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  • Display problem with fresh install of 12.04

    - by Dan
    Just intalled Ubuntu 12.04 from CD and install went with no problems. After rebooting, I get the initial purple screen and then a black screen with mouse pointer and a few stray pixels at the bottom left of screen. Occasionally during the boot process, the purple screen comes back momentarily but then back to the black screen with the mouse pointer. When I finally give up and press the power button, the purple screen returns with the Shut Down box visible as it is shutting down. Any ideas? I have tried adding nomodeset after quiet splash, but no change. Possibly not doing it correctly, since I am somewhat of a newbie to linux. Thanks! Dan

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  • Cocos2dx InApp Purchase for ios

    - by Ahmad dar
    I am trying to integrate In App Purchases in my app made by using cocos2d x c++. I am using easyNdk Helper for In App Purchases. My In App Purchases works perfectly for my Objective C apps. But for cocos2d x it is throwing error for the following line if ([[RageIAPHelper sharedInstance] productPurchased:productP.productIdentifier]) Actually value came from CPP file perfectly in form of arguments and Properly shows their value in NSLog , But it always shows the objects as nil even objetcs print their stored value in NSLog also @try catch condition is not working and finally throw the following error Please Help me what i have to do ? Thanks

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  • Flash 10.2 RC + Crystal HD for HW accelerated video on Ubuntu

    - by Gee
    I have a netbook with a N450 Atom and a BCM70012 aka Crystal HD card. On Windows 7 I can play HD flash video with very little CPU usage because of the RC of Flash 10.2. I did some reading and saw posts claiming that the Crystal HD card is finally supported by the newer Flash 10.2 RC in Ubuntu but I can't get it to work. I can confirm that flash 10.2 is loaded and used, and there's even a HW acceleration option that is enabled in the settings but performance is horrible. From what I read, the Crystal HD card is supposed to be enabled on 10.10 by default - I don't know if it is. I tried installing drivers for it in various ways but HD flash video is still a slideshow So does anyone have it working? If so, how'd you set it up?

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  • Create Device Reccieve SMS Parse To Text ( SMS Gateway )

    - by Chris Okyen
    I want to use a server as a device to run a script to parse a SMS text in the following way. I. The person types in a specific and special cell phone number (Similar to Facebook’s 32556 number used to post on your wall) II. The user types a text message. III. The user sends the text message. IV. The message is sent to some kind of Device (the server) or SMS Gateway and receives it. V. The thing described above that the message is sent to then parse the test message. I understand that these three question will mix Programming and Server Stuff and could reside here or at DBA.SE How would I make such a cell phone number (described in step I) that would be sent to the Device? How do I create the device that then would receive it? Finally, how do I Parse the text message?

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  • Oracle Social Network Developer Challenge Winners

    - by kellsey.ruppel
    Originally posted by Jake Kuramoto on The Apps Lab blog. Now that OpenWorld 2012 has wrapped, I have time to tell you all about what happened. Maybe you recall that Noel (@noelportugal) and I were running a modified hackathon during the show, the Oracle Social Network Developer Challenge. Without further ado, congratulations to Dimitri Gielis (@dgielis) and Martin Giffy D’Souza (@martindsouza) on their winning entry, an integration between Oracle APEX and Oracle Social Network that integrates feedback and bug submission with Oracle Social Network Conversations, allowing developers, end-users and project leaders to view and discuss the feedback on their APEX applications from within Oracle Social Network. Update: Bob Rhubart of OTN (@brhubart) interviewed Dimitri and Martin right after their big win. Money quote from Dimitri when asked what he’d buy with the $500 in Amazon gift cards, “Oracle Social Network.” Nice one. In their own words: In the developers perspective it’s important to get feedback soon, so after a first iteration and end-users start to test, they can give feedback of the application. Previously it stopped there, and it was up to the developer to communicate further with email, phone etc. With OSN every feedback and communication gets logged and other people can see the discussion immediately as well. For the end users perspective he can now communicate in a more efficient way to not only the developers, but also between themselves. Maybe many end-users (in different locations) would like to change some behaviour, by using OSN they can see the entry somebody put in with a screenshot and they can just start to chat about it. Some key technical end users can have lighten the tasks of the development team by looking at the feedback first and start to communicate with their peers. For the project manager he has now the ability to really see what communication has taken place in certain areas and can make decisions on that. Later, if things come up again, he can always go back in OSN and see what was said at that moment in time. Integrating OSN in the APEX applications enhances the user experience, makes the lives of the developers easier and gives a better overview to project managers. Incidentally, you may already know Dimitri and Martin, since both are Oracle Ace Directors. I ran into Martin at the Ace Director briefings Friday before the conference started, and at that point, he wasn’t sure he’d have time to enter the Challenge. After some coaxing, he and Dimitri agreed to give it a go and banged out their entry on Tuesday night, or more accurately, very early Wednesday morning, the day of the Challenge judging. I think they said it took them about four hours of hardcore coding to get it done, very much like a traditional hackathon, which is essentially a code sprint from idea to finished product. Here are some screenshots of the workflow they built. #gallery-1 { margin: auto; } #gallery-1 .gallery-item { float: left; margin-top: 10px; text-align: center; width: 33%; } #gallery-1 img { border: 2px solid #cfcfcf; } #gallery-1 .gallery-caption { margin-left: 0; } I love this idea, i.e. closing the loop between web developers and users, a very common pain point, and so did our judges. Speaking of, special thanks to our panel of three judges: Reggie Bradford (@reggiebradford), serial entrepreneur, founder of Vitrue and SVP of Cloud Product Development at Oracle Robert Hipps (@roberthipps), VP of Development for Oracle Social Network and my former boss Roland Smart (@rsmartx), VP of Social Marketing and the brains behind the Oracle Social Developer Community Finally, thanks to everyone who made this possible, including: The three other teams from HarQen (@harqen), TEAM Informatics (@teaminformatics) and Fishbowl Solutions (@fishbowle20) featuring Friend of the ‘Lab John Sim (@jrsim_uix), who finished and presented entries. I’ll be posting the details of their work this week. The one guy who finished an entry, but couldn’t make the judging, Bex Huff (@bex). Bex rallied from a hospitalization due to an allergic reaction during the show; he’s fine, don’t worry. I’ll post details of his work next week, too. The 40-plus people who registered to compete in the Challenge. Noel for all his hard work, sample code, and flying monkey target, more on that to come. The Oracle Social Network development team for supporting this event. Everyone in legal and the beta program office for their help. And finally, the Oracle Technology Network (@oracletechnet) for hosting the event and providing countless hours of operational and moral support. Sorry if I’ve missed some people, since this was a huge team effort. This event was a big success, and we plan to do similar events in the future. Stay tuned to this channel for more. 

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  • Remote Debug Windows Azure Cloud Service

    - by Shaun
    Originally posted on: http://geekswithblogs.net/shaunxu/archive/2013/11/02/remote-debug-windows-azure-cloud-service.aspxOn the 22nd of October Microsoft Announced the new Windows Azure SDK 2.2. It introduced a lot of cool features but one of it shocked most, which is the remote debug support for Windows Azure Cloud Service (a.k.a. WACS).   Live Debug is Nightmare for Cloud Application When we are developing against public cloud, debug might be the most difficult task, especially after the application had been deployed. In order to minimize the debug effort, Microsoft provided local emulator for cloud service and storage once the Windows Azure platform was announced. By using local emulator developers could be able run their application on local machine with almost the same behavior as running on Windows Azure, and that could be debug easily and quickly. But when we deployed our application to Azure, we have to use log, diagnostic monitor to debug, which is very low efficient. Visual Studio 2012 introduced a new feature named "anonymous remote debug" which allows any workstation under any user could be able to attach the remote process. This is less secure comparing the authenticated remote debug but much easier and simpler to use. Now in Windows Azure SDK 2.2, we could be able to attach our application from our local machine to Windows Azure, and it's very easy.   How to Use Remote Debugger First, let's create a new Windows Azure Cloud Project in Visual Studio and selected ASP.NET Web Role. Then create an ASP.NET WebForm application. Then right click on the cloud project and select "publish". In the publish dialog we need to make sure the application will be built in debug mode, since .NET assembly cannot be debugged in release mode. I enabled Remote Desktop as I will log into the virtual machine later in this post. It's NOT necessary for remote debug. And selected "advanced settings" tab, make sure we checked "Enable Remote Debugger for all roles". In WACS, a cloud service could be able to have one or more roles and each role could be able to have one or more instances. The remote debugger will be enabled for all roles and all instances if we checked. Currently there's no way for us to specify which role(s) and which instance(s) to enable. Finally click "publish" button. In the windows azure activity window in Visual Studio we can find some information about remote debugger. To attache remote process would be easy. Open the "server explorer" window in Visual Studio and expand "cloud services" node, find the cloud service, role and instance we had just published and wanted to debug, right click on the instance and select "attach debugger". Then after a while (it's based on how fast our Internet connect to Windows Azure Data Center) the Visual Studio will be switched to debug mode. Let's add a breakpoint in the default web page's form load function and refresh the page in browser to see what's happen. We can see that the our application was stopped at the breakpoint. The call stack, watch features are all available to use. Now let's hit F5 to continue the step, then back to the browser we will find the page was rendered successfully.   What Under the Hood Remote debugger is a WACS plugin. When we checked the "enable remote debugger" in the publish dialog, Visual Studio will add two cloud configuration settings in the CSCFG file. Since they were appended when deployment, we cannot find in our project's CSCFG file. But if we opened the publish package we could find as below. At the same time, Visual Studio will generate a certificate and included into the package for remote debugger. If we went to the azure management portal we will find there will a certificate under our application which was created, uploaded by remote debugger plugin. Since I enabled Remote Desktop there will be two certificates in the screenshot below. The other one is for remote debugger. When our application was deployed, windows azure system will open related ports for remote debugger. As below you can see there are two new ports opened on my application. Finally, in our WACS virtual machine, windows azure system will copy the remote debug component based on which version of Visual Studio we are using and start. Our application then can be debugged remotely through the visual studio remote debugger. Below is the task manager on the virtual machine of my WACS application.   Summary In this post I demonstrated one of the feature introduced in Windows Azure SDK 2.2, which is Remote Debugger. It allows us to attach our application from local machine to windows azure virtual machine once it had been deployed. Remote debugger is powerful and easy to use, but it brings more security risk. And since it's only available for debug build this means the performance will be worse than release build. Hence we should only use this feature for staging test and bug fix (publish our beta version to azure staging slot), rather than for production.   Hope this helps, Shaun All documents and related graphics, codes are provided "AS IS" without warranty of any kind. Copyright © Shaun Ziyan Xu. This work is licensed under the Creative Commons License.

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  • Vacations on Rodrigues 2014

    And now something completely different compared to the usual technical or community related articles here on this blog. Yes, this time I'm writing some lines on my (and my family's) activities during our long weekend stay on Rodrigues. So, please bear with me, it's eventually a bit more personal... Grab a soda, some popcorn and a cosy place to continue to read. var googleAlbumLink = "https://plus.google.com/photos/117698191428446859536/albums/6047895311458281985"; //optional----------------------- var mySlideWidth = 580; var mySlideHeight = 340; var mySlideDelay = 7000; //delay in milliseconds Special promotions during school holidays Originally, our children started to ask more frequently about going on the plane again. Obviously, after their aunty from Germany was around during May, they were really eager to travel again. So, we decided that it might be a great opportunity to book some vacations during their school holidays. And just in time the local hotels and hotel groups started to advertise their special promotions for citizens and residents. After collecting multiple brochures over several days, we got attracted by various hotel packages on Rodrigues - most interestingly the expenses for the stay and flight ticket were less compared to other resorts here on the main island. As we have been to Rodrigues already back in 2008, we followed up on this idea and got in touch with a couple travel agencies. Well, I have to report that you should be really careful about the promotions from some of them. We had a very negative experience with Shamal Travel Agency in Quatre Bornes regarding their adverts and the actual price levels and age definition for children. Please, stay away from them if you are interested in transparent cost and services. Anyway, after some arrangements with two other close families we managed to confirm our stay at the Cotton Bay Hotel in Rodrigues. Given the fact that we already stayed there, and the hotel has been renovated recently, and it is under new management all looked very promising and relaxed for our vacation. Counting the days... As we already booked in July our children were counting down the days. And it got more interesting as soon as they were on school holidays finally. Well, the day arrived and waking them up at 2:30 hrs wasn't a problem after all. Quite the opposite it was fascinating for us parents to watch them waiting for the transport and later on during the airport transfer. Despite the early hours both didn't fall asleep and it was all so exciting. We are taking the plane! Well organised by the Cotton Bay Hotel Honestly, it was a breeze and a smooth ride during our stay at the hotel. From the airport transfer, the cleanliness of our bungalow, the organisation of our day trips, and the SPA - all very well and enjoyable. The children had great fun, and although it was a bit too windy to plunge into the pool they had a lot of fun with other activities on the beach and at the Kid's Club. Oh, and we had our private petting zoo with cows, sheep and goats just close to the terrace. Some of us went to check out the SPA facilities and I have to admit that the services regarding Hammam and Sauna are better than at some other hotels in Mauritius. I don't know after how many months or years I was once again enjoying a very hot sauna. Little draw-back but nothing to worry about... There is no cold water or at least ice cubes to cool down the body, but hey there was a nice breeze coming over the hills. Some day trips to mention Based on a friend's recommendation we walked to a "restaurant" called Chez Solange & Robert. Hahaha, restaurant is widely stretched in this case, as we enjoyed a great BBQ with fresh lobster, whole fish, and pieces of chicken breast in an open cottage. Just some wooden structure covered with dried palm leaves on the roof - island feeling pure! The other day we went to the Giant Tortoise & Cave Reserve Francois Leguat to observe the giant Aldabra turtles and to visit the Grande Caverne. The biggest limestone cave on the island. Compared to our last visit this was a novelty after checking out the Caverne Partate. The formations of stalactites and stalagmites are very impressive and imaginative. Our guide had lots of funny terms and despite the low light conditions the kids had a great time wandering around on the narrow wooden paths and stairs. And last but not least, we decided to check out the Tyrodrig zip lines... Everyone was allowed to join the trip through the air, and our little ones stayed close to our field guides. But finally went on their own on the very last traversal. Puuuh, it was astounishing to glide over the valley, and for sure something to repeat next time. Impressions of our vacation on Rodrigues 2014   Next stay has been discussed already Oh yes, Rodrigues baby! We are going to come again! Tentative dates have been discussed already and now it's up to us to earn enough our next holiday on that wonderful remote piece of paradise. Eventually, a little bit longer than this time. We'll see...

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  • Go From Social Glum to Guru at the Social Media Rally Station @ OOW

    - by Kristin Rose
    Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Times New Roman","serif";} @OPN Partners,We have some #exciting news for you! Just when you thought Oracle OpenWorld #OOW couldn’t get any better; OPN wants to announce a little something called the Social Media Rally Station™. #OMG!Enough with the social talk, hash tags and @’s, since there will be plenty of that at Oracle OpenWorld! This awesome station full of experts is the opportunity you've been looking for to optimize your online presence. You’ll start by receiving an overall evaluation of where you stand online, and get customized, face-to-face, expert advice on how to better engage with your customers and find new prospects online! Here’s what will happen at the Social Media Rally Stations: Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Times New Roman","serif";} Partners will check in with a Rally Coordinator who will assess your needs and move you to the appropriate station. You will take part in a Professional Photo Station where you’ll get a head shot to use on social profiles, your own website, or for articles and posts about your company. Finally, the One-2-One Station Consultants will walk you through how you’re using social media today and next steps including, Google Alerts, Google Analytics, Search Engine Optimization, LinkedIn, Twitter, Facebook, Google+ and more. Finally, this is a custom engagement so you can decide how you want to focus the time. Go from Social Media glum to guru in under 25 minutes! Oh and a few other things to remember… Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Times New Roman","serif";} These Social Media Rally Stations will be taking place on: Sunday, 9/30 from 3-5 p.m.PT at the Esplanade level, Moscone South and Monday, 10/1 from 10 a.m. – 6 p.m. PT at the OPN Lounge in Moscone South, Exhibit Hall Level Please wear professional attire from the waist up for your head-shot Bring any login info for your social platforms Come prepared with questions for our One-2-One Consultants! If you have any questions before the hitting the ground running at the Social Media Station™ sponsored by Oracle and provided by Channel Maven Consulting, or if you’d like to schedule some time while you’re at Oracle OpenWorld, send an email to [email protected]. Oh and don’t forget to RT this post on Twitter and ‘like’ us on Facebook to spread the word! #Thanks!See you around the social-sphere,#OPN

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  • Working with FusionCharts using ASP.NET

    Nowadays, users are constantly looking for more intuitive user interfaces. Because of this, it is vital to develop ASP.NET applications with diagrams such as Charts. FusionCharts enables you to plug-in several charts from a wide range of sources easily with a small amount of code. In this article, Anand examines the usage of FusionCharts in a step-by-step manner using three different scenarios. He initially examines the plotting of charts using the data from an XML file and also demonstrates the same using the values entered by users. Finally, Anand delves deep into the database connectivity aspects using an Access 2010 database with the help of relevant source code examples and screenshots.

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  • 2010 FIFA World Cup Silverlight Smooth Streaming Player with Live Messenger

    - by FernandoCortes
    Finally after weeks of hard work the World Cup Silverlight player is ready to watch the spanish team in action. This Silverlight Player use Smooth Streaming technology, enables adaptive streaming of media to Silverlight and other clients over HTTP. Smooth Streaming provides a high-quality viewing experience that scales massively on content distribution networks, making true HD 1080p media experiences a reality. The player integrate leading social networks such as Microsoft Live Messenger, Twitter and Facebook to chat in a public chat and with your Windows Live Messenger contacts list completely private. All supported on Microsoft Azure in one of the biggest deployments in this platform (350 instances). We integrate Windows Live Messenger with Siverlight using the javascript messenger library, version 3.5. Check out this video, in spanish, where Antón and me explain how to integrate Silverlight and Live Messenger: http://www.channels.com/episodes/show/8900143/-Codecamp-es-2009-Messenger-Cortes-Molleda   Player Uri http://mundial2010.telecinco.es/ (Spanish Television)   Developer & Design Team Antón Molleda (Developer) Luis Guerrero (Developer) Raúl Varela (Designer) Ricardo Acosta (Designer) Fernando Cortés Hierro (myself)

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  • Disable default error pages/error messages in IIS

    - by Antoine
    I have this web application (ASP.Net MVC 3) that on certain conditions returns a custom JSON string with a HTTP status code for an error (403, 415, 500). It is deployed on a Win 2008 R2 server with IIS 7.5 Initially I was gettting the standard HTML pages for the error instead of the JSON data. I removed the error pages for these errors in the app settings. But now my queries which should return some JSON data return a single error line. When the server gives me 403, I have the message "You do not have permission to view this directory or page." (simple line, no HTML around it). What can I do to deactivate this and finally get what the app is returning and not what the server wants to return?

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  • Anyone know how to get an LTSP image working with VIA VX855 chipset?

    - by Bryan
    I'm running an LTSP server on Ubuntu 11.10 and can load the i386 image via PXE boot on a VirtualBox VM just fine. However, when I PXE boot a Dell FX130 thin client on the LTSP network the login screen ends up being a white screen with a bunch of wavy black lines going up and down it. The 11.10 splash screen displays just fine as the image is booted, then I get a "INVALID CARD NUMBER" message, then a black screen, then finally the white screen with wavy lines. I'm not sure if the "INVALID CARD NUMBER" message has anything to do with the issue, but in the end the white screen with wavy lines makes me think it's a video driver problem. On the LTSP server, I chrooted into /opt/ltsp/i386 and made sure xserver-xorg-video-openchrome was installed. I did notice that no xorg.conf exits in /etc/X11 though.

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  • SQL Server Capacity Planner

    Apart from the capacity planner tool for System Center and SharePoint Server, I was looking for a tool which can help me to estimate the capacity of SQL Server. I found an article on Microsoft.com for SQL Server 2000 sizing but unfortunately the links are obseleted and dead: Dell PowerMatch Server Sizing Software Compaq Active Answer Resources Finally I found an article that is "close" to my interest: Hardware and Software Requirements for Installing SQL Server 2008 If any of you...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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  • Formatting and installing Ubuntu over Windows 7 without admin password

    - by Emiliano Pasqualetti
    A borrowed a friend workstation with Windows 7 and Ubuntu 10.10. I do not have the administrator password and I would like to format everything and install Ubuntu 12.04. I have put the iso on the usb using PendriveLinux and restarted the machine. At the boot I am presented with several options but those Ubuntu ones simply load my friends Ubuntu 10.10 OS (for which I have no password). edit: I fixed this by pressing F12 at the boot before it gave me that prompt (called GRUB). I clicked USB and finally install.

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  • How to nest transactions nicely - &quot;begin transaction&quot; vs &quot;save transaction&quot; and SQL Server

    - by Brian Biales
    Do you write stored procedures that might be used by others?  And those others may or may not have already started a transaction?  And your SP does several things, but if any of them fail, you have to undo them all and return with a code indicating it failed? Well, I have written such code, and it wasn’t working right until I finally figured out how to handle the case when we are already in a transaction, as well as the case where the caller did not start a transaction.  When a problem occurred, my “ROLLBACK TRANSACTION” would roll back not just my nested transaction, but the caller’s transaction as well.  So when I tested the procedure stand-alone, it seemed to work fine, but when others used it, it would cause a problem if it had to rollback.  When something went wrong in my procedure, their entire transaction was rolled back.  This was not appreciated. Now, I knew one could "nest" transactions, but the technical documentation was very confusing.  And I still have not found the approach below documented anywhere.  So here is a very brief description of how I got it to work, I hope you find this helpful. My example is a stored procedure that must figure out on its own if the caller has started a transaction or not.  This can be done in SQL Server by checking the @@TRANCOUNT value.  If no BEGIN TRANSACTION has occurred yet, this will have a value of 0.  Any number greater than zero means that a transaction is in progress.  If there is no current transaction, my SP begins a transaction. But if a transaction is already in progress, my SP uses SAVE TRANSACTION and gives it a name.  SAVE TRANSACTION creates a “save point”.  Note that creating a save point has no effect on @@TRANCOUNT.  So my SP starts with something like this: DECLARE @startingTranCount int SET @startingTranCount = @@TRANCOUNT IF @startingTranCount > 0 SAVE TRANSACTION mySavePointName ELSE BEGIN TRANSACTION -- … Then, when ready to commit the changes, you only need to commit if we started the transaction ourselves: IF @startingTranCount = 0 COMMIT TRANSACTION And finally, to roll back just your changes so far: -- Roll back changes... IF @startingTranCount > 0 ROLLBACK TRANSACTION MySavePointName ELSE ROLLBACK TRANSACTION Here is some code that you can try that will demonstrate how the save points work inside a transaction. This sample code creates a temporary table, then executes selects and updates, documenting what is going on, then deletes the temporary table. if running in SQL Management Studio, set Query Results to: Text for best readability of the results. -- Create a temporary table to test with, we'll drop it at the end. CREATE TABLE #ATable( [Column_A] [varchar](5) NULL ) ON [PRIMARY] GO SET NOCOUNT ON -- Ensure just one row - delete all rows, add one DELETE #ATable -- Insert just one row INSERT INTO #ATable VALUES('000') SELECT 'Before TRANSACTION starts, value in table is: ' AS Note, * FROM #ATable SELECT @@trancount AS CurrentTrancount --insert into a values ('abc') UPDATE #ATable SET Column_A = 'abc' SELECT 'UPDATED without a TRANSACTION, value in table is: ' AS Note, * FROM #ATable BEGIN TRANSACTION SELECT 'BEGIN TRANSACTION, trancount is now ' AS Note, @@TRANCOUNT AS TranCount UPDATE #ATable SET Column_A = '123' SELECT 'Row updated inside TRANSACTION, value in table is: ' AS Note, * FROM #ATable SAVE TRANSACTION MySavepoint SELECT 'Save point MySavepoint created, transaction count now:' as Note, @@TRANCOUNT AS TranCount UPDATE #ATable SET Column_A = '456' SELECT 'Updated after MySavepoint created, value in table is: ' AS Note, * FROM #ATable SAVE TRANSACTION point2 SELECT 'Save point point2 created, transaction count now:' as Note, @@TRANCOUNT AS TranCount UPDATE #ATable SET Column_A = '789' SELECT 'Updated after point2 savepoint created, value in table is: ' AS Note, * FROM #ATable ROLLBACK TRANSACTION point2 SELECT 'Just rolled back savepoint "point2", value in table is: ' AS Note, * FROM #ATable ROLLBACK TRANSACTION MySavepoint SELECT 'Just rolled back savepoint "MySavepoint", value in table is: ' AS Note, * FROM #ATable SELECT 'Both save points were rolled back, transaction count still:' as Note, @@TRANCOUNT AS TranCount ROLLBACK TRANSACTION SELECT 'Just rolled back the entire transaction..., value in table is: ' AS Note, * FROM #ATable DROP TABLE #ATable The output should look like this: Note                                           Column_A ---------------------------------------------- -------- Before TRANSACTION starts, value in table is:  000 CurrentTrancount ---------------- 0 Note                                               Column_A -------------------------------------------------- -------- UPDATED without a TRANSACTION, value in table is:  abc Note                                 TranCount ------------------------------------ ----------- BEGIN TRANSACTION, trancount is now  1 Note                                                Column_A --------------------------------------------------- -------- Row updated inside TRANSACTION, value in table is:  123 Note                                                   TranCount ------------------------------------------------------ ----------- Save point MySavepoint created, transaction count now: 1 Note                                                   Column_A ------------------------------------------------------ -------- Updated after MySavepoint created, value in table is:  456 Note                                              TranCount ------------------------------------------------- ----------- Save point point2 created, transaction count now: 1 Note                                                        Column_A ----------------------------------------------------------- -------- Updated after point2 savepoint created, value in table is:  789 Note                                                     Column_A -------------------------------------------------------- -------- Just rolled back savepoint "point2", value in table is:  456 Note                                                          Column_A ------------------------------------------------------------- -------- Just rolled back savepoint "MySavepoint", value in table is:  123 Note                                                        TranCount ----------------------------------------------------------- ----------- Both save points were rolled back, transaction count still: 1 Note                                                            Column_A --------------------------------------------------------------- -------- Just rolled back the entire transaction..., value in table is:  abc

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  • Calculated Columns in Entity Framework Code First Migrations

    - by David Paquette
    I had a couple people ask me about calculated properties / columns in Entity Framework this week.  The question was, is there a way to specify a property in my C# class that is the result of some calculation involving 2 properties of the same class.  For example, in my database, I store a FirstName and a LastName column and I would like a FullName property that is computed from the FirstName and LastName columns.  My initial answer was: 1: public string FullName 2: { 3: get { return string.Format("{0} {1}", FirstName, LastName); } 4: } Of course, this works fine, but this does not give us the ability to write queries using the FullName property.  For example, this query: 1: var users = context.Users.Where(u => u.FullName.Contains("anan")); Would result in the following NotSupportedException: The specified type member 'FullName' is not supported in LINQ to Entities. Only initializers, entity members, and entity navigation properties are supported. It turns out there is a way to support this type of behavior with Entity Framework Code First Migrations by making use of Computed Columns in SQL Server.  While there is no native support for computed columns in Code First Migrations, we can manually configure our migration to use computed columns. Let’s start by defining our C# classes and DbContext: 1: public class UserProfile 2: { 3: public int Id { get; set; } 4: 5: public string FirstName { get; set; } 6: public string LastName { get; set; } 7: 8: [DatabaseGenerated(DatabaseGeneratedOption.Computed)] 9: public string FullName { get; private set; } 10: } 11: 12: public class UserContext : DbContext 13: { 14: public DbSet<UserProfile> Users { get; set; } 15: } The DatabaseGenerated attribute is needed on our FullName property.  This is a hint to let Entity Framework Code First know that the database will be computing this property for us. Next, we need to run 2 commands in the Package Manager Console.  First, run Enable-Migrations to enable Code First Migrations for the UserContext.  Next, run Add-Migration Initial to create an initial migration.  This will create a migration that creates the UserProfile table with 3 columns: FirstName, LastName, and FullName.  This is where we need to make a small change.  Instead of allowing Code First Migrations to create the FullName property, we will manually add that column as a computed column. 1: public partial class Initial : DbMigration 2: { 3: public override void Up() 4: { 5: CreateTable( 6: "dbo.UserProfiles", 7: c => new 8: { 9: Id = c.Int(nullable: false, identity: true), 10: FirstName = c.String(), 11: LastName = c.String(), 12: //FullName = c.String(), 13: }) 14: .PrimaryKey(t => t.Id); 15: Sql("ALTER TABLE dbo.UserProfiles ADD FullName AS FirstName + ' ' + LastName"); 16: } 17: 18: 19: public override void Down() 20: { 21: DropTable("dbo.UserProfiles"); 22: } 23: } Finally, run the Update-Database command.  Now we can query for Users using the FullName property and that query will be executed on the database server.  However, we encounter another potential problem. Since the FullName property is calculated by the database, it will get out of sync on the object side as soon as we make a change to the FirstName or LastName property.  Luckily, we can have the best of both worlds here by also adding the calculation back to the getter on the FullName property: 1: [DatabaseGenerated(DatabaseGeneratedOption.Computed)] 2: public string FullName 3: { 4: get { return FirstName + " " + LastName; } 5: private set 6: { 7: //Just need this here to trick EF 8: } 9: } Now we can both query for Users using the FullName property and we also won’t need to worry about the FullName property being out of sync with the FirstName and LastName properties.  When we run this code: 1: using(UserContext context = new UserContext()) 2: { 3: UserProfile userProfile = new UserProfile {FirstName = "Chanandler", LastName = "Bong"}; 4: 5: Console.WriteLine("Before saving: " + userProfile.FullName); 6: 7: context.Users.Add(userProfile); 8: context.SaveChanges(); 9:  10: Console.WriteLine("After saving: " + userProfile.FullName); 11:  12: UserProfile chanandler = context.Users.First(u => u.FullName == "Chanandler Bong"); 13: Console.WriteLine("After reading: " + chanandler.FullName); 14:  15: chanandler.FirstName = "Chandler"; 16: chanandler.LastName = "Bing"; 17:  18: Console.WriteLine("After changing: " + chanandler.FullName); 19:  20: } We get this output: It took a bit of work, but finally Chandler’s TV Guide can be delivered to the right person. The obvious downside to this implementation is that the FullName calculation is duplicated in the database and in the UserProfile class. This sample was written using Visual Studio 2012 and Entity Framework 5. Download the source code here.

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  • Assembly Resources Expression Builder

    - by João Angelo
    In ASP.NET you can tackle the internationalization requirement by taking advantage of native support to local and global resources used with the ResourceExpressionBuilder. But with this approach you cannot access public resources defined in external assemblies referenced by your Web application. However, since you can extend the .NET resource provider mechanism and create new expression builders you can workaround this limitation and use external resources in your ASPX pages much like you use local or global resources. Finally, if you are thinking, okay this is all very nice but where’s the code I can use? Well, it was too much to publish directly here so download it from Helpers.Web@Codeplex, where you also find a sample on how to configure and use it.

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  • The illusion of Competence

    - by tony_lombardo
    Working as a contractor opened my eyes to the developer food chain.  Even though I had similar experiences earlier in my career, the challenges seemed much more vivid this time through.  I thought I’d share a couple of experiences with you, and the lessons that can be taken from them. Lesson 1: Beware of the “funnel” guy.  The funnel guy is the one who wants you to funnel all thoughts, ideas and code changes through him.  He may say it’s because he wants to avoid conflicts in source control, but the real reason is likely that he wants to hide your contributions.  Here’s an example.  When I finally got access to the code on one of my projects, I was told by the developer that I had to funnel all of my changes through him.  There were 4 of us coding on the project, but only 2 of us working on the UI.  The other 2 were working on a separate application, but part of the overall project.  So I figured, I’ll check it into SVN, he reviews and accepts then merges in.  Not even close.  I didn’t even have checkin rights to SVN, I had to email my changes to the developer so he could check those changes in.  Lesson 2: If you point out flaws in code to someone supposedly ‘higher’ than you in the developer chain, they’re going to get defensive.  My first task on this project was to review the code, familiarize myself with it.  So of course, that’s what I did.  And in familiarizing myself with it, I saw so many bad practices and code smells that I immediately started coming up with solutions to fix it.  Of course, when I reviewed these changes with the developer (guy who originally wrote the code), he smiled and nodded and said, we can’t make those changes now, it’s too destabilizing.  I recommended we create a new branch and start working on refactoring, but branching was a new concept for this guy and he was worried we would somehow break SVN. How about some concrete examples? I started out by recommending we remove NUnit dependency and tests from the application project, and create a separate Unit testing project.  This was met with a little bit of resistance because - “How do I access the private methods?”  As it turned out there weren’t really any private methods that weren’t exposed by public methods, so I quickly calmed this fear. Win 1 Loss 0 Next, I recommended that all of the File IO access be wrapped in Using clauses, or at least properly wrapped in try catch finally.  This recommendation was accepted.. but never implemented. Win 2  Loss 1 Next recommendation was to refactor the command pattern implementation.  The command pattern was implemented, but it wasn’t really necessary for the application.  More over, the fact that we had 100 different command classes, each with it’s own specific command parameters class, made maintenance a huge hassle.  The same code repeated over and over and over.  This recommendation was declined, the code was too fragile and this change would destabilize it.  I couldn’t disagree, though it was the commands themselves in many cases that were fragile. Win 2 Loss 2 Next recommendation was to aid performance (and responsiveness) of the application by using asynchronous service calls.  This on was accepted. Win 2 Loss 3 If you’re paying any attention, you’re wondering why the async service calls was scored as a loss.. Let me explain.  The service call was made using the async pattern.  Followed by a thread.sleep  <facepalm>. Now it’s easy to be harsh on this kind of code, especially if you’re an experienced developer.  But I understood how most of this happened.  One junior guy, working as hard as he can to build his first real world application, with little or no guidance from anyone else.  He had his pattern book and theory of programming to help him, but no real world experience.  He didn’t know how difficult it would be to trace the crashes to the coding issues above, but he will one day.  The part that amazed me was the management position that “this guy should be a team lead, because he’s worked so hard”.  I’m all for rewarding hard work, but when you reward someone by promoting them past the point of their competence, you’re setting yourself and them up for failure.  And that’s lesson 3.  Just because you’ve got a hard worker, doesn’t mean he should be leading a development project.  If you’re a junior guy busting your ass, keep at it.  I encourage you to try new things, but most importantly to learn from your mistakes.  And correct your mistakes.  And if someone else looks at your code and shows you a laundry list of things that should be done differently, don’t take it personally – they’re really trying to help you.  And if you’re a senior guy, working with a junior guy, it’s your duty to point out the flaws in the code.  Even if it does make you the bad guy.  And while I’ve used “guy” above, I mean both men and women.  And in some cases mutant dinosaurs. 

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  • Minecraft flickers sometimes and colors get buggy on an Intel HD Graphics 3000

    - by Oskar
    I really like Ubuntu, but I always had to switch back to Windows just because I couldn't get my Intel HD Graphics 3000 to work. So, 11.10 came out and I'm trying to get things work in this update, so I can finally stay with Ubuntu and use it. Anyways, things seem to be more stable here, but they're still a bit fishy. I'm doing tests with Minecraft. Currently, there's only 1 minor bug. The game flickers from time to time and the colors get buggy or something I read that maybe I should update to kernel 3.1? Maybe 32-bit Ubuntu is better? It was impossible to play Minecraft in 11.04, but 11.10 is so much more stable.

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  • Orchard CMS translation in Macedonian language

    - by hajan
    In the past two weeks I have been working on translating Orchard CMS in my native (Macedonian) language. Finally, the translation is completed and it is available for download in the Orchard Localization page. About 90% of the strings are translated. If you are Macedonian native speaker, you can take a look at it and if you have any remarks or have better translations for some phrases or strings, please provide me your feedback on my mkdot.net email: hajan[at]mkdot.net. I would also like to thank my friend Jane Stanojovski for his contribution in this project. He has translated part of the modules and the themes translation files. You can find the same blog post in Macedonian language here. Regards,Hajan

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  • Technology/Programming mailing lists How do you manage?

    - by AdityaGameProgrammer
    Email Alerts, Blog /Forum updates, discussion subscriptions general programming/technology update emails that we often subscribe to.Do you actually read them ? or go direct to the source when you find time. Often we might the mail of programmers filled with loads of unread subscription mail from technology they previously were following or worked on or things they wish to follow .Some or a majority of these mail just keep on piling up . I personally have few updates that i wish i read but constantly avoid and keep of for latter and finally delete them in effort keep the in box clean. Few questions come to mind regarding this Do you keep such mail in separate accounts? Do you read all the mail you have subscribed to? Do you ever unsubscribe to any such email if you aren't reading them? How much do you really value these email. Lastly do you keep your in box clean ? wish to deal with this in a better way.

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  • Expandable or Auto-Resize TextBox Height

    Recently, I was asked to prepare a Facebook like expandable textbox in a ASP.NET web application, where user can input text and the textbox can be re-sized (more specifically the height) dynamically. I searched for a while and found quite a lot of solutions that use jQuery (example). However, I was looking for something more intrinsic and simple, and finally I found another script on a forum that just use few lines of JavaScript codes: 1. Control declaration: <asp:TextBox ID="txtMsg"...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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  • PTLQueue : a scalable bounded-capacity MPMC queue

    - by Dave
    Title: Fast concurrent MPMC queue -- I've used the following concurrent queue algorithm enough that it warrants a blog entry. I'll sketch out the design of a fast and scalable multiple-producer multiple-consumer (MPSC) concurrent queue called PTLQueue. The queue has bounded capacity and is implemented via a circular array. Bounded capacity can be a useful property if there's a mismatch between producer rates and consumer rates where an unbounded queue might otherwise result in excessive memory consumption by virtue of the container nodes that -- in some queue implementations -- are used to hold values. A bounded-capacity queue can provide flow control between components. Beware, however, that bounded collections can also result in resource deadlock if abused. The put() and take() operators are partial and wait for the collection to become non-full or non-empty, respectively. Put() and take() do not allocate memory, and are not vulnerable to the ABA pathologies. The PTLQueue algorithm can be implemented equally well in C/C++ and Java. Partial operators are often more convenient than total methods. In many use cases if the preconditions aren't met, there's nothing else useful the thread can do, so it may as well wait via a partial method. An exception is in the case of work-stealing queues where a thief might scan a set of queues from which it could potentially steal. Total methods return ASAP with a success-failure indication. (It's tempting to describe a queue or API as blocking or non-blocking instead of partial or total, but non-blocking is already an overloaded concurrency term. Perhaps waiting/non-waiting or patient/impatient might be better terms). It's also trivial to construct partial operators by busy-waiting via total operators, but such constructs may be less efficient than an operator explicitly and intentionally designed to wait. A PTLQueue instance contains an array of slots, where each slot has volatile Turn and MailBox fields. The array has power-of-two length allowing mod/div operations to be replaced by masking. We assume sensible padding and alignment to reduce the impact of false sharing. (On x86 I recommend 128-byte alignment and padding because of the adjacent-sector prefetch facility). Each queue also has PutCursor and TakeCursor cursor variables, each of which should be sequestered as the sole occupant of a cache line or sector. You can opt to use 64-bit integers if concerned about wrap-around aliasing in the cursor variables. Put(null) is considered illegal, but the caller or implementation can easily check for and convert null to a distinguished non-null proxy value if null happens to be a value you'd like to pass. Take() will accordingly convert the proxy value back to null. An advantage of PTLQueue is that you can use atomic fetch-and-increment for the partial methods. We initialize each slot at index I with (Turn=I, MailBox=null). Both cursors are initially 0. All shared variables are considered "volatile" and atomics such as CAS and AtomicFetchAndIncrement are presumed to have bidirectional fence semantics. Finally T is the templated type. I've sketched out a total tryTake() method below that allows the caller to poll the queue. tryPut() has an analogous construction. Zebra stripping : alternating row colors for nice-looking code listings. See also google code "prettify" : https://code.google.com/p/google-code-prettify/ Prettify is a javascript module that yields the HTML/CSS/JS equivalent of pretty-print. -- pre:nth-child(odd) { background-color:#ff0000; } pre:nth-child(even) { background-color:#0000ff; } border-left: 11px solid #ccc; margin: 1.7em 0 1.7em 0.3em; background-color:#BFB; font-size:12px; line-height:65%; " // PTLQueue : Put(v) : // producer : partial method - waits as necessary assert v != null assert Mask = 1 && (Mask & (Mask+1)) == 0 // Document invariants // doorway step // Obtain a sequence number -- ticket // As a practical concern the ticket value is temporally unique // The ticket also identifies and selects a slot auto tkt = AtomicFetchIncrement (&PutCursor, 1) slot * s = &Slots[tkt & Mask] // waiting phase : // wait for slot's generation to match the tkt value assigned to this put() invocation. // The "generation" is implicitly encoded as the upper bits in the cursor // above those used to specify the index : tkt div (Mask+1) // The generation serves as an epoch number to identify a cohort of threads // accessing disjoint slots while s-Turn != tkt : Pause assert s-MailBox == null s-MailBox = v // deposit and pass message Take() : // consumer : partial method - waits as necessary auto tkt = AtomicFetchIncrement (&TakeCursor,1) slot * s = &Slots[tkt & Mask] // 2-stage waiting : // First wait for turn for our generation // Acquire exclusive "take" access to slot's MailBox field // Then wait for the slot to become occupied while s-Turn != tkt : Pause // Concurrency in this section of code is now reduced to just 1 producer thread // vs 1 consumer thread. // For a given queue and slot, there will be most one Take() operation running // in this section. // Consumer waits for producer to arrive and make slot non-empty // Extract message; clear mailbox; advance Turn indicator // We have an obvious happens-before relation : // Put(m) happens-before corresponding Take() that returns that same "m" for T v = s-MailBox if v != null : s-MailBox = null ST-ST barrier s-Turn = tkt + Mask + 1 // unlock slot to admit next producer and consumer return v Pause tryTake() : // total method - returns ASAP with failure indication for auto tkt = TakeCursor slot * s = &Slots[tkt & Mask] if s-Turn != tkt : return null T v = s-MailBox // presumptive return value if v == null : return null // ratify tkt and v values and commit by advancing cursor if CAS (&TakeCursor, tkt, tkt+1) != tkt : continue s-MailBox = null ST-ST barrier s-Turn = tkt + Mask + 1 return v The basic idea derives from the Partitioned Ticket Lock "PTL" (US20120240126-A1) and the MultiLane Concurrent Bag (US8689237). The latter is essentially a circular ring-buffer where the elements themselves are queues or concurrent collections. You can think of the PTLQueue as a partitioned ticket lock "PTL" augmented to pass values from lock to unlock via the slots. Alternatively, you could conceptualize of PTLQueue as a degenerate MultiLane bag where each slot or "lane" consists of a simple single-word MailBox instead of a general queue. Each lane in PTLQueue also has a private Turn field which acts like the Turn (Grant) variables found in PTL. Turn enforces strict FIFO ordering and restricts concurrency on the slot mailbox field to at most one simultaneous put() and take() operation. PTL uses a single "ticket" variable and per-slot Turn (grant) fields while MultiLane has distinct PutCursor and TakeCursor cursors and abstract per-slot sub-queues. Both PTL and MultiLane advance their cursor and ticket variables with atomic fetch-and-increment. PTLQueue borrows from both PTL and MultiLane and has distinct put and take cursors and per-slot Turn fields. Instead of a per-slot queues, PTLQueue uses a simple single-word MailBox field. PutCursor and TakeCursor act like a pair of ticket locks, conferring "put" and "take" access to a given slot. PutCursor, for instance, assigns an incoming put() request to a slot and serves as a PTL "Ticket" to acquire "put" permission to that slot's MailBox field. To better explain the operation of PTLQueue we deconstruct the operation of put() and take() as follows. Put() first increments PutCursor obtaining a new unique ticket. That ticket value also identifies a slot. Put() next waits for that slot's Turn field to match that ticket value. This is tantamount to using a PTL to acquire "put" permission on the slot's MailBox field. Finally, having obtained exclusive "put" permission on the slot, put() stores the message value into the slot's MailBox. Take() similarly advances TakeCursor, identifying a slot, and then acquires and secures "take" permission on a slot by waiting for Turn. Take() then waits for the slot's MailBox to become non-empty, extracts the message, and clears MailBox. Finally, take() advances the slot's Turn field, which releases both "put" and "take" access to the slot's MailBox. Note the asymmetry : put() acquires "put" access to the slot, but take() releases that lock. At any given time, for a given slot in a PTLQueue, at most one thread has "put" access and at most one thread has "take" access. This restricts concurrency from general MPMC to 1-vs-1. We have 2 ticket locks -- one for put() and one for take() -- each with its own "ticket" variable in the form of the corresponding cursor, but they share a single "Grant" egress variable in the form of the slot's Turn variable. Advancing the PutCursor, for instance, serves two purposes. First, we obtain a unique ticket which identifies a slot. Second, incrementing the cursor is the doorway protocol step to acquire the per-slot mutual exclusion "put" lock. The cursors and operations to increment those cursors serve double-duty : slot-selection and ticket assignment for locking the slot's MailBox field. At any given time a slot MailBox field can be in one of the following states: empty with no pending operations -- neutral state; empty with one or more waiting take() operations pending -- deficit; occupied with no pending operations; occupied with one or more waiting put() operations -- surplus; empty with a pending put() or pending put() and take() operations -- transitional; or occupied with a pending take() or pending put() and take() operations -- transitional. The partial put() and take() operators can be implemented with an atomic fetch-and-increment operation, which may confer a performance advantage over a CAS-based loop. In addition we have independent PutCursor and TakeCursor cursors. Critically, a put() operation modifies PutCursor but does not access the TakeCursor and a take() operation modifies the TakeCursor cursor but does not access the PutCursor. This acts to reduce coherence traffic relative to some other queue designs. It's worth noting that slow threads or obstruction in one slot (or "lane") does not impede or obstruct operations in other slots -- this gives us some degree of obstruction isolation. PTLQueue is not lock-free, however. The implementation above is expressed with polite busy-waiting (Pause) but it's trivial to implement per-slot parking and unparking to deschedule waiting threads. It's also easy to convert the queue to a more general deque by replacing the PutCursor and TakeCursor cursors with Left/Front and Right/Back cursors that can move either direction. Specifically, to push and pop from the "left" side of the deque we would decrement and increment the Left cursor, respectively, and to push and pop from the "right" side of the deque we would increment and decrement the Right cursor, respectively. We used a variation of PTLQueue for message passing in our recent OPODIS 2013 paper. ul { list-style:none; padding-left:0; padding:0; margin:0; margin-left:0; } ul#myTagID { padding: 0px; margin: 0px; list-style:none; margin-left:0;} -- -- There's quite a bit of related literature in this area. I'll call out a few relevant references: Wilson's NYU Courant Institute UltraComputer dissertation from 1988 is classic and the canonical starting point : Operating System Data Structures for Shared-Memory MIMD Machines with Fetch-and-Add. Regarding provenance and priority, I think PTLQueue or queues effectively equivalent to PTLQueue have been independently rediscovered a number of times. See CB-Queue and BNPBV, below, for instance. But Wilson's dissertation anticipates the basic idea and seems to predate all the others. Gottlieb et al : Basic Techniques for the Efficient Coordination of Very Large Numbers of Cooperating Sequential Processors Orozco et al : CB-Queue in Toward high-throughput algorithms on many-core architectures which appeared in TACO 2012. Meneghin et al : BNPVB family in Performance evaluation of inter-thread communication mechanisms on multicore/multithreaded architecture Dmitry Vyukov : bounded MPMC queue (highly recommended) Alex Otenko : US8607249 (highly related). John Mellor-Crummey : Concurrent queues: Practical fetch-and-phi algorithms. Technical Report 229, Department of Computer Science, University of Rochester Thomasson : FIFO Distributed Bakery Algorithm (very similar to PTLQueue). Scott and Scherer : Dual Data Structures I'll propose an optimization left as an exercise for the reader. Say we wanted to reduce memory usage by eliminating inter-slot padding. Such padding is usually "dark" memory and otherwise unused and wasted. But eliminating the padding leaves us at risk of increased false sharing. Furthermore lets say it was usually the case that the PutCursor and TakeCursor were numerically close to each other. (That's true in some use cases). We might still reduce false sharing by incrementing the cursors by some value other than 1 that is not trivially small and is coprime with the number of slots. Alternatively, we might increment the cursor by one and mask as usual, resulting in a logical index. We then use that logical index value to index into a permutation table, yielding an effective index for use in the slot array. The permutation table would be constructed so that nearby logical indices would map to more distant effective indices. (Open question: what should that permutation look like? Possibly some perversion of a Gray code or De Bruijn sequence might be suitable). As an aside, say we need to busy-wait for some condition as follows : "while C == 0 : Pause". Lets say that C is usually non-zero, so we typically don't wait. But when C happens to be 0 we'll have to spin for some period, possibly brief. We can arrange for the code to be more machine-friendly with respect to the branch predictors by transforming the loop into : "if C == 0 : for { Pause; if C != 0 : break; }". Critically, we want to restructure the loop so there's one branch that controls entry and another that controls loop exit. A concern is that your compiler or JIT might be clever enough to transform this back to "while C == 0 : Pause". You can sometimes avoid this by inserting a call to a some type of very cheap "opaque" method that the compiler can't elide or reorder. On Solaris, for instance, you could use :"if C == 0 : { gethrtime(); for { Pause; if C != 0 : break; }}". It's worth noting the obvious duality between locks and queues. If you have strict FIFO lock implementation with local spinning and succession by direct handoff such as MCS or CLH,then you can usually transform that lock into a queue. Hidden commentary and annotations - invisible : * And of course there's a well-known duality between queues and locks, but I'll leave that topic for another blog post. * Compare and contrast : PTLQ vs PTL and MultiLane * Equivalent : Turn; seq; sequence; pos; position; ticket * Put = Lock; Deposit Take = identify and reserve slot; wait; extract & clear; unlock * conceptualize : Distinct PutLock and TakeLock implemented as ticket lock or PTL Distinct arrival cursors but share per-slot "Turn" variable provides exclusive role-based access to slot's mailbox field put() acquires exclusive access to a slot for purposes of "deposit" assigns slot round-robin and then acquires deposit access rights/perms to that slot take() acquires exclusive access to slot for purposes of "withdrawal" assigns slot round-robin and then acquires withdrawal access rights/perms to that slot At any given time, only one thread can have withdrawal access to a slot at any given time, only one thread can have deposit access to a slot Permissible for T1 to have deposit access and T2 to simultaneously have withdrawal access * round-robin for the purposes of; role-based; access mode; access role mailslot; mailbox; allocate/assign/identify slot rights; permission; license; access permission; * PTL/Ticket hybrid Asymmetric usage ; owner oblivious lock-unlock pairing K-exclusion add Grant cursor pass message m from lock to unlock via Slots[] array Cursor performs 2 functions : + PTL ticket + Assigns request to slot in round-robin fashion Deconstruct protocol : explication put() : allocate slot in round-robin fashion acquire PTL for "put" access store message into slot associated with PTL index take() : Acquire PTL for "take" access // doorway step seq = fetchAdd (&Grant, 1) s = &Slots[seq & Mask] // waiting phase while s-Turn != seq : pause Extract : wait for s-mailbox to be full v = s-mailbox s-mailbox = null Release PTL for both "put" and "take" access s-Turn = seq + Mask + 1 * Slot round-robin assignment and lock "doorway" protocol leverage the same cursor and FetchAdd operation on that cursor FetchAdd (&Cursor,1) + round-robin slot assignment and dispersal + PTL/ticket lock "doorway" step waiting phase is via "Turn" field in slot * PTLQueue uses 2 cursors -- put and take. Acquire "put" access to slot via PTL-like lock Acquire "take" access to slot via PTL-like lock 2 locks : put and take -- at most one thread can access slot's mailbox Both locks use same "turn" field Like multilane : 2 cursors : put and take slot is simple 1-capacity mailbox instead of queue Borrow per-slot turn/grant from PTL Provides strict FIFO Lock slot : put-vs-put take-vs-take at most one put accesses slot at any one time at most one put accesses take at any one time reduction to 1-vs-1 instead of N-vs-M concurrency Per slot locks for put/take Release put/take by advancing turn * is instrumental in ... * P-V Semaphore vs lock vs K-exclusion * See also : FastQueues-excerpt.java dice-etc/queue-mpmc-bounded-blocking-circular-xadd/ * PTLQueue is the same as PTLQB - identical * Expedient return; ASAP; prompt; immediately * Lamport's Bakery algorithm : doorway step then waiting phase Threads arriving at doorway obtain a unique ticket number Threads enter in ticket order * In the terminology of Reed and Kanodia a ticket lock corresponds to the busy-wait implementation of a semaphore using an eventcount and a sequencer It can also be thought of as an optimization of Lamport's bakery lock was designed for fault-tolerance rather than performance Instead of spinning on the release counter, processors using a bakery lock repeatedly examine the tickets of their peers --

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  • Legal Precautions of Customizing Ubuntu LiveCD

    - by Voulnet
    Hello everyone, the organization I work at wants to create a custom Ubuntu LiveCD, the customizations are: Pre-installed programs, plugins, some device drivers, and aesthetics such as icons and backgrounds, as well as changing Firefox's homepage and removing unneeded packages. Not big changes, obviously, and we wish to distribute this custom image for clients to use as a bootable CD or USB stick in order to have a quick environment where all our tools are available instantly. What are the licensing and legal consequences of this? What if some of the programs or plugins that are to be pre-packaged are not GPL'd? I should finally note that we are not changing any code in the kernel or any other distro component. Thank you for your time!

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  • A new SQL, a new Analysis Services, a new Workshop! #ssas #sql2012

    - by Marco Russo (SQLBI)
    One week ago Microsoft SQL Server 2012 finally debuted with a virtual launch event and you can find many intro sessions there (20 minutes each). There is a lot of new content available if you want to learn more about SQL 2012 and in this blog post I’d like to provide a few link to sessions, documents, bits and courses that are available now or very soon. First of all, the release of Analysis Services 2012 has finally released PowerPivot 2012 (many of us called it PowerPivot v2 before this official name) and also the new Data Mining Add-in for Microsoft Office 2010, now available also for Excel 64bit! And, of course, don’t miss the Microsoft SQL Server 2012 Feature Pack, there are a lot of upgrades for both DBAs and developers. I just discovered there is a new LocalDB version of SQL Express that can run in user mode without any setup. Is this the end of SQL CE? But now, back to Analysis Services: if you want some tutorial on Tabular, the Microsoft Virtual Academy has a whole track dedicated to Analysis Services 2012 but you will probably be interested also in the one about Reporting Services 2012. If you think that virtual is good but it’s not enough, there are plenty of conferences in the coming months – these are just those where I and Alberto will deliver some SSAS Tabular presentations: SQLBits X, London, March 29-31, 2012: if you are in London or want a good reason to go, this is the most important SQL Server event in Europe this year, no doubts about it. And not only because of the high number of attendees, but also because there is an impressive number of speakers (excluding me, of course) coming from all over the world. This is an event second only to PASS Summit in Seattle so there are no good reasons to not attend it. Microsoft SQL Server & Business Intelligence Conference 2012, Milan, March 28-29, 2012: this is an Italian conference so the language might be a barrier, but many of us also speak English and the food is good! Just a few seats still available. TechEd North America, Orlando, June 11-14, 2012: you know, this is a big event and it contains everything – if you want to spend a whole day learning the SSAS Tabular model with me and Alberto, don’t miss our pre-conference day “Using BISM Tabular in Microsoft SQL Server Analysis Services 2012” (be careful, it is on June 10, a nice study-Sunday!). TechEd Europe, Amsterdam, June 26-29, 2012: the European version of TechEd provides almost the same content and you don’t have to go overseas. We also run the same pre-conference day “Using BISM Tabular in Microsoft SQL Server Analysis Services 2012” (in this case, it is on June 25, that’s a regular Monday). I and Alberto will also speak at some user group meeting around Europe during… well, we’re going to travel a lot in the next months. In fact, if you want to get a complete training on SSAS Tabular, you should spend two days with us in one of our SSAS Tabular Workshop! We prepared a 2-day seminar, a very intense one, that start from the simple tabular modeling and cover architecture, DAX, query, advanced modeling, security, deployment, optimization, monitoring, relationships with PowerPivot and Multidimensional… Really, there are a lot of stuffs here! We announced the first dates in Europe and also an online edition optimized for America’s time zone: Apr 16-17, 2012 – Amsterdam, Netherlands Apr 26-27, 2012 – Copenhagen, Denmark May 7-8, 2012 – Online for America’s time zone May 14-15, 2012 – Brussels, Belgium May 21-22, 2012 – Oslo, Norway May 24-25, 2012 – Stockholm, Sweden May 28-29, 2012 – London, United Kingdom May 31-Jun 1, 2012 – Milan, Italy (Italian language) Also Chris Webb will join us in this workshop and in every date you can find who is the speaker on the web site. The course is based on our upcoming book, almost 600 pages (!) about SSAS Tabular, an incredible effort that will be available very soon in a preview (rough cuts from O’Reilly) and will be on the shelf in May. I will provide a link to order it as soon as we have one! And if you think that this is not enough… you’re right! Do you know what is the only thing you can do to optimize your Tabular model? Optimize your DAX code. Learning DAX is easy, mastering DAX requires some knowledge… and our DAX Advanced Workshop will provide exactly the required content. Public classes will be available later this year, by now we just deliver it on demand.

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