Anil Yadav

Tuesday, 24 June 2014

Display day month and current time through javascript

Tuesday, 25 March 2014

Redefine Constant in php

runkit_constant_redefine — Redefine an already defined constant

Thursday, 13 March 2014

Beginner questionfor html

Every .html page we create requires tags to start and end html file an recognize it as a html file.
But even when I don't give any HTML tags and simply write a text in .html file, the file gets opened in the browser with the text I have written in the .html file without using any of the HTML tags.
How is the text getting displayed in the browser without using any HTML tags?
Does the browser automatically add HTML tags behind the scenes??
When I viewed the page source in that also it shows simply the text not the HTML tags...

Thursday, 6 February 2014

Adding image in dropdown select box

Wednesday, 25 December 2013

post and get method

    GET requests can be cached
    GET requests remain in the browser history
    GET requests can be bookmarked
    GET requests should never be used when dealing with sensitive data
    GET requests have length restrictions
    GET requests should be used only to retrieve data
    since form data is in the URL and URL length is restricted. A safe URL length limit is often 2048 characters but varies by browser and web server.


    POST supports advanced functionality such as support for multi-part binary input used for file uploads to web servers.
    POST requests are never cached
    POST requests do not remain in the browser history
    POST requests cannot be bookmarked
    POST requests have no restrictions on data length

Tuesday, 24 December 2013

array_merge and array_combine

array_merge merges the elements of one or more than one array such that the value of one array appended at the end of first array. If the arrays have same strings key then the later value overrides the previous value for that key .

<?php
$array1 = array("course1" => "java","course2" => "sql");
$array2 = array(("course1" => "php","course3" => "html");
$result = array_merge($array1, $array2);
print_r($result);
?>

OUTPUT :

Array

(

[course1] => php

[course2] => sql

[course3] => html

)

Array_combine creates a new array by using the key of one array as keys and using the value of other array as values.

It returns the combine array of array 1 and array2 .

<?php
$array1 = array("course1","course2","course3");
$array2 = array(("php","html","css");

$new_array = array_combine($array1, $array2);
print_r($new_array);
?>

OUTPUT :

Array

(

[course1] => php

[course2] => html

[course3] =>css

)

Wednesday, 25 September 2013

http and https

What is HTTPS?

HTTPS (Hypertext Transfer Protocol over Secure Socket Layer, or HTTP over SSL) is a web protocol developed by Netscape.

One can say: HTTPS = HTTP + SSL

HTTPS uses Secure Socket Layer (SSL) as a sublayer under its regular HTTP application layering.

Need of HTTPS:

Hypertext Transfer Protocol (HTTP) is a protocol for transmitting and receiving information across the Internet. HTTP serves as a request and response procedure that all agents on the Internet follow so that information can be rapidly, easily, and accurately disseminated between servers, which hold information, and clients, who are trying to access it. You normally use HTTP when you are browsing the web, its not secure, so someone can eavesdrop on the conversation between your computer and the web server. In many cases, clients may be exchanging confidential information with a server, which needs to be secured in order to prevent unauthorized access. For this reason, https, or secure http, was developed by Netscape corporation to allow authorization and secured transactions.

Similarity between HTTP and HTTPS:

In many ways, https is identical to http, because it follows the same basic protocols. The http or https client, such as a Web browser, establishes a connection to a server on a standard port. When a server receives a request, it returns a status and a message, which may contain the requested information or indicate an error if part of the process malfunctioned. Both systems use the same Uniform Resource Identifier (URI) scheme, so that resources can be universally identified. Use of https in a URI scheme rather than http indicates that an encrypted connection is desired.

Difference between HTTP and HTTPS:

1. URL begins with “http://" in case of HTTP while the URL begins with “https://” in case of HTTPS.
2. HTTP is unsecured while HTTPS is secured.
3. HTTP uses port 80 for communication while HTTPS uses port 443 for communication.
4. HTTP operates at Application Layer while HTTPS operates at Transport Layer.
5. No encryption is there in HTTP while HTTPS uses encryption.
6. No certificates required in HTTP while certificates required in HTTPS.

How HTTPS works?

For HTTPS connection, public key and signed certificates are required for the server.

When using an https connection, the server responds to the initial connection by offering a list of encryption methods it supports. In response, the client selects a connection method, and the client and server exchange certificates to authenticate their identities. After this is done, both parties exchange the encrypted information after ensuring that both are using the same key, and the connection is closed. In order to host https connections, a server must have a public key certificate, which embeds key information with a verification of the key owner's identity. Most certificates are verified by a third party so that clients are assured that the key is secure.

In other words, we can say, HTTPS works similar to HTTP but SSL adds some spice in it.

HTTP includes the following actions:

1. The browser opens a TCP connection.
2. The browser sends a HTTP request to the server
3. The server sends a HTTP response to the browser. 4. The TCP connection is closed.

SSL will include the following actions:

1. Authenticate the server to the client.
2. Allow the client and server to select the cryptographic algorithms, or ciphers, that they both support.
3. Optionally authenticate the client to the server.
4. Use public-key encryption techniques to generate shared secrets.
5. Establish an encrypted SSL connection.

6. Once the SSL connection is established the usual transfer of HTTP requests will continue.

Where should https be used?

HTTPS should be used in Banking Websites, Payment Gateway, Shopping Websites, Login Pages, Emails (Gmail offers HTTPS by default in Chrome browser) and Corporate Sector Websites. For example:

PayPal: https://www.paypal.com
Google AdSense: https://www.google.com/adsense/