MS Windows – Technoserene

How do I use Java with the Google Chrome browser?

NPAPI support by Chrome

The Java plug-in for web browsers relies on the cross platform plugin architecture NPAPI, which has long been, and currently is, supported by all major web browsers. Google announced in September 2013 plans to remove NPAPI support from Chrome by “the end of 2014”, thus effectively dropping support for Silverlight, Java, Facebook Video and other similar NPAPI based plugins.

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Enabling NPAPI in Chrome Version 42 and later

As of Chrome Version 42, an additional configuration step is required to continue using NPAPI plugins.

In your URL bar, enter:
chrome://flags/#enable-npapi
Click the Enable link for the Enable NPAPI configuration option.
Click the Relaunch button that now appears at the bottom of the configuration page.

Java plug-in needs permission

If you see a message within Chrome that says Java(TM) needs your permission to run, you will need to respond to the Chrome options in order to run plug-ins on the page. Options vary according to the version of Chrome.

Chrome plug-in blocked icon (in address bar)

Look for the blocked plug-in icon in the Chrome address bar. Clicking on the icon will display Plug-ins were blocked on this page and plug-in options

Click Always allow plug-ins on [name of site] to allow plug-ins (including Java) to run on all this site’s pages.
Click Run all plug-ins this time to allow the plug-in (including Java) content on the page to run only until you leave this page.
Click Continue blocking plug-ins to prevent plug-ins from running on the page.

In addition, you can manage permissions on a site basis through the Manage plug-in blocking option.

Chrome message bar

Click Run this time to allow the Java content on the page to run only until you leave this page.
Click Always run on this site to allow Java to run on all this site’s pages. You will not see this message again for pages on this site.

Additional plug-in required

If you see a message bar within Chrome that says Java(TM) is required to display some elements on this page, click on Install plug-in in the Chrome message bar, or download from java.com.

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Plug-in out of date

If you see a message bar within Chrome that says Java(TM) was blocked because it is out of date, click on Update plug-in in the Chrome message bar to get the latest Java.

Reference:

https://java.com/en/download/faq/chrome.xml

Alternatives to NPAPI plugin

After upgrading the earlier versions of Chromium browsers to later versions greater than 42, internet users have started complaints that the JAVA plugins are not supported by chrome. After a bit research, found that chromium browsers have disabled NPAPI plugin-in on their latest versions. The deprecation of NPAPI plug-in caused the JAVA plugins to be blocked in Chrome.

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What is NPAPI plug-in? (Source: Wiki)

Netscape Plugin Application Programming Interface (NPAPI) is a cross-platform plugin architecture used by many web browsers.

It was first developed for Netscape browsers, starting in 1995 with Netscape Navigator 2.0, but was subsequently adopted in Internet Explorer 3 in 1996 and implemented by many other browsers, although some browsers later dropped support.

For stability and security reasons, Google Chrome decided, in 2013, to start phasing out support for NPAPI. As of Chrome version 42, NPAPI is disabled by default and must be re-enabled explicitly. Google intends to remove support entirely in version 45, due in September 2015.

Alternatives to NPAPI (Source: chromium.org)

With the deprecation of NPAPI, some developers have asked which modern technologies can be used to implement features which in the past would have relied on a platform-specific NPAPI plug-in. In answer to these questions we have composed the following list of common NPAPI use cases and web platform alternatives.

In general, the core standards-based web technologies (HTML/CSS/JS) are suitable for most client software development. If your application requires access to features outside the web sandbox, myriad Chrome Extension and App APIs offer access to OS features.

Video and audio

A common use case for NPAPI plug-ins on the modern web is embedded video and/or audio. A range of modern web technologies exist to facilitate media streaming. The basic building blocks are WebRTC and media elements:

HTML5 Media Elements: The HTML5 Specification provides a rich media platform through the <audio> and <video> elements. More complicated use cases can be achieved using the <canvas> element (for example check out the Video FX Chrome Experiment).

WebRTC: WebRTC was designed for real time communication between peers and the technology can also be used for applications like live streaming media and data. Google’s Chromecast device uses WebRTC to stream HD video between a browser and TV.

Several features on top of these building blocks support more advanced use cases:

Adaptive Streaming

The ability to adapt media streaming to an individual consumer is critical in delivering high-quality content to a large audience. In the past this capability has been provided by technologies such as Silverlight’s smooth streaming and Quicktime’s HTTP live streaming. The Media Source Extensions to the HTML media element provide the capability to adapt a stream to an individual consumer on the modern web. Html5rocks has put together a great example of how to use the Media Source Extensions to implement some of these common use cases.

Video Conferencing

Several of the most popular NPAPI extensions including Facebook Video Chat and Google Talk provide video conferencing functionality within the browser. With the introduction of WebRTC video conferencing is facilitated directly through JavaScript APIs. The Cube Slam Chrome Experiment provides an example of peer to peer video conferencing via WebRTC.

Digital Rights Management

Encrypted Media Extensions give HTML5 video the DRM capabilities that previously would have required the use of a platform specific plug-in. The WebM project has provided a demo which performs video playback using the Encrypted Media Extensions of the video element. For more information, check out the EME HTML5 Rocks article.

Closed Captioning

WebVTT and the <track> element (a child element of <video>) enable web developers to add timed-text captioning capabilities to their HTML apps.

Communicating with native applications

Try the Native Messaging API for Chrome Apps and Extensions.

Games & 3D

Native Client (NaCL) provides a rich environment for cross-platform game development. Many games have already been ported to or designed for NaCL. A number of examples and detailed tutorials to get started with NaCL are available on the NaCL development site. The WebGL specification provides a high-performance platform for hardware-accelerated 3D graphics in the browser. Chrome experiments has an entire category dedicated to examples and demos of various WebGL use cases.

Security

Some services have relied on NPAPI-based security techniques. We recommend switching to TLS or, soon, Web Crypto.

Hardware access

In the past it has often been necessary to write platform specific plug-ins to access system hardware such as webcams, microphones, USB devices, and bluetooth. Direct access to local media streams such as webcams and microphones can now be requested directly from the web via the WebRTC Media Capture specification. Chromium also provides an App API for access to USB hardware and another API for accessing Bluetooth devices.

Screen capture

Chrome extensions can perform screen capture or streaming using either Desktop Capture for full screen capture or the Tabs API captureVisibleTab for individual tab content capture.

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Reference:

http://www.chromium.org/developers/npapi-deprecation

http://en.wikipedia.org/wiki/NPAPI

Eport data to excel using Codeigniter and Oracle (OCI)

Below is a simple code snippet that will help you to export data to CSV/Excel format using Codeigniter and Oracle. Yes, it is obvious that you must have knowledge regarding Codeigniter and Oracle before you proceed further reading.

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The code below contains few PHP variables and function calls. I hope that you understand the same in a better way and please give your feedback if you feel this needs.

$sql = "SELECT * FROM your_table_name";
$filename = "Name_of_the_file.csv";
$countRow = functionCountRow();

$this->searchkyc_model->ExportToExcel($sql,$filename,$countRow);

public function ExportToExcel($sql,$filename,$countRow) { 	

		$output = "";

		$this->epfo_db = $this->load->database('EPFO', true);		

		$stmt = oci_parse($this->epfo_db->conn_id, $sql);

		oci_execute($stmt);

		$ncols = oci_num_fields($stmt);

		for ($i = 1; $i <= $ncols; ++$i) { 			
                    $colname = oci_field_name($stmt, $i);			 			
                    $output .= '"'.$colname.'",'; 		
                 } 		
                $output.="n"; 		 		
                $row = oci_fetch_all($stmt, $result); 		
                oci_free_statement($stmt); 		
                oci_close($this->epfo_db->conn_id);	

		// Get Records from the table
		for($i=0;$i<$countRow;$i++){ 				 				                
                    foreach($result as $key=>$val){
					$output.='"'.$val[$i].'",';
		          }
				$output.="n";
		}

		// Download the file	
		header('Content-type: application/csv');
		header('Content-Disposition: attachment; filename='.$filename);

		echo $output;
		exit;

	 }

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VMware Player unrecoverable error: (vmx)

When I opened my VMware today, following error was displayed:

VMware Player unrecoverable error: (vmx)

Exception 0xc0000006 (disk error while paging) has occurred.

A log file is available in "C:UsersacerDocumentsVirtual MachinesRed Hat Enterprise Linux 6 64-bitvmware.log".

You can request support.

To collect data to submit to VMware technical support, run "vm-support".

We will respond on the basis of your support entitlement.

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Solution: Remove the following two files from the VMware installed directory. You can check the installed directory from Player -> Manage -> Virtual Machine Settings -> Options

Red Hat Enterprise Linux 6 64-bit-93cd0331.vmem
Red Hat Enterprise Linux 6 64-bit-93cd0331.vmss

[Source: http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1002347]

MTNL Broadband Browsing Problem

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I am using MTNL Broadband for 1 and a half years. I had never faced Webpage browsing problem since then. I called MTNL Customer Care many times but they fooled me. Problem still not solved.

Then I started searching regarding the problem my own. I googled with the same title as this post. I found that huge number of MTNL Customers facing the same problem.

After continuous haunt for the solution I found a blog where the author introduced me about opendns. It was a new topic to me and was not that concerned. I followed the comments on that post I found some dns ips and was told that if updated on your system’s network config Browsing Problem would vanish.

Immediately, I updated my dns configuration. God damn, it worked. Thanks to the auther.

Following are the DNS IPs :

208.67.222.222,

208.67.220.220

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How to Recover Files Hidden by Virus in Pen Drive?

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Open Windows Command Prompt in elevated mode (for Windows 8, 7, Vista)
Go to path of pen drive i.e. my case it is F, type f: and hit enter
Type attrib -s -h -r /S /D and hit enter

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Load Testing on Web Servers using Apache Benchmark

After working on many websites, I found one of my site getting too many traffic bringing down the site. I contacted the technical support who fixed the problem. I had never tested load on any of my site. So, I started studying load testing on web servers. This helped me to understand how many users can be handled by my website so that it can run smoothly.

I found a very light and strong linux tool called Apache Benchmark Tool that can test load on Web Servers. This can benchmark Apache, IIS and other web server with apache benchmarking tool called ab. There are also other open source tools that helps to test load on web servers.

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I executed following command on my linux terminal:

[code]

ab -c 1000 -n 1000 -t 60 -k http://ignou.ac.in

[/code]

Option -c : This option says there are 1000 concurrent users logged in on the Web Server.

Option -n : This option sends 1000 requests to the Web Server.

Option -t : This option says users will be logged in for 60 seconds.

Option -k : For Keep Alive On

I logged in to the web server and executed the following command to test the actual load.

[code]

top

[/code]

This command helped to track down the load average, CPU and Memory Utilization of the web server.

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How to redirect http requests to https on Debian Linux with Apache Web Server?

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Do the following to redirect http requests to https running on Debian Linux with Apache Web Server.

File : /etc/apache2/ports.conf

[code]
NameVirtualHost *:80
Listen 80
[/code]

File : /etc/apache2/sites-availabe/default

[code]
<VirtualHost *:80>
ServerName www.example.com
Redirect / https://www.example.com/
</VirtualHost>

<VirtualHost *:443>
ServerName www.example.com
# … SSL configuration goes here
</VirtualHost>
[/code]

Restart Apache Webserver

[code]
/etc/init.d/apache2 restart
[/code]

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Installing and Configuring Commercial SSL on Debian Linux

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Note: Please note that commercial SSL certificates require a unique IP address for SSL-enabled sites.

a. Enable SSL for Apache and make a directory named “ssl” inside “/etc/apache2/”

[code]
a2enmod ssl
mkdir /etc/apache2/ssl
[/code]

b. Create a Certificate Signing Request

[code]
cd /etc/apache2/ssl
openssl req -new -days 365 -nodes -keyout www.mydomain.com.key -out www.mydomain.com.csr
[/code]

The above command will create a certificate signing request (CSR) for the site which you’d like to use with SSL. Leave the challenge password blank.
Execute the following command to protect the key:

[code]
chmod 400 /etc/apache2/ssl/www.mydomain.com.key
[/code]

Files for your domain will be created in /etc/apache2/ssl. You may now submit the file ending in .csr to a commercial SSL provider for signing. You will receive a signed file after the CA signs the request. Save this file as /etc/apache2/ssl/www.mydomain.com.crt.
Execute the following command to protect the signed certificate:

[code]
chmod 400 /etc/apache2/ssl/www.mydomain.com.crt
[/code]

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c. Get the CA Root Certificate
You’ll need to get the root certificate for the CA that you paid to sign your certificate. You may obtain the root certs for various providers from these sites:
Verisign
Thawte
Globalsign
Comodo
For example, if we downloaded a root cert for Verisign, we would save it to /etc/apache2/ssl/verisign.cer.
d. Configure Apache to use the Signed SSL Certificate.
We’ll add an entry to /etc/apache2/ports.conf for the IP address you’ll be using to host your SSL-enabled site.
File excerpt:/etc/apache2/ports.conf

[code]
NameVirtualHost 12.34.56.78:443
Listen 443
[/code]

Replace the above IP address with your dedicated IP Address. Next, we edit the VirtualHost Configuration file i.e. /etc/apache2/sites-available/default in our case.

[code]
<Virtualhost 10.10.10.109:443>
SSLEngine On SSLCertificateFile /etc/apache2/ssl/www.mydomain.com.crt
SSLCertificateKeyFile /etc/apache2/ssl/www.mydomain.com.key
SSLCACertificateFile /etc/apache2/ssl/verisign.cer

ServerAdmin info@mydomain.com
ServerName www.mydomain.com
DocumentRoot /var/www/
ErrorLog /var/log/apache2/error.log
CustomLog /var/log/apache2/access.log combined
</Vritaulhost>
[/code]

NOTE: You can edit your existing Virtualhost Configuration file (Virtualhost *:80) by adding the above attributes within the Virtualhost tag.

e. Restart Apache:

[code]
/etc/init.d/apache2 restart
[/code]

f. Congratulations, you’ve installed a commercial SSL certificate! You can visit your site with SSL enabled. i.e. https://mydomain.com OR https://localhost/your_website/

[Source: https://library.linode.com/web-servers/apache/ssl-guides/debian-5-lenny]

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Solution to Url Encoded Slashes (%2F) Problem in Apache

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I was working on Drupal 6. I had to troubleshoot a site that has a problem in its link. The ugly URL looks like this: http://rcportblair.ignou.ac.in/admin/build/employee/search/result/none/0/none/%252F1

The last argument in the link i.e. %252F is a forward slash automatically added by the Drupal engine which was creating problem while generating result. There are many ways to handle these urls. One way is listed below:

<VirtualHost *:80>
    AllowEncodedSlashes On
</VirtualHost>

This directive may be set in server config file (e.g. httpd.conf OR /etc/apache2/sites-available/default) and may appear inside <VirtualHost> containers to affect certain websites. Using it in .htaccess files is not allowed.

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