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  • HP Deskjet 720C USB printer doesn't finish

    - by 213441265152351
    I have an HP Deskjet 720C connected through a USB cable to an Ubuntu 12.04 laptop. When I plugged the printer for the first time into the fresh 12.04 laptop install, it auto-detected the printer correctly and choose the recommended drivers without a problem. The document print fine until they reach the end of the last page, then suddenly stop just about the end leaving the page unfinished. I have checked that the margins are the correct ones. I have the latest version of cups installed. I have also tried changing the options of usb-unidir-default and usb-no-reattach-default via lpadmin, but the printing stops even earlier. EDIT: It seems like the problem is with the last page. So if I am printing 3 pages, the first two work well but the last few lines in the last page are not printed. Any ideas?

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  • SQL Server devs–what source control system do you use, if any? (answer and maybe win free stuff)

    - by jamiet
    Recently I noticed a tweet from notable SQL Server author and community dude-at-large Steve Jones in which he asked how many SQL Server developers were putting their SQL Server source code (i.e. DDL) under source control (I’m paraphrasing because I can’t remember the exact tweet and Twitter’s search functionality is useless). The question surprised me slightly as I thought a more pertinent question would be “how many SQL Server developers are not using source control?” because I have been doing just that for many years now and I simply assumed that use of source control is a given in this day and age. Then I started thinking about it. “Perhaps I’m wrong” I pondered, “perhaps the SQL Server folks that do use source control in their day-to-day jobs are in the minority”. So, dear reader, I’m interested to know a little bit more about your use of source control. Are you putting your SQL Server code into a source control system? If so, what source control server software (e.g. TFS, Git, SVN, Mercurial, SourceSafe, Perforce) are you using? What source control client software are you using (e.g. TFS Team Explorer, Tortoise, Red Gate SQL Source Control, Red Gate SQL Connect, Git Bash, etc…)? Why did you make those particular software choices? Any interesting anecdotes to share in regard to your use of source control and SQL Server? To encourage you to contribute I have five pairs of licenses for Red Gate SQL Source Control and Red Gate SQL Connect to give away to what I consider to be the five best replies (“best” is totally subjective of course but this is my blog so my decision is final ), if you want to be considered don’t forget to leave contact details; email address, Twitter handle or similar will do. To start you off and to perhaps get the brain cells whirring, here are my answers to the questions above: Are you putting your SQL Server code into a source control system? As I think I’ve already said…yes. Always. If so, what source control server software (e.g. TFS, Git, SVN, Mercurial, SourceSafe, Perforce) are you using? I move around a lot between many clients so it changes on a fairly regular basis; my current client uses Team Foundation Server (aka TFS) and as part of a separate project is trialing the use of Team Foundation Service. I have used SVN extensively in the past which I am a fan of (I generally prefer it to TFS) and am trying to get my head around Git by using it for ObjectStorageHelper. What source control client software are you using (e.g. TFS Team Explorer, Tortoise, Red Gate SQL Source Control, Red Gate SQL Connect, Git Bash, etc…)? On my current project, Team Explorer. In the past I have used Tortoise to connect to SVN. Why did you make those particular software choices? I generally use whatever the client uses and given that I work with SQL Server I find that the majority of my clients use TFS, I guess simply because they are Microsoft development shops. Any interesting anecdotes to share in regard to your use of source control and SQL Server? Not an anecdote as such but I am going to share some frustrations about TFS. In many ways TFS is a great product because it integrates many separate functions (source control, work item tracking, build agents) into one whole and I’m firmly of the opinion that that is a good thing if for no reason other than being able to associate your check-ins with a work-item. However, like many people there are aspects to TFS source control that annoy me day-in, day-out. Chief among them has to be the fact that it uses a file’s read-only property to determine if a file should be checked-out or not and, if it determines that it should, it will happily do that check-out on your behalf without you even asking it to. I didn’t realise how ridiculous this was until I first used SVN about three years ago – with SVN you make any changes you wish and then use your source control client to determine which files have changed and thus be checked-in; the notion of “check-out” doesn’t even exist. That sounds like a small thing but you don’t realise how liberating it is until you actually start working that way. Hoping to hear some more anecdotes and opinions in the comments. Remember….free software is up for grabs! @jamiet 

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  • Nothing seems to be syncing with Ubuntu One

    - by Anthony Papillion
    So earlier tonight I set up Ubuntu One on a fresh install of Ubuntu 10.10. In my "Ubuntu One" directory, I created symbolic links to /Documents /Pictures and /Music. Right now, there is VERY little in those directories but what IS there isn't syncing at all. When I go to the Ubuntu One web interface, it tells me I'm using 0.00% of my storage space. When I try to view the files in the web interface, I am told 'Something has gone wrong' and I don't see anything. Can anyone help? Even my Tomboy notes aren't syncing! And yes, I am connected and the software says 'Synchronisation Complete' Thanks, Anthony

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  • Simplified INotifyPropertyChanged Implementation with WeakReference Support and Typed Property Acces

    - by Daniel Cazzulino
    I've grown a bit tired of implementing INotifyPropertyChanged. I've tried ways to improve it before (like this "ViewModel" custom tool which even generates strong-typed event accessors). But my fellow Clarius teammate Mariano thought it was overkill and didn't like that tool much. He mentioned an alternative approach also, which I didn't like too much because it relied on the consumer changing his typical interaction with the object events, but also because it has a substantial design flaw that causes handlers not to be called at all after a garbage collection happens. A very simple unit test will showcase this bug....Read full article

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  • Cloud Computing Architecture Patterns: Don’t Focus on the Client

    - by BuckWoody
    Normally I try to put topics in the positive in other words "Do this" not "Don't do that". Sometimes its clearer to focus on what *not* to do. Popular development processes often start with screen mockups, or user input descriptions. In a scale-out pattern like Cloud Computing on Windows Azure, that's the wrong place to start. Start with the Data    Instead, I recommend that you start with the data that a process requires. That data might be temporary or persisted, but starting with the data and its requirements helps to define not only the storage engine you need but also drives everything from security to the integrity of the application. For instance, assume the requirements show that the user must enter their phone number, and that this datum is used in a contact management system further down the application chain. For that datum, you can determine what data type you need (U.S. only or International?) the security requirements, whether it needs ACID compliance, how it will be searched, indexed and so on. From one small data point you can extrapolate out your options for storing and processing the data. Here's the interesting part, which begins to break the patterns that we've used for decades: all of the data doesn't have the same requirements. The phone number might be best suited for a list, or an element, or a string, with either BASE or ACID requirements, based on how it is used. That means we don't have to dump everything into XML, an RDBMS, a NoSQL engine, or a flat file exclusively. In fact, one record might use all of those depending on the use-case requirements. Next Is Data Management  With the data defined, we can move on to how to store the data. Again, the requirements now dictate whether we need a full relational calculus or set-based operations, or we can choose another method based on the requirements for the data. And breaking another pattern its OK to store in more than once, in more than one location. We do this all the time for reporting systems and Business Intelligence systems, so this is a pattern we need to think about even for OLTP data. Move to Data Transport How does the data get around? We can use a connection-based method, sending the data along a transport to the storage engine, but in some cases we may want to use a cache, a queue, the Service Bus, or Complex Event Processing. Finally, Data Processing Most RDBMS engines, NoSQL, and certainly Big Data engines not only store data, but can process and manipulate it as well. Its doubtful that you'll calculate that phone number right? Well, if you're the phone company, you most certainly will. And so we see that even once we've chosen the data type, storage and engine, the same element can have different computing requirements based on how it is used. Sure, We Need A Front-End At Some Point Not all data is entered by human hands in fact most data isn't. We don't really need a Graphical User Interface (GUI) we need some way for a GUI to get data into and out of the systems listed earlier.   But when we do need to allow users to enter or examine data, that should be left to the GUI that best fits the device the user has. Ever tried to use an application designed for a web browser on a phone? Or one designed for a tablet on a phone? Its usually quite painful. The siren song of "We'll just write one interface for all devices" is strong, and has beguiled many an unsuspecting architect. But they just don't work out.   Instead, focus on the data, its transport and processing. Create API calls or a message system that allows for resilient transport to the device or interface, and let it do what it does best. References Microsoft Architecture Journal:   http://msdn.microsoft.com/en-us/architecture/bb410935.aspx Patterns and Practices:   http://msdn.microsoft.com/en-us/library/ff921345.aspx Windows Azure iOS, Android, Windows 8 Mobile Devices SDK: http://www.windowsazure.com/en-us/develop/mobile/tutorials/get-started-ios/ Windows Azure Facebook SDK: http://ntotten.com/2013/03/14/using-windows-azure-mobile-services-with-the-facebook-sdk-for-windows-phone/

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  • Login failed for user 'sa' because the account is currently locked out. The system administrator can

    - by cabhilash
    Login failed for user 'sa' because the account is currently locked out. The system administrator can unlock it. (Microsoft SQL Server, Error: 18486) SQL server has local password policies. If policy is enabled which locks down the account after X number of failed attempts then the account is automatically locked down.This error with 'sa' account is very common. sa is default administartor login available with SQL server. So there are chances that an ousider has tried to bruteforce your system. (This can cause even if a legitimate tries to access the account with wrong password.Sometimes a user would have changed the password without informing others. So the other users would try to lo) You can unlock the account with the following options (use another admin account or connect via windows authentication) Alter account & unlock ALTER LOGIN sa WITH PASSWORD='password' UNLOCK Use another account Almost everyone is aware of the sa account. This can be the potential security risk. Even if you provide strong password hackers can lock the account by providing the wrong password. ( You can provide extra security by installing firewall or changing the default port but these measures are not always practical). As a best practice you can disable the sa account and use another account with same privileges.ALTER LOGIN sa DISABLE You can edit the lock-ot options using gpedit.msc( in command prompt type gpedit.msc and press enter). Navigate to Account Lokout policy as shown in the figure The Following options are available Account lockout threshold This security setting determines the number of failed logon attempts that causes a user account to be locked out. A locked-out account cannot be used until it is reset by an administrator or until the lockout duration for the account has expired. You can set a value between 0 and 999 failed logon attempts. If you set the value to 0, the account will never be locked out. Failed password attempts against workstations or member servers that have been locked using either CTRL+ALT+DELETE or password-protected screen savers count as failed logon attempts. Account lockout duration This security setting determines the number of minutes a locked-out account remains locked out before automatically becoming unlocked. The available range is from 0 minutes through 99,999 minutes. If you set the account lockout duration to 0, the account will be locked out until an administrator explicitly unlocks it. If an account lockout threshold is defined, the account lockout duration must be greater than or equal to the reset time. Default: None, because this policy setting only has meaning when an Account lockout threshold is specified. Reset account lockout counter after This security setting determines the number of minutes that must elapse after a failed logon attempt before the failed logon attempt counter is reset to 0 bad logon attempts. The available range is 1 minute to 99,999 minutes. If an account lockout threshold is defined, this reset time must be less than or equal to the Account lockout duration. Default: None, because this policy setting only has meaning when an Account lockout threshold is specified.When creating SQL user you can set CHECK_POLICY=on which will enforce the windows password policy on the account. The following policies will be applied Define the Enforce password history policy setting so that several previous passwords are remembered. With this policy setting, users cannot use the same password when their password expires.  Define the Maximum password age policy setting so that passwords expire as often as necessary for your environment, typically, every 30 to 90 days. With this policy setting, if an attacker cracks a password, the attacker only has access to the network until the password expires.  Define the Minimum password age policy setting so that passwords cannot be changed until they are more than a certain number of days old. This policy setting works in combination with the Enforce password historypolicy setting. If a minimum password age is defined, users cannot repeatedly change their passwords to get around the Enforce password history policy setting and then use their original password. Users must wait the specified number of days to change their passwords.  Define a Minimum password length policy setting so that passwords must consist of at least a specified number of characters. Long passwords--seven or more characters--are usually stronger than short ones. With this policy setting, users cannot use blank passwords, and they have to create passwords that are a certain number of characters long.  Enable the Password must meet complexity requirements policy setting. This policy setting checks all new passwords to ensure that they meet basic strong password requirements.  Password must meet the following complexity requirement, when they are changed or created: Not contain the user's entire Account Name or entire Full Name. The Account Name and Full Name are parsed for delimiters: commas, periods, dashes or hyphens, underscores, spaces, pound signs, and tabs. If any of these delimiters are found, the Account Name or Full Name are split and all sections are verified not to be included in the password. There is no check for any character or any three characters in succession. Contain characters from three of the following five categories:  English uppercase characters (A through Z) English lowercase characters (a through z) Base 10 digits (0 through 9) Non-alphabetic characters (for example, !, $, #, %) A catch-all category of any Unicode character that does not fall under the previous four categories. This fifth category can be regionally specific.

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  • Flash is not working in Chrome

    - by Jim Ford
    I have google Chrome 8.0.552.237 on Ubuntu 10.10 64-bit and flash is not working, I have tried a variety of methods to install flash, including Firefox flash-aid and the flash-installer package and nothing is working for me. I have even uninstalled and reinstalled chrome to no avail. I get "missing plugin" message where flash plugin should be in a website. What am I missing? UPDATE I have a variety of plugins returned by jgbelacqua's command: /usr/lib/chromium-browser/plugins/flashplugin-alternative.so /usr/lib/firefox/plugins/flashplugin-alternative.so /usr/lib/flashplugin-installer/libflashplayer.so /usr/lib/iceape/plugins/flashplugin-alternative.so /usr/lib/iceweasel/plugins/flashplugin-alternative.so /usr/lib/midbrowser/plugins/flashplugin-alternative.so /usr/lib/mozilla/plugins/flashplugin-alternative.so /usr/lib/xulrunner/plugins/flashplugin-alternative.so /usr/lib/xulrunner-addons/plugins/flashplugin-alternative.so /usr/share/ubufox/plugins/libflashplayer.so /var/cache/flashplugin-installer/libflashplayer.so I'm not sure which is necessary and which not. I should note tho that my Chromium does have flash and it does work... just not chrome or firefox.

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  • GDC 2012: DXT is NOT ENOUGH! Advanced texture compression for games

    GDC 2012: DXT is NOT ENOUGH! Advanced texture compression for games (Pre-recorded GDC content) Tired of fighting to fit your textures on disk? Too many bad reviews on long download times? Fix it! Don't settle for putting your raw DXT files in a ZIP, instead, compress your DXT textures by an extra 50%-70%! This talk will cover various ways to increase the compression of your game textures to allow for smaller distributables without introducing error, and allowing for fast on-demand decompression at run time. We'll cover how to losslessly squeeze your data with Huffman, block expansion, vector quantization, and we'll even take a look at what MegaTexture is doing too. If you've ever fought to fit textures into memory, this is the talk for you. Speaker: Colt McAnlis From: GoogleDevelopers Views: 1132 21 ratings Time: 33:05 More in Science & Technology

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  • Virus that makes all files and folders read-only filesystem on a usb drive

    - by ren florento
    Is there any way on how to remove a virus from Windows that makes the files and folders and the usb drive itself a read-only filesystem as this is an annoying one because the virus keeps copying itself as long as it sees a folder and keeps running which prevents you from creating and deleting files and folders from the usb drive and makes " mount -o remount,rw '/path' " ineffective ? btw i'm not really sure if it is a virus but what makes me think that it is a virus is for the reason the it creates a .exe file within every folder which was named after folder and it also immediately reverts to read-only filesystem which locks the files and folders even after executing the command " mount -o remount,rw '/path' ". i also think the virus is just running only within the usb drive as it is not affecting the folders on ubuntu. I could choose to reformat the usb drive as it only contains few important files but what concerns me is if such virus or whatever you may call it gets into my backup drives that contains many important files.Thanks for any help and advice you could give.

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  • HTML5 and Visual Studio 2010

    - by Harish Ranganathan
    All of us work with Visual Studio (or the free Visual Web Developer Express Edition) for developing web applications targeting ASP.NET / ASP.NET MVC or Silverlight etc.,  Over the years, Visual Studio has grown to a great extent.  From being a simple limited functionality tool in VS.NET 2002 to the multi-faceted, MEF driven Visual Studio 2010, it has come a long way.  And as much as Visual Studio supports rapid web development by generating HTML mark up, it also added intellisense for some of the HTML specifications that one has otherwise monotonously type every time.  Ex.- In Visual Studio 2010, one can just type the angular bracket “<” and then the first keyword “h” or “x” for html or xhtml respectively and then press tab twice and it would render the entire markup required for XHTML or HTML 1.0/1.1 strict/transitional and the fully qualified W3C URL. The same holds good for specifying HTML type declaration.  Now, the difference between HTML and XHTML has been discussed in detail already, though, if you are interested to know, you can read it from http://www.w3schools.com/xhtml/xhtml_html.asp But, the industry trend or the buzz around is HTML5.  With browsers like IE9 Beta, Google Chrome, Firefox 4 etc., supporting HTML5 standards big time, everyone wants to start developing HTML5 based websites. VS developers (like me) often get the question around when would VS start supporting HTML5.  VS 2010 was released last year and HTML5 is still specifications under development.  Clearly, with the timelines we started developing Visual Studio (way back in 2008), HTML5 specs were almost non-existent.  Even today, the HTML5 body recommends not to fully depend on the entire mark up set as they are still under development specs and might change in the future. However, with Visual Studio 2010 SP1 beta, there is quite a bit of support for HTML5 based web development.  In fact, one of my colleagues pointed out that SP1 beta’s major enhancement is its ability to support HTML5 tags and even add server mode to them. Lets look at the existing validation schema available in Visual Studio (Tools – Options – Validation) This is before installing Visual Studio 2010 SP1 Beta.  Clearly, the validation options are restricted to HTML 4.01 and XHTML 1.1 transitional and below. Also, lets consider using some of the new HTML5 input type elements.  (I found out this, just today from my friend, also an, ASP.NET team member) <input type=”email”> is one of the new input type elements according to the HTML5 specification.  Now, this works well if you type it as is  in Visual Studio and the page renders without any issue (since the default behaviour is, if there is an “undefined” type specified to input tag, it would fall back on the default mode, which is text. The moment you add <input type=”email” runat=”server” >, you get an error Naturally you don’t get intellisense support as well for these new tags.  Once you install Visual Studio 2010 Service Pack 1 Beta from here (it takes a while so you need to be patient for the installation to complete), you will start getting additional Validation templates for HTML5, as below:- Once you set this, you can start using HTML5 elements in your web page without getting errors/warnings.  Look at the screen shot below, for the new “video” tag which is showing up in intellisense (video is a part of the new HTML5 specifications)     note that, you still need to hook up the <!DOCTYPE html /> on the top manually as it doesn’t change automatically  (from the default XHTML 1.0 strict) when you create a new page. Also, the new input type tags in HTML5 are also supported One, can also use the <asp:TextBox type=”email” which would in turn generate the <input type=”email”> markup when the page is rendered.  In fact, as of SP1 beta, this is the only way to put the new input type tags with the runat=”server” attribute (otherwise you will get the parser error mentioned above.  This issue would be fixed by the final release of SP1 beta) Going further, there may be more support for having server tags for some of the common HTML5 elements, but this is work in progress currently. So, other than not having runat=”server” support for the new HTML5  input tags, you can pretty much build and target HTML5 websites with Visual Studio 2010 SP1 Beta, today.  For those who are running Visual Studio 2008, you also have the “HTML5 intellisense for Visual Studio 2010 and 2008” available for download, from http://visualstudiogallery.msdn.microsoft.com/d771cbc8-d60a-40b0-a1d8-f19fc393127d/ Note that, if you are running Visual Studio 2010, the recommended approach is to install the SP1 beta which would be the way forward for HTML5 support in Visual Studio. Of course, you need to test these on a browser supporting HTML5 such as IE9 Beta or Chrome or FireFox 4.  You can download IE9 Beta from here You can also follow the Visual Web Developer Team Blog for more updates on the stuff they are building. Cheers !!!

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  • DVI+HDMI out, at startup only HDMI is available

    - by Alasjo
    I have my computer next to my hdtv. The main screen is connected via DVI while the tv is connected via HDMI. If I start the computer without the HDMI plugged in, everything is ok: I see the login screen and sound is output through analog out. But if the HDMI is plugged in before I start the computer, only the tv gets an image (the login screen), the main screen is black or at some times purple, but even after login the main screen is black. Also sound is still output through analog out. Not sure whether it's a hw issue, or an Ubuntu issue, or a combined hardware/Ubuntu compatibility issue (Sandy Bridge). This is my setup: Ubuntu 11.10 Oneiric Ocelot (64bit) ASUS P8H67-M LE Intel Core i3-2100 I don't have any custom video settings, my main screen is recognized properly when HDMI is not plugged in at startup. Cheers.

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  • The incomplete list of impolite WP7 dev requests

    In my previous list of WP7 user requests, I piled all of my user hopes and dreams for my new WP7 phone (delivery date: who the hell knows) onto the universe as a way to make good things happen. And all that’s fine, but I’m not just a user; like most of my readers, I’m also a developer and have a need to control my phone with code. I have a long list of applications I want to write and an even longer list of applications I want other developers to write for me.   Today at 1:30p...Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • How to comply with this guideline for submitting an application to the Software Center?

    - by George Edison
    I was reading through the Ubuntu Developer Programme Agreement for submitting applications to the Software Center and stubled across the following clause: 3.1 You must first test Apps you submit to confirm they are compatible with all currently supported versions of Ubuntu (as listed on Canonical's website at the date of submission by you) and your Apps must comply with the Publishing Policy. Does this mean I must install both the 32 and 64 bit versions of Ubuntu 8.04, 10.04, 10.10, 11.04, and 11.10? If so, that's 10 installations of Ubuntu - is that really feasible (even with virtual machines)? Alternatively, does anyone have suggestions for testing the application without actually installing each version? Some sort of chroot tool, perhaps?

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  • Computer Science or Computer Engineering for Data Science and Machine Learning

    - by ATMathew
    I'm a 25 year old data consultant who is considering returning to school to get a second bachelors degree in computer science or engineering. My interest is data science and machine learning. I use programming as a means to an end, and use languages like Python, R, C, Java, and Hadoop to find meaning in large data sets. Would a computer science or computer engineering degree be better for this? I realize that a statistics degree may be even more beneficial, but I'll be at a school which dosn't have a stats department or a computational math department.

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  • Toughest Developer Puzzle Ever

    - by Josh Holmes
    For the second year in a row, my friend and colleague Jeff Blankenburg has created what is quickly proving to live up to it’s namesake – the Toughest Developer Puzzle Ever. Some of the puzzles are technical, some are not but all require that you understand the web, development and technology to solve. Even if you don’t get in on the fantastic prizes that Jeff has lined up, there’s great bragging rights in being able to solve the Toughest Developer Puzzle Ever. This year, I was honored enough to get to create three of the puzzles myself – let me know what you think of them. I’m not going to tell you which ones I created now and definitely don’t ask me for hints – Jeff has threatened me if I give any of the puzzle away… ;) All I can say now is “Good luck!”

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  • htaccess code for maintenance page redirect

    - by Force Flow
    I set up a maintenance page that I could enable through an htaccess file. The html file is located in a folder called "maintenance". The html file has some images in it. However, visitors to the page see no images, even though I added a line to allow them. If I try to visit an image in the browser directly, it redirects to the maintenance.htm page. Am I missing something? # Redirects visitors to maintenance page except for specific IP addresses # uncomment lines when redirecting visitors to maintenance page; comment when done. # Also see the section on "redirects visitors from maintenance page to homepage" # #RewriteCond %{REMOTE_ADDR} !^127.0.0.1$ #RewriteCond %{REMOTE_ADDR} !^111.111.111.111$ RewriteCond %{REQUEST_URI} !/maintenance/maintenance\.htm$ [NC] RewriteCond %{REQUEST_URI} !\.(jpg|jpeg|png|gif|css|ico)$ [NC] RewriteRule ^(.*)$ /maintenance/maintenance.htm [R=302,L] # # end redirects visitors to maintenance page # Redirects visitors from maintenance page to homepage # comment lines when redirecting visitors to maintenance page; uncomment when done # #Redirect 301 /maintenance/maintenance.htm / # # end redirects visitors from maintenance page to homepage

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  • Cosmic Journeys – Supermassive Black Hole at the Center of the Galaxy

    - by Akemi Iwaya
    Even though the center of our galaxy is obscured by thick dust and blinding starlight, that has not stopped scientists from piecing together clues about what may lie there. Sit back and enjoy a ‘cosmic journey’ with this excellent half-hour video from YouTube channel SpaceRip discussing what scientists have learned about the supermassive black hole at the center of our galaxy, and their work on getting a ‘direct image’ of it. Cosmic Journeys: Supermassive Black Hole at the Center of the Galaxy [YouTube]     

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  • Wireless iwconfig rate auto too low

    - by Jamie Kitson
    Hi, left to its own devices my wireless connects at too low a speed. I have a 20meg internet connection and my wireless is slowing it down to like 3meg. When I reboot into windows it's fine. When I run iwconfig eth1 rate 24M or even 48M the connection is much faster and runs fine, why won't it automatically go higher? Is this the fault of the driver? I am running Broadcom's driver compiled from source. Would adding iwconfig eth1 rate 24M to rc.local be the right way to force it at boot? Output from iwconfig when rate=auto: eth1 IEEE 802.11 ESSID:"honeypot" Mode:Managed Frequency:2.417 GHz Access Point: xxx Bit Rate=1 Mb/s Tx-Power:24 dBm Retry min limit:7 RTS thr:off Fragment thr:off Encryption key:off Power Management:off Link Quality=5/5 Signal level=-47 dBm Noise level=-91 dBm Rx invalid nwid:0 Rx invalid crypt:2 Rx invalid frag:0 Tx excessive retries:0 Invalid misc:0 Missed beacon:0 Thanks, Jamie

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  • Analysing and measuring the performance of a .NET application (survey results)

    - by Laila
    Back in December last year, I asked myself: could it be that .NET developers think that you need three days and a PhD to do performance profiling on their code? What if developers are shunning profilers because they perceive them as too complex to use? If so, then what method do they use to measure and analyse the performance of their .NET applications? Do they even care about performance? So, a few weeks ago, I decided to get a 1-minute survey up and running in the hopes that some good, hard data would clear the matter up once and for all. I posted the survey on Simple Talk and got help from a few people to promote it. The survey consisted of 3 simple questions: Amazingly, 533 developers took the time to respond - which means I had enough data to get representative results! So before I go any further, I would like to thank all of you who contributed, because I now have some pretty good answers to the troubling questions I was asking myself. To thank you properly, I thought I would share some of the results with you. First of all, application performance is indeed important to most of you. In fact, performance is an intrinsic part of the development cycle for a good 40% of you, which is much higher than I had anticipated, I have to admit. (I know, "Have a little faith Laila!") When asked what tool you use to measure and analyse application performance, I found that nearly half of the respondents use logging statements, a third use performance counters, and 70% of respondents use a profiler of some sort (a 3rd party performance profilers, the CLR profiler or the Visual Studio profiler). The importance attributed to logging statements did surprise me a little. I am still not sure why somebody would go to the trouble of manually instrumenting code in order to measure its performance, instead of just using a profiler. I personally find the process of annotating code, calculating times from log files, and relating it all back to your source terrifyingly laborious. Not to mention that you then need to remember to turn it all off later! Even when you have logging in place throughout all your code anyway, you still have a fair amount of potentially error-prone calculation to sift through the results; in addition, you'll only get method-level rather than line-level timings, and you won't get timings from any framework or library methods you don't have source for. To top it all, we all know that bottlenecks are rarely where you would expect them to be, so you could be wasting time looking for a performance problem in the wrong place. On the other hand, profilers do all the work for you: they automatically collect the CPU and wall-clock timings, and present the results from method timing all the way down to individual lines of code. Maybe I'm missing a trick. I would love to know about the types of scenarios where you actively prefer to use logging statements. Finally, while a third of the respondents didn't have a strong opinion about code performance profilers, those who had an opinion thought that they were mainly complex to use and time consuming. Three respondents in particular summarised this perfectly: "sometimes, they are rather complex to use, adding an additional time-sink to the process of trying to resolve the existing problem". "they are simple to use, but the results are hard to understand" "Complex to find the more advanced things, easy to find some low hanging fruit". These results confirmed my suspicions: Profilers are seen to be designed for more advanced users who can use them effectively and make sense of the results. I found yet more interesting information when I started comparing samples of "developers for whom performance is an important part of the dev cycle", with those "to whom performance is only looked at in times of crisis", and "developers to whom performance is not important, as long as the app works". See the three graphs below. Sample of developers to whom performance is an important part of the dev cycle: Sample of developers to whom performance is important only in times of crisis: Sample of developers to whom performance is not important, as long as the app works: As you can see, there is a strong correlation between the usage of a profiler and the importance attributed to performance: indeed, the more important performance is to a development team, the more likely they are to use a profiler. In addition, developers to whom performance is an important part of the dev cycle have a higher tendency to use a much wider range of methods for performance measurement and analysis. And, unsurprisingly, the less important performance is, the less varied the methods of measurement are. So all in all, to come back to my random questions: .NET developers do care about performance. Those who care the most use a wider range of performance measurement methods than those who care less. But overall, logging statements, performance counters and third party performance profilers are the performance measurement methods of choice for most developers. Finally, although most of you find code profilers complex to use, those of you who care the most about performance tend to use profilers more than those of you to whom performance is not so important.

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  • Thunderbird uses the wrong browser

    - by Aaron Digulla
    I'm unable to make Thunderbird open the default browser. In the browser preferences, Chromium is selected as the default browser. It's also selected in "Default Applications" in System Settings. In Thunderbird, I read "Chrome (Default)" which is wrong on all levels: Chrome itself complains that it's not the default browser when I click a link inside Thunderbird. In all other places, that I could find, Chromium is the default Here is what I tried: I used update-alternatives --config x-www-browser to select chromium-browser as well (see How do I change the default browser?). And even when I select a different browser from the list in the Thunderbird preferences, it still opens Chrome. My current solution is to create a link from /usr/bin/google-chrome to chromium-browser. How can I force Thunderbird to use the browser I want??? EDIT I also updated gnome-www-browser (update-alternatives --config gnome-www-browser) after feedback from roadmr but that didn't help. At least sensible-browser opens Chromium, now, but Thunderbird is stubborn.

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  • Why lock-free data structures just aren't lock-free enough

    - by Alex.Davies
    Today's post will explore why the current ways to communicate between threads don't scale, and show you a possible way to build scalable parallel programming on top of shared memory. The problem with shared memory Soon, we will have dozens, hundreds and then millions of cores in our computers. It's inevitable, because individual cores just can't get much faster. At some point, that's going to mean that we have to rethink our architecture entirely, as millions of cores can't all access a shared memory space efficiently. But millions of cores are still a long way off, and in the meantime we'll see machines with dozens of cores, struggling with shared memory. Alex's tip: The best way for an application to make use of that increasing parallel power is to use a concurrency model like actors, that deals with synchronisation issues for you. Then, the maintainer of the actors framework can find the most efficient way to coordinate access to shared memory to allow your actors to pass messages to each other efficiently. At the moment, NAct uses the .NET thread pool and a few locks to marshal messages. It works well on dual and quad core machines, but it won't scale to more cores. Every time we use a lock, our core performs an atomic memory operation (eg. CAS) on a cell of memory representing the lock, so it's sure that no other core can possibly have that lock. This is very fast when the lock isn't contended, but we need to notify all the other cores, in case they held the cell of memory in a cache. As the number of cores increases, the total cost of a lock increases linearly. A lot of work has been done on "lock-free" data structures, which avoid locks by using atomic memory operations directly. These give fairly dramatic performance improvements, particularly on systems with a few (2 to 4) cores. The .NET 4 concurrent collections in System.Collections.Concurrent are mostly lock-free. However, lock-free data structures still don't scale indefinitely, because any use of an atomic memory operation still involves every core in the system. A sync-free data structure Some concurrent data structures are possible to write in a completely synchronization-free way, without using any atomic memory operations. One useful example is a single producer, single consumer (SPSC) queue. It's easy to write a sync-free fixed size SPSC queue using a circular buffer*. Slightly trickier is a queue that grows as needed. You can use a linked list to represent the queue, but if you leave the nodes to be garbage collected once you're done with them, the GC will need to involve all the cores in collecting the finished nodes. Instead, I've implemented a proof of concept inspired by this intel article which reuses the nodes by putting them in a second queue to send back to the producer. * In all these cases, you need to use memory barriers correctly, but these are local to a core, so don't have the same scalability problems as atomic memory operations. Performance tests I tried benchmarking my SPSC queue against the .NET ConcurrentQueue, and against a standard Queue protected by locks. In some ways, this isn't a fair comparison, because both of these support multiple producers and multiple consumers, but I'll come to that later. I started on my dual-core laptop, running a simple test that had one thread producing 64 bit integers, and another consuming them, to measure the pure overhead of the queue. So, nothing very interesting here. Both concurrent collections perform better than the lock-based one as expected, but there's not a lot to choose between the ConcurrentQueue and my SPSC queue. I was a little disappointed, but then, the .NET Framework team spent a lot longer optimising it than I did. So I dug out a more powerful machine that Red Gate's DBA tools team had been using for testing. It is a 6 core Intel i7 machine with hyperthreading, adding up to 12 logical cores. Now the results get more interesting. As I increased the number of producer-consumer pairs to 6 (to saturate all 12 logical cores), the locking approach was slow, and got even slower, as you'd expect. What I didn't expect to be so clear was the drop-off in performance of the lock-free ConcurrentQueue. I could see the machine only using about 20% of available CPU cycles when it should have been saturated. My interpretation is that as all the cores used atomic memory operations to safely access the queue, they ended up spending most of the time notifying each other about cache lines that need invalidating. The sync-free approach scaled perfectly, despite still working via shared memory, which after all, should still be a bottleneck. I can't quite believe that the results are so clear, so if you can think of any other effects that might cause them, please comment! Obviously, this benchmark isn't realistic because we're only measuring the overhead of the queue. Any real workload, even on a machine with 12 cores, would dwarf the overhead, and there'd be no point worrying about this effect. But would that be true on a machine with 100 cores? Still to be solved. The trouble is, you can't build many concurrent algorithms using only an SPSC queue to communicate. In particular, I can't see a way to build something as general purpose as actors on top of just SPSC queues. Fundamentally, an actor needs to be able to receive messages from multiple other actors, which seems to need an MPSC queue. I've been thinking about ways to build a sync-free MPSC queue out of multiple SPSC queues and some kind of sign-up mechanism. Hopefully I'll have something to tell you about soon, but leave a comment if you have any ideas.

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  • Is hiding content with JavaScript or "text-indent: -9999px" bad for SEO?

    - by Samuel
    So apparently hiding content using "display: none" is bad for SEO and seen by googlebot as being deceptive. This according to a lot of the posts I read online and questions even on this site. But what if I hide keyword rich text using javascript? A jquery example: $(function() { $('#keywordRichTextContainer').hide(); }); or using visibility hidden: $(function() { $('#keywordRichTextContainer').css({ visibility: 'hidden', position: 'absolute' }); }); Would any of these techniques cause my site to be penalized? If googlebot can't read javascript then if I'm hiding through js it shouldn't know right? What about using "text-indent: -9999px"?

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  • Add AD Domain user to sudoers from the command line

    - by Wyatt Barnett
    I'm setting up an Ubuntu 11.04 server VM for use as a database server. It would make everyone's lives easier if we could have folks login using windows credentials and perhaps even make the machine work with the current AD-driven security we've got elsewhere. The first leg of this was really easy to accomplish -- apt-get install likewise-open and I was pretty much in business. The problem I'm having is getting our admins into the sudoers groups -- I can't seem to get anything to take. I've tried: a) usermod -aG sudoers [username] b) adding the user names in several formats (DOMAIN\user, user@domain) to the sudoers file. None of which seemed to take, I still get told "DOMAIN\user is not in the sudoers file. This incident will be reported." So, how do I add non-local users to the sudoers?

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  • Good Atom Based Tablets that run Ubuntu?

    - by Anthony Papillion
    I'm starting a software project for a company that will deploy on tablet computers. They want to stick with Intel processors so they are looking for a good tablet that runs on an Atom processor. MY requirement is that it needs to also be able to run Ubuntu. It doesn't have to come with Ubuntu, I just need to be able to install it with no hassle. But, if it comes with Ubuntu preinstalled, that's even better. Can anyone make a recommend? Thanks! Anthony

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  • What You Said: Do You Use the Command Line?

    - by Jason Fitzpatrick
    Earlier this week we asked you to sound off with your love (or lack there of) for the command line. You sounded off in force and now we’re back with a comment roundup. It turns out you all pretty much love the command line with that love ranging from not even liking Graphic User Interfaces (GUIs) to using the command line to get serious work done but having a long standing affair with your OS’s GUI. Many of you lamented the poor command line implementation in Windows—especially after you’d had experience with other operation systems. Mike writes: Of course. Some things are easier that was. Like ping and ipconfig. With a strong Unix background I still write and use batch files. It would be nice is the command line included more nice things like grep, sleep, touch. Maybe, someday, Windows will mature into a full OS. What is a Histogram, and How Can I Use it to Improve My Photos?How To Easily Access Your Home Network From Anywhere With DDNSHow To Recover After Your Email Password Is Compromised

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