Sunday, January 2, 2011

Check if a browser supports HTML5

Check if a browser supports HTML5

HTML5 is a new way of developing interactive websites, HTML5 is still a emerging technology but we can already see lot of work being done and browsers supporting this new technology.

Anyone who will develop HTML5 will need to know how he can detect the browser is capable of supporting HTML5? or How he can detect which features the browser is compatible with.

The simplest way to do that is creating a canvas object using document.createElement method. After creating the object we can check if 2D context can be created, here is an example below:

<script type="text/javascript">
function supports_canvas() {
 //Check if browser supports canvas
 return !!document.createElement('canvas').getContext;
}
</script>

We have a open source solution as well, with help of which we can all the features supported by a browser, this is a javascript include file which can be obtained from Modernizr. We simply need to include this file in the head section, no call to any function, on its include it executes and initialize few boolean properties which can be accessed to check different HTML5 feature support.

<!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8">
  <title>Dive Into HTML5</title>
  <script src="modernizr.min.js"></script>
</head>
<body>
  ...
</body>
</html>

The Modernizr.canvas property will return false if your browser does not support the HTML5 canvas API, following check will be used:
if (Modernizr.canvas) {
  // let's perform some 2d graphics!
} else {
  // no canvas support available!
}
Posted by Team Lead at 9:44 AM 0 comments

Saturday, January 1, 2011

HTML5 Hello World Application

I consider HTML5 canvas the backbone of all the features available in HTML5, i recently got chance to work on a HTML5 application and really enjoyed learning new things and was really impressed with myself. Actually anyone who already knows some JavaScript and traditional HTML can kick start working on it.

For those who have just started working on it, i have created a Hello world application, this is a simple application, but will give overall view of how it works. Like in our graduation we always create a Hello world application to get start learning things, so here how it works:

First of all we should know whether the browser supports HTML5 canvas, for this you can view my post at Check if browser supports HTML.

I will use following method:
function supports_canvas() {
 //Check if browser supports canvas
 return !!document.createElement('canvas').getContext;
}


Next we need a Canvas element which supports 2D graphic drawings, it is the canvas on which we can draw different shapes like circle, rectangle, arcs, circle, etc also we can write text, and draw images from some source files.

This sample focuses on creating a canvas and writing hello world on it. For this i will create a DIV element in my document, than add a Canvas element in the DIV using JavaScript:

function initializeCanvas(containerid, canvasWidth, canvasHeight) {
  var container = document.getElementById(containerid);
  if ( supports_canvas() ) {
    //Create canvas element
    var canvas = document.createElement('canvas');
    canvas.setAttribute('width', canvasWidth);
    canvas.setAttribute('height', canvasHeight);
    container.appendChild(canvas);
    //Context of canvas for performing 2d graphics operations
    context = canvas.getContext('2d');
    return context;
  } else {
    container.innerHTML = 'This is a HTML5 app,
    you need a HTML5 capable browser like Firefox,
    Chrome, Safari or Internet Explorer 9.'
    
    return null;
  }
}


Here is the working sample: Sample Hello World
Posted by Team Lead at 2:57 AM 0 comments

Friday, December 31, 2010

Crystal Reports .NET Error: Load Report Failed

Most of the ASP.NET developers might be familiar with this problem and faced it too. When we Google for it, most of the solutions indicate that the C:\Windows\Temp folder needs permission for NETWORK SERVICE account in Windows Server and ASP NET account in Windows Client.

On my web server i can clearly see temporary files of crystal reports being created when a report is called from ASP.NET page. It is recommended to set a special permission no C:\Windows\Temp folder as follows:

Add permission to List folder and Read
Add permission to Create files, Append files
Add permission to Delete files

This should fix the problem in 80% of the cases. Although there are other scenarios as well which cause this problem. But i have here indicated the one common problem, i hope it works for most of you and save you a day.

Another issue might be in the coding section, if report documents are not properly closed and disposed off, this will trigger the error as well. Whenever a report is called in a web application a copy in C:\Windows\Temp folder is created and than served to the client response.

You should inspect the C:\Windows\Temp folder to see if these temp files are not hanging around, if so that means the report documents are not properly close and disposed after processing. Crystal report document need to be closed by calling the Close() method and than the Dispose() method to clean.

There is a recommendation for this in SAP Crystal reports document, and the code should look similar to the following:
private void Page_Unload(object sender, EventArgs e)
{
  if (boReportDocument != null)
  {
    boReportDocument.Close();
    boReportDocument.Dispose();
    GC.Collect();
  }
}


Reference: Troubleshooting the “Load Report Failed” Error
Posted by Team Lead at 10:14 PM 0 comments

SQL Database Snapshot

Create Database Snapshot on Current database:

USE TEST

GO

DECLARE @name VARCHAR(1000),
@filename VARCHAR(1000),
@dbname VARCHAR(1000),
@dbssname VARCHAR(1000),
@dbssfilename VARCHAR(1000)

DECLARE @hour VARCHAR(2),
@minute VARCHAR(2)

SET @hour = DATENAME(HOUR,GETDATE())
IF LEN(@hour) = 1 SET @hour = '0'+@hour
SET @minute = DATENAME(MINUTE,GETDATE())
IF LEN(@minute) = 1 SET @minute = '0'+@minute

SET @dbname = Db_Name();
SET @dbssname = @dbname+'_data_'+@hour+@minute
SET @dbssfilename = 'C:\Program Files\Microsoft SQL Server\MSSQL10_50.MSSQLSERVER\MSSQL\Data\'+@dbssname+'.ss'

SELECT @name = [name], @filename = [filename]
FROM sys.sysfiles
WHERE groupid = 1;


--CREATE SNAPSHOT
EXEC( 'CREATE DATABASE ' + @dbname + '_dbss' +@hour+@minute + ' ON
( NAME =' + @name + ', FILENAME = '''+@dbssfilename +''')
AS SNAPSHOT OF '+@dbname);


Restore Database to a Database Snapshot:
USE master;
GO
-- Reverting TEST to TEST_dbss1717
RESTORE DATABASE TEST from
DATABASE_SNAPSHOT = 'TEST_dbss1717';
GO

Drop Database Snapshot:
USE master;
GO
DROP DATABASE TEST_dbss1717;
Posted by Team Lead at 4:15 AM 0 comments
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