Develop Reference

How can I scan a document using ASP.net MVC 5 with the help of Twain

Please help me out by sharing the step by step procedure to achieve the scanning functionality using Twain in ASP.Net MVC5. Thank you

Solution is here:
In ASP.Net/Core Project you send message to call winform project:
var start = function () {
var i = 0;
var wsImpl = window.WebSocket || window.MozWebSocket;
window.ws = new wsImpl('ws://localhost:8181/');
ws.onmessage = function (e) {
$('#submit').hide();
$('#scanBtn').hide();
$('.loader').show();
if (typeof e.data === "string") {
//IF Received Data is String
}
else if (e.data instanceof ArrayBuffer) {
//IF Received Data is ArrayBuffer
}
else if (e.data instanceof Blob) {
i++;
var f = e.data;
f.name = "File" + i;
storedFiles.push(f);
formdata.append(f.name, f);
var reader = new FileReader();
reader.onload = function (e) {
var html = "<div class=\"col-sm-2 text-center\"
style=\"border: 1px solid black; margin-left: 2px;\"><img
height=\"200px\" width=\"200px\" src=\"" + e.target.result + "\"
data-file='" + f.name + "' class='selFile' title='Click to
remove'><br/>" + i + "</div>";
selDiv.append(html);
$('#submit').show();
$('#scanBtn').show();
$('.loader').hide();
}
reader.readAsDataURL(f);
}
};
ws.onopen = function () {
//Do whatever u want when connected succesfully
};
ws.onclose = function () {
$('.dalert').modal('show');
};
}
window.onload = start;
function scanImage() {
ws.send("1100");
};
https://javascript.info/websocket
In Winforms Project you scan document and send graphic data back to Asp.Net/Core project:
public partial class Form1 : Form
{
ImageCodecInfo _tiffCodecInfo;
TwainSession _twain;
bool _stopScan;
bool _loadingCaps;
List allSockets;
WebSocketServer server;
public Form1()
{
InitializeComponent();
if (NTwain.PlatformInfo.Current.IsApp64Bit)
{
Text = Text + " (64bit)";
}
else
{
Text = Text + " (32bit)";
}
foreach (var enc in ImageCodecInfo.GetImageEncoders())
{
if (enc.MimeType == "image/tiff") { _tiffCodecInfo = enc; break; }
}
this.WindowState = FormWindowState.Minimized;
this.ShowInTaskbar = false;
allSockets = new List<IWebSocketConnection>();
server = new WebSocketServer("ws://0.0.0.0:8181");
server.Start(socket =>
{
socket.OnOpen = () =>
{
Console.WriteLine("Open!");
allSockets.Add(socket);
};
socket.OnClose = () =>
{
Console.WriteLine("Close!");
allSockets.Remove(socket);
};
socket.OnMessage = message =>
{
if (message == "1100")
{
this.Invoke(new Action(()=> {
this.WindowState = FormWindowState.Normal;
}));
}
};
});
}
Link to project.
https://github.com/mgriit/ScanAppForWeb
You can remake this project, as you want.

At this moment, none of the browsers support scanning out of the box. You need to use a third-party library (not part of Microsoft's .NET core components). Below example uses Scanner.js, which is a product offered by our company:
Enable Scanning from TWAIN Scanners to ASP.NET Pages: Step by Step
Below steps use Scanner.js as example; they may differ for other products.
1) Include the scanning library in your HTML code:
<script type="text/javascript" src="//asprise.azureedge.net/scannerjs/scanner.js"></script>
2) Add a button to trigger the scanning process:
function scanToJpg() {
scanner.scan(displayImagesOnPage,
{
"twain_cap_setting" : {
"ICAP_PIXELTYPE" : "TWPT_RGB", // Color
"ICAP_XRESOLUTION" : "100", // DPI: 100
"ICAP_YRESOLUTION" : "100",
"ICAP_SUPPORTEDSIZES" : "TWSS_USLETTER" // Paper size: TWSS_USLETTER, TWSS_A4, ...
},
"output_settings" :
[
{
"type" : "return-base64",
"format" : "jpg"
}
]
}
);
}
3) Handle the scan result - display, upload, etc.
Below code creates an img element for each image scanned to display on the current web page:
/** Processes the scan result */
function displayImagesOnPage(successful, mesg, response) {
var scannedImages = scanner.getScannedImage(response, true, false); // returns an array of ScannedImage
for(var i = 0; (scannedImages instanceof Array) && i < scannedImages.length; i++) {
var scannedImage = scannedImages[i];
processScannedImage(scannedImage);
}
}
/** Images scanned so far. */
var imagesScanned = [];
/** Processes a ScannedImage */
function processScannedImage(scannedImage) {
imagesScanned.push(scannedImage);
var elementImg = createDomElementFromModel( {
'name': 'img',
'attributes': {
'class': 'scanned',
'src': scannedImage.src
}
});
document.getElementById('images').appendChild(elementImg);
}
For examples of scanning into PDF formats and direct uploading, please visit the code repository: https://github.com/Asprise/scannerjs.javascript-scanner-access-in-browsers-chrome-ie.scanner.js

Call back from server to client

I am using ASP.NET MVC 4 application, I need to Display messages in the Client, by sending messages from Controller to Client.
My requirement is user click a button in UI and i will process the files on the server and Display message in UI on end of each foreach file i process. i need to show the File names in the Client Using ASP.NET MVC.
Can any one Help how to show the messages in the Client by calling client method from server on for-each loop each time.
I am able to call the controller and end of each controller I am sending final message to UI, but how to send on each foreach loop iteration?

Try this:
Script method to update progress based on predefined interval you want
Controller:
public class HomeController : Controller
{
private static IDictionary<Guid, int> tasks = new Dictionary<Guid, int>();
public ActionResult Index()
{
return View();
}
public ActionResult Start()
{
var taskId = Guid.NewGuid();
tasks.Add(taskId, 0);
Task.Factory.StartNew(() =>
{
for (var i = 0; i <= 100; i++)
{
tasks[taskId] = i; // update task progress
Thread.Sleep(50); // simulate long running operation
}
tasks.Remove(taskId);
});
return Json(taskId);
}
public ActionResult Progress(Guid id)
{
return Json(tasks.Keys.Contains(id) ? tasks[id] : 100);
}
}
View:
<script type="text/javascript">
function updateMonitor(taskId, status) {
$("#" + taskId).html("Task [" + taskId + "]: " + status);
}
$(function () {
$("#start").click(function (e) {
e.preventDefault();
$.post("Home/Start", {}, function (taskId) {
// Init monitors
$("#monitors").append($("<p id='" + taskId + "'/>"));
updateMonitor(taskId, "Started");
// Periodically update monitors
var intervalId = setInterval(function () {
$.post("Home/Progress", { id: taskId }, function (progress) {
if (progress >= 100) {
updateMonitor(taskId, "Completed");
clearInterval(intervalId);
} else {
updateMonitor(taskId, progress + "%");
}
});
}, 100);
});
});
});
Start new task …

You have to write an ActionResult that progressively write result to the response. so you can show the user some data in every foreach loop iteration. I have written a simple ActionResult that writes a number every 2 seconds:
public class ProgressiveResult : ActionResult
{
public override void ExecuteResult(ControllerContext context)
{
for (int i = 0; i < 20; i++)
{
context.HttpContext.Response.Write(i.ToString());
Thread.Sleep(2000);
context.HttpContext.Response.Flush();
}
context.HttpContext.Response.End();
}
}
and this is an action that returns this result:
public ActionResult LongProcess()
{
return new ProgressiveResult();
}
So you can write an ActionResult and write your foreach code in ExecuteResult method.
UPDATE:
You can make this call with an Ajax request and return result with a simple code like the following code:
var result = "";
function showResult() {
if (result !== oReq.responseText) {
result = oReq.responseText;
console.log(result);
}
}
var oReq = new XMLHttpRequest();
oReq.open("get", "/Home/LongProcess", true);
oReq.send();
setInterval(showResult, 1000);

MVC3 Async jQuery progress bar on a insert query

So I am trying to add an async progress bar on a really slow and long query that inserts a bunch of rows to a database. My implementation is based off this example: http://blog.janjonas.net/2012-01-02/asp_net-mvc_3-async-jquery-progress-indicator-long-running-tasks
Here is the javascript code for the progress bar
function updateMonitor(taskId, status) {
$("#" + taskId).html("Task [" + taskId + "]: " + status);
}
//other code
if (doSend == true) {
$.post("/SendBatch/HandleBatchRequest", {
//other code
},
function (taskId) {
// Init monitors
//breakpoint here does not stop it, it never enters this somehow?
$("#monitors").append($("<p id='" + taskId + "'/>"));
updateMonitor(taskId, "Started");
// Periodically update monitors
var intervalId = setInterval(function () {
$.post("SendBatch/Progress", { id: taskId }, function (progress) {
if (progress >= 100) {
updateMonitor(taskId, "Completed");
clearInterval(intervalId);
} else {
updateMonitor(taskId, progress + "%");
}
});
}, 100);
}
,"html");
Then there is the DIV within the display part of the website
<div id="monitors"></div>
Here is how the controller looks
public SendBatchController
//some code
private static IDictionary<Guid, int> tasks = new Dictionary<Guid, int>();
public ActionResult HandleBatchRequest(
//some code
)
{
var taskId = Guid.NewGuid();
tasks.Add(taskId, 0);
var batchId = Guid.NewGuid().ToString("N");
var costd = cost.ToDecimal();
IEnumerable<BatchListModel> customers;
try
{
customers = new CustomerService(_customerRepository.Session).GetCustomers(
//some code
);
}
catch (Exception err)
{
return Json(err.Message);
}
if (doSend)
{
var sent = 0;
foreach (var c in customers)
{
try
{
var usr = _customerRepository.LoadByID(c.ID);
var message = new ComLog
{
//insertions to log
};
_comLogRepository.Save(message);
sent++;
//progress bar part inside here that is important comes here:
tasks[taskId] = sent;
}
catch (Exception e)
{
Log.WriteLine("ERR:" + e);
}
tasks.Remove(taskId);
}
return Json(taskId);
}
return Json(customers.Count() + " customers");
}
public ActionResult Progress(Guid id)
{
return Json(tasks.Keys.Contains(id) ? tasks[id] : 100);
}
This does not work. The process works in the background. It is only the div that never shows up and never gives any indication. I know this is a lot of code to read but I am really stuck and would love some input on how to fix this.

try change your updateMonitor function into this :
function updateMonitor(taskId, status) {
$("#monitors").html("Task [" + taskId + "]: " + status);
}

Issues with HttpContext.Current.Response.Redirect in a class

I have written a class which gets the post data using jquerypost and then perform some crud operations. Its works fine adding stuff to the database , but it doesnt redirects to the page when passing certain data , below is the code :
$('#clickme').click(function (e) {
e.preventDefault();
indx = $("#DropDownList1 option:selected").index();
indx += 1;
var test = $("#DropDownList" + (indx + 1));
var url = "/Base/performOperations/shootme/"
jQuery.post(url, { name: jQuery("#name").val(), email: jQuery("#email").val(), federation: jQuery(test).val(), selectedscheme: jQuery("#DropDownList1").val() },
function (data) {
if (data == scheme1) {
window.location = "http://www.openme.com"
}
});
});
namespace pw
{
public class performOperations
{
public static string ShootMe() {
HttpRequest post = HttpContext.Current.Request;
string name = post["name"];
string email = post["email"];
string selectedscheme = post["selectedscheme"];
string federation = post["federation"];
string conn = System.Configuration.ConfigurationManager.AppSettings["mydb"];
string sql = "INSERT INTO dbo.mydb(Email,Name,schemes,LoginDate,schemeType) VALUES(#email,#name,#scheme,#dateTime,#federation)";
SqlHelper.ExecuteNonQuery(conn, CommandType.Text, sql,
new SqlParameter("#email", email),
new SqlParameter("#name", name),
new SqlParameter("#scheme", selectedscheme),
new SqlParameter("#dateTime", DateTime.Now),
new SqlParameter("#federation", federation));
return selectedscheme;
}
}
}
Any ideas why the redirect doesnt takes place, or am i doing it in a wrong way , i need to redirect to a particular page once the data is injected to the db.
Any assistance will be appreciated

If you are calling the POST method using AJAX, redirection at server side will not work.
You will have to redirect it at client side after request completion using javascript the request.
$('#clickme').click(function (e) {
e.preventDefault();
indx = $("#DropDownList1 option:selected").index();
indx += 1;
var test = $("#DropDownList" + (indx + 1));
var url = "/Base/sample/Hello/"
jQuery.post(url, { name: jQuery("#name").val(), email: jQuery("#email").val(), federation: jQuery(test).val(), selectedscheme: jQuery("#DropDownList1").val() },
function (data) {
if (data == "shoothim") {
window.location = "http://www.cuthishead.com"
}
else if(data == "shoother")
{
window.location = "http://www.chopherbody.com"
}
else if(data == "shootboth")
{
window.location = "http://www.fulldeath.tv"
}
});

return selectedscheme or URL from your page method
set window.location based on web method result on jquery
need to set WebMethod attribute for your C# method
Check Using jQuery to Call ASP.NET AJAX Page Methods – By Example

C# false http response

I have a thread that returns a site's http response status, but sometimes my program returns false results. and after a while it gives good results.
False result:
it takes a big a mount of time to check, and then it says that (for example) Google is down, which is quite not reasonable, but after a few seconds it returns good results
Can you take a look and tell me whats wrong? or how I can I improve it?
Checks all sites in datagrid:
private void CheckSites()
{
if (CheckSelected())
{
int rowCount = dataGrid.BindingContext[dataGrid.DataSource, dataGrid.DataMember].Count;
string url;
for (int i = 0; i < rowCount; i++)
{
url = dataGrid.Rows[i].Cells[2].Value.ToString();
if (url != null)
{
Task<string[]> task = Task.Factory.StartNew<string[]>
(() => checkSite(url));
// We can do other work here and it will execute in parallel:
//Loading...
// When we need the task's return value, we query its Result property:
// If it's still executing, the current thread will now block (wait)
// until the task finishes:
string[] result = task.Result;
selectRows();
if (result[0] != System.Net.HttpStatusCode.OK.ToString() && result[0] != System.Net.HttpStatusCode.Found.ToString() && result[0] != System.Net.HttpStatusCode.MovedPermanently.ToString())
{
//bad
notifyIcon1.ShowBalloonTip(5000, "Site Down", dataGrid.Rows[i].Cells[2].Value.ToString() + ", has a status code of:" + result, ToolTipIcon.Error);
dataGrid.Rows[i].DefaultCellStyle.BackColor = System.Drawing.Color.Wheat;
TimeSpan ts;
TimeSpan timeTaken = TimeSpan.Parse(result[1]);
dataGrid.Rows[i].Cells[3].Value = result[0];
dataGrid.Rows[i].Cells[3].Style.BackColor = System.Drawing.Color.Red;
dataGrid.Rows[i].Cells[4].Value = timeTaken.Seconds.ToString() + "." + String.Format("{0:0.00000}", timeTaken.Milliseconds.ToString()) + " seconds.";
string sec = (DateTime.Now.Second < 10) ? "0" + DateTime.Now.Second.ToString() : DateTime.Now.Second.ToString();
string min = (DateTime.Now.Minute < 10) ? "0" + DateTime.Now.Minute.ToString() : DateTime.Now.Minute.ToString();
string hour = (DateTime.Now.Hour < 10) ? "0" + DateTime.Now.Hour.ToString() : DateTime.Now.Hour.ToString();
dataGrid.Rows[i].Cells[5].Value = hour + ":" + min + ":" + sec;
//loadbar
}
else if (result[0] == "catch")//catch
{
notifyIcon1.ShowBalloonTip(10000, "SITE DOWN", dataGrid.Rows[i].Cells[1].Value.ToString() + ", Error:" +result[1], ToolTipIcon.Error);
dataGrid.Rows[i].Cells[3].Value = result[1];
dataGrid.Rows[i].Cells[3].Style.BackColor = System.Drawing.Color.Red;
//loadbar
}
else
{
//good
TimeSpan timeTaken = TimeSpan.Parse(result[1]);
dataGrid.Rows[i].Cells[3].Value = result[0];
dataGrid.Rows[i].Cells[3].Style.BackColor = System.Drawing.Color.LightGreen;
dataGrid.Rows[i].Cells[4].Value = timeTaken.Seconds.ToString() + "." + String.Format("{0:0.00000}", timeTaken.Milliseconds.ToString()) + " seconds.";
string sec = (DateTime.Now.Second < 10) ? "0" + DateTime.Now.Second.ToString() : DateTime.Now.Second.ToString();
string min = (DateTime.Now.Minute < 10) ? "0" + DateTime.Now.Minute.ToString() : DateTime.Now.Minute.ToString();
string hour = (DateTime.Now.Hour < 10) ? "0" + DateTime.Now.Hour.ToString() : DateTime.Now.Hour.ToString();
dataGrid.Rows[i].Cells[5].Value = hour + ":" + min + ":" + sec;
//loadbar
}
selectRows();
}
}
}
}
Checks a site:
/////////////////////////////////
////Check datagrid websites-button - returns response
/////////////////////////////////
private string[] checkSite(string url)
{
string[] response = new string[2];
url = dataGrid.Rows[0].Cells[2].Value.ToString();
if (url != null)
{
try
{
HttpWebRequest httpReq;
httpReq.Timeout = 10000;
//loadbar
dataGrid.Rows[0].DefaultCellStyle.BackColor = System.Drawing.Color.Wheat;
System.Diagnostics.Stopwatch timer = new System.Diagnostics.Stopwatch();
timer.Start();
HttpWebResponse httpRes = (HttpWebResponse)httpReq.GetResponse(); //httpRes.Close();
timer.Stop();
//loadbar
HttpStatusCode httpStatus = httpRes.StatusCode;
response[0] = httpStatus.ToString();
response[1] = timer.Elapsed.ToString();//*
httpRes.Close();
return response;
}
catch (Exception he)
{
response[0] = "catch";
response[1] = he.Message;
return response;
}
}
response[0] = "catch";
response[1] = "No URL entered";
return response;
//dataGrid.Rows[i].DefaultCellStyle.BackColor = System.Drawing.Color.Blue;
}
Thanks in advance.

Assuming the code provided is the actual code used:
First of all, your definition of 'False result' and 'Good result' is wrong. If you expect A but get B, that doesn't mean B is invalid. If your wife is giving birth and you expect a boy but it turns out the be a girl, its not a false result. Just unexpected.
That said: lets analyze your work: If it takes a long long time to check a site only to finally get a ??? result which isn't a 200 response code. We can almost savely assume you are dealing with a timeout. If your router, google or any fundamental network device in between is having problems, its expected to get an unexpected answer. "Timeout", "Bad Request", "Server not available" etc. Why would this happen? Its impossible to say for certain without having direct access to your environment.
Looking at your code however, i see that you're using the default TaskScheduler for making each check run as a task in the background (assuming you havent changed the default task scheduler which would be a vey bad practice to begin with). The default task scheduler, schedules each task on the threadpool which results in many many tasks running simultanious. Here we have a good candidate for overloading your network. Many sites (esspecially google) are kinda sensitive for handling many requests from the same source (esspecially if the frequency is high) so maybe google is blocking you temporarily or holding you back. Again, at this point it's pure speculation but the fact that you're running all checks simultaniously (unless the thread pool is on his max) is very likely the cause of your problem.
UPDATE
I would recommend working with a LimitedConcurrencyTaskScheduler ( see here: http://blogs.msdn.com/b/pfxteam/archive/2010/04/09/9990424.aspx ). Here you can limit the amount of tasks that can be run asynchronously. You have to do some testing for what number works ideally in your situation. Also make sure that the frequency is not 'too' high. Its hard to define what is too high, only testing can proof that.

In order to simulate your scenario, I have created a Winform with data grid and a button. On load of the form, I programmatically creates list of url’s (in a table) and bind to data grid. And on button click, we start the download process. In concise, the you have to write more defensive code and the following code only a skeleton of how you can fix the issue.
using System;
using System.Data;
using System.Net;
using System.Threading.Tasks;
using System.Windows.Forms;
namespace app
{
public partial class Form1 : Form
{
DataTable urls = new DataTable();
public Form1()
{
InitializeComponent();
}
//Fill your uri's and bind to a data grid.
void InitTable()
{
//Silly logic to simulate your scenario.
urls = new DataTable();
urls.Columns.Add(new DataColumn("Srl", typeof(string)));
urls.Columns.Add(new DataColumn("Urls", typeof(Uri)));
urls.Columns.Add(new DataColumn("Result", typeof(string)));
DataRow dr = urls.NewRow();
dr["Srl"] = "1";
dr["Urls"] = new Uri("http://www.microsoft.com");
dr["Result"] = string.Empty;
urls.Rows.Add(dr);
dr = urls.NewRow();
dr["Srl"] = "2";
dr["Urls"] = new Uri("http://www.google.com");
dr["Result"] = string.Empty;
urls.Rows.Add(dr);
dr = urls.NewRow();
dr["Srl"] = "3";
dr["Urls"] = new Uri("http://www.stackoverflow.com");
dr["Result"] = string.Empty;
urls.Rows.Add(dr);
urls.AcceptChanges();
}
void UpdateResult()
{
dataGridView1.DataSource = urls;
}
//Important
// This example will freeze UI. You can avoid this while implementing
//background worker or pool with some event synchronization. I haven't covered those area since
//we are addressing different issue. Let me know if you would like to address UI freeze
//issue. Or can do it your self.
private void button1_Click(object sender, EventArgs e)
{
//Create array for Task to parallelize multiple download.
var tasks = new Task<string[]>[urls.Rows.Count];
//Initialize those task based on number of Uri's
for(int i=0;i<urls.Rows.Count;i++)
{
int index = i;//Do not change this. This is to avoid data race
//Assign responsibility and start task.
tasks[index] = new Task<string[]>(
() => checkSite(
new TaskInput(urls.Rows[index]["Urls"].ToString(), urls.Rows[index]["Srl"].ToString())));
tasks[index].Start();
}
//Wait for all task to complete. Check other overloaded if interested.
Task.WaitAll(tasks);
//block shows how to access result from task
foreach (var item in tasks)
{
DataRow[] rows=urls.Select("Srl='"+item.Result[2]+"'");
foreach (var row in rows)
row["Result"]=item.Result[0]+"|"+item.Result[1];
}
UpdateResult();
}
//This is dummy method which in your case 'Check Site'. You can have your own
string[] checkSite(TaskInput input)
{
string[] response = new string[3];
if (input != null)
{
try
{
WebResponse wResponse = WebRequest.Create(input.Url).GetResponse();
response[0] = wResponse.ContentLength.ToString();
response[1] = wResponse.ContentType;
response[2] = input.Srl;
return response;
}
catch (Exception he)
{
response[0] = "catch";
response[1] = he.Message;
response[2] = input.Srl;
return response;
}
}
response[0] = "catch";
response[1] = "No URL entered";
response[2] = input.Srl;
return response;
}
private void Form1_Load(object sender, EventArgs e)
{
InitTable();
UpdateResult();
}
}
//Supply custom object for simplicity
public class TaskInput
{
public TaskInput(){}
public TaskInput(string url, string srl)
{
Url = url;
Srl = srl;
}
public string Srl { get; set; }
public string Url { get; set; }
}
}