XtraGrid Control Overview

XtraGrid is an advanced customizable control that allows you to present data in a tabular, banded tabular or card form. It allows you to work both with data-aware sources and data created at runtime. The grid control is represented by the GridControl class. Its GridControl.DataSource and GridControl.DataMember properties allow you to bind the grid to a data source.


Views
The grid control displays data using Views. You can think of a View as a visual component incorporated into the grid control which:
� presents data from a data source to an end-user
� provides the means to edit data
� contains multiple edit, customization and behavior options, etc

You can use one of the following Views to display data: Grid View, Layout View, Banded Grid View, Advanced Banded Grid View or Card View. Or, you can create a custom View if the standard Views do not suit your particular needs.

XtraGrid supports master-detail data representation. Master and detail tables are presented using independent Views. For instance, you can display the master table in a Grid View while displaying detail tables using card Views. The hierarchical structure of Views reflects master-detail relationships between the tables in the data source.

To access the View displayed at the top hierarchy level, use the GridControl.MainView property. This View represents the table referenced by the GridControl.DataSource and GridControl.DataMember properties. When the grid control is created, its GridControl.MainView property already refers to an instance of the GridView class, i.e. the top level data table will be represented using a Grid View.

The GridControl.LevelTree property allows you to specify pattern Views for representing particular master-detail relationships. These Views are never displayed onscreen. They only provide settings for creating real detail Views (clones) that appear when master rows are expanded.


Appearances
The XtraGrid provides a number of ways to customize its look and feel. The GridControl.LookAndFeel property allows you to control the overall look and feel of the grid (how headers, scrollbars, borders, buttons and other elements are painted). By default, all the Views use these look and feel settings. It's also possible to specify look and feel settings for individual Views. This can be done via a View's BaseView.PaintStyleName property.

The Appearance technology allows the styles of particular visual elements in a View to be controlled. Each View has an BaseView.Appearance property which contains multiple style properties that correspond to all the available visual elements. You can specify the element's foreground, background colors, font settings, gradient mode, text options, etc.

The XtraGrid also provides various predefined painting schemes which facilitate customizing the grid.

Skins is another way to bring a unique and unconventional look and feel to the control.


Design-Time Capabilities
XtraGrid provides the Level Designer and XtraGrid Designer to customize the control and Views at design time.

The Level Designer shows the hierarchical structure of Views representing master-detail relationships. It helps you access and change the main View and pattern Views, and create new levels("relation name - pattern view" associations). The latter can be useful if you wish to implement master-detail relationships via code, but create and customize pattern Views at design time.

You can select a View in the Level Designer to access its settings via the Properties window. If a pattern View is selected, the grid displays it as if it were the main View. If you need to access a column's settings at design time, you can simply click its header right on the form. This displays the column settings in the Properties window.

For a Grid View or its descendant, you can customize the layout right on the form, using only mouse operations.

Some tasks (such as creating columns and bands, accessing columns in a card view, applying grid formats, etc) can only be performed via the grid's designer. The XtraGrid Designer allows you to manage levels, Views, bands, columns, summaries, column editors (repository items), style settings and printing options.

? Dev Components ? DevExpress Controls for WinForms ? DevExpress XtraGrid

Source of Information : 1998-2010 Developer Express Inc Help

Automated Tests as an Aid to Debugging

So, what makes automated tests valuable when debugging? They help out at all stages:

� First and foremost, well-tested code tends to have fewer bugs in the first place. The easiest bug to fix is the bug that never existed.

� The shorter the delay between a mistake being made and subsequently being discovered, the easier and cheaper it is to fix. Early testing means that most bugs are discovered very shortly (often immediately) after they�re introduced.

� Automated testing is a key enabler of continuous integration, in which code is integrated with the whole product as soon as it�s complete.  

� Automated tests allow you to frequently release new versions of the software with high confidence that the new release is functional. This means that you get end-user feedback on new features and bug fixes much more quickly than would otherwise be the case (again, reducing the time between code being written and bugs being discovered within the code). It can also reduce the need to back-port bug fixes to previous versions of the software or to release patches.

� For code to be tested, it needs to be structured in such a way as to provide access to intermediate results and internal state that might otherwise be unavailable. This kind of access turns out to be a great help during later debugging.

� Writing a test is an excellent way to reproduce a bug during the diagnostic process. Many of the techniques created to support automated testing are extremely useful for reliably reproducing bugs.

� After you�ve completed your diagnosis, automated tests provide powerful protection against the fix introducing regressions.

� If, during diagnosis, you make a habit of always writing a test that reproduces the bug, you naturally end up with a regression test that ensures that the bug won�t be reintroduced at some point in the future.

� Automated tests are a key enabler of refactoring, which is the most powerful weapon at your disposal to ensure that code remains well-structured and flexible throughout its lifetime.

Automated tests are a particularly powerful debugging tool when allied with a technique that has risen in popularity alongside them�test doubles.

Source of Information :  Paul Butcher - Debug it Find repair and prevent bugs

Wireless Signal Propagation

A radio signal can be described in three domains: time domain, frequency domain, and phase domain. In the time domain, the amplitude of the signal varies with time; in the frequency domain, the amplitude of the signal varies with frequency; and in the phase domain, the amplitude and phase of the signal are shown on polar coordinates. According to Fourier�s theorem, any periodic signal is composed of a superposition of a series of pure sine waves and cosine waves whose frequencies are harmonics (multiples) of the fundamental frequency of the signal; therefore, any periodic signal, no matter how it was originally produced, can be reproduced using a sufficient number of pure waves.

Electronic signals for wireless communication must be converted into electromagnetic waves by an antenna for transmission. Conversely, an antenna at the receiver side is responsible for converting electromagnetic waves into electronic signals. An antenna can be omnidirectional or directional, depending on specific usage scenarios. For an antenna to be effective, it must be of a size consistent with the wavelength of the signals being transmitted or received. Antennas used in cell phones are omnidirectional and can be a short rod on the handset or hidden within the handset. A recent advancement in antenna technology is the multiple-in, multiple out (MIMO) antenna, or smart antenna, which combines spatially, separated small antennas to provide high bandwidth without consuming more power or spectrum. To take advantage of multipath propagation, these small antennas must be separated by at least half of the wavelength of the signal being transmitted or received.

A signal emitted by an antenna travels in the air following three types of propagation modes: ground-wave propagation, sky-wave propagation, and line-of-sight (LOS) propagation. AM radio is a kind of ground-wave propagation, where signals follow the contour of the Earth to reach a receiver. SW radio and HAM amateur radio are examples of sky-wave propagation, where radio signals are reflected by ionosphere and the ground along the way. Beyond 30 MHz, LOS propagation dominates, meaning that signal waves propagate on a direct, straight path in the air. It is noteworthy that radio signals of LOS propagation can also penetrate objects, especially signals of large wavelength (and thus low frequency). Satellite links, infrared light, and communication between base stations of a cellular network are examples of LOS propagation.



Attenuation
The strength or power of wireless signals decreases when they propagate in the air, just as visible light does. As soon as radio waves leave the transmitter�s antenna, some amount of energy will be lost as the electromagnetic field propagates. The effect will become more evident over a long distance as the signal disperses in space; therefore, the received power of the signal is invariably less than the signal power at the transmitting antenna. In the most ideal circumstances (i.e., in vacuum), signal power attenuation is proportional to d 2 , where d denotes the distance between the transmitter and the receiver. This effect is sometimes referred to as free space loss. In reality, beside free space loss, a number of other factors have to be considered to determine signal attenuation, such as weather conditions, atmospheric absorption, and space rays. In addition, signal attenuation is more severe at high frequencies than at low frequencies, resulting in signal distortion.

When it encounters obstacles along the path, a signal may experience more complex attenuation than power reduction. For example, for visible light we are well aware of the following effects: shadowing, reflection, and refraction. Likewise, for high-frequency wireless signals, such effects also exist. Shadowing and reflection occur when a signal encounters an object that is much larger than its wavelength. Though the reflected signal and the shadowed signal are comparatively weak, they in effect help to propagate the signal to spaces where LOS is impossible. For example, when reflection and shadowing are caused by buildings in an urban area, signals from an antenna of a base station may be able to reach cell phone users within a building in the area, although it might be a good idea for the user to walk close to the window for better signal strength (perceived as a number of �bars� displayed on the cell phone screen). Refraction (bending) occurs when a wave passes across the boundary of two media. Moreover, wireless signals are also subject to scattering and diffraction. Specifically, when the size of an obstacle is on the order of the signal wavelength or less, the signal will be scattered into a number of weaker pieces. Diffraction occurs when a signal hits the edge of an obstacle and is deflected into a number of directions.


Noise
The receiver of a wireless communication system must be able to detect transmitted (most likely attenuated and distorted) signals from unwanted noises. Common types of noise are thermal noise (white noise) produced by any electronic circuitry; intermodulation noise, which occurs when two frequencies of signals are modulated and transmitted over the same medium; crosstalk between two channels; and impulse noise generated by instantaneous electromagnetic changes. To cope with noises in received signals, a wireless system has to ensure that the transmitted signals are sufficiently stronger than the noises. Another approach is to employ spread spectrum schemes (explained below) that convert a signal over a wide range of frequencies of low power density as random noise. Wireless signals are subject to various impairments or distortion along the way from the transmitter to the receiver. To quantify these effects, the signal-to-noise ratio (SNR) is used to represent the ratio of the power in a signal to the power of the noise. SNR is usually computed in decibels as the product of 10 and the logarithm of the raw power ratio.


Multipath Propagation
The receiver of a wireless system is exposed to all radio waves in its surrounding environment; therefore, it may receive indirect signals from different paths, such as reflected signals, shadowed signals, and refracted signals, as well as signals generated by other means of propagation, all carrying the same signal with different levels of attenuation and distortion. These signals may impose some negative effect on the direct signal to a great extent. The most severe effect of multipath propagation is intersymbol interference (ISI). ISI is caused by overlapping of delayed multipath pulses (of a primary pulse) and subsequent primary LOS pulses, where one or multiple pulses represent a bit. The degree of attenuation of these pulses may vary from time to time due to path changes or environmental disturbances, making it more difficult to recover the transmitted bits. To prevent ISI from occurring, the first primary pulse and the second pulse have to be separated by a sufficient time difference such that the delayed multipath pulses of the first can be differentiated from the second LOS pulse. This implies that the symbol rate of the signal and bandwidth of the radio channel are limited by multipath propagation.

Source of Information :  Elsevier Wireless Networking Complete 2010

iPhone Power Tricks

There are many ways to switch your iPhone on and off. The following are the most important methods that every iPhone owner should know.


Unlocking Your iPhone
When your iPhone has been idle for a while, it automatically locks, and the screen goes dark. When this happens, press Home. To unlock your phone, swipe the slider from the left to the right. The lock screen clears, and the Home screen springs into place.

Screen locking is a form of power saving. If your iPhone never turned off its bright display, it would go through a battery charge much faster. Shutting down the screen and going into lock mode extends your battery life and optionally allows you to protect your iPhone by requiring a passcode to use the device after it has been locked.

If it seems like your iPhone is locking too frequently, you can adjust how long it should wait before locking. Tap your way to Settings ? General ? Auto-Lock, and select how many minutes you want your iPhone to wait before going dark. Sometimes you may want to just power the iPhone off by yourself and disable autolocking. There�s a choice for that in the autolock settings, when you set the duration to Never. Make sure you have a good power source available at all times if you disable autolocking, since autolocking is a power-saving feature. Disabling it means your iPhone will use up battery power more rapidly.


Putting Your iPhone to Sleep
For iPhones, sleep mode offers a power-saving way to use your device. Press the Sleep/Wake button once. The screen turns off, and your iPhone locks and enters its lowpower mode. You can still listen to music and receive phone calls. The volume control buttons on the left side of your iPhone work, and the switch on your iPhone headset continues to control music playback and allows you to answer calls. Under iOS 4.0 on devices newer than the iPhone 3G, some apps can continue to run in the background even when the device is asleep. As an example, some location-aware apps continuously update the location of the iPhone although it is asleep. To wake up your iPhone again, press Home, and swipe to unlock.


Securing Your iPhone with a Passcode Lock
For security, you can assign a passcode lock for your iPhone. There are two types of passcodes: a simple passcode, which consists of four easily remembered and typed numbers, and a regular passcode, which can include text. When locked, your iPhone cannot be used except for emergency calls. Go to Settings ? General, and tap Passcode Lock to establish a new passcode. There�s a button that turns on the passcode lock feature. If a four-digit simple passcode is all you�d like to enter, make sure that the Simple Passcode switch is set to the default value of on. If you�d rather enter a text passcode, flip that switch to the off position.

Once you�ve decided what kind of passcode you want, tap Turn Passcode On to enter it. If you have chosen simple passcode, you�re prompted to enter four digits twice� once to enter the numbers and again to verify that you entered it correctly the first time. For regular passcodes, you�re prompted to enter your passcode with text, symbols, and numbers. Once again, you�ll have to enter the passcode twice to make sure that it has been entered properly.

As soon as you�ve set a passcode, you can change some other settings that are related to the passcode lock. Tap the Require Passcode button to set the time interval before your iPhone requests the passcode. Shorter times are more secure, although you�ll need to enter your passcode more frequently as a result.

If you like to use Voice Control and your iPhone or Bluetooth headset to do voice dialing or control the iPod app, slide the Voice Dial switch to on to make sure that Voice Control is always enabled, even when the phone is locked. This makes it handy for you to use a Bluetooth headset to dial and control your phone, even when it�s sitting in your pocket or in a briefcase or purse.

The final button on the Passcode Lock screen ensures absolute security in case your iPhone is lost or stolen. Sliding the Erase Data button to on will erase the contents of the iPhone if someone incorrectly enters the passcode ten times. Before you engage this setting, be sure that you know your password.

How can you test your passcode? Press the Sleep/Wake button once to put your iPhone to sleep, wait for the time interval to pass, and then wake the iPhone by either pressing the Sleep/Wake button again or pressing the Home button. A passcode challenge screen appears. Enter your passcode correctly, and your iPhone unlocks.

To remove the passcode from your iPhone, go back to the Passcode Lock screen. Tap the Turn Passcode Off button, and then reenter the passcode one more time to confirm that the rightful owner of the iPhone is making the request.

What can you do if you forget your passcode or a mean-spirited colleague adds one to your iPhone without telling you? Unfortunately, you will have to connect the iPhone to your computer and use iTunes to restore the iPhone to factory defaults. Why? Well, for security reasons, there�s absolutely no way to reset the passcode since that would defeat the purpose of the passcode.


Multitasking and Quitting Applications
Prior to iOS 4, iPhones could not perform more than one task at a time. Well, they could play music from the iPod app while performing some other tasks, but that was about it. iOS now acts more like a modern multitasking operating system by allowing multiple apps to run simultaneously. One example that many people pointed at as proof of the need for iOS multitasking was being able to play tunes using the popular Pandora music-streaming app while performing other tasks, such as reading e-mail, at the same time.

When you�re using an app, pressing the Home button returns you to the Home screen, but the app is either suspended or may actually be running. In fact, if the app has been written to take advantage of back grounding, it will continue to run when you�re viewing the Home screen or running other apps. In other words, don�t assume that when an app is out of sight, it�s shut down.

To see what�s currently running on your iPhone under iOS 4, double-click the Home button. The current Home screen becomes transparent, and a side-scrolling list of active apps appears at the bottom of the screen.

Flicking the active apps to the right, you�ll eventually get to a control panel for whatever music app happens to be active at the time. This control panel is equipped with play, pause, fast-forward, and fast-reverse buttons, as well as a screen orientation lock button. The far-right icon on the control panel shows which music app you�re currently controlling.

On an iPhone 3G or 3GS running iOS4, having multiple apps still running in background can increase usage of the processor to the point that your iPhone heats up, the device uses much more power, and the response of the phone becomes sluggish. Even with the iPhone 4�s powerful and fast Apple A4 processor, too many apps running simultaneously can slow things down dramatically. Idle applications occupy your iPhone�s memory, which may eventually cause it to balk when you try to open another app.

So, how do you quit apps? Double-click the Home button, and at the bottom of the iPhone display you�ll see a side-scrolling list of all the apps that are currently running. To turn off an app, tap and hold an app icon in the list until it begins to jiggle. A small minus sign in a red circle appears at the top-left corner of the icon. Tap the minus sign to quit the application.


Powering Your iPhone Off and On
To power off your iPhone, press and hold the Sleep/Wake button for about five seconds. A slider appears prompting you to slide the red button that appears to the right in order to power off. To cancel, either tap Cancel or just wait about ten seconds. The iPhone automatically returns you to the Home screen if you don�t power down within that time. When your iPhone is powered off, it ceases to function. You cannot listen to music. You cannot receive phone calls. You must power your iPhone back on for it to do these things.

To power on your iPhone, press and hold Sleep/Wake for two to three seconds. Release the button when you see the white Apple icon. The iPhone starts up and returns you automatically to the unlock screen.


Rebooting Your iPhone
At times, you may need to reboot your iPhone. The most common reason for doing this is that you have installed a new app that recommends a reboot after installation. Although you can reboot just by powering down and then powering back up, Apple provides a much easier way do this. Press and hold both the Home and Sleep/Wake buttons for eight to ten seconds. Ignore the �slide to power off� message, and keep holding both buttons until the white Apple logo appears. Once it shows up, release both buttons, and let the iPhone finish its reboot. You will return automatically to the unlock screen.


Placing Your iPhone into Recovery Mode
On occasion, you might encounter one of these odd symptoms:
� Your iPhone continually restarts but never displays the Home screen.

� An update or restore did not complete, and the device is no longer recognized in iTunes.

� The iPhone stops responding, displaying the Apple logo with no progress bar or a stopped progress bar for more than ten minutes.

If this happens to you, you can place the iPhone into recovery mode and attempt to restore it. Here�s how to put your iPhone into recovery mode:

1. Disconnect the USB cable from your iPhone, but leave the other end connected to the USB port on your computer.

2. Turn off your iPhone. Press and hold the Sleep/Wake button until the red slider appears, and then slide it to the right. Wait for the iPhone to turn off. If you can�t turn off the iPhone using the slider, press and hold the Sleep/Wake and Home buttons at the same time. When the iPhone finally turns off, release the buttons.

3. While pressing and holding the Home button, reconnect the USB cable to your iPhone. When you reconnect the USB cable, the device should power on. If a depleted battery\ icon appears on the iPhone screen, let your iPhone charge for at least ten minutes and then start over again at step 2.

4. Hold the Home button down until you see the Connect to iTunes screen. It displays an iTunes icon (a music CD with musical notes in front of it) and a USB cable.

5. At this point, if iTunes isn�t running on your computer, launch it. You should see a �recovery mode� prompt in iTunes that says, �iTunes has detected an iPhone in recovery mode. You must restore this iPhone before it can be used with iTunes.� Click the OK button to begin using iTunes to restore the iPhone.

Source of Information :  Taking Your iPhone 4 to the Max

Can Web Browsers Really Cover Your Tracks?

Firefox calls it �Private Browsing.� Chrome calls it �Incognito Mode.� Whatever the name, about every major Web browser now has a special mode designed to retain as little information as possible about your browsing activity. But how private is �private�? As it turns out, private browsing can only ensure so much privacy. It has its limits, and not all of those limits can be fixed in a newer version of the browser.


Why �Private� Browsing Really Isn�t
The idea behind a Web browser�s private browsing mode seems simple enough. Any activity that takes place in that browser while private mode is engaged is either erased at the end of the session or stored in such a way that it is inaccessible after the fact. Anyone who inspects the computer later will find no traces of the user�s activity. That�s the theory. As it turns out, it�s extremely difficult to implement all this in a practical way. Many of the current worries about private browsing stem from a recently published research paper, �An Analysis of Private Browsing Modes in Modern Browsers,� presented at the 2010 USENIX conference. The authors (Gaurav Aggarwal, Elie Bursztein, Collin Jackson, and Dan Boneh) created a test suite for private browsing and found many flaws, both conceptual and methodological, with the way private browsing works. Some of them are immediately fixable; some. . . less so.

Every browser leaves behind something from private mode. The sheer number of ways a browser interacts with the surrounding OS, the file system, and the user almost guarantees something will be left behind. Bookmarks, form auto-complete data, user-approved self-signed SSL certificates, and downloaded files are four common examples. Granted, not every browsing session involves these things, but it�s easy to leave traces without realizing it.

Part of the study�s test regimen consisted of restricting attacks to what they called �after the fact forensics,� that is, analyzing the system after the private browsing session was closed. They observed that not all state changes during private browsing should be erased�emphasis on should, because to erase some of them might be theoretically outside of the scope of the application�s behavior. Take downloads, for instance: Would it be wise for the browser to automatically scrub the file system of any files downloaded during private browsing? Some might argue it�s not the browser�s responsibility to clean up such things, but that only highlights just how complex the interactions are between the browser and the rest of the system.

Each browser has a slightly different version of private browsing. The exact things that are sanitized at the end of the session vary enormously, and the ways in which they are sanitized also vary. Something that might be dealt with cleanly in one browser may be handled poorly in another, as much for reasons of policy by the browser�s makers as anything technical.

For example, Chrome forbids extensions from running when in Incognito mode, to prevent user data from being leaked to disk. The user has to elect to allow any individual extension to run in Incognito mode, because Chrome has no way to ensure that extensions themselves don�t write data. But Firefox (as of version 3.6.10) allows extensions to run in Private Browsing. Mozilla�s design documents for extension developers do describe how to detect private browsing and act accordingly, but it�s still a possible privacy hole.

Browser extensions create security loopholes in private mode. Each browser also handles third-party add-ons differently in private mode. To wit: Firefox permits add-ons to run unrestricted (a major loophole); Chrome is a little more secure by default, but you can activate extensions manually if desired (and plug-ins, such as QuickTime or Flash, are always running); and IE disables browser helper object extensions but allows ActiveX add-ons to run by default. It�s a hodgepodge, in large part because every browser�s add-on architecture is different.

Server-side privacy is still a problem. Apart from the fact that private mode doesn�t provide you with any additional protection for your data, your IP address is logged by the sites you visit, which is all but impossible to avoid anyway unless you use a proxy server.

Even putting this aside, there are other betrayals of anonymity. Even if you�re in private browsing mode, a browser can be uniquely fingerprinted using JavaScript to analyze things such as the screen size, available fonts, time zone, and many other bits of data. The Electronic Frontier Foundation�s Panopticlick project (panopticlick.eff.org) demonstrates how easy it is to harvest all this information. We tried the EFF�s test ourselves and found that just about every browser in the market can be unmasked regardless of whether you�ve enabled private browsing. Firefox 3.6.10 and 4 (beta), Internet Explorer 8 and 9 (beta), Chrome 8, Opera 10.62, and Safari 5 all returned �at least 20 bits of identifying information� from Panopticlick, even when we used each browser�s privacy mode.

Browsers are vulnerable to attacks directed at the system itself. Although the following wasn�t a chief concern of the aforementioned study, it bears mentioning: Because the browser has to interact with the rest of the system in some way, attacks aimed at the OS, such as scanning the system swap file or RAM, are far harder to thwart or detect. Security consultant Rob Fuller demonstrated how to use commonly available tools, such as Process Memory Dumper (bit.ly/dbfqkv) to extract all sorts of private information from a Firefox session. Although this kind of attack requires that the process in question still be running (as opposed to forensics after the fact), it�s one more example of how the browser can only protect you against so much.


Our Own Testing
On a virtual machine loaded with a fresh copy of Windows 7 Home Premium, we installed and ran the latest versions of the following Web browsers: Chrome 7, Firefox 3.6.10, Opera 10.62, Internet Explorer 8, and Safari 5.0.2. Our test was deliberately simple: After browsing to a specific page in both conventional and private mode, we used NirSoft�s SearchMyFiles (bit.ly/a1fiez) to look within files created or modified by each browser for telltale strings�the page�s URL, its title, text found on the page, etc.

What we found further demonstrated how private browsing is implemented in a highly inconsistent way from one browser to the next. Chrome, Firefox, and Opera all showed no traces of the pages in question during and after a private browsing session. But Safari�s Web site icon cache (WebpageIcons.db) leaked information about visited domains from private sessions, and data from Internet Explorer�s browsing sessions were visible while the browser was open (although it was cleared after the browser was closed). This suggests that the first three browsers store private browsing cache information more securely�e.g., by encrypting the files that are written to disk. However, don�t take for granted that those cache files are entirely secure�they�re just less likely to give up their contents on casual inspection.

Browsers that write private-session data to disk leave themselves exposed to attacks that involve reading data left behind by deleted files. We checked to see if we could undermine Internet Explorer�s private browsing in this way, and found that we could locate phrases encountered on Web pages during private browsing sessions in IE simply by searching the disk�s unused space. It seems that IE doesn�t securely erase the cached files in question but simply marks them as deleted. Also, the beta version of IE9 appeared to handle private data the same as IE8. Browsers that store private session information securely (e.g., Chrome) don�t seem to suffer from this issue.


Possible Solutions
If private browsing by itself is imperfect, what about using it in conjunction with other security measures? That�s an available tactic, but adding more security manually often creates drawbacks as well�most of them obstacles of inconvenience.

Virtual machines. One way to isolate the browser from outside attacks is to run it in a virtual machine, which creates an additional layer of protection from the main OS. But this approach creates at least as many problems as it solves. It�s clunky to use casually, unfriendly to many novice users, and considerably more memory-intensive.

Sandboxing. A close cousin to using a VM is sandboxing, which involves running the browser through an application that intercepts all disk operations from the program and mops them up, leaving as few traces as possible. Sandboxie (www.sandboxie.com) is one such program, but its authors admit its protection only goes so far and doesn�t protect against, for example, swap file attacks.

Use a standalone OS. More than one article has been written about booting a Linux live CD and using that to run a browsing session that leaves behind no traces. Although it does leave behind far fewer traces�only the host�s RAM is touched, and this is cleared once the machine is rebooted�it�s an impractical solution for daily use.

Encryption. Another way to thwart attempts to read the on-disk traces left by anonymous browsing is to encrypt the system�s disks. This isn�t as unworkable as it used to be, because you can use either native OS features (NTFS filelevel encryption or Microsoft BitLocker) or third-party applications, such as TrueCrypt, to accomplish this. Its main drawback is that it only resists attacks that are executed when the encrypted volumes aren�t mounted. Any attack executed while the drive is unlocked (and, presumably, the browser is running) could bypass this entirely.

It�s also possible to encrypt portions of the system that are vulnerable to attack, such as the swap file, for example. One can automatically encrypt the swap file in Vista and Win7 by using the command fsutil behavior set encryptpagingfile 1. (See bit.ly/9Rn1nP for more details.)

Standalone browsing. This involves using a version of the browser that has been designed to run in its own directory, such as those found in the PortableApps.com collection. The PortableApps.com editions of Chrome and Firefox, for instance, don�t appear to leave anything on the host machine that could be used to analyze one�s browsing history. If a standalone browser was run from a removable drive that had on-disk encryption, this would make after the fact analysis even more difficult. This is probably the least impractical solution, because it doesn�t require a truly huge change in browsing habits.


�Safe� Is A Variable, Not An Absolute
Truth be told, most people don�t risk much by using private browsing modes. They prevent casual invasions of privacy in the same way that locking your car prevents someone walking by from stealing what�s in your backseat.

But a determined thief will always find a way into your car. Likewise, the sheer amount of information left behind by any browsing session, �private� or not, provides plenty of clues for a determined forensic researcher. And once the process of searching for those things is automated, it�s easier for them to end up in the hands of far more thieves, as well.

The biggest reason why private browsing can only grant so much privacy is the behavior of the end user. In addition to the things that users do casually that may compromise their privacy, developers must face the problem that users may end up shunning any privacy tool that makes doing anything online more difficult. The more privacy, the less functionality�and for most people, convenience trumps security.

It�s tough to predict how vulnerable people will be to attacks designed to exploit the few things not protected (or protectable) by private browsing. Worse, not all of these gaps in protection can be closed off. Some, such as file downloads, are a function of the browser being an application that interacts with the rest of the OS and not a self-contained unit.

To that end, we shouldn�t think about private browsing as an absolute. There are degrees of privacy with accompanying degrees of inconvenience. Feel free to browse in private but always keep in mind that �private� is a relative term.

Source of Information : Computer Power User (CPU) December 2010

Comparing Processor Architectures: Westmere vs. Sandy Bridge

When comparing the architectures in Westmere and Sandy Bridge, you can see the significant changes Intel has made with the new Sandy Bridge architecture. As you can see from these illustrations, Westmere included a separate northbridge, which contained the graphics and other components. With Sandy Bridge, though, the GPU is on the same die as the CPU, removing one of the key components of the northbridge. In Sandy Bridge, the System Agent serves as the equivalent to the northbridge (what Intel in the past sometimes called the �uncore�). The System Agent contains the display engine, DMI (desktop management interface), memory controller, PCI-E 2.0, and PCU (power control unit). The PCU handles all of the power and thermal management for the chip. It also controls the turbo technology built into Sandy Bridge. The System Agent is connected to the ring bus (the black line and red blocks in the illustration that connect the LLC, cores, graphics, and System Agent), another new addition in Sandy Bridge. Using a ring bus in a quad-core Sandy Bridge chip provides four times the LLC (last level cache, a.k.a. L3 cache) bandwidth than was available in the previous generation.

Source of Information : Computer Power User (CPU) December 2010

Effective Automated Testing

Agile software development has dramatically changed software construction through the widespread adoption of automated testing and refactoring. There�s more to effective automated testing than simply automating your tests. To achieve maximum benefit, your tests need to satisfy the following goals:

Unambiguous pass/fail: Each test outputs a single bit�pass or fail. No shades of gray, no qualitative output, no interpretation required. Just a simple yes or no.

Self-contained: No setup required before running a test. Before it runs, it sets up whatever environment it needs automatically, and just as important, it undoes any changes to the environment afterward, leaving everything as it found it.

Single-click to run all the tests: All tests can be run in one step without interfering with each other. As with a single test, the output of the complete test suite is a simple pass or fail�pass if every test passes, fail otherwise.

Comprehensive coverage: It�s easy to prove that achieving complete coverage for any nontrivial body of code is prohibitively expensive. But don�t allow that theoretical limitation to put you off�it is possible to achieve close enough to complete coverage as to make no practical difference.

Source of Information :  Paul Butcher - Debug it Find repair and prevent bugs

Intel : Behind The Name

Intel hasn�t officially announced the code for deciphering the names of the soon-to-be-released Sandy Bridge chips, but Intel sources have confirmed the names will work as shown here.

Intel will retain the Core i3, i5, i7 brand names from the previous generation for these processors. Intel has changed the �badge,� or logo, for the Sandy Bridge processors, as the i7, i5, and i3 names are more prominent than they were with the Nehalem architecture. For comparison, you can see the previous generation i7 badge, where the �i7� text designation is shaded and not as obvious and prominent.

A sample model name is shown below�Intel Core i5 2500K�along with a photo of a Sandy Bridge chip. We�ve broken down each segment of the model name so you know exactly what�s going on with Sandy Bridge�s naming scheme.

� The brand name and chip designation will lead off the model name.

� Next, because Sandy Bridge is the second generation of the Core i3/i5/i7 chips, Intel will add a �2� in front of the model number.

� Finally, some chips will include a letter as a final designation. The exact significance of all of the different letters is still not official, but �K� should signify a chip that can be overclocked, for example. An �S� chip should be a chip with a low clock speed, while a �T� chip should be one that runs at a low clock speed with a low TDP. Not every chip will have a letter identifier.

Source of Information : Computer Power User (CPU) December 2010