I have some difficulties with the QtNetworkAccesManager.
I want to fetch the source code from an URL. The problem is that I'm getting only parts of the HTML source code, but not all of it. Can you tell me, what I am missing?
void MyClass::importFromWeb()
{
QUrl url = QUrl("https://doc.qt.io/qt-5/classes.html");
QNetworkAccessManager* manager = new QNetworkAccessManager(this);
QObject::connect(manager, &QNetworkAccessManager::finished, this, &MyClass::onNetworkReply);
response = manager->get(QNetworkRequest(url));
}
void MyClass::onNetworkReply()
{
QFile* data = new QFile("test.txt");
data->open(QIODevice::WriteOnly);
QTextStream write(dat koa);
write << response->readAll();
data->close();
}
For example if i want to fetch the source code of "https://doc.qt.io/qt-5/classes.html", the result size of test.txt is of 134 ko
However html code size when i'm doing a "ctrl+s" on the web site is of 192 ko.
So is missing some source code but what and why ?
Thanks for your help.
We're trying to have the web page served by the Arduino update without having to refresh the page. Our current code is below. Right now the page is refreshing as fast as possible (about once a second), but we'd like to have the data update without having to refresh. Is there a way to do this with html?
Thanks for your help!
void loop() {
WiFiClient client = server.available(); // listen for incoming clients
if (client) { // if you get a client,
Serial.println("new client"); // print a message out the serial port
String currentLine = ""; // make a String to hold incoming data from the client
while (client.connected()) { // loop while the client's connected
if (client.available()) { // if there's bytes to read from the client,
char c = client.read(); // read a byte, then
Serial.write(c); // print it out the serial monitor
if (c == '\n') { // if the byte is a newline character
// if the current line is blank, you got two newline characters in a row.
// that's the end of the client HTTP request, so send a response:
if (currentLine.length() == 0) {
// HTTP headers always start with a response code (e.g. HTTP/1.1 200 OK)
// and a content-type so the client knows what's coming, then a blank line:
client.println("HTTP/1.1 200 OK");
client.println("Content-type:text/html");
client.println();
voltageReading = analogRead(A0);
//meta-refresh page as fast as possible
client.print("<HEAD>");
client.print("<meta http-equiv=\"refresh\" content=\"0\">");
client.print("<TITLE />Smart 3 Phase Relay TCNJ</title>");
client.print("</head>");
// the content of the HTTP response follows the header:
client.print("Voltage Reading: ");
client.print(voltageReading);
// The HTTP response ends with another blank line:
client.println();
// break out of the while loop:
break;
}
else { // if you got a newline, then clear currentLine:
currentLine = "";
}
}
else if (c != '\r') { // if you got anything else but a carriage return character,
currentLine += c; // add it to the end of the currentLine
}
// Check to see if the client request was "GET /H" or "GET /L":
if (currentLine.endsWith("GET /H")) {
digitalWrite(9, HIGH); // GET /H turns the LED on
}
if (currentLine.endsWith("GET /L")) {
digitalWrite(9, LOW); // GET /L turns the LED off
}
}
}
// close the connection:
client.stop();
Serial.println("client disonnected");
}
}
HTML is connectionless, that means you can't know if the data has changed. It is said that you can only "PULL", and ajax still pull, but it take xml/json data instead of all html.
But as far as i can understnd, you want a "PUSH" technology, with means the server send new data to clients when avaiable; that is possible using "WebSocket", but it need a server rewrite to support the protocol, or you can use a library
A websocket can be used like a normal socket (with some security restriction enforced by browser, principally you can only connecf to the same domain/ip of the HTML server), that means that once a connection is established, you can just print and read it like you do with a Serial!
I am trying to make an application that gets the streaming video data using JavaCV and send it to Web socket server. Then, the Web socket server distributes the video data to connected client(s).
1. Application gets live streaming data(MP4) from my PC's webcam using JavaCV.
2. Application keeps sending it to web socket server.
3. The server gets it as binary and send it to connected client.
4. Web browser connects to the server and Javascript running on browser shows the live video after receiving it from server.
I am new to JavaCV and OpenCV. The snippet below works for drawing video using com.googlecode.javacv.CanvasFrame with no problem. However, I am not sure how to grab MP4 data as live streaming data.
try {
FrameGrabber grabber = FrameGrabber.createDefault(0);
grabber.setFormat("mp4");;
grabber.setFrameRate(30);
grabber.setImageWidth(640);
grabber.setImageHeight(480);
grabber.start();
double frameRate = grabber.getFrameRate();
long wait = (long) (1000 / (frameRate == 0 ? 10 : frameRate));
ByteBuffer buf = null;
while (true) {
Thread.sleep(wait);
IplImage image = grabber.grab();
if(image != null) {
buf = image.getByteBuffer();
send(buf); // Send video data using web socket.
}
}
} catch (FrameGrabber.Exception ex) {
Logger.getLogger(WSockClient.class.getName()).log(Level.SEVERE, null, ex);
}
The below are the code for web socket server and Javascript/HTML5 client.
The both code works fine if the application reads MP4 file from local disk, and send it to the server. But the data using JavaCV like above seems to be invalid for showing on browser.
The server just receives the data and distribute it to the clients. I believe there seems to have no problem. Here is the code.
#OnMessage
public void binaryMessage(ByteBuffer buf, Session client) throws IOException, EncodeException {
for (Session otherSession : peers) {
if (!otherSession.equals(client)) {
otherSession.getAsyncRemote().sendBinary(buf, new StreamHandler());
}
}
}
Here is the Javascript/HTML5.
<body>
<video controls width="640" height="480" autoplay></video><br>
<canvas id="canvas1" width="640" height="480"></canvas><br>
</body>
<script>
var ws;
var protocol = 'ws';
var host = "localhost:8080";
var url = protocol + "://" + host + "/live/stream";
ws = new WebSocket(url);
ws.binaryType = 'arraybuffer';
ws.addEventListener("open",onOpenWebSocket,false);
ws.addEventListener("close",onCloseWebSocket,false);
ws.addEventListener("message",onMessageWebSocket,false);
window.addEventListener("unload",onUnload,false);
...
function onMessageWebSocket(event){
var blob = new Blob([event.data], {type: 'video/mp4'});
var rb = blob.slice(0, blob.size, 'video/mp4');
video.src = window.URL.createObjectURL(rb);
}
...
</script>
I think I need to obtain MP4 data as stream using JavaCV, but don't know how to do that. Please help.
Any comment, suggestions would be appreciated. Thank you.
I'm using a web server to control devices in the house with a microcontroller running .netMF (netduino plus 2). The code below writes a simple html page to a device that connects to the microcontroller over the internet.
while (true)
{
Socket clientSocket = listenerSocket.Accept();
bool dataReady = clientSocket.Poll(5000000, SelectMode.SelectRead);
if (dataReady && clientSocket.Available > 0)
{
byte[] buffer = new byte[clientSocket.Available];
int bytesRead = clientSocket.Receive(buffer);
string request =
new string(System.Text.Encoding.UTF8.GetChars(buffer));
if (request.IndexOf("ON") >= 0)
{
outD7.Write(true);
}
else if (request.IndexOf("OFF") >= 0)
{
outD7.Write(false);
}
string statusText = "Light is " + (outD7.Read() ? "ON" : "OFF") + ".";
string response = WebPage.startHTML(statusText, ip);
clientSocket.Send(System.Text.Encoding.UTF8.GetBytes(response));
}
clientSocket.Close();
}
public static string startHTML(string ledStatus, string ip)
{
string code = "<html><head><title>Netduino Home Automation</title></head><body> <div class=\"status\"><p>" + ledStatus + " </p></div> <div class=\"switch\"><p>On</p><p>Off</p></div></body></html>";
return code;
}
This works great, so I wrote a full jquery mobile website to use instead of the simple html. This website is stored on the SD card of the device and using the code below, should write the full website in place of the simple html above.
However, my problem is the netduino only writes the single HTML page to the browser, with none of the JS/CSS style files that are referenced in the HTML. How can I make sure the browser reads all of these files, as a full website?
The code I wrote to read the website from the SD is:
private static string getWebsite()
{
try
{
using (StreamReader reader = new StreamReader(#"\SD\index.html"))
{
text = reader.ReadToEnd();
}
}
catch (Exception e)
{
throw new Exception("Failed to read " + e.Message);
}
return text;
}
I replaced string code = " etc bit with
string code = getWebsite();
How can I make sure the browser reads all of these files, as a full website?
Isn't it already? Use an HTTP debugging tool like Fiddler. As I read from your code, your listenerSocket is supposed to listen on port 80. Your browser will first retrieve the results of the getWebsite call and parse the HTML.
Then it'll fire more requests, as it finds CSS and JS references in your HTML (none shown). These requests will, as far as we can see from your code, again receive the results of the getWebsite call.
You'll need to parse the incoming HTTP request to see what resource is being requested. It'll become a lot easier if the .NET implementation you run supports the HttpListener class (and it seems to).
I'm attempting to create a PDF file from an HTML file. After looking around a little I've found: wkhtmltopdf to be perfect. I need to call this .exe from the ASP.NET server. I've attempted:
Process p = new Process();
p.StartInfo.UseShellExecute = false;
p.StartInfo.FileName = HttpContext.Current.Server.MapPath("wkhtmltopdf.exe");
p.StartInfo.Arguments = "TestPDF.htm TestPDF.pdf";
p.Start();
p.WaitForExit();
With no success of any files being created on the server. Can anyone give me a pointer in the right direction? I put the wkhtmltopdf.exe file at the top level directory of the site. Is there anywhere else it should be held?
Edit: If anyone has better solutions to dynamically create pdf files from html, please let me know.
Update:
My answer below, creates the pdf file on the disk. I then streamed that file to the users browser as a download. Consider using something like Hath's answer below to get wkhtml2pdf to output to a stream instead and then send that directly to the user - that will bypass lots of issues with file permissions etc.
My original answer:
Make sure you've specified an output path for the PDF that is writeable by the ASP.NET process of IIS running on your server (usually NETWORK_SERVICE I think).
Mine looks like this (and it works):
/// <summary>
/// Convert Html page at a given URL to a PDF file using open-source tool wkhtml2pdf
/// </summary>
/// <param name="Url"></param>
/// <param name="outputFilename"></param>
/// <returns></returns>
public static bool HtmlToPdf(string Url, string outputFilename)
{
// assemble destination PDF file name
string filename = ConfigurationManager.AppSettings["ExportFilePath"] + "\\" + outputFilename + ".pdf";
// get proj no for header
Project project = new Project(int.Parse(outputFilename));
var p = new System.Diagnostics.Process();
p.StartInfo.FileName = ConfigurationManager.AppSettings["HtmlToPdfExePath"];
string switches = "--print-media-type ";
switches += "--margin-top 4mm --margin-bottom 4mm --margin-right 0mm --margin-left 0mm ";
switches += "--page-size A4 ";
switches += "--no-background ";
switches += "--redirect-delay 100";
p.StartInfo.Arguments = switches + " " + Url + " " + filename;
p.StartInfo.UseShellExecute = false; // needs to be false in order to redirect output
p.StartInfo.RedirectStandardOutput = true;
p.StartInfo.RedirectStandardError = true;
p.StartInfo.RedirectStandardInput = true; // redirect all 3, as it should be all 3 or none
p.StartInfo.WorkingDirectory = StripFilenameFromFullPath(p.StartInfo.FileName);
p.Start();
// read the output here...
string output = p.StandardOutput.ReadToEnd();
// ...then wait n milliseconds for exit (as after exit, it can't read the output)
p.WaitForExit(60000);
// read the exit code, close process
int returnCode = p.ExitCode;
p.Close();
// if 0 or 2, it worked (not sure about other values, I want a better way to confirm this)
return (returnCode == 0 || returnCode == 2);
}
I had the same problem when i tried using msmq with a windows service but it was very slow for some reason. (the process part).
This is what finally worked:
private void DoDownload()
{
var url = Request.Url.GetLeftPart(UriPartial.Authority) + "/CPCDownload.aspx?IsPDF=False?UserID=" + this.CurrentUser.UserID.ToString();
var file = WKHtmlToPdf(url);
if (file != null)
{
Response.ContentType = "Application/pdf";
Response.BinaryWrite(file);
Response.End();
}
}
public byte[] WKHtmlToPdf(string url)
{
var fileName = " - ";
var wkhtmlDir = "C:\\Program Files\\wkhtmltopdf\\";
var wkhtml = "C:\\Program Files\\wkhtmltopdf\\wkhtmltopdf.exe";
var p = new Process();
p.StartInfo.CreateNoWindow = true;
p.StartInfo.RedirectStandardOutput = true;
p.StartInfo.RedirectStandardError = true;
p.StartInfo.RedirectStandardInput = true;
p.StartInfo.UseShellExecute = false;
p.StartInfo.FileName = wkhtml;
p.StartInfo.WorkingDirectory = wkhtmlDir;
string switches = "";
switches += "--print-media-type ";
switches += "--margin-top 10mm --margin-bottom 10mm --margin-right 10mm --margin-left 10mm ";
switches += "--page-size Letter ";
p.StartInfo.Arguments = switches + " " + url + " " + fileName;
p.Start();
//read output
byte[] buffer = new byte[32768];
byte[] file;
using(var ms = new MemoryStream())
{
while(true)
{
int read = p.StandardOutput.BaseStream.Read(buffer, 0,buffer.Length);
if(read <=0)
{
break;
}
ms.Write(buffer, 0, read);
}
file = ms.ToArray();
}
// wait or exit
p.WaitForExit(60000);
// read the exit code, close process
int returnCode = p.ExitCode;
p.Close();
return returnCode == 0 ? file : null;
}
Thanks Graham Ambrose and everyone else.
OK, so this is an old question, but an excellent one. And since I did not find a good answer, I made my own :) Also, I've posted this super simple project to GitHub.
Here is some sample code:
var pdfData = HtmlToXConverter.ConvertToPdf("<h1>SOO COOL!</h1>");
Here are some key points:
No P/Invoke
No creating of a new process
No file-system (all in RAM)
Native .NET DLL with intellisense, etc.
Ability to generate a PDF or PNG (HtmlToXConverter.ConvertToPng)
Check out the C# wrapper library (using P/Invoke) for the wkhtmltopdf library: https://github.com/pruiz/WkHtmlToXSharp
There are many reason why this is generally a bad idea. How are you going to control the executables that get spawned off but end up living on in memory if there is a crash? What about denial-of-service attacks, or if something malicious gets into TestPDF.htm?
My understanding is that the ASP.NET user account will not have the rights to logon locally. It also needs to have the correct file permissions to access the executable and to write to the file system. You need to edit the local security policy and let the ASP.NET user account (maybe ASPNET) logon locally (it may be in the deny list by default). Then you need to edit the permissions on the NTFS filesystem for the other files. If you are in a shared hosting environment it may be impossible to apply the configuration you need.
The best way to use an external executable like this is to queue jobs from the ASP.NET code and have some sort of service monitor the queue. If you do this you will protect yourself from all sorts of bad things happening. The maintenance issues with changing the user account are not worth the effort in my opinion, and whilst setting up a service or scheduled job is a pain, its just a better design. The ASP.NET page should poll a result queue for the output and you can present the user with a wait page. This is acceptable in most cases.
You can tell wkhtmltopdf to send it's output to sout by specifying "-" as the output file.
You can then read the output from the process into the response stream and avoid the permissions issues with writing to the file system.
My take on this with 2018 stuff.
I am using async. I am streaming to and from wkhtmltopdf. I created a new StreamWriter because wkhtmltopdf is expecting utf-8 by default but it is set to something else when the process starts.
I didn't include a lot of arguments since those varies from user to user. You can add what you need using additionalArgs.
I removed p.WaitForExit(...) since I wasn't handling if it fails and it would hang anyway on await tStandardOutput. If timeout is needed, then you would have to call Wait(...) on the different tasks with a cancellationtoken or timeout and handle accordingly.
public async Task<byte[]> GeneratePdf(string html, string additionalArgs)
{
ProcessStartInfo psi = new ProcessStartInfo
{
FileName = #"C:\Program Files\wkhtmltopdf\wkhtmltopdf.exe",
UseShellExecute = false,
CreateNoWindow = true,
RedirectStandardInput = true,
RedirectStandardOutput = true,
RedirectStandardError = true,
Arguments = "-q -n " + additionalArgs + " - -";
};
using (var p = Process.Start(psi))
using (var pdfSream = new MemoryStream())
using (var utf8Writer = new StreamWriter(p.StandardInput.BaseStream,
Encoding.UTF8))
{
await utf8Writer.WriteAsync(html);
utf8Writer.Close();
var tStdOut = p.StandardOutput.BaseStream.CopyToAsync(pdfSream);
var tStdError = p.StandardError.ReadToEndAsync();
await tStandardOutput;
string errors = await tStandardError;
if (!string.IsNullOrEmpty(errors)) { /* deal/log with errors */ }
return pdfSream.ToArray();
}
}
Things I haven't included in there but could be useful if you have images, css or other stuff that wkhtmltopdf will have to load when rendering the html page:
you can pass the authentication cookie using --cookie
in the header of the html page, you can set the base tag with href pointing to the server and wkhtmltopdf will use that if need be
Thanks for the question / answer / all the comments above. I came upon this when I was writing my own C# wrapper for WKHTMLtoPDF and it answered a couple of the problems I had. I ended up writing about this in a blog post - which also contains my wrapper (you'll no doubt see the "inspiration" from the entries above seeping into my code...)
Making PDFs from HTML in C# using WKHTMLtoPDF
Thanks again guys!
The ASP .Net process probably doesn't have write access to the directory.
Try telling it to write to %TEMP%, and see if it works.
Also, make your ASP .Net page echo the process's stdout and stderr, and check for error messages.
Generally return code =0 is coming if the pdf file is created properly and correctly.If it's not created then the value is in -ve range.
using System;
using System.Diagnostics;
using System.Web;
public partial class pdftest : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
}
private void fn_test()
{
try
{
string url = HttpContext.Current.Request.Url.AbsoluteUri;
Response.Write(url);
ProcessStartInfo startInfo = new ProcessStartInfo();
startInfo.FileName =
#"C:\PROGRA~1\WKHTML~1\wkhtmltopdf.exe";//"wkhtmltopdf.exe";
startInfo.Arguments = url + #" C:\test"
+ Guid.NewGuid().ToString() + ".pdf";
Process.Start(startInfo);
}
catch (Exception ex)
{
string xx = ex.Message.ToString();
Response.Write("<br>" + xx);
}
}
protected void btn_test_Click(object sender, EventArgs e)
{
fn_test();
}
}