MRF Web

Welcome To Our Website

January 31, 2009

Mrf Web Technologies specialize in quality website management services for your business. We can assist you from the earliest development stages of your website plan to the very end stages and even more. Our support staff of graphic designers, creative writers, and marketing specialists will ensure your website solution will be creative, unique and effective for all your business needs. Visit the many services that we offer, to find out how Delta Decisions will promote your website identity to the website market at all levels.
WEBSITE DESIGN & DEVELOPMENT SERVICES
Mrf Web Technologies Providing Professional website design services for your business. We take pride in creating quality designs that meet all your needs. See our website design section; it’s one of our many website management services.
WEBSITE E-COMMERCE SOLUTIONS
Mrf Web Technologies Providing Powerful, affordable e-commerce solutions for your business. From free to very robust shopping solutions, we have something to fit your needs. See our website e-commerce section; it’s one of our valuable website management services.
WEBSITE BRANDING SOLUTIONS
Create a professional unique website presence. Brand your business domain, your products, and your website layout!
WEBSITE MARKETING SERVICES
Increase your online visibility and watch your business grow. Have your business website searchable in all major search engines. See our website marketing section; it’s one of our website management services.
WEBSITE HOSTING SERVICES
Mrf Web Technologies Providing World-class quality Tier 1 Internet Data Centers that are optimized to provide an industry-leading web, data and applications hosting environment. See our website hosting section; it’s one of our first class website management services.
WEBSITE CONTENT MANAGEMENT SYSTEM SERVICES
Mrf web technologies are now providing custom designed Mambo/Joomla content management systems for your business. Use our custom interface to control your entire internet or intranet. Create new menus, add images, save files as PDF’s all in a matter of minutes.

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DHTML Slide Show Script (On Click)

January 30, 2009

***********************************************/

//["ID of content to frequency cap", "Display frequency interval (full hours only)"]

var capcontent=new Array()

capcontent[0]=["myad", "1 hr"]

capcontent[1]=["mynote", "3 hr"]

function resetcookie(id){

var expireDate = new Date()

expireDate.setHours(expireDate.getHours()-10)

document.cookie = id+”=;path=/;expires=” + expireDate.toGMTString()

}

document.write(‘\n’)

for (i=0; i<capcontent.length; i++){

if (get_cookie(capcontent[i][0])!=parseInt(capcontent[i][1]))

resetcookie(capcontent[i][0])

showorhide(capcontent[i])

}

document.write(”)

//some content

//some content

//rest of table here

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Online Shoping Trade

January 22, 2009

Online Shoping Trade

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Web Development Most Welcome

January 16, 2009

More datail please visit our website
Web Management India
Web Solution Tools.
Mrf Web Design
Mrf Web Development
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Website

January 10, 2009

A web site is a collection of Web pages, images, videos or other digital assets that is

hosted on one or more web servers, usually accessible via the Internet.

A Web page is a document, typically written in (X)HTML, that is almost always

accessible via HTTP, a protocol that transfers information from the Web server to

display in the user’s Web browser.

All publicly accessible websites are seen collectively as constituting the “World Wide

Web”.

The pages of a website can usually be accessed from a common root URL called the

homepage, and usually reside on the same physical server. The URLs of the pages

organize them into a hierarchy, although the hyperlinks between them control how the

reader perceives the overall structure and how the traffic flows between the different

parts of the site.

Some websites require a subscription to access some or all of their content. Examples

of subscription sites include many business sites, parts of many news sites, academic

journal sites, gaming sites, message boards, Web-based e-mail, services, social

networking websites, and sites providing real-time stock market data. Because they

require authentication to view the content they are technically an Intranet site.
History

The World Wide Web was created in 1990 by CERN engineer, Tim Berners-Lee.[1] On

30 April 1993, CERN announced that the World Wide Web would be free to anyone.[2]

Before the introduction of HTML and HTTP other protocols such as file transfer protocol

and the gopher protocol were used to retrieve individual files from a server. These

protocols offer a simple directory structure which the user navigates and chooses files

to download. Documents were most often presented as plain text files without

formatting or were encoded in word processor formats.

Overview

Organized by function a website may be

* a personal website
* a commercial website
* a government website
* a non-profit organization website

It could be the work of an individual, a business or other organization, and is typically

dedicated to some particular topic or purpose. Any website can contain a hyperlink to

any other website, so the distinction between individual sites, as perceived by the

user, may sometimes be blurred.

Websites are written in, or dynamically converted to, HTML (Hyper Text Markup

Language) and are accessed using a software interface classified as an user agent.

Web pages can be viewed or otherwise accessed from a range of computer-based and

Internet-enabled devices of various sizes, including desktop computers, laptops, PDAs

and cell phones.

A website is hosted on a computer system known as a web server, also called an HTTP

server, and these terms can also refer to the software that runs on these systems and

that retrieves and delivers the Web pages in response to requests from the website

users. Apache is the most commonly used Web server software (according to Netcraft

statistics) and Microsoft’s Internet Information Server (IIS) is also commonly used.

Website styles

Static Website

A Static Website is one that has web pages stored on the server in the same form as

the user will view them. It is primarily coded in HTML (Hyper-text Markup Language).

A static website is also called a Classic website, a 5-page website or a Brochure

website because it simply presents pre-defined information to the user. It may include

information about a company and its products and services via text, photos, Flash

animation, audio/video and interactive menus and navigation.

This type of website usually displays the same information to all visitors, thus the

information is static. Similar to handing out a printed brochure to customers or clients,

a static website will generally provide consistent, standard information for an extended

period of time. Although the website owner may make updates periodically, it is a

manual process to edit the text, photos and other content and may require basic

website design skills and software.

In summary, visitors are not able to control what information they receive via a static

website, and must instead settle for whatever content the website owner has decided

to offer at that time.

They are edited using four broad categories of software:

* Text editors, such as Notepad or TextEdit, where the HTML is manipulated directly

within the editor program
* WYSIWYG offline editors, such as Microsoft FrontPage and Adobe Dreamweaver

(previously Macromedia Dreamweaver), where the site is edited using a GUI interface

and the underlying HTML is generated automatically by the editor software
* WYSIWYG Online editors, where the any media rich online presentation like

websites, widgets, intro, blogs etc. are created on a flash based platform.
* Template-based editors, such as Rapidweaver and iWeb, which allow users to

quickly create and upload websites to a web server without having to know anything

about HTML, as they just pick a suitable template from a palette and add pictures and

text to it in a DTP-like fashion without ever having to see any HTML code.

MRF Web Technologies
Mrf Web Design
Web Management India
Web Design Devlopment
Web Solution Tools

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World Wide Web

January 10, 2009

The World Wide Web (commonly shortened to the Web) is a system of interlinked

hypertext documents accessed via the Internet. With a Web browser, one can view

Web pages that may contain text, images, videos, and other multimedia and navigate

between them using hyperlinks. Using concepts from earlier hypertext systems, the

World Wide Web was begun in 1989 by English scientist Tim Berners-Lee, working at

the European Organization for Nuclear Research (CERN) in Geneva, Switzerland. In

1990, he proposed building a “web of nodes” storing “hypertext pages” viewed by

“browsers” on a network,[1] and released that web in 1992. Connected by the existing

Internet, other websites were created, around the world, adding international

standards for domain names & the HTML language. Since then, Berners-Lee has played

an active role in guiding the development of Web standards (such as the markup

languages in which Web pages are composed), and in recent years has advocated his

vision of a Semantic Web.

The World Wide Web enabled the spread of information over the Internet through an

easy-to-use and flexible format. It thus played an important role in popularising use of

the Internet, [2] to the extent that the World Wide Web has become a synonym for

Internet, with the two being conflated in popular use. [3]

How it works

Viewing a Web page on the World Wide Web normally begins either by typing the URL

of the page into a Web browser, or by following a hyperlink to that page or resource.

The Web browser then initiates a series of communication messages, behind the

scenes, in order to fetch and display it.

First, the server-name portion of the URL is resolved into an IP address using the

global, distributed Internet database known as the domain name system, or DNS. This

IP address is necessary to contact and send data packets to the Web server.

The browser then requests the resource by sending an HTTP request to the Web server

at that particular address. In the case of a typical Web page, the HTML text of the

page is requested first and parsed immediately by the Web browser, which will then

make additional requests for images and any other files that form a part of the page.

Statistics measuring a website’s popularity are usually based on the number of ‘page

views’ or associated server ‘hits’, or file requests, which take place.

Having received the required files from the Web server, the browser then renders the

page onto the screen as specified by its HTML, CSS, and other Web languages. Any

images and other resources are incorporated to produce the on-screen Web page that

the user sees.

Most Web pages will themselves contain hyperlinks to other related pages and perhaps

to downloads, source documents, definitions and other Web resources. Such a

collection of useful, related resources, interconnected via hypertext links, is what was

dubbed a “web” of information. Making it available on the Internet created what Tim

Berners-Lee first called the WorldWideWeb (a term written in CamelCase, subsequently

discarded) in November 1990.[1]

Berners-Lee has said that the most important feature of the World Wide Web is “Error

404″, which tells the user that a file does not exist. Without this feature, he said, the

web would have ground to a halt long ago.

Berners-Lee has also expressed regret over the format of the URL. Currently it is

divided into two parts – the route to the server which is divided by dots, and the file

path separated by slashes. The server route starts with the least significant element

and ends with the most significant, then the file path reverses this, moving from high

to low. Berners-Lee would have liked to see this rationalised. So an address which is

currently (e.g.) “http://www.mrfweb.we.bs /document/pictures/illustration.jpg” would

become http:/uk/co/examplesite/documents/pictures/illustration.jpg. In this format the

server no longer has any special place in the address, which is simply one coherent

hierarchical path.

History

History of the World Wide Web

This NeXT Computer used by Sir Tim Berners-Lee at CERN became the first Web server.

The underlying ideas of the Web can be traced as far back as 1980, when, at CERN in

Switzerland, Sir Tim Berners-Lee built ENQUIRE (a reference to Enquire Within Upon

Everything, a book he recalled from his youth). While it was rather different from the

system in use today, it contained many of the same core ideas (and even some of the

ideas of Berners-Lee’s next project after the World Wide Web, the Semantic Web).

In March 1989, Berners-Lee wrote a proposal[4] which referenced ENQUIRE and

described a more elaborate information management system. With help from Robert

Cailliau, he published a more formal proposal (on November 12, 1990) to build a

“Hypertext project” called “WorldWideWeb” (one word, also “W3″)[1] as a “web of

nodes” with “hypertext documents” to store data. That data would be viewed in

“hypertext pages” (webpages) by various “browsers” (line-mode or full-screen) on the

computer network, using an “access protocol” connecting the “Internet and DECnet

protocol worlds”.[1]

The proposal had been modeled after EBT’s (Electronic Book Technology, a spin-off

from the Institute for Research in Information and Scholarship at Brown University)

Dynatext SGML reader that CERN had licensed. The Dynatext system, although

technically advanced (a key player in the extension of SGML ISO 8879:1986 to

Hypermedia within HyTime), was considered too expensive and with an inappropriate

licensing policy for general HEP (High Energy Physics) community use: a fee for each

document and each time a document was charged.

A NeXT Computer was used by Berners-Lee as the world’s first Web server and also to

write the first Web browser, WorldWideWeb, in 1990. By Christmas 1990, Berners-Lee

had built all the tools necessary for a working Web:[5] the first Web browser (which

was a Web editor as well), the first Web server, and the first Web pages[6] which

described the project itself.

On August 6, 1991, he posted a short summary of the World Wide Web project on the

alt.hypertext newsgroup.[7] This date also marked the debut of the Web as a publicly

available service on the Internet.

The first server outside Europe was set up at SLAC in December 1991 [8].

The crucial underlying concept of hypertext originated with older projects from the

1960s, such as the Hypertext Editing System (HES) at Brown University— among

others Ted Nelson and Andries van Dam— Ted Nelson’s Project Xanadu and Douglas

Engelbart’s oN-Line System (NLS). Both Nelson and Engelbart were in turn inspired by

Vannevar Bush’s microfilm-based “memex,” which was described in the 1945 essay “As

We May Think”.

Berners-Lee’s breakthrough was to marry hypertext to the Internet. In his book

Weaving The Web, he explains that he had repeatedly suggested that a marriage

between the two technologies was possible to members of both technical communities,

but when no one took up his invitation, he finally tackled the project himself. In the

process, he developed a system of globally unique identifiers for resources on the Web

and elsewhere: the Uniform Resource Identifier.

The World Wide Web had a number of differences from other hypertext systems that

were then available. The Web required only unidirectional links rather than bidirectional

ones. This made it possible for someone to link to another resource without action by

the owner of that resource. It also significantly reduced the difficulty of implementing

Web servers and browsers (in comparison to earlier systems), but in turn presented the

chronic problem of link rot. Unlike predecessors such as HyperCard, the World Wide

Web was non-proprietary, making it possible to develop servers and clients

independently and to add extensions without licensing restrictions.

On April 30, 1993, CERN announced[9] that the World Wide Web would be free to

anyone, with no fees due. Coming two months after the announcement that the Gopher

protocol was no longer free to use, this produced a rapid shift away from Gopher and

towards the Web. An early popular Web browser was ViolaWWW, which was based

upon HyperCard.

Scholars generally agree, however, that the turning point for the World Wide Web

began with the introduction[10] of the Mosaic Web browser[11] in 1993, a graphical

browser developed by a team at the National Center for Supercomputing Applications at

the University of Illinois at Urbana-Champaign (NCSA-UIUC), led by Marc Andreessen.

Funding for Mosaic came from the High-Performance Computing and Communications

Initiative, a funding program initiated by the High Performance Computing and

Communication Act of 1991, one of several computing developments initiated by

Senator Al Gore.[12] Prior to the release of Mosaic, graphics were not commonly mixed

with text in Web pages, and its popularity was less than older protocols in use over the

Internet, such as Gopher and Wide Area Information Servers (WAIS). Mosaic’s graphical

user interface allowed the Web to become, by far, the most popular Internet protocol.

The World Wide Web Consortium (W3C) was founded by Tim Berners-Lee after he left

the European Organization for Nuclear Research (CERN) in October, 1994. It was

founded at the Massachusetts Institute of Technology Laboratory for Computer Science

(MIT/LCS) with support from the Defense Advanced Research Projects Agency

(DARPA)—which had pioneered the Internet—and the European Commission.

Standards
Web standards

Many formal standards and other technical specifications define the operation of

different aspects of the World Wide Web, the Internet, and computer information

exchange. Many of the documents are the work of the World Wide Web Consortium

(W3C), headed by Berners-Lee, but some are produced by the Internet Engineering

Task Force (IETF) and other organizations.

Usually, when Web standards are discussed, the following publications are seen as

foundational:

* Recommendations for markup languages, especially HTML and XHTML, from the

W3C. These define the structure and interpretation of hypertext documents.
* Recommendations for stylesheets, especially CSS, from the W3C.
* Standards for ECMAScript (usually in the form of JavaScript), from Ecma

International.
* Recommendations for the Document Object Model, from W3C.

Additional publications provide definitions of other essential technologies for the World

Wide Web, including, but not limited to, the following:

* Uniform Resource Identifier (URI), which is a universal system for referencing

resources on the Internet, such as hypertext documents and images. URIs, often called

URLs, are defined by the IETF’s RFC 3986 / STD 66: Uniform Resource Identifier (URI):

Generic Syntax, as well as its predecessors and numerous URI scheme-defining RFCs;
* HyperText Transfer Protocol (HTTP), especially as defined by RFC 2616: http://1.1

and RFC 2617: HTTP Authentication, which specify how the browser and server

authenticate each other.

Privacy

Computer users, who save time and money, and who gain conveniences and

entertainment, may or may not have surrendered the right to privacy in exchange for

using a number of technologies including the Web.[13] Worldwide, more than a half

billion people have used a social network service,[14] and of Americans who grew up

with the Web, half created an online profile[15] and are part of a generational shift

that could be changing norms.[16][17] Among services paid for by advertising, Yahoo!

could collect the most data about users of commercial websites, about 2,500 bits of

information per month about each typical user of its site and its affiliated advertising

network sites. Yahoo! was followed by MySpace with about half that potential and then

by AOL-TimeWarner, Google, Facebook, Microsoft, and eBay.[18]

Privacy representatives from 60 countries have resolved to ask for laws to complement

industry self-regulation, for education for children and other minors who use the Web,

and for default protections for users of social networks.[19] They also believe data

protection for personally identifiable information benefits business more than the sale

of that information.[19] Users can opt-in to features in browsers from companies such

as Apple, Google, Microsoft (beta) and Mozilla (beta) to clear their personal histories

locally and block some cookies and advertising networks[20] but they are still tracked

in websites’ server logs.[citation needed] Berners-Lee and colleagues see hope in

accountability and appropriate use achieved by extending the Web’s architecture to

policy awareness, perhaps with audit logging, reasoners and appliances.[21]

Security

The Web has become criminals’ preferred pathway for spreading malware. Cybercrime

carried out on the Web can include identity theft, fraud, espionage and intelligence

gathering.[22] Web-based vulnerabilities now outnumber traditional computer security

concerns,[23] and as measured by Google, about one in ten Web pages may contain

malicious code.[24] Most Web-based attacks take place on legitimate websites, and

most, as measured by Sophos, are hosted in the United States, China and Russia.[25]

The most common of all malware threats is SQL injection attacks against websites.[26]

Through HTML and URIs the Web was vulnerable to attacks like cross-site scripting

(XSS) that came with the introduction of JavaScript[27] and were exacerbated to some

degree by Web 2.0 and Ajax web design that favors the use of scripts.[28] Today by

one estimate, 70% of all websites are open to XSS attacks on their users.[29]

Proposed solutions vary to extremes. Large security vendors like McAfee already design

governance and compliance suites to meet post-9/11 regulations,[30] and some, like

Finjan have recommended active real-time inspection of code and all content regardless

of its source.[22] Some have argued that for enterprise to see security as a business

opportunity rather than a cost center,[31] “ubiquitous, always-on digital rights

management” enforced in the infrastructure by a handful of organizations must replace

the hundreds of companies that today secure data and networks.[32] Jonathan Zittrain

has said users sharing responsibility for computing safety is far preferable to locking

down the Internet.[33]

Web accessibility

Many countries regulate web accessibility as a requirement for web sites.

Java

A significant advance in Web technology was Sun Microsystems’ Java platform. It

enables Web pages to embed small programs (called applets) directly into the view.

These applets run on the end-user’s computer, providing a richer user interface than

simple Web pages. Java client-side applets never gained the popularity that Sun had

hoped for a variety of reasons, including lack of integration with other content (applets

were confined to small boxes within the rendered page) and the fact that many

computers at the time were supplied to end users without a suitably installed Java

Virtual Machine, and so required a download by the user before applets would appear.

Adobe Flash now performs many of the functions that were originally envisioned for

Java applets, including the playing of video content, animation, and some rich GUI

features. Java itself has become more widely used as a platform and language for

server-side and other programming.

JavaScript

JavaScript, on the other hand, is a scripting language that was initially developed for

use within Web pages. The standardized version is ECMAScript. While its name is

similar to Java, JavaScript was developed by Netscape and has very little to do with

Java, although the syntax of both languages is derived from the C programming

language. In conjunction with a Web page’s Document Object Model (DOM), JavaScript

has become a much more powerful technology than its creators originally

envisioned.[citation needed] The manipulation of a page’s DOM after the page is

delivered to the client has been called Dynamic HTML (DHTML), to emphasize a shift

away from static HTML displays.

In simple cases, all the optional information and actions available on a

JavaScript-enhanced Web page will have been downloaded when the page was first

delivered. Ajax (“Asynchronous JavaScript and XML”) is a group of interrelated web

development techniques used for creating interactive web applications that provide a

method whereby parts within a Web page may be updated, using new information

obtained over the network at a later time in response to user actions. This allows the

page to be more responsive, interactive and interesting, without the user having to

wait for whole-page reloads. Ajax is seen as an important aspect of what is being

called Web 2.0. Examples of Ajax techniques currently in use can be seen in Gmail,

Google Maps, and other dynamic Web applications.

Publishing Web pages

Web page production is available to individuals outside the mass media. In order to

publish a Web page, one does not have to go through a publisher or other media

institution, and potential readers could be found in all corners of the globe.

Many different kinds of information are available on the Web, and for those who wish

to know other societies, cultures, and peoples, it has become easier.

The increased opportunity to publish materials is observable in the countless personal

and social networking pages, as well as sites by families, small shops, etc., facilitated

by the emergence of free Web hosting services.

Statistics

According to a 2001 study, there were massively more than 550 billion documents on

the Web, mostly in the invisible Web, or deep Web.[34] A 2002 survey of 2,024 million

Web pages[35] determined that by far the most Web content was in English: 56.4%;

next were pages in German (7.7%), French (5.6%), and Japanese (4.9%). A more

recent study, which used Web searches in 75 different languages to sample the Web,

determined that there were over 11.5 billion Web pages in the publicly indexable Web

as of the end of January 2005.[36] As of June 2008, the indexable web contains at

least 63 billion pages.[37] On July 25, 2008, Google software engineers Jesse Alpert

and Nissan Hajaj announced that Google Search had discovered one trillion unique

URLs.[38]

Over 100.1 million websites operated as of March 2008.[39] Of these 74% were

commercial or other sites operating in the .com generic top-level domain.[39]

Speed issues

Frustration over congestion issues in the Internet infrastructure and the high latency

that results in slow browsing has led to an alternative, pejorative name for the World

Wide Web: the World Wide Wait.[citation needed] Speeding up the Internet is an

ongoing discussion over the use of peering and QoS technologies. Other solutions to

reduce the World Wide Wait can be found on W3C.

Standard guidelines for ideal Web response times are:[40]

* 0.1 second (one tenth of a second). Ideal response time. The user doesn’t sense

any interruption.
* 1 second. Highest acceptable response time. Download times above 1 second

interrupt the user experience.
* 10 seconds. Unacceptable response time. The user experience is interrupted and

the user is likely to leave the site or system.

These numbers are useful for planning server capacity.

Caching

If a user revisits a Web page after only a short interval, the page data may not need to

be re-obtained from the source Web server. Almost all Web browsers cache

recently-obtained data, usually on the local hard drive. HTTP requests sent by a

browser will usually only ask for data that has changed since the last download. If the

locally-cached data are still current, it will be reused.

Caching helps reduce the amount of Web traffic on the Internet. The decision about

expiration is made independently for each downloaded file, whether image, stylesheet,

JavaScript, HTML, or whatever other content the site may provide. Thus even on sites

with highly dynamic content, many of the basic resources only need to be refreshed

occasionally. Web site designers find it worthwhile to collate resources such as CSS

data and JavaScript into a few site-wide files so that they can be cached efficiently.

This helps reduce page download times and lowers demands on the Web server.

There are other components of the Internet that can cache Web content. Corporate and

academic firewalls often cache Web resources requested by one user for the benefit of

all. (See also Caching proxy server.) Some search engines, such as Google or Yahoo!,

also store cached content from websites.

Apart from the facilities built into Web servers that can determine when files have

been updated and so need to be re-sent, designers of dynamically-generated Web

pages can control the HTTP headers sent back to requesting users, so that transient or

sensitive pages are not cached. Internet banking and news sites frequently use this

facility.

Data requested with an HTTP ‘GET’ is likely to be cached if other conditions are met;

data obtained in response to a ‘POST’ is assumed to depend on the data that was

POSTed and so is not cached.

Link rot and Web archival

Main article: Link rot

Over time, many Web resources pointed to by hyperlinks disappear, relocate, or are

replaced with different content. This phenomenon is referred to in some circles as “link

rot” and the hyperlinks affected by it are often called “dead links”.

The ephemeral nature of the Web has prompted many efforts to archive Web sites. The

Internet Archive is one of the most well-known efforts; it has been active since 1996.

Academic conferences

The major academic event covering the Web is the World Wide Web Conference,

promoted by IW3C2.

WWW prefix in Web addresses

The letters “www” are commonly found at the beginning of Web addresses because of

the long-standing practice of naming Internet hosts (servers) according to the services

they provide. So for example, the host name for a Web server is often “www”; for an

FTP server, “ftp”; and for a USENET news server, “news” or “nntp” (after the news

protocol NNTP). These host names appear as DNS subdomain names, as in

“www.mrfweb.we.bs”.

This use of such prefixes is not required by any technical standard; indeed, the first

Web server was at “nxoc01.cern.ch”,[41] and even today many Web sites exist without

a “www” prefix. The “www” prefix has no meaning in the way the main Web site is

shown. The “www” prefix is simply one choice for a Web site’s host name.

However, some website addresses require the www. prefix, and if typed without one,

won’t work; there are also some which must be typed without the prefix. Sites that do

not have Host Headers properly setup are the cause of this. Some hosting companies

do not setup a www or @ A record in the web server configuration and/or at the DNS

server level.

Some Web browsers will automatically try adding “www.” to the beginning, and

possibly “.com” to the end, of typed URLs if no host is found without them. All major

web browsers will also prefix “http://www.mrfweb.we.bs/” and append “.com” to the

address bar contents if the Control and Enter keys are pressed simultaneously. For

example, entering “example” in the address bar and then pressing either Enter or

Control+Enter will usually resolve to “http://www.mrfweb.we.bs”, depending on the

exact browser version and its settings.
Web Management India
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Web server

January 10, 2009

1. HTTP: every web server program operates by accepting HTTP requests from the

client, and providing an HTTP response to the client. The HTTP response usually

consists of an HTML document, but can also be a raw file, an image, or some other

type of document (defined by MIME-types). If some error is found in client request or

while trying to serve it, a web server has to send an error response which may include

some custom HTML or text messages to better explain the problem to end users.
2. Logging: usually web servers have also the capability of logging some detailed

information, about client requests and server responses, to log files; this allows the

webmaster to collect statistics by running log analyzers on these files.

In practice many web servers implement the following features also:

1. Authentication, optional authorization request (request of user name and

password) before allowing access to some or all kind of resources.
2. Handling of static content (file content recorded in server’s filesystem(s)) and

dynamic content by supporting one or more related interfaces (SSI, CGI, SCGI, FastCGI,

JSP, PHP, ASP, ASP.NET, Server API such as NSAPI, ISAPI, etc.).
3. HTTPS support (by SSL or TLS) to allow secure (encrypted) connections to the

server on the standard port 443 instead of usual port 80.
4. Content compression (i.e. by gzip encoding) to reduce the size of the responses

(to lower bandwidth usage, etc.).
5. Virtual hosting to serve many web sites using one IP address.
6. Large file support to be able to serve files whose size is greater than 2 GB on 32

bit OS.
7. Bandwidth throttling to limit the speed of responses in order to not saturate the

network and to be able to serve more clients.

Origin of returned content

The origin of the content sent by server is called:

* static if it comes from an existing file lying on a filesystem;
* dynamic if it is dynamically generated by some other program or script or

application programming interface (API) called by the web server.

Serving static content is usually much faster (from 2 to 100 times) than serving

dynamic content, especially if the latter involves data pulled from a database.

Path translation

Web servers are able to map the path component of a Uniform Resource Locator (URL)

into:

* a local file system resource (for static requests);
* an internal or external program name (for dynamic requests).

For a static request the URL path specified by the client is relative to the Web server’s

root directory.

Consider the following URL as it would be requested by a client:

http://www.mrfweb.we.bs/index.html

The client’s web browser will translate it into a connection to www.example.com with

the following HTTP 1.1 request:

GET /path/file.html HTTP/1.1
Host: www.mrfweb.we.bs

The web server on www.mrfweb.we.bs will append the given path to the path of its

root directory. On Unix machines, this is commonly /var/www. The result is the local

file system resource:

/var/www/path/file.html

The web server will then read the file, if it exists, and send a response to the client’s

web browser. The response will describe the content of the file and contain the file

itself. ……….

Load limits

A web server (program) has defined load limits, because it can handle only a limited

number of concurrent client connections (usually between 2 and 60,000, by default

between 500 and 1,000) per IP address (and TCP port) and it can serve only a certain

maximum number of requests per second depending on:

* its own settings;
* the HTTP request type;
* content origin (static or dynamic);
* the fact that the served content is or is not cached;
* the hardware and software limits of the OS where it is working.

When a web server is near to or over its limits, it becomes overloaded and thus

unresponsive.

Overload causes
A daily graph of a web server’s load, indicating a spike in the load early in the day.

At any time web servers can be overloaded because of:

* Too much legitimate web traffic (i.e. thousands or even millions of clients hitting

the web site in a short interval of time. e.g. Slashdot effect);
* DDoS (Distributed Denial of Service) attacks;
* Computer worms that sometimes cause abnormal traffic because of millions of

infected computers (not coordinated among them);
* XSS viruses can cause high traffic because of millions of infected browsers and/or

web servers;
* Internet web robots traffic not filtered/limited on large web sites with very few

resources (bandwidth, etc.);
* Internet (network) slowdowns, so that client requests are served more slowly and

the number of connections increases so much that server limits are reached;
* Web servers (computers) partial unavailability, this can happen because of

required or urgent maintenance or upgrade, HW or SW failures, back-end (i.e. DB)

failures, etc.; in these cases the remaining web servers get too much traffic and

become overloaded.

Overload symptoms

The symptoms of an overloaded web server are:

* requests are served with (possibly long) delays (from 1 second to a few hundred

seconds);
* 500, 502, 503, 504 HTTP errors are returned to clients (sometimes also unrelated

404 error or even 408 error may be returned);
* TCP connections are refused or reset (interrupted) before any content is sent to

clients;
* in very rare cases, only partial contents are sent (but this behavior may well be

considered a bug, even if it usually depends on unavailable system resources).

Anti-overload techniques

To partially overcome above load limits and to prevent overload, most popular web

sites use common techniques like:

* managing network traffic, by using:
o Firewalls to block unwanted traffic coming from bad IP sources or having bad

patterns;
o HTTP traffic managers to drop, redirect or rewrite requests having bad HTTP

patterns;
o Bandwidth management and traffic shaping, in order to smooth down peaks in

network usage;
* deploying web cache techniques;
* using different domain names to serve different (static and dynamic) content by

separate Web servers, i.e.:
o

http://images.mrfweb.we.bs/
o

http://www.mrfweb.we.bs/

* using different domain names and/or computers to separate big files from small

and medium sized files; the idea is to be able to fully cache small and medium sized

files and to efficiently serve big or huge (over 10 – 1000 MB) files by using different

settings;
* using many Web servers (programs) per computer, each one bound to its own

network card and IP address;
* using many Web servers (computers) that are grouped together so that they act or

are seen as one big Web server, see also: Load balancer;
* adding more hardware resources (i.e. RAM, disks) to each computer;
* tuning OS parameters for hardware capabilities and usage;
* using more efficient computer programs for web servers, etc.;
* using other workarounds, especially if dynamic content is involved.

Historical notes
The world’s first web server.

In 1989 Tim Berners-Lee proposed to his employer CERN (European Organization for

Nuclear Research) a new project, which had the goal of easing the exchange of

information between scientists by using a hypertext system. As a result of the

implementation of this project, in 1990 Berners-Lee wrote two programs:

* a browser called WorldWideWeb;
* the world’s first web server, later known as CERN HTTPd, which ran on NeXTSTEP.

Between 1991 and 1994 the simplicity and effectiveness of early technologies used to

surf and exchange data through the World Wide Web helped to port them to many

different operating systems and spread their use among lots of different social groups

of people, first in scientific organizations, then in universities and finally in industry.

In 1994 Tim Berners-Lee decided to constitute the World Wide Web Consortium to

regulate the further development of the many technologies involved (HTTP, HTML, etc.)

through a standardization process.

The following years are recent history which has seen an exponential growth of the

number of web sites and servers.

Market structure

Given below is a list of top Web server software vendors published in a Netcraft survey

in September 2008.
Vendor Product Web Sites Hosted Percent
Apache Apache 91,068,713 50.24%
Microsoft IIS 62,364,634 34.4%
Google GWS 10,072,687 5.56%
lighttpd lighttpd 3,095,928 1.71%
nginx nginx 2,562,554 1.41%
Oversee Oversee 1,938,953 1.07%
Others – 10,174,366 5.61%
Total – 181,277,835 100.00%

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Modern programming

January 10, 2009

Quality requirements

Whatever the approach to software development may be, the final program must

satisfy some fundamental properties. The following five properties are among the most

relevant:

* Efficiency/Performance: the amount of system resources a program consumes

(processor time, memory space, slow devices, network bandwidth and to some extent

even user interaction), the less the better.
* Reliability: how often the results of a program are correct. This depends on

prevention of error propagation resulting from data conversion and prevention of errors

resulting from buffer overflows, underflows and zero division.
* Robustness: how well a program anticipates situations of data type conflict and

other incompatibilities that result in run time errors and program halts. The focus is

mainly on user interaction and the handling of exceptions.
* Usability: the clarity and intuitiveness of a programs output can make or break its

success. This involves a wide range of textual and graphical elements that makes a

program easy and comfortable to use.
* Portability: the range of computer hardware and operating system platforms on

which the source code of a program can be compiled/interpreted and run. This depends

mainly on the range of platform specific compilers for the language of the source code

rather than anything having to do with the program directly.

Algorithmic complexity

The academic field and the engineering practice of computer programming are both

largely concerned with discovering and implementing the most efficient algorithms for a

given class of problem. For this purpose, algorithms are classified into orders using

so-called Big O notation, O(n), which expresses resource use, such as execution time

or memory consumption, in terms of the size of an input. Expert programmers are

familiar with a variety of well-established algorithms and their respective complexities

and use this knowledge to choose algorithms that are best suited to the circumstances.

Methodologies

The first step in most formal software development projects is requirements analysis,

followed by testing to determine value modeling, implementation, and failure

elimination (debugging). There exist a lot of differing approaches for each of those

tasks. One approach popular for requirements analysis is Use Case analysis.

Popular modeling techniques include Object-Oriented Analysis and Design (OOAD) and

Model-Driven Architecture (MDA). The Unified Modeling Language (UML) is a notation

used for both OOAD and MDA.

A similar technique used for database design is Entity-Relationship Modeling (ER

Modeling).

Implementation techniques include imperative languages (object-oriented or

procedural), functional languages, and logic languages.

Measuring language usage

It is very difficult to determine what are the most popular of modern programming

languages. Some languages are very popular for particular kinds of applications (e.g.,

COBOL is still strong in the corporate data center, often on large mainframes, FORTRAN

in engineering applications, and C in embedded applications), while some languages

are regularly used to write many different kinds of applications.

Methods of measuring language popularity include: counting the number of job

advertisements that mention the language[7], the number of books teaching the

language that are sold (this overestimates the importance of newer languages), and

estimates of the number of existing lines of code written in the language (this

underestimates the number of users of business languages such as COBOL).

Debugging
A bug which was debugged in 1947.

Debugging is a very important task in the software development process, because an

erroneous program can have significant consequences for its users. Some languages are

more prone to some kinds of faults because their specification does not require

compilers to perform as much checking as other languages. Use of a static analysis tool

can help detect some possible problems.

Debugging is often done with IDEs like Visual Studio, NetBeans, and Eclipse.

Standalone debuggers like gdb are also used, and these often provide less of a visual

environment, usually using a command line.

Programming languages

Main articles: Programming language and List of programming languages

Different programming languages support different styles of programming (called

programming paradigms). The choice of language used is subject to many

considerations, such as company policy, suitability to task, availability of third-party

packages, or individual preference. Ideally, the programming language best suited for

the task at hand will be selected. Trade-offs from this ideal involve finding enough

programmers who know the language to build a team, the availability of compilers for

that language, and the efficiency with which programs written in a given language

execute.

Allen Downey, in his book How To Think Like A Computer Scientist, writes:

The details look different in different languages, but a few basic instructions appear

in just about every language: input: Get data from the keyboard, a file, or some other

device. output: Display data on the screen or send data to a file or other device. math:

Perform basic mathematical operations like addition and multiplication. conditional

execution: Check for certain conditions and execute the appropriate sequence of

statements. repetition: Perform some action repeatedly, usually with some variation.

Many computer languages provide a mechanism to call functions provided by libraries.

Provided the functions in a library follow the appropriate runtime conventions (eg,

method of passing arguments), then these functions may be written in any other

language.

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Computer programming

January 10, 2009

Computer programming (often shortened to programming or coding) is the process of

writing, testing, debugging/troubleshooting, and maintaining the source code of

computer programs. This source code is written in a programming language. The code

may be a modification of an existing source or something completely new. The purpose

of programming is to create a program that exhibits a certain desired behavior

(customization). The process of writing source code often requires expertise in many

different subjects, including knowledge of the application domain, specialized

algorithms and formal logic.
Overview

Within software engineering, programming (the implementation) is regarded as one

phase in a software development process.

There is an ongoing debate on the extent to which the writing of programs is an art, a

craft or an engineering discipline.[1] Good programming is generally considered to be

the measured application of all three, with the goal of producing an efficient and

evolvable software solution (the criteria for “efficient” and “evolvable” vary

considerably). The discipline differs from many other technical professions in that

programmers generally do not need to be licensed or pass any standardized (or

governmentally regulated) certification tests in order to call themselves “programmers”

or even “software engineers.” However, representing oneself as a “Professional

Software Engineer” without a license from an accredited institution is illegal in many

parts of the world.

Another ongoing debate is the extent to which the programming language used in

writing computer programs affects the form that the final program takes. This debate is

analogous to that surrounding the Sapir-Whorf hypothesis [2] in linguistics, that

postulates that a particular language’s nature influences the habitual thought of its

speakers. Different language patterns yield different patterns of thought. This idea

challenges the possibility of representing the world perfectly with language, because it

acknowledges that the mechanisms of any language condition the thoughts of its

speaker community.

Said another way, programming is the craft of transforming requirements into

something that a computer can execute.

History of programming

See also: History of programming languages

Wired plug board for an IBM 402 Accounting Machine.

The concept of devices that operate following a pre-defined set of instructions traces

back to Greek Mythology, notably Hephaestus and his mechanical servants[3]. The

Antikythera mechanism was a calculater utilizing gears of various sizes and

configuration to determine its operation. The earliest known programmable machines

(machines whose behavior can be controlled and predicted with a set of instructions)

were Al-Jazari’s programmable Automata in 1206.[4] One of Al-Jazari’s robots was

originally a boat with four automatic musicians that floated on a lake to entertain

guests at royal drinking parties. Programming this mechanism’s behavior meant placing

pegs and cams into a wooden drum at specific locations. These would then bump into

little levers that operate a percussion instrument. The output of this device was a

small drummer playing various rhythms and drum patterns.[5][6] Another sophisticated

programmable machine by Al-Jazari was the castle clock, notable for its concept of

variables which the operator could manipulate as necessary (i.e. the length of day and

night). The Jacquard Loom, which Joseph Marie Jacquard developed in 1801, uses a

series of pasteboard cards with holes punched in them. The hole pattern represented

the pattern that the loom had to follow in weaving cloth. The loom could produce

entirely different weaves using different sets of cards. Charles Babbage adopted the

use of punched cards around 1830 to control his Analytical Engine. The synthesis of

numerical calculation, predetermined operation and output, along with a way to

organize and input instructions in a manner relatively easy for humans to conceive and

produce, led to the modern development of computer programming.

Development of computer programming accelerated through the Industrial Revolution.

The punch card innovation was later refined by Herman Hollerith who, in 1896 founded

the Tabulating Machine Company (which became IBM). He invented the Hollerith

punched card, the card reader, and the key punch machine. These inventions were the

foundation of the modern information processing industry. The addition of a plug-board

to his 1906 Type I Tabulator allowed it to do different jobs without having to be

physically rebuilt. By the late 1940s there were a variety of plug-board programmable

machines, called unit record equipment, to perform data processing tasks (card

reading). Early computer programmers used plug-boards for the variety of complex

calculations requested of the newly invented machines.
Data and instructions could be stored on external punch cards, which were kept in order

and arranged in program decks.

The invention of the Von Neumann architecture allowed computer programs to be

stored in computer memory. Early programs had to be painstakingly crafted using the

instructions of the particular machine, often in binary notation. Every model of

computer would be likely to need different instructions to do the same task. Later

assembly languages were developed that let the programmer specify each instruction in

a text format, entering abbreviations for each operation code instead of a number and

specifying addresses in symbolic form (e.g. ADD X, TOTAL). In 1954 Fortran, the first

higher level programming language, was invented. This allowed programmers to specify

calculations by entering a formula directly (e.g. Y = X*2 + 5*X + 9). The program text,

or source, was converted into machine instructions using a special program called a

compiler. Many other languages were developed, including ones for commercial

programming, such as COBOL. Programs were mostly still entered using punch cards or

paper tape. (See computer programming in the punch card era). By the late 1960s, data

storage devices and computer terminals became inexpensive enough so programs could

be created by typing directly into the computers. Text editors were developed that

allowed changes and corrections to be made much more easily than with punch cards.

As time has progressed, computers have made giant leaps in the area of processing

power. This has brought about newer programming languages that are more abstracted

from the underlying hardware. Although these more abstracted languages require

additional overhead, in most cases the huge increase in speed of modern computers

has brought about little performance decrease compared to earlier counterparts. The

benefits of these more abstracted languages is that they allow both an easier learning

curve for people less familiar with the older lower-level programming languages, and

they also allow a more experienced programmer to develop simple applications quickly.

Despite these benefits, large complicated programs, and programs that are more

dependent on speed still require the faster and relatively lower-level languages with

today’s hardware. (The same concerns were raised about the original Fortran language.)

Throughout the second half of the twentieth century, programming was an attractive

career in most developed countries. Some forms of programming have been increasingly

subject to offshore outsourcing (importing software and services from other countries,

usually at a lower wage), making programming career decisions in developed countries

more complicated, while increasing economic opportunities in less developed areas. It

is unclear how far this trend will continue and how deeply it will impact programmer

wages and opportunities.
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Computer Programming