
CComQIPtr<IWebBrowser2> webBrowser(pDisp);
if (webBrowser == m_WebBrowser) {
// This is the top-level page.
}
I want to implement a method to download Image from website to laptop.
public static void DownloadRemoteImageFile(string uri, string fileName)
{
HttpWebRequest request = (HttpWebRequest)WebRequest.Create(uri);
HttpWebResponse response = (HttpWebResponse)request.GetResponse();
if ((response.StatusCode == HttpStatusCode.OK ||
response.StatusCode == HttpStatusCode.Moved ||
response.StatusCode == HttpStatusCode.Redirect) &&
response.ContentType.StartsWith("image", StringComparison.OrdinalIgnoreCase))
{
//if the remote file was found, download it
using (Stream inputStream = response.GetResponseStream())
using (Stream outputStream = File.OpenWrite(fileName))
{
byte[] buffer = new byte[4096];
int bytesRead;
do
{
bytesRead = inputStream.Read(buffer, 0, buffer.Length);
outputStream.Write(buffer, 0, bytesRead);
} while (bytesRead != 0);
}
}
}
But the ContentType of request or response is not "image/jpg" or "image/png". They're always "text/html". I think that's why after I save them to local, they has incorrect content and I cannot view them.
Can anyone has a solution here?
Thanks
Try setting the content type to specific image type
Response.ContentType = "image/jpeg";
You can use this code - based on JpegBitmapDecoder class
JpegBitmapDecoder decoder = new JpegBitmapDecoder(YourImageStreamSource, BitmapCreateOptions.PreservePixelFormat, BitmapCacheOption.Default);
//here you can adjust your YourImageStreamSource with outputStream value
BitmapSource bitmapSource = decoder.Frames[0];
Image myImage = new Image();
myImage.Source = bitmapSource;
myImage.Save("YourImage.jpg", System.Drawing.Imaging.ImageFormat.Jpeg);
Link : http://msdn.microsoft.com/en-us/library/aa970689.aspx
It may be possible that the sites you wish to get the image(s) from may need a cookie(s). Sometimes when we use our browsers to go to the site, we may not notice it, but the browser actually goes to the site for perhaps a millisecond, before quickly reloading, while at the same time getting the cookie. But before loading the site again, our browser would then pass it the cookie this time, whereby the site accepts it and returns the image.
To elaborate, this means your method would be doing only half of what your browser is actually doing. Half of 2 GET request methods. The first one would be to get the cookie, and the second one to actually get the image itself.
Information from (and maybe a bit related): C# generate a cookie dynamically that site will accept?
Your code is ok, but what you are trying to do is often considered undesired behavior by web site owners. Most sites want you to see images on the site but not download them at random. You can search for oposite of your question to know what techniqes and protections your are against to.
I strongly recommend to read usage agreement or any similar document on the site you are trying to scrape beore continuing.
I'm trying to obtain an image to encode to a WordML document. The original version of this function used files, but I needed to change it to get images created on the fly with an aspx page. I've adapted the code to use HttpWebRequest instead of a WebClient. The problem is that I don't think the page request is getting resolved and so the image stream is invalid, generating the error "parameter is not valid" when I invoke Image.FromStream.
public string RenderCitationTableImage(string citation_table_id)
{
string image_content = "";
string _strBaseURL = String.Format("http://{0}",
HttpContext.Current.Request.Url.GetComponents(UriComponents.HostAndPort, UriFormat.Unescaped));
string _strPageURL = String.Format("{0}{1}", _strBaseURL,
ResolveUrl("~/Publication/render_citation_chart.aspx"));
string _staticURL = String.Format("{0}{1}", _strBaseURL,
ResolveUrl("~/Images/table.gif"));
string _fullURL = String.Format("{0}?publication_id={1}&citation_table_layout_id={2}",
_strPageURL, publication_id, citation_table_id);
try
{
HttpWebRequest request = (HttpWebRequest)WebRequest.Create(_fullURL);
HttpWebResponse response = (HttpWebResponse)request.GetResponse();
Stream image_stream = response.GetResponseStream();
// Read the image data
MemoryStream ms = new MemoryStream();
int num_read;
byte[] crlf = System.Text.Encoding.Default.GetBytes("\r\n");
byte[] buffer = new byte[1024];
for (num_read = image_stream.Read(buffer, 0, 1024); num_read > 0; num_read = image_stream.Read(buffer, 0, 1024))
{
ms.Write(buffer, 0, num_read);
}
// Base 64 Encode the image data
byte[] image_bytes = ms.ToArray();
string encodedImage = Convert.ToBase64String(image_bytes);
ms.Position = 0;
System.Drawing.Image image_original = System.Drawing.Image.FromStream(ms); // <---error here: parameter is not valid
image_stream.Close();
image_content = string.Format("<w:p>{4}<w:r><w:pict><w:binData w:name=\"wordml://{0}\">{1}</w:binData>" +
"<v:shape style=\"width:{2}px;height:{3}px\">" +
"<v:imagedata src=\"wordml://{0}\"/>" +
"</v:shape>" +
"</w:pict></w:r></w:p>", _word_image_id, encodedImage, 800, 400, alignment.center);
image_content = "<w:br w:type=\"text-wrapping\"/>" + image_content + "<w:br w:type=\"text-wrapping\"/>";
}
catch (Exception ex)
{
return ex.ToString();
}
return image_content;
Using a static URI it works fine. If I replace "staticURL" with "fullURL" in the WebRequest.Create method I get the error. Any ideas as to why the page request doesn't fully resolve?
And yes, the full URL resolves fine and shows an image if I post it in the address bar.
UPDATE:
Just read your updated question. Since you're running into login issues, try doing this before you execute the request:
request.Credentials = CredentialCache.DefaultCredentials
If this doesn't work, then perhaps the problem is that authentication is not being enforced on static files, but is being enforced on dynamic files. In this case, you'll need to log in first (using your client code) and retain the login cookie (using HttpWebRequest.CookieContainer on the login request as well as on the second request) or turn off authentication on the page you're trying to access.
ORIGINAL:
Since it works with one HTTP URL and doesn't work with another, the place to start diagnosing this is figuring out what's different between the two requests, at the HTTP level, which accounts for the difference in behavior in your code.
To figure out the difference, I'd use Fiddler (http://fiddlertool.com) to compare the two requests. Compare the HTTP headers. Are they the same? In particular, are they the same HTTP content type? If not, that's likely the source of your problem.
If headers are the same, make sure both the static and dynamic image are exactly the same content and file type on the server. (e.g. use File...Save As to save the image in a browser to your disk). Then use Fiddler's Hex View to compare the image content. Can you see any obvious differences?
Finally, I'm sure you've already checked this, but just making sure: /Publication/render_citation_chart.aspx refers to an actual image file, not an HTML wrapper around an IMG element, right? This would account for the behavior you're seeing, where a browser renders the image OK but your code doesn't.
Here's the purpose of my console program: Make a web request > Save results from web request > Use QueryString to get next page from web request > Save those results > Use QueryString to get next page from web request, etc.
So here's some pseudocode for how I set the code up.
for (int i = 0; i < 3; i++)
{
strPageNo = Convert.ToString(i);
//creates the url I want, with incrementing pages
strURL = "http://www.website.com/results.aspx?page=" + strPageNo;
//makes the web request
wrGETURL = WebRequest.Create(strURL);
//gets the web page for me
objStream = wrGETURL.GetResponse().GetResponseStream();
//for reading web page
objReader = new StreamReader(objStream);
//--------
// -snip- code that saves it to file, etc.
//--------
objStream.Close();
objReader.Close();
//so the server doesn't get hammered
System.Threading.Thread.Sleep(1000);
}
Pretty simple, right? The problem is, even though it increments the page number to get a different web page, I'm getting the exact same results page each time the loop runs.
i IS incrementing correctly, and I can cut/paste the url strURL creates into a web browser and it works just fine.
I can manually type in &page=1, &page=2, &page=3, and it'll return the correct pages. Somehow putting the increment in there screws it up.
Does it have anything to do with sessions, or what? I make sure I close both the stream and the reader before it loops again...
Have you tried creating a new WebRequest object for each time during the loop, it could be the Create() method isn't adequately flushing out all of its old data.
Another thing to check is that the ResponseStream is adequately flushed out before the next loop iteration.
This code works fine for me:
var urls = new [] { "http://www.google.com", "http://www.yahoo.com", "http://www.live.com" };
foreach (var url in urls)
{
WebRequest request = WebRequest.Create(url);
using (Stream responseStream = request.GetResponse().GetResponseStream())
using (Stream outputStream = new FileStream("file" + DateTime.Now.Ticks.ToString(), FileMode.Create, FileAccess.Write, FileShare.None))
{
const int chunkSize = 1024;
byte[] buffer = new byte[chunkSize];
int bytesRead;
while ((bytesRead = responseStream.Read(buffer, 0, buffer.Length)) > 0)
{
byte[] actual = new byte[bytesRead];
Buffer.BlockCopy(buffer, 0, actual, 0, bytesRead);
outputStream.Write(actual, 0, actual.Length);
}
}
Thread.Sleep(1000);
}
Just a suggestion, try disposing the Stream, and the Reader. I've seen some weird cases where not disposing objects like these and using them in loops can yield some wacky results....
That URL doesn't quite make sense to me unless you are using MVC or something that can interpret the querystring correctly.
http://www.website.com/results.aspx&page=
should be:
http://www.website.com/results.aspx?page=
Some browsers will accept poorly formed URLs and render them fine. Others may not which may be the problem with your console app.
Here's my terrible, hack-ish, workaround solution:
Make another console app that calls THIS one, in which the first console app passes an argument at the end of strURL. It works, but I feel so dirty.