India starts blocking file storage websites in a move against piracy

India starts blocking file storage websites in a move against piracy

File storage websites such as Megaupload, Putlocker, Rapidshare are being blocked in India.

A thread started on a popular online forum focused on developments in Indian broadband has furious and surprised users sharing a list of websites blocked by their Internet service providers. Going through the thread and my Twitter interactions, India’s Department of Telecommunication is behind the block.

Some users say they are not able to browse the file uploading websites, others say they can access and download content. A screenshot shared by Sunny Chahal on Twitter confirms that the block is in effect. Some other users are seeing the same notice. The error message:

Users of popular Internet Service Providers MTNL, BSNL and Airtel have confirmed seeing the same error while visiting some or all of the following websites:

Megaupload.com
Mediafire.com
Megavideo.com
VideoBB.com
Novamov.com
Movshare.net
Rapidshare.com
Putlocker.com
Hotfile.com
Fileserve.com
Filesonic.com
Filesonic.in
Depositfiles.com
Wupload.com

The decision behind banning the websites looks like piracy. Most of these websites are widely used to share content production houses and record labels would want users to pay for. Users are comparing the ban to Internet rules in China. The Department of Homeland Security in the US also made definitive moves against piracy by seizing domains of websites hosting pirated content.

As of now there is no official word from the DoT, the story will be updated as we get more information.

Update: Reliance BIG Pictures obtained a court order to get the sites banned. Users are reporting that most of these websites are now working.

Boost Weak Cell Service at Home: Your Options

Boost Weak Cell Service at Home: Your Options

Even the best wireless networks often can't deliver a consistent signal inside your house. Femtocells and repeaters will usually help, but they'll cost you.

The problem is familiar to many cell phone users: When you're indoors, even within your carrier's coverage area, the network's signal sometimes simply isn't strong enough to support voice calls or data services. With so many consumers ditching their landlines for cell phones, poor reception at home is no longer acceptable. Fortunately, a slew of products now address the problem, though they don't come cheap.

Ssignal-boosting products generally fall into one of two categories: femtocells or signal repeaters. Both types of equipment can deliver strong signals within buildings, but they work in fundamentally different ways.

Femtocells act as miniature cell phone towers that connect to a home network router and use your wired broadband connection to move voice calls and data services to and from your carrier's network. Femtocells don't rely on the carrier's towers at all, but because they use technology that can direct data and calls back to the carrier networks over the Internet, most of them are sold by the carriers themselves.

Repeaters and boosters, on the other hand, amplify and rebroadcast cell tower signals. Since they don't require carrier support, they tend to be manufactured and sold by third parties such as Wi-Ex (under the brand name ZBoost) and Wilson Electronics.
Understanding Femtocells

While repeaters have been around for several years, femtocells are relative newcomers to the mobile scene. Of the four major U.S. carriers, two--Sprint and Verizon--have been selling femtocells (under the brand names Airave and Network Extender, respectively) for the past few years; AT&T introduced its 3G MicroCell femtocell last year.

The first Sprint and Verizon Wireless femtocells supported only voice calls, but current models support high-speed data as well as voice. Sprint charges $130 for its Airave access point (with a two-year service plan); there's no additional charge for using Airave to enhance coverage with an existing plan, but Sprint does offer a $25-a-month unlimited calling plan for Airave calls--which might appeal to anyone who is considering dropping landline voice service. Current Airave access points support EvDO Rev. A 3G data speeds and up to six simultaneous calls.

Verizon Wireless charges $250 for its Network Extender, which also supports 3G data, and the carrier imposes no monthly service fee. AT&T sells the MicroCell for $150, also with no mandatory service fee; it also offer an optional $20-a-month unlimited calling plan, plus price breaks for customers who sign up for the company's DSL service.

The Beauty of the Femtocell

AT&T's 3G MicroCell, made by Cisco.

Femtocells appeal to consumers and carriers on several levels. Consumers like them because they provide immediate five-bar coverage across an area of up to 2500 square feet, regardless of how far you are from a cell phone tower. A strong signal typically means better voice quality, fewer dropped calls, and faster data speeds. Good signals also improve a phone's battery life, since its radios don't have to work as hard.

Femtocells are low-power wireless access points that operate within a licensed spectrum to connect standard mobile devices to a mobile operator’s network via residential DSL or cable broadband connections.

Another benefit: You can configure the femtocell to recognize and prioritize the phones you authorize, so neighbors can't mooch off your service at your expense. Interestingly, Verizon Wireless's FAQ for its Network Extender says that, though you can prioritize up to 50 Verizon Wireless numbers, the device will remain available to all Verizon Wireless subscribers within range when priority numbers aren't using it.

This brings us to a big reason why wireless providers like femtocells: They offload some of the expense that the carriers might otherwise incur in order to expand network capacity and/or coverage. Femtocells also help retain customers in locations where carriers can't significantly improve reception on their own (such as basements, suburbs that don't want new cell towers, locales with difficult topography such as steep hills and valleys, and skyscrapers with thick walls). In fact, forum posts indicate that Sprint has occasionally given customers Airave units to keep them from switching to another carrier.


Femtocell Weaknesses

Price aside, femtocells have some limitations. For one thing, you can use a femtocell only at the address where it is registered. To enforce that restriction, the FCC stipulates that all femtocells must be equipped with GPS receivers, and that they either must be placed close enough to a window to receive GPS signals directly or must be connected to a GPS antenna that can pick up the signals.

David Nowicki, marketing vice president for femtocell vendor Airvana and for the Femto Forum trade association, says that the FCC imposed the location restriction to enable carriers to track the femtocell's position and disable its operation in areas where the carrier doesn't own the frequencies that the femtocell supports and where, consequently, using the femtocell might interfere with another carrier's network. Even so, forum posts suggest that femtocells sometimes hurt neighbors' regular network reception when deployed in close proximity.

Then again, it’s not necessarily a bad thing that femtocells are aware of their location. That, coupled with the device's ability to recognize when an authorized phone is nearby, could enable carriers to offer customers additional services that go beyond improving reception, including 911 services.

Network handoff issues are another concern. You can start a call on femtocell service and then hand it off to the regular network as you leave the femtocell's coverage area (assuming that the nearest cell tower is close enough). But calls initiated on the regular network can't be handed off to a femtocell.

And finally, critics complain about having to pay for a service that essentially deliver what the wireless network is supposed to have provided all along. "It's a fair point," Nowicki concedes. But carrier spokespeople say that no carrier can provide coverage in all locations of its service area. Verizon Wireless spokesperson Thomas Pica describes the Network Extender as a "niche product," given that the vast majority of Verizon customers don't need one because of the carrier's robust network.

What about the broadband ISP that now gets to carry the wireless carrier's traffic? Nowicki says that the bandwidth consumption of mobile devices is tiny compared to that of most home and office networks. For that reason, femtocells don't impose a significant burden on the ISP, which in some cases is run by the same company as the mobile carrier anyway.
T-Mobile’s Approach

T-Mobile has taken a different approach to improving weak cell signals. Phones that support Wi-Fi Calling use UMA (Unified Mobile Access) technology to route calls over Wi-Fi hotspots. T-Mobile notes that this helps with calls made through any hotspot that its phones can access, and not just at a single location (which is the case with femtocells). However, T-Mobile's Android phones can't hand off calls made using Wi-Fi hotspots to T-Mobile's cellular network; other phones that support Wi-Fi Calling can. T-Mobile has no announced plans to introduce femtocells, but a spokesperson says that the carrier continues to review customer equipment options for improving coverage.


Repeaters and Boosters

Repeaters (also called "boosters")--the other class of products designed to improve poor cell reception--depend on at least a weak cell tower signal to amplify and rebroadcast. They work with specific frequencies, independent of carrier; some support more than one frequency. On the frequencies they support, repeaters improve both voice calls and data speeds.




Many repeaters have multiple parts, starting with an antenna that you place as close as possible to the strongest cell tower signal--typically, near a window or even outdoors. The antenna transmits signals over a cable connected to an amplifier, which boosts the signal and retransmits it indoors. In some cases, the amplifier and indoor antenna are integrated; in others, the amplifier hooks up to a separate, centrally located indoor antenna in the home or office. The area of coverage depends on the strength of the amplifier and of the signal being amplified.

Unlike femtocells, repeaters can't be configured to recognize specific phones. Consequently, the amplified signals benefit any mobile device within range that operates on the supported frequencies--though obviously the owner's devices are more likely to benefit than a neighbor's devices located farther away from the indoor antenna. It's up to you (with the help of your reseller) to ensure that your repeater kit amplifies the frequency or frequencies that your carrier uses in your area. You can get help in choosing the right repeater kit from specialty retailers such as wpsantennas.com or RepeaterStore.
Repeaters Don’t Come Cheap

Repeater kits can be more expensive than femtocells. Pricing depends on how large an area you want to cover. Wi-Ex's ZBoost line includes SoHo products that range in price from $169 to $399, and you can spend up to $600 for kits that cover areas larger than 2500 feet--the maximum handled by femtocells. On the other hand, Wi-Ex marketing vice president Sharon Cupett notes, there are no monthly fees for repeaters--and of course, no broadband service is involved.

Though repeaters rebroadcast over carrier-owned frequencies, they are legal if they don't interfere with cell tower signals (which is why repeater signals have limited strength). One way to avoid problems is to look for FCC-certified repeaters; some are still awaiting approval, however. Check with the reseller.
Repeater vs. Femtocell

Should you get a repeater or a femtocell? Generally, femtocells are a good match for cell phone customers with broadband service who don't want to pay $300 or more for equivalent repeater coverage and who want to avoid many of the antenna-positioning hassles that repeaters entail. You do need a GPS signal, but those are available pretty much everywhere. Cell tower sites with signals that repeaters can work with are probably less common. But if your carrier doesn't offer a femtocell, a repeater may be the only way to improve your indoor coverage.

Review : D-Link DIR-685 Xtreme N Storage Router

D-Link DIR-685 Xtreme N Storage Router
Price: Rs 13,000

Summary

Wireless routers are generally seen as boring devices that only serve to provide signal coverage for Internet access throughout the house. But the latest "storage router" from D-Link is quite a big exception, and an exciting one at that. Those who live in geek-land will be glad to see that the DIR-685 offers plenty of opportunities for tweaking and making full-use of the router long after its initial setup.




Pros:

* Two USB ports for storage/print server
* Internal SATA 2.5-inch drive bay
* Wired Gigabit ports
* Wireless-N (802.11n)
* Built-in color LCD screen as photo frame and status info

Cons:

* Can get noisy with HDD installed
* Expensive, yet only 1 year warranty

The built-in 3.2-inch LCD screen in front is about as large as many mobile phone screens today.

Full Review

The D-Link DIR-685 Xtreme N Storage Router is quite the multi-functional device. It is only as small as other wireless routers, but it packs in a lot more than just Wi-Fi and wired Ethernet ports. In addition to the basic functionality of a networking device, you can also use it as a networked storage device (NAS or file server), print server (by sharing it out via USB), streaming media server, digital photo frame, RSS reader and as a digital weather-man.

This glossy black colored Wireless-N router with internal antenna looks stylish whether it is wall-mounted or stood on its stand. It is a high-end product and does not skimp on the feature-set, with 5 Ethernet ports, 2 USB ports, a SATA 2.5-inch HDD internal drive bay, built-in LCD screen and touch-buttons to control the LCD. Since you can see a detailed list of features on the "Specifications" tab of this review and the product's homepage"http://www.dlink.com/products/?pid=DIR-685&print=1", we shall get into our observations and the real-world user experience right away.

Significant Features
Not only were the 4 LAN ports of the Gigabit type, but the WAN port (network uplink for internet or cascading network) was a Gigabit one too, thus being faster than the usual 100Mbps ports. The power cable had a switch in the middle, which you could use to switch on/off the router and that was a nice touch. Setting up the router was a cinch with its easy interface and help tips. All of the usual security standards and routing settings were present. The WPS (Wi-Fi Protected Standard) functionality was straight-forward with a touch button to be pressed for quick connection, and the small LCD screen provided status updates and hand-holding all the way. Considering that it has 3 possible storage options, storage settings were well provided for, with user access control, streaming media server support, and BitTorrent download manager. You can have it e-mail activity logs to an administrative mail address of your choice, you need to provide details of the outgoing mail server of course.

For home users whose external IP address would keep changing, hosting a publicly accessible Internet server is made possible via support for Dynamic DNS updating services. In addition to the widely used DynDNS, it also supports D-Link's own DDNS service – note that this second option is not currently supported by other router brands or even by D-Link’s own lower-end ones – so stick to DynDNS if you are likely to change routers frequently. A “website filter” is offered, using which you can implement parental control – up to 25 sites can be listed on the filter, which you can then either whitelist (only allow these) or blacklist (only block these) as per your requirement. The “guest zone” and its controls of schedule, allowed clients and routing/isolation is mention-worthy. There is a “Schedule” configuration option, which is used to manage rules for "Internet Setup", "Wireless Setup", "Network Filter", "Guest Zone", "Firewall Settings" and "Website Filter".

Web UI
Logging in through the Web UI (web browser-based user interface) to administer the D-Link DIR-685 Xtreme N router threw up interesting features. You can have CAPTCHA enabled even for Web UI login, which it terms as "graphical authentication", this could theoretically stave off brute-force bot/malware logins. A "System Check" option allows for checking to graphically view which wired Ethernet ports are physically connected, which helps while trouble-shooting connection problems. As usual, the settings could be exported/imported from a saved file, and the firmware was upgradable. A version 2.0 of the firmware was available with improvements for the router, so we promptly upgraded to the newer firmware downloaded off D-Link’s support section.

The Web UI is the one that allows for configuring settings/security, and we found this to be well organized. It uses a system of 4-way navigation. Main configuration sections are at a top navigation bar, sub-sections when you enter each of these show up on a left-hand pane, and the actual settings/options being configured show in the middle pane. The fourth pane is on the right-hand side, and calls itself "Helpful Hints". Unfortunately these "hints" are not as in-depth as expected and there is no context-sensitive help on a per-setting basis. The "hints" only offer the most basic information, of the sort that the user already knows (a person who’d pour Rs. 13k into this kind of a router rarely is a novice). Mercifully, the "Save Settings" button which you have to click after making changes in any section is quite responsive and quick in functionality (unlike some routers that take almost a minute each time you save settings to get back to a usable state, which can quickly get exasperating).

LCD and touch-buttons
The touch-based buttons on the front of the device were workable but unresponsive at times. So while there is a lot you can do directly with the router and its buttons, you’d try to avoid using the buttons after the novelty has faded off. The Framechannel service is the one that delivers internet content (weather forecast, RSS feed, photo sites) directly onto the router’s screen. The 3.2-inch LCD screen is about as large as many mobile phone screens today, and while watching photos on it is not optimal, the fact that it can be done at all is pretty good. Photos can be viewed from any of the connected storage devices, and you can configure the brightness/idle time of the screen. During idle time in-between uses, the screen displays a clock with time and date for the specified idle time, and then blanks out when it enters standby mode.

Performance
During tests, the D-Link DIR-685 WiFi router did not match the levels we saw with the Asus RT-N16, but still performed quite well. The range was good enough to cover a large home across three floors (router was in the intermediate floor) and yet have some range left to cover the lawn. The area (range) it did cover could see good speeds, never going below 65% signal strength (three bars out of five). What we have in the performance tab is the consistent performance averaged over a period of time. The speeds seen are all from real world testing, and include walls and floors (of a multi-storey building) placed in-between the wireless router and client. On flat open ground/surface with no objects to interfere in between and no walls, just a green field – we saw a maximum range of 27m for the wireless signal when no other devices were interfering.

Wrapping up
Besides the minor negatives already mentioned above, there were some other things to report. Firstly, at its price-level it is strange that the DIR-685 is not a dual-band router, it operates only over 2.4 GHz spectrum and not 5 GHz unlike other routers that sell at half its price. This means you have to keep watching out for interference and speed/signal strength drops. Secondly, the provided 2-pin Indian plug does not have grounding, so be careful with the metal parts of the 2 USB ports at the back, it is possible to receive a slight shock. Thirdly, the internal hard drive bay was a good idea but needs better implementation. The bay only supports 2.5-inch laptop internal HDDs, so we inserted a 500GB drive. But there was a problem with removing it, since the eject mechanism (a deep-push button at the back) could only do so much, and we had to use other tools to pull the HDD out. When the HDD is plugged in and gets warm (which is normal with a 24x7 device like a router), the router’s internal fan becomes very audible in the midst of silence. The router supports power conservation and can “suspend” the internal hard disk, but this is still something to keep in mind. D-Link offers a warranty of one year with this product, as against some other brands with a warranty period of 3 years.

Bottom Line

All said and done, this router turns in a respectable performance as a router, and the extra features are great for enthusiasts. Being able to fit all of that functionality in there and making it compact enough to facilitate carrying an internal HDD is not something to sneer at. If converging so much into a single device is the template for wireless routers in the future, the DIR-685 sure is a pioneer even if some of its features still need polishing. At the moment though, the high price and lack of dual-band operation is a deterrent and stands between it and an even better rating.


Source : PCW

The battle of the Web browsers

The Best Web Browser

Not too long ago the job of a Web browser was simple: Get the text from the Internet and pour it into the window. If a tag like comes along, change the font. Now the challenges are greater because the browser is becoming the home for almost everything we do. Do you have documents to edit? There's a website for that. Did you miss a television show? There's a website for that. Do you want to announce your engagement? There's a website for that too. The Web browser handles all of that and more.

Choosing a best browser is an impossible job. On one hand, the programs are as close to commodities as there are in the computer industry. The core standards are pretty solid and the job of rendering the document is well understood. Most differences can be smoothed over when the Web designers use cross-platform libraries like jQuery. Many websites look the same in all of the major browsers, a testament to the hard work of the developers and their desire to get their information out to the largest audience.

On the other hand, there's a lot of competition, and some very smart people are working hard to produce very clever new innovations. Yes, some of the so-called innovations are trivial, but if you're going so spend all day with a piece of software, it makes sense to be picky. While you may not care if someone moves a button from the left to the right, other users do -- and the discussion forums are filled with debate.

It may be impossible to be rational about many of the cosmetic issues, like the placement of buttons or the location of the tabs. These are intensely personal decisions, and the look and feel can often be changed with add-ons. There's not much point debating these issues.

The technical details can also be a bit personal and political, but they have bigger implications for developers and consumers everywhere. You may or may not like Adobe Flash, but the support or lack of support is important for all of us. Careers of Flash developers and the fate of projects they build will rise and fall on these issues. And Flash is just the beginning -- all of the browsers are rolling out various combinations of new features, but developers can't begin to use them until there's a stable platform with wide enough adoption. The control of the living room screen is worth billions of dollars, and the success or failure of the browser's video delivery mechanism will determine who may or may not have control over that shimmering rectangle and the zombie eyes glued to it.

Choosing a Web browser is made even harder because solid numbers are often preludes to debate. Some people complain when their browsers suck up every spare byte of memory. Others want their browsers to respond immediately. In many cases there's a trade-off because the programmers gain speed by filling up the memory and pre-computing and pre-compiling every part of the Web page. You can have small or you can have fast, but you can't have both.

Often, the bloat isn't the fault of the browsers themselves, but the Web designers who lard up the site with endless AJAX calls and slick morphing features. Some users may blame the browser when they have 80-odd tabs opened to pages that are issuing AJAX calls left and right. The poor browser has to try to keep them all ready in case someone wants to see any of those tabs immediately.

Choosing among Chrome, Firefox, Internet Explorer, Opera, and Safari is not simple. All are perfectly good choices, but one may be slightly better for certain users than others. Sophisticated users, including developers, may want a browser that supports the latest standards, while casual users may want to avoid the cutting edge for simplicity and stability. Others may have a favorite plug-in they can't live without. Some users may want to choose based on the location of the buttons. The choices are close enough that this could be fair if you really care about your interface.


The battle of the Web browsers: Google Chrome 5.0

It's easy for a programmer to be enthusiastic about Google's Chrome because Google has been emphasizing some of the things that programmers love. Chrome sticks each Web page in a completely separate process, which you can see by opening up Windows Task Manager. If some Web programmer creates an infinite loop or a bad AJAX call in a Web page, Chrome isolates the trouble. Your other pages can keep on running. This isolation isn't perfect, though, because Chrome users have still experienced crashes.

The good news is that Chrome is among the fastest current browsers, at least when using long-running JavaScript loops as benchmarks. It also offers good support of the HTML5 standards and will continue to push them, at least in spirit.

There is some confusion afoot, though, because in addition to backing HTML5, Google is also embracing Adobe Flash. Google is supporting Flash by including it in the Android OS, and reports claim future versions of Chrome will sport their own, well-tuned version of the Flash plug-in, an approach that will probably do even more to fix crashes and annoying bugs. The developers won't be able to point at each other across the moat and blame the other side.

Google also encourages plug-ins, and the collection for Chrome is growing quickly. Chrome's plug-in architecture is much simpler than Firefox's because it only lets coders write in HTML, CSS, and JavaScript. This is typically more than adequate, and many Firefox developers port their creations to Chrome with little extra work.

If there's one complaint about Chrome, it's that it remains a relatively small presence; thus, Web developers usually get around to testing their work on Chrome only after trying IE, Firefox, and Safari first. Just the other day, one of Facebook's AJAX calls failed on Chrome but worked when I tried the same button on IE. Chrome offers nice developer tools, though, and I suspect that the Web development gap will slowly disappear.

If that's not enough for you, Chrome is also the one and only component of the Chromium OS. When the operating system boots, it starts up Chrome, then it's nothing but HTML for your machine. It's a very lightweight vision of the future.

Best for: People who want to juggle many windows filled with code that crashes every so often.

Worst for: People who get upset when a website breaks because the developer tested the site on IE only.


The battle of the Web browsers: Firefox 4.0 beta

The old Netscape died years ago, but somehow it begat the Firefox browser that gave us many of the innovations being copied by IE and others. The project found a nice source of revenue by routing search requests to Google, and this supported much of the work of the last few years.

No one knows how stable this source of revenue will be in the future. Google leapfrogged Firefox by building a browser of its own, in part to fix the headaches caused by malfunctioning plug-ins like Flash. Firefox is now offering its own "crash protection," which restarts plug-ins when they stop delivering. Firefox handles this internally, though, because the browser still runs most of the work in one process. Chrome relies more on the operating system by sticking each page in different OS processes, an approach that the Mozilla group will probably eventually come around to using.

One of the strengths of Firefox continues to be the large collection of extensions and plug-ins. These can all be written in a mixture of JavaScript, CSS, and HTML, something that makes them a bit easier for the average Web developer to tackle. (In contrast, Microsoft's add-ons can be written in C++.)

Firefox add-ons like Greasemonkey make it even easier to write simple scripts that meddle with the DOM of incoming data, a nice playpen for creating your own quick add-ons. Firefox's model is pretty sophisticated too. While many widgets and extensions in the world are limited to JavaScript, CSS, and HTML, Firefox offers serious programmers more control with XUL. Is it necessary? I'm not sure, but it certainly makes it possible to create more sophisticated applications.

Firefox has not offered the fastest JavaScript performance on the computation-heavy JavaScript benchmarks, but that may not be important for most users. The speed of rendering and the responsiveness of the Internet connection are probably much more important to average browsing. Nevertheless, the Mozilla developers say a new JavaScript engine will be arriving in the fall.

Best for: People who enjoy the wide-open collection of extensions.

Worst for: People who write long-running scientific simulations in JavaScript.


The battle of the Web browsers: Microsoft Internet Explorer 9.0 beta

The days when practically everyone used Internet Explorer are long gone, but the browser continues to dominate, thanks to the fact that it may or may not be integrated with the Windows operating system, depending upon the political winds. Microsoft noticed the erosion from total world domination several years ago and is now rapidly adopting some of the best features from the alternatives. Tabs were added some time ago, and Internet Explorer add-ons are now plentiful enough to form a gallery. Many of the innovations that began with Firefox and Opera are now available with IE8.

Some of Microsoft's claims may strike you as a bit funny. The company notes on a checklist that IE8 supports "Web standards," then points out it supports only CSS 2.1 because it's more common than the newer CSS 3.0. Well, yes, and CSS 2.1 will remain more customary until IE officially adopts it because most Web developers will want to avoid heavy use of any feature that doesn't work on one of the most ubiquitous browsers.

But if Microsoft isn't on the cutting edge of the new standards collectively called HTML5, it's pushing its own features. IE8 helps people "browse safely," a worthy goal that it pursues by offering more and better ways to check the provenance of the information. I'm not sure whether it's possible to actually attach a number to this protection -- Microsoft claims that IE is "5 times better than Chrome" and "2.9 times better than Firefox in protecting against malicious malware." The company claims IE can do a better job of catching fake URLs and URLs that lead to sites pretending to be something they're not. Whether or not this can be quantified, it's a promising path to take because the provenance of information is a big, big challenge for the Internet.

This focus, however, is coming after a long series of security holes in either IE or the add-ons given too much power by IE. Any search engine can help you find stories about hundreds of vulnerabilities found and patched. The root of all of these troubles seems to come when IE is a bit too generous to plug-in packages. This is almost certainly a deep failure of a strategy to let developers add many features that work very well with Windows and not other systems. ActiveX controls, for instance, offer nice performance through deep integration with the operating system, so they help cement IE and Windows' position. The only problem is that this deep integration has produced many, many vulnerabilities over the years, and it's not clear that Microsoft has finally stopped them all.

I'm personally torn about the approach Microsoft has taken. While this deep integration has opened up many opportunities, it has also created problems beyond the security dangers. Add-on developers have access to the registry and other weird corners of the operating system, a big difference from the simpler sandboxes used by the other browsers. I'm sure some Web-based game developers appreciate this speed, but I think a simpler model would have been easier on everyone.

IE9 now offers many of the features that drew me to other browsers. There's a nicer developer tool for debugging JavaScript, and the speed is catching up to the others. The collection of IE add-ons is large and markedly different in style from those for other browsers. Many come from merchants who offer to help make it easier to search their catalogs, spy good deals, and of course spend money. There are so many toolbars that it's easy to build a browser with a fat header and a tiny spot for real content.

In the end, IE's greatest strength may continue to be its fading dominance. Web developers may skip testing on Safari or Opera, but they know that the boss or the boss's boss is probably using the default browser shipped with the computer. Despite the prevalence of good cross-platform libraries, I continue to find Web pages that only work on IE. This is the kind of feedback loop that reinforces dominance.

Best for: People who don't care or don't want to care. IE is still the most likely to work with most websites.

Worst for: People who worry about browser-based attacks and those who want to try the latest HTML5.


The battle of the Web browsers: Opera 10.60

For a long time, Opera's main selling point was raw speed. The company was proud of how its browser rendered a page faster than any other. This domination continues. Opera version 10.60 on Windows got the fastest results in the SunSpider JavaScript benchmarks of any of the browsers I tested. All of the browser developers are reporting big gains in SunSpider and similar benchmarks, but Opera still seems to be leading.

I'm not sure if this is a critical point for users because the main bottleneck seems to be the speed of the Internet itself. However, JavaScript execution speed may become more important when people start using their browsers to do large amounts of data manipulation and raw computation. The SunSpider benchmark includes many computationally complex operations, like AES encryption and searching for prime numbers with a sieve. Still, much of the work handled by JavaScript today is rendering some XML data or changing some background color.

Opera the company, though, is not focused strictly on the browser. It continues to offer smart, out-of-the-box software that rethinks the current model. Opera Turbo, for instance, is a layer of proxy servers on fast Internet lines. Opera Turbo will fetch the pages for you, then compress them to save bandwidth. This may not be a big win for people with fast lines to their desk, but it should be valuable to mobile browsers with slower network connections and -- this is important -- tight limits on the amount of data that can be consumed each month.

Another neat solution is Opera's widgets, little Web applications that run on your Windows, Mac, or Linux desktop. I'm not sure I would go so far as to call them "native applications," as some documentation does, because the widgets are written in Web languages (HTML, CSS, JavaScript) and run in some Opera sandbox. But somewhere in the stack there's some x86 code, right? These are structurally pretty similar to the widgets that are part of Mac OS X. Opera also has a few tools that make it relatively easy for anyone with a hint of programming ability to create a widget.

Indeed, it's almost unfair to focus too much on the desktop version of Opera browser because the company is tightly connected with the mobile market. It continues to innovate and surprise me more than any of the other teams.

Best for: Raw speed and innovation.

Worst for: People who can't imagine straying from the pack.


The battle of the Web browsers: Apple Safari 5.0

Apple took the old Konqueror browser from the Linux world and injected a large amount of development talent to produce a very nice browser for Mac and Windows. Safari's WebKit engine is also the heart of the browsers in the iPhone and the iPad.

Safari is a very good option. The speed is competitive, the controls are simple yet comprehensive, and the developer tools are nice. Apple is just opening up an extensions gallery to the general public, and some developers have already ported popular extensions from Chrome and Firefox. There's nothing missing from Safari that a user might want, but on the other hand there's little to make Safari unique or irresistible.

The biggest interest in Safari on the desktop may come from the Web developers who want to target the iOS world of the iPhone and iPad. Creating customized Web pages is simple to do with a few extra tags, and the result often runs like a native app developed for the platform. Plus, Safari isn't the only browser built on WebKit. Google also uses the WebKit rendering engine for its Android phones, and the iOS and Android browsers behave similarly in many but not all cases. When RIM's BlackBerry team releases its own WebKit browser, WebKit's dominance of the mobile Web will be even greater.

Apple is pushing HTML5 as part of its skirmish with Adobe over Flash. Safari already offers many of the most important HTML5 features, and it will almost certainly get more of them quickly.

Best for: Web developers who want to support WebKit phones.

Worst for: Lovers of extensions and add-ons.
The battle of the Web browsers: Apple Safari 5.0



Source : PCW

Applications and Layered architecture

Applications and Layered architecture

Communication network must support wide range of services. Normally people use networks to communicate, send e-mails, transfer of files and so on. Industry people use communication network for transfer of funds, update information about the product and so on. Hence, to provide support for current service and future services, a complete plan is required. This necessitates developing a complete flexibility in network architecture.

communications functions are grouped into the following tasks
• The transport across a network of data from a process in one machine to the process at another machine.
• The routing and forwarding of packets across multiple hops in a network
• The transfer of a frame of data from one physical interface to another.

To reduce their design complexity, most networks are organized as a series of layers or levels, each one built upon its predecessor. The number of layers, the name of the each layer, the contents of each layer and the function of each layer differ from network to network.

Interaction between the layers must be defined precisely. Interaction is done with definition of the service provided by each layer and to the layer above. Interface between layers through which a service is requested and through which results are conveyed. New services that build on existing services can be introduced even at the later stage. The layered approach accommodates incremental changes readily.


We know , in all networks, the purpose of each layer is to offer certain services to the higher layers. The entities comprising the corresponding layers on different machines are called peer processes. Between each pair of adjacent layers there is an interface. The interface defines which primitive operations and services the lower layer offers to the upper one. The set of layers and protocols is called the network architecture.

A protocol is a set of rules that governs how two or more communicating devices are to interact. HTTP protocol enables retrieval of web pages and TCP protocol enables the reliable transfer of streams of information between computers.

HTTP

Let us consider a client/server architecture, a server process in a computer waits for incoming requests by listening to a port. Port is an address that identifies which process is to receive a message that is delivered to a given machine. The server provide response to the requests. The server process always runs a process in the background called daemon. httpd refers to server daemon for HTTP. The documents are prepared using Hyper Text Markup Language (HTML) which consists of text, graphics and other media are interconnected by links that appear within the documents. The www is accessed through a browser program that displays the documents and allows the user to access other documents by clicking one of these links. Each link provides the browser with a uniform resource Locator (URL) that specifies the name of the machine where the document is located and the name of the file that contains the requested document. The HTTP ( Hyper Text Transfer Protocol ) specifies rules by which the client and server interacts so as to retrieve a document.


In HTTP, we use two-way connection that transfer a stream of bytes in correct sequential order and without errors. The TCP protocol provides this type of communication service between two processes in two machines connected to a network. Each HTTP inserts its messages into a buffer and TCP transmits the contents of the buffer to the other TCP in blocks of information called segments. Each segment contains port number information in addition to the HTTP message information. The following figure shows how communication is carried between HTTP client and HTTP server.

Computing environments

Computing environments

Introduction

We know, in information technology era, sharing of resources and easy communication are acting as a backbone of any network. Popular example is our Internet. With the help of internet we are able to exchange information and share resources. Hence in this chapter we study different advantages of the network and different forms of the network and their features.

The learning objectives of this chapter are to know
What is a computer network ?
How network is advantageous ?
What are different forms of networks ?
What is a e-mail ?


Networking of computers and its advantages.

Computer network is defined as an interconnection of autonomous computer. Here autonomous means, there is no master and slave relationship. All computers are equal. Computer network enables to share the resources. Computer networking also refers to connecting computers to share data, application software and hardware devices. Networks allow sharing of information among various computers and permit users to share files. For example a students accesses compilers sitting at one place, where compiler may be stored on the other machine. The students takes printout with the help of one printer connected to the network. The printer can be shared among many students.

Network offers the opportunity to communicate more efficiently with others through electronic mail. Networks allow companies to share software and peripherals such as printers, plotters, scanners and so on. With networking all the computers in an office can be connected to a single printer and scanner. It also helps in using storage devices efficiently.

Computer network acts as a very powerful communication medium. It means people exchange their information. When compared to mainframe computers, network of computers saves money.

Types of networks

Depending the nature of the distances, protocols ( the set of rules used for communication) the network can be classified into LAN (Local Area Network ), MAN (Metropolitan Area Network ) and WAN ( Wide Area Network).

Local Area Network (LAN)
A LAN (local area network) is a group of computers and network devices connected together, usually within the same building. By definition, the connections must be high-speed and relatively inexpensive (e.g., token ring or Ethernet). They function to link computers together and provide shared access to printers, file servers, and other services.

Any individual computer connected to a network is called workstation. A workstation may not need a floppy disk or hard disk. A LAN or local area network connects computers and peripherals in a limited area. LAN requires cables to connect workstations. For example LAN is used in a hall or within a building. Figure 5.1 shows Local Area Network , where various departments are connected.

Metropolitan Area Network (MAN)

A MAN ( Metropolitan Area Network) is used to connect computers to cover the city or town. The range may be approximately 50 Kilometers. Normally cables and fiber optic cables are used to connect computers. The routing of the messages are fast. Normally central library in a city may be connected by a MAN, so users can access the information. Figure 5.2 shows a typical view of Metropolitan Area Network.

Wide Area Network (WAN)
A WAN (Wide Area Network) covers large distance like state, country or continents. The WAN uses the fiber optics, cables and even satellites also. Here communication circuits are connected with the help of hardware device called routers. Routers forward small pieces of information called packets from one to another. Internet is the popular one comes under WAN. Some of the examples makes use of internet are reservation of airplane tickets, railway tickets and even cinema tickets. Another facility called e-commerce, where business is carried out through internet. Here people can buy books, articles and so on through registering their wants through the internet. Figure 5.3 shows a typical view of Wide Area Network.




Internet
The internet is a massive wide area network ,connecting thousands of computer networks around the world. The internet is a world wide “network of networks”. It is a collection of thousands of smaller networks in different countries around the world. It links thousands of academic government, military and public computers, enabling millions of people to share information and other resources.

Internet pathways are used to exchange digitized computer data. The basic services that form the foundation of the internet are e-mail , telnet and FTP. With internet we can easily exchange electronic mail with friends and family anywhere in the world.

Telnet allows you to connect to a remote computer. We can access any of the public services or tools and library databases at the remote site. FTP(File Transfer Protocol) provides for transferring files from one computer to another across the internet.

Internet has many uses. For individuals, the most important uses of internet are e-mail and surfing the Web. One can read the topics of interest like sports, a hobby, a country or any place of interest.

E-mail:
The e-mail stands for electronic mail. One of the major features of computer networking is that messages can be sent electronically to various terminals on the network. The messages are sent very quickly and accurately. E-mail uses the concept of Storing and forwarding messages. It saves a lot of money for the users. Here user registers his/her account with one of the providers. The e-mail account normally contains username and the provider name. For example abc @ yahoo.com , represents abc is the name of the user , who is registered in yahoo provider.

Summary:
• Computer network is defined as a interconnection of autonomous computers.
• Computer networking enables us to connect computers to share data, application software and hardware devices.
• Networks allow sharing of information among various computers and permit users to share files.
• A LAN or local area network connects computers and peripherals in a limited area.
• A MAN covers the city or town.
• A Wide Area Network covers a large area.
• The internet is a massive wide area network, connecting thousands of computer networks around the world.
• E-mail is a cost effective communication

Quiz questions

1. Computer network defined as a interconnection of ---------- computers
2. Computer network allows user to ----- the resources
3. -------- network confined to hall or building.
4. ------- is one example of WAN.
5. ------ business is carried our through internet.
6. Small piece of information called ---- are forwarded by router in Internet.

Answers
1. Autonomous
2. share
3. Local area
4. Internet
5. E-commerce
6. packets

Services

Services

We know the operation of modern communication networks is a very complex process that involves the interaction of many systems. A communication network , is a set of equipment and facilities that provides a service, the transfer of information between users located at various geographical points. The ability of communication networks to transfer communication at extremely high speeds, allows users to gather information in large volumes almost instantly with the help of computers for long distances.

Radio and television broadcasting are probably the most common communication services. Various stations transmit an ensemble of signals simultaneously over radio or cable distribution networks.

Telephone service is the most common real-time service provided by a network. Two people are able to communicate by transmitting their voices across the network. The service is considered as connection-oriented in the sense that users must first interact with the network to set up a connection


Telephone networks provide a broad class of call management services that use the originating number or the destination number to determine the handling of a call. For example , in call return the last originating number is retained to allow it to be automatically called by the destination user at a later point in time. Caller ID allows the originating number and sometimes name, of the originating call to be displayed to the destination user when the receiving device is display capable. Voice mail allows a destination user to have calls forwarded to a message receiving device when the destination user is not available.

Cellular telephone service extends the normal telephone service to mobile users who are free to move within a regional area covered by an interconnected array of smaller geographical areas called cells. Each cell has a radio transmission system that allows it to communicate with users in its area. Cellular system should handle “handoff” when user moves from one area to another area.

Electronic mail (e-mail) is another popular network service. The user provides a text message and a name and/or address to a mail application. The application interacts with a local mail server, which in turn transmits the message to a destination server across a computer network. The destination user retrieves the message by using a mail application. E-mail is not a real-time service , where large delays can be tolerated. Here security and privacy is matter of concern.

Many applications that involve an interaction between processes running in two computers may be characterized by client/server interaction. Internet is an example of distributed system. The World Wide Web (WWW) is accessed through a browser program that displays the document and allows the user to access other documents by clicking the links. Each link provides the browser with a uniform resource locator (URL) that specifies the name of the machine where the document is located as well as the name of the file that contains the requested document.

Video on demand characterization another type of interactive service. The objective of the service is to provide access to a video library. The user initiates the service by accessing a menu from which a selection is made. Video which requires lot of bandwidth to pass from source computer to the destination.

Streamed audiovisual services over the internet provide an example of a service with some of the feature of video on demand. An application like “real player “ can be used to access a channel that provides an audio visual stream to the client machine.

Another class of service is audio-visual conferencing. Here both audio and video are transmitted over a distance. This service requires real-time response requirement. This service is being used by many companies for training, client interaction from a site, group discussion etc.

System Functions

System Functions

Communications systems serve many functions. It is possible to divide into four categories on functions.
a) Point-to-point
b) Broadcasting
c) Switched
d) Networked


Point-to-point

A point-to-point configuration provides a dedicated link between two devices. The entire capacity of the channel is reserved for transmission between those two devices. Most point-to-point line configuration use an actual length of wire or cable to connect the two ends.

Broadcasting

A broadcast system send the same signal to everyone who receives it. In its usual form , transmission is one way, from the signal source to the individual. Local radio and television transmission are good examples of pure one-way broadcast systems.

Switched systems

A switched system makes temporary connections between terminals so they can exchange information. The telephone is a good example.

Networking

A network connects many terminals that can communicate with each other. For example Local Area Network is belongs to this category.

Protocols and standards

Protocols and standards

The Communication occurs between entities in different systems. An entity is anything capable of sending or receiving information. But two entities cannot just send bit streams to each other and expect to be understood. For communication to occur the entities must agree on a protocol. The key elements of a protocol are syntax, semantics and timing.

Syntax : Syntax refers to the structure or format of the data, meaning the order in which they are presented. For example , a simple protocol might expect the first eight bits of data to be the address of the sender , the second eight bits to be the address of receiver and rest of the stream to be the message itself.

Semantics : Semantics refers to the meaning of each section of bits. How is a particular pattern to be interpreted and what action is to be taken based on that information.

Timing : Timing refers to two characteristics. When data should be sent and how fast it can be sent. For example , if a sender produces data at 100 Mbps but the receiver can process data at only 1 Mbps, the transmission will overload and receiver and data will be largely lost.

Standards

Standards are essential in creating and maintaining an open and competitive market fro equipment manufacturers and in guaranteeing national and international operational ability of data and telecommunication technology and processes. They provide guidelines to manufacturers, vendors, government agencies and other service providers to ensure the king of interconnectivity necessary in today’s marketplace and in international communications.


Data communications standards fall into two categories

1. de facto ( by fact)
2. de jure ( by law)

De jure standards are those that have been legislated by an officially recognized body.

De facto standards are often established originally by manufacturers seeking the functionality of a new product or technology.

Standards organization

Standards are developed by cooperation among standard creation committees forums and government regulatory agencies.

i) The International Standards Organization (ISO)
ii) The International Telecommunication Union (ITU-T)
iii) ANSI (American National Standards Institute)
iv) The Institute of Electrical and Electronics Engineer (IEEE)
v) The Electronic Industries Association (EIA)

The ISO is an organization dedicated to worldwide agreement on international standards in variety of fields. ITU-T is an international standards organization related to the United Nations that develops standards for telecommunications. Two popular standards developed by ITU-T are the V series and X series. ANSI , a nonprofit organization is the United States, voting representative to both the ISO and ITU-T. The IEEE is the largest national professional group involved in developing standards for computing , communication, electrical engineering and electronics. It sponsored an important standard for Local Area Network (LAN) called project 802. EIA is an association of electronics manufacturers in the United States. It is responsible for developing the EIA-232-D and EIA-530 standards.

Signals and systems

Signals and systems

Information is the one transmitted via communication. It may be very simple message like “yes” or “no”. It can be huge and complex message, such as he files containing the book or a television broadcast of a movie. It doesn’t matter if the “information” doesn’t contain anything a critic might agree was “information”.

A signal transmits that information. Signals may take many forms, such as optical, acoustic, electronic or radio-frequency. Signals may be converted from one form into another and still contain the same information. When we make a long-distance telephone call, the sound waves from our mouth are converted to an electrical signal at the telephone, that electrical signal is converted to optical form at the telephone switching office, back to electrical form at the local switching office on the other end and back to sound waves at the other person’s telephone.

A system is the equipment that performs a task, like transmitting signals. We often speak of telephone system as if it is the whole network of telephone equipment from our phone to the high-capacity fiber-optics cables that carry long-distance calls. However, parts of the telephone system also may be called systems, such as a switching systems that directs phone calls. We can assume a system which is a collection of stuffs designed to work together.

Basic components of data communication system

A data communication system is made up of five components.

i) Message

ii) Sender

iii) Receiver

iv) Medium

v) Protocol

Message - the message is the information to be communicated

Sender – The sender is the device that sends the data message. It can be computer, workstation, telephone etc.,

Receiver – The receiver is the device that receives the message. It can be a computer , workstations, telephone, fax machine

Medium – The transmitting medium is the physical path by which a message travels from sender to receiver . It can consists of twisted pair wire, coaxial cable, fiber optic cable or radio waves.

Protocol – A protocol is a set of rules that govern data communication. It represents an agreement between the communicating devices. Without a protocol two devices may be connected but not communicating , just as a person speaking German cannot be understood by a person who speaks only Russian.