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• SpaceX’s Falcon 9 Launch Success And Reusable Rockets Test Partially Successful

  - by Gopinath

  Elon Musk’s SpaceX is closing on the dream of developing reusable rockets and likely in an year or two space launch rockets will be reusable just like flights, ships and cars. Today SpaceX launched an upgraded Falcon 9 rocket in to space to deliver satellites as well as to test their reusable rocket launching technology. All on board satellites were released on to the orbit and the first stage of rocket partially succeeded in returning back to Earth. This is a huge leap in space technology.   Couple of years ago reusable rockets were considered as impossible. NASA, Russian Space Agency, China, India or for that matter any other space agency never even attempted to build reusable rockets. But SpaceX’s revolutionary technology partially succeeded in doing the impossible! Elon Musk founded SpaceX with the goal of building reusable rockets and transporting humans to & from other planets like Mars. He says If one can figure out how to effectively reuse rockets just like airplanes, the cost of access to space will be reduced by as much as a factor of a hundred.  A fully reusable vehicle has never been done before. That really is the fundamental breakthrough needed to revolutionize access to space. Normally the first stage of a rocket falls back to Earth after burning out and is destroyed. But today SpaceX reignited first stage rocket after its separation and attempted to descend smoothly on to ocean’s surface. Though it did not fully succeed, the test was partially successful and SpaceX was able to recovers portions of first stage. Rocket booster relit twice (supersonic retro & landing), but spun up due to aero torque, so fuel centrifuged & we flamed out — Elon Musk (@elonmusk) September 29, 2013 With the partial success of recovering first stage, SpaceX gathered huge amount of information and experience it can use to improve Falcon 9 and build a fully reusable rocket. In post launch press conference Musk said if things go "super well", could refly a Falcon 9 1st stage by the end of next year. Falcon 9 Launch Video Next reusable first tests delayed by at least two launches SpaceX has a busy schedule for next several months with more than 50 missions scheduled using the new Falcon 9 rocket. Ten of those missions are to fly cargo to the International Space Shuttle for NASA.  SpaceX announced that they will not attempt to recover the first stage of Falcon 9 in next two missions. The next test will be conducted on  the fourth mission of Falcon 9 which is planned to carry cargo to Internation Space Station sometime next year. This will give time required for SpaceX to analyze the information gathered from today’s mission and improve first stage reentry systems. More reading Here are few interesting sources to read more about today’s SpaceX launch SpaceX post mission press conference details and discussion on Reddit Giant Leaps for Space Firms Orbital, SpaceX Hacker News community discussion on SpaceX launch SpaceX Launches Next-Generation Private Falcon 9 Rocket on Big Test Flight

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• Add Bookmarks and Notes to Delicious in IE 8

  - by Asian Angel

  Are you constantly adding bookmarks to your Delicious account while browsing but want to keep UI use to a minimum? Add bookmarks directly to your account from the context menu using the Share with Delicious accelerator. Share with Delicious in Action To add the accelerator click on Add to Internet Explorer and confirm the installation when the secondary window appears. This is going to be much better than having the Favorites Bar or a new toolbar taking up precious UI room. When you find a webpage that you would like to bookmark right click within the page, go to All Accelerators and select Share with Delicious. The form for the new bookmark will open in a new tab with the URL and title filled in. All that you need to do is add any desired notes/tags and save the bookmark. Suppose that you want notes from the page added to the bookmark. Highlight the desired text, right click on it, then go to All Accelerators and select Share with Delicious. As before the form will open in a new tab…you can see the highlighted text was entered into the notes section for the new bookmark. All that is left to do is add an appropriate tag and save. Once you save your new bookmark the tab will auto navigate to the webpage that you just saved. Returning to our account showed the new bookmark ready for future use along with a the notes for later reference. Conclusion If you add bookmarks to your Delicious account but want to save UI room, then the Share with Delicious accelerator will make a nice addition to Internet Explorer. Links Add the Share with Delicious accelerator to Internet Explorer 8 Similar Articles Productive Geek Tips Access and Manage Your Delicious Bookmarks the Easy WayQuickly Add Bookmarks to Delicious in FirefoxAutomate Adding Bookmarks to del.icio.usHow Many Times Has an Article Been Bookmarked on del.icio.us?Add Social Bookmarking (Digg This!) Links to your Wordpress Blog TouchFreeze Alternative in AutoHotkey The Icy Undertow Desktop Windows Home Server – Backup to LAN The Clear & Clean Desktop Use This Bookmarklet to Easily Get Albums Use AutoHotkey to Assign a Hotkey to a Specific Window Latest Software Reviews Tinyhacker Random Tips Xobni Plus for Outlook All My Movies 5.9 CloudBerry Online Backup 1.5 for Windows Home Server Snagit 10 Use ILovePDF To Split and Merge PDF Files TimeToMeet is a Simple Online Meeting Planning Tool Easily Create More Bookmark Toolbars in Firefox Filevo is a Cool File Hosting & Sharing Site Get a free copy of WinUtilities Pro 2010 World Cup Schedule

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• Keep website and webservices warm with zero coding

  - by oazabir

  If you want to keep your websites or webservices warm and save user from seeing the long warm up time after an application pool recycle, or IIS restart or new code deployment or even windows restart, you can use the tinyget command line tool, that comes with IIS Resource Kit, to hit the site and services and keep them warm. Here’s how: First get tinyget from here. Download and install the IIS 6.0 Resource Kit on some PC. Then copy the tinyget.exe from “c:\program files…\IIS 6.0 ResourceKit\Tools'\tinyget” to the server where your IIS 6.0 or IIS 7 is running. Then create a batch file that will hit the pages and webservices. Something like this: SET TINYGET=C:\Program Files (x86)\IIS Resources\TinyGet\tinyget.exe"%TINYGET%" -srv:dropthings.omaralzabir.com -uri:http://dropthings.omaralzabir.com/ -status:200"%TINYGET%" -srv:dropthings.omaralzabir.com -uri:http://dropthings.omaralzabir.com/WidgetService.asmx?WSDL - status:200 First I am hitting the homepage to keep the webpage warm. Then I am hitting the webservice URL with ?WSDL parameter, which allows ASP.NET to compile the service if not already compiled and walk through all the operations and reflect on them and thus loading all related DLLs into memory and reducing the warmup time when hit. Tinyget gets the servers name or IP in the –srv parameter and then the actual URI in the –uri. I have specified what’s the HTTP response code to expect in –status parameter. It ensures the site is alive and is returning http 200 code. Besides just warming up a site, you can do some load test on the site. Tinyget can run in multiple threads and run loops to hit some URL. You can literally blow up a site with commands like this: "%TINYGET%" -threads:30 -loop:100 -srv:google.com -uri:http://www.google.com/ -status:200 Tinyget is also pretty useful to run automated tests. You can record http posts in a text file and then use it to make http posts to some page. Then you can put matching clause to check for certain string in the output to ensure the correct response is given. Thus with some simple command line commands, you can warm up, do some transactions, validate the site is giving off correct response as well as run a load test to ensure the server performing well. Very cheap way to get a lot done.

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• Infinite detail inside Perlin noise procedural mapping

  - by Dave Jellison

  I am very new to game development but I was able to scour the internet to figure out Perlin noise enough to implement a very simple 2D tile infinite procedural world. Here's the question and it's more conceptual than code-based in answer, I think. I understand the concept of "I plug in (x, y) and get back from Perlin noise p" (I'll call it p). P will always be the same value for the same (x, y) (as long as the Perlin algorithm parameters haven't changed, like altering number of octaves, et cetera). What I want to do is be able to zoom into a square and be able to generate smaller squares inside of the already generated overhead tile of terrain. Let's say I have a jungle tile for overhead terrain but I want to zoom in and maybe see a small river tile that would only be a creek and not large enough to be a full "big tile" of water in the overhead. Of course, I want the same net effect as a Perlin equation inside a Perlin equation if that makes sense? (aka. I want two people playing the game with the same settings to get the same terrain and details every time). I can conceptually wrap my head around the large tile being based on an "zoomed out" coordinate leaving enough room to drill into but this approach doesn't make sense in my head (maybe I'm wrong). I'm guessing with this approach my overhead terrain would lose all of the cohesiveness delivered by the Perlin. Imagine I calculate (0, 0) as overhead tile 1 and then to the east of that I plug in (50, 0). OK, great, I now have 49 pixels of detail I could then "drill down" into. The issue I have in my head with this approach (without attempting it) is that there's no guarantee from my Perlin noise that (0,0) would be a good neighbor to (50,0) as they could have wildly different "elevations" or p/resultant values returning from the Perlin equation when I generate the overhead map. I think I can conceive of using the Perlin noise for the overhead tile to then reuse the p value as a seed for the "detail" level of noise once I zoom in. That would ensure my detail Perlin is always the same configuration for (0,0), (1,0), etc. ad nauseam but I'm not sure if there are better approaches out there or if this is a sound approach at all.

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• How can I fix these errors with Panda3D's sample projects?

  - by lhk

  I just installed the latest Panda3D packages on a Mint 12 32-bit virtual machine. Then I downloaded and configured Eclipse and tried to run the Asteroids sample project. The window is created properly. But after rendering the scence once the game freezes. This happens with the other sample apps, too. Here's the error log: DirectStart: Starting the game. Known pipe types: glxGraphicsPipe (all display modules loaded.) :display:gsg:glgsg(warning): Occlusion queries advertised as supported by OpenGL runtime, but could not get pointers to extension functions. OpenGL Warning: glXChooseFBConfig returning NULL, due to attrib=0x6, next=0xffffffff :display:glxdisplay(warning): No suitable FBConfig contexts available; using XVisual only. depth_bits=16 color_bits=24 alpha_bits=8 stencil_bits=8 accum_bits=64 back_buffers=1 stereo=1 force_hardware=1 AL lib: pulseaudio.c:331: PulseAudio returned minreq > tlength/2; expect break up :display:gsg:glgsg(error): at 4765 of panda/src/glstuff/glGraphicsStateGuardian_src.cxx : invalid enumerant :display:gsg:glgsg(error): at 5703 of panda/src/glstuff/glGraphicsStateGuardian_src.cxx : invalid operation :display:gsg:glgsg(error): at 4654 of panda/src/glstuff/glGraphicsStateGuardian_src.cxx : invalid operation :display:gsg:glgsg(error): at 4654 of panda/src/glstuff/glGraphicsStateGuardian_src.cxx : invalid operation :display:gsg:glgsg(error): at 4765 of panda/src/glstuff/glGraphicsStateGuardian_src.cxx : invalid enumerant :display:gsg:glgsg(error): at 5703 of panda/src/glstuff/glGraphicsStateGuardian_src.cxx : invalid operation :display:gsg:glgsg(error): at 3057 of panda/src/glstuff/glGraphicsStateGuardian_src.cxx : invalid operation :display:gsg:glgsg(error): at 3057 of panda/src/glstuff/glGraphicsStateGuardian_src.cxx : invalid operation :display:gsg:glgsg(error): at 4765 of panda/src/glstuff/glGraphicsStateGuardian_src.cxx : invalid enumerant OpenGL Warning: No pincher, please call crStateSetCurrentPointers() in your SPU :display:gsg:glgsg(error): at 4765 of panda/src/glstuff/glGraphicsStateGuardian_src.cxx : invalid enumerant :display:gsg:glgsg(error): at 5703 of panda/src/glstuff/glGraphicsStateGuardian_src.cxx : invalid operation :display:gsg:glgsg(error): at 4765 of panda/src/glstuff/glGraphicsStateGuardian_src.cxx : invalid enumerant :display:gsg:glgsg(error): at 4765 of panda/src/glstuff/glGraphicsStateGuardian_src.cxx : invalid operation :display:gsg:glgsg(error): at 4765 of panda/src/glstuff/glGraphicsStateGuardian_src.cxx : invalid operation :display:gsg:glgsg(error): at 5703 of panda/src/glstuff/glGraphicsStateGuardian_src.cxx : invalid operation :display:gsg:glgsg(error): at 3661 of panda/src/glstuff/glGraphicsStateGuardian_src.cxx : invalid operation :display:gsg:glgsg(error): at 3661 of panda/src/glstuff/glGraphicsStateGuardian_src.cxx : invalid operation :display:gsg:glgsg(error): at 4765 of panda/src/glstuff/glGraphicsStateGuardian_src.cxx : invalid enumerant :display:gsg:glgsg(error): at 4765 of panda/src/glstuff/glGraphicsStateGuardian_src.cxx : invalid enumerant :display:gsg:glgsg(error): at 5703 of panda/src/glstuff/glGraphicsStateGuardian_src.cxx : invalid operation :display(error): Deactivating glxGraphicsStateGuardian. What can I do to fix the problem ?

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• Extending Currying: Partial Functions in Javascript

  - by kerry

  Last week I posted about function currying in javascript.  This week I am taking it a step further by adding the ability to call partial functions. Suppose we have a graphing application that will pull data via Ajax and perform some calculation to update a graph.  Using a method with the signature ‘updateGraph(id,value)’. To do this, we have do something like this: 1: for(var i=0;i<objects.length;i++) { 2: Ajax.request('/some/data',{id:objects[i].id},function(json) { 3: updateGraph(json.id, json.value); 4: } 5: } This works fine.  But, using this method we need to return the id in the json response from the server.  This works fine, but is not that elegant and increase network traffic. Using partial function currying we can bind the id parameter and add the second parameter later (when returning from the asynchronous call).  To do this, we will need the updated curry method.  I have added support for sending additional parameters at runtime for curried methods. 1: Function.prototype.curry = function(scope) { 2: scope = scope || window 3: var args = []; 4: for (var i=1, len = arguments.length; i < len; ++i) { 5: args.push(arguments[i]); 6: } 7: var m = this; 8: return function() { 9: for (var i=0, len = arguments.length; i < len; ++i) { 10: args.push(arguments[i]); 11: } 12: return m.apply(scope, args); 13: }; 14: } To partially curry this method we will call the curry method with the id parameter, then the request will callback on it with just the value.  Any additional parameters are appended to the method call. 1: for(var i=0;i<objects.length;i++) { 2: var id=objects[i].id; 3: Ajax.request('/some/data',{id: id}, updateGraph.curry(id)); 4: } As you can see, partial currying gives is a very useful tool and this simple method should be a part of every developer’s toolbox.

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• Strengthening code with possibly useless exception handling

  - by rdurand

  Is it a good practice to implement useless exception handling, just in case another part of the code is not coded correctly? Basic example A simple one, so I don't loose everybody :). Let's say I'm writing an app that will display a person's information (name, address, etc.), the data being extracted from a database. Let's say I'm the one coding the UI part, and someone else is writing the DB query code. Now imagine that the specifications of your app say that if the person's information is incomplete (let's say, the name is missing in the database), the person coding the query should handle this by returning "NA" for the missing field. What if the query is poorly coded and doesn't handle this case? What if the guy who wrote the query handles you an incomplete result, and when you try to display the informations, everything crashes, because your code isn't prepared to display empty stuff? This example is very basic. I believe most of you will say "it's not your problem, you're not responsible for this crash". But, it's still your part of the code which is crashing. Another example Let's say now I'm the one writing the query. The specifications don't say the same as above, but that the guy writing the "insert" query should make sure all the fields are complete when adding a person to the database to avoid inserting incomplete information. Should I protect my "select" query to make sure I give the UI guy complete informations? The questions What if the specifications don't explicitly say "this guy is the one in charge of handling this situation"? What if a third person implements another query (similar to the first one, but on another DB) and uses your UI code to display it, but doesn't handle this case in his code? Should I do what's necessary to prevent a possible crash, even if I'm not the one supposed to handle the bad case? I'm not looking for an answer like "(s)he's the one responsible for the crash", as I'm not solving a conflict here, I'd like to know, should I protect my code against situations it's not my responsibility to handle? Here, a simple "if empty do something" would suffice. In general, this question tackles redundant exception handling. I'm asking it because when I work alone on a project, I may code 2-3 times a similar exception handling in successive functions, "just in case" I did something wrong and let a bad case come through.

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• VirtualBox 4.2.14 is now available

  - by user12611829

  The VirtualBox development team has just released version 4.2.14, and it is now available for download. This is a maintenance release for version 4.2 and contains quite a few fixes. Here is the list from the official Changelog. VMM: another TLB invalidation fix for non-present pages VMM: fixed a performance regression (4.2.8 regression; bug #11674) GUI: fixed a crash on shutdown GUI: prevent stuck keys under certain conditions on Windows hosts (bugs #2613, #6171) VRDP: fixed a rare crash on the guest screen resize VRDP: allow to change VRDP parameters (including enabling/disabling the server) if the VM is paused USB: fixed passing through devices on Mac OS X host to a VM with 2 or more virtual CPUs (bug #7462) USB: fixed hang during isochronous transfer with certain devices (4.1 regression; Windows hosts only; bug #11839) USB: properly handle orphaned URBs (bug #11207) BIOS: fixed function for returning the PCI interrupt routing table (fixes NetWare 6.x guests) BIOS: don't use the ENTER / LEAVE instructions in the BIOS as these don't work in the real mode as set up by certain guests (e.g. Plan 9 and QNX 4) DMI: allow to configure DmiChassisType (bug #11832) Storage: fixed lost writes if iSCSI is used with snapshots and asynchronous I/O (bug #11479) Storage: fixed accessing certain VHDX images created by Windows 8 (bug #11502) Storage: fixed hang when creating a snapshot using Parallels disk images (bug #9617) 3D: seamless + 3D fixes (bug #11723) 3D: version 4.2.12 was not able to read saved states of older versions under certain conditions (bug #11718) Main/Properties: don't create a guest property for non-running VMs if the property does not exist and is about to be removed (bug #11765) Main/Properties: don't forget to make new guest properties persistent after the VM was terminated (bug #11719) Main/Display: don't lose seamless regions during screen resize Main/OVF: don't crash during import if the client forgot to call Appliance::interpret() (bug #10845) Main/OVF: don't create invalid appliances by stripping the file name if the VM name is very long (bug #11814) Main/OVF: don't fail if the appliance contains multiple file references (bug #10689) Main/Metrics: fixed Solaris file descriptor leak Settings: limit depth of snapshot tree to 250 levels, as more will lead to decreased performance and may trigger crashes VBoxManage: fixed setting the parent UUID on diff images using sethdparentuuid Linux hosts: work around for not crashing as a result of automatic NUMA balancing which was introduced in Linux 3.8 (bug #11610) Windows installer: force the installation of the public certificate in background (i.e. completely prevent user interaction) if the --silent command line option is specified Windows Additions: fixed problems with partial install in the unattended case Windows Additions: fixed display glitch with the Start button in seamless mode for some themes Windows Additions: Seamless mode and auto-resize fixes Windows Additions: fixed trying to to retrieve new auto-logon credentials if current ones were not processed yet Windows Additions installer: added the /with_wddm switch to select the experimental WDDM driver by default Linux Additions: fixed setting own timed out and aborted texts in information label of the lightdm greeter Linux Additions: fixed compilation against Linux 3.2.0 Ubuntu kernels (4.2.12 regression as a side effect of the Debian kernel build fix; bug #11709) X11 Additions: reduced the CPU load of VBoxClient in drag'and'drop mode OS/2 Additions: made the mouse wheel work (bug #6793) Guest Additions: fixed problems copying and pasting between two guests on an X11 host (bug #11792) The full changelog can be found here. You can download binaries for Solaris, Linux, Windows and MacOS hosts at http://www.virtualbox.org/wiki/Downloads Technocrati Tags: Oracle Virtualization VirtualBox

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• How do I reinstate my admin user privileges to global read/write

  - by Matt

  I am running Ubuntu 12.04 LTS. I only have the one user which I created when I installed Ubuntu. Everything has been fine - love it - until I updated a software package recently from the command line using sudo (not gksudo). I was having a little bother which did not make sense to me and in a fluff changed my user read/write privileges through the GUI (not even clear how I got there!). After restart I was stuck in a login loop - using the right login password but kept getting looped back to the login and could only login as Guest. I could still login with my user/password via ctrl + alt + f1 Eventually I was able to login again at start up. Not sure exactly what it was I changed that worked but it was one of/or a combination of installing latest security updates, changing login manager from LightDM to DGM and back again, removing the ICE/Xauthority and chown user. Current dilemma is my primary admin user privileges were read only. In the command line ls -ls /home/user returned this value: drwx------ 48 username username 20480 I have since changed this using sudo chmod 0755 /home/username (from my limited understanding 755 should return my user privileges to their original read/write glory). ls -ld /home/user currently shows my user privileges as: drwxr-xr-x 48 username username 20480 I still seem to have only read access permissions. I've been through lots of threads (and the help file) that talk about creating new users/groups permissions etc. but specific info on returning my existing global/admin/primary users privileges to what they were when I first created that user - baffling me. I feel this is something really simple I'm just not getting it. Please help! sudo mount /dev/sda1 on / type ext4 (rw,errors=remount-ro) proc on /proc type proc (rw,noexec,nosuid,nodev) sysfs on /proc type sysfs (rw,noexec,nosuid,nodev) none on /sys/fs/fuse/connections type fusect1 (rw) none on /sys/kernel/debug type debugfs (rw) none on /sys/kernel/security type securityfs (rw) udev on /dev type devtmpfs (rw,mode=07pe tmpfs55) devpts on /dev/pts type devpts (rw,noexec,nosuid,gid=5,mode=0620) tmpfs on /run type tmpfs (rw,noexec,nosuid,size=10%,mode=0755) none on /run/lock type tmpfs (rw, ,nosuid,nodev,size=5242880 none on /run/shm type tmpfs (rw,nosuid,nodev) gvfs-fuse-daemon on /home/meng/.gvfs type fuse.gvfs-fuse-daemon (rw,nosuid,nodev,user=meng) none on /tmp/guest-1R2Fi5 type tmpsf (rw,mode=700)

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• MiniMax function throws null pointer exception

  - by Sven

  I'm working on a school project, I have to build a tic tac toe game with the AI based on the MiniMax algorithm. The two player mode works like it should. I followed the code example on http://ethangunderson.com/blog/minimax-algorithm-in-c/. The only thing is that I get a NullPointer Exception when I run the code. And I can't wrap my finger around it. I placed a comment in the code where the exception is thrown. The recursive call is returning a null pointer, what is very strange because it can't.. When I place a breakpoint on the null return with the help of a if statement, then I see that there ARE still 2 to 3 empty places.. I probably overlooking something. Hope someone can tell me what I'm doing wrong. Here is the MiniMax code (the tic tac toe code is not important): /* * To change this template, choose Tools | Templates * and open the template in the editor. */ package MiniMax; import Game.Block; import Game.Board; import java.util.ArrayList; public class MiniMax { public static Place getBestMove(Board gameBoard, Block.TYPE player) { Place bestPlace = null; ArrayList<Place> emptyPlaces = gameBoard.getEmptyPlaces(); Board newBoard; //loop trough all the empty places for(Place emptyPlace : emptyPlaces) { newBoard = gameBoard.clone(); newBoard.setBlock(emptyPlace.getRow(), emptyPlace.getCell(), player); //no game won and still room to move if(newBoard.getWinner() == Block.TYPE.NONE && newBoard.getEmptyPlaces().size() > 0) { //is an node (has children) Place tempPlace = getBestMove(newBoard, invertPlayer(player)); //ERROR is thrown here! tempPlace is null. emptyPlace.setScore(tempPlace.getScore()); } else { //is an leaf if(newBoard.getWinner() == Block.TYPE.NONE) { emptyPlace.setScore(0); } else if(newBoard.getWinner() == Block.TYPE.X) { emptyPlace.setScore(-1); } else if(newBoard.getWinner() == Block.TYPE.O) { emptyPlace.setScore(1); } //if this move is better then our prev move, take it! if((bestPlace == null) || (player == Block.TYPE.X && emptyPlace.getScore() < bestPlace.getScore()) || (player == Block.TYPE.O && emptyPlace.getScore() > bestPlace.getScore())) { bestPlace = emptyPlace; } } } //This should never be null, but it does.. return bestPlace; } private static Block.TYPE invertPlayer(Block.TYPE player) { if(player == Block.TYPE.X) { return Block.TYPE.O; } return Block.TYPE.X; } }

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• "sr0" I/O read boot error in Xubuntu 12.10

  - by Entropicurity

  Just recently upgraded Xubuntu 12.10 after having installed 12.04 originally. Ever since that happened, any time I inserted a disk into my DVD/CD reader/writer I would end up getting a number of error messages from my DVD player/Audio player softer, typically with any of them either crashing or returning a GStreamer backend error. So doing some research I tried to mount it manually, and it typically returned the error messages you'll see below: (using the dmesg | grep "sr0" command) [17545.435584] end_request: I/O error, dev sr0, sector 0 [17545.492968] sr 3:0:0:0: >[sr0] [17545.492981] sr 3:0:0:0: >[sr0] [17545.492992] sr 3:0:0:0: >[sr0] [17545.493003] sr 3:0:0:0: >[sr0] CDB: [17545.493020] end_request: I/O error, dev sr0, sector 0 [17545.493058] EXT3-fs (sr0): error: unable to read superblock [17545.553224] sr 3:0:0:0: >[sr0] [17545.553237] sr 3:0:0:0: >[sr0] [17545.553247] sr 3:0:0:0: >[sr0] [17545.553258] sr 3:0:0:0: >[sr0] CDB: [17545.553275] end_request: I/O error, dev sr0, sector 0 [17545.553312] EXT4-fs (sr0): unable to read superblock [17545.611482] sr 3:0:0:0: >[sr0] [17545.611494] sr 3:0:0:0: >[sr0] [17545.611504] sr 3:0:0:0: >[sr0] [17545.611514] sr 3:0:0:0: >[sr0] CDB: [17545.611531] end_request: I/O error, dev sr0, sector 0 [17545.611568] FAT-fs (sr0): unable to read boot sector When I grepped this, the number of error messages just seemed to spill all over the screen, and typically all revolve around the I/O error. I then went into VLC and tried to run the stuff through there, but for some reason it won't read with the default devices. Instead I have to manually input sr0 into each of the /dev/ references and it will play just fine, until I exit out of the program, at which point I have to re-input everything. I have already installed all the media dependencies, both open source and restricted, through the software center. I just found this strange, as out of the box 12.04 there wasn't any problem what so ever. At this point, it could be that all my audio CD's are not in a format that is familiar with the OS (I've read in some places that EXTF4 has issues with this) but I don't see how that could be a problem when the above error messages even tested to see if it is EXT3 as well? I've tried my best to troubleshoot this up till now using existing topics, but it seems that this is a regular problem with a multitude of varying factors that incorporate into it, including but not limited to read/write problems with the format of the CD and right protection. Is there something integral that I am missing?

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• Upgarde from Asp.Net MVC 1 to MVC 2 - how to and issues with JsonRequestBehavior

  - by Renso

  Goal Upgrade your MVC 1 app to MVC 2 Issues You may get errors about your Json data being returned via a GET request violating security principles - we also address this here. This post is not intended to delve into why the Json GET request is or may be an issue, just how to resolve it as part of upgrading from MVC1 to 2. Solution First remove all references from your projects to the MVC 1 dll and replace it with the MVC 2 dll. Now update your web.config file in your web app root folder by simply changing references to assembly="System.Web.Mvc, Version 1.0.0.0 to Version 2.0.0.0, there are a couple of references in your config file, here are probably most of them you may have:         <compilation debug="true" defaultLanguage="c#">             <assemblies>                        <add assembly="System.Web.Mvc, Version=2.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" />             </assemblies>         </compilation>           <pages masterPageFile="~/Views/Masters/CRMTemplate.master" pageParserFilterType="System.Web.Mvc.ViewTypeParserFilter, System.Web.Mvc, Version=2.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" pageBaseType="System.Web.Mvc.ViewPage, System.Web.Mvc, Version=2.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" userControlBaseType="System.Web.Mvc.ViewUserControl, System.Web.Mvc, Version=2.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" validateRequest="False">             <controls>                 <add assembly="System.Web.Mvc, Version=2.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" namespace="System.Web.Mvc" tagPrefix="mvc" />   Secondly, if you return Json objects from an ajax call via the GET method you ahve several options to fix this depending on your situation: 1. The simplest, as in my case I did this for an internal web app, you may simply do:             return Json(myObject, JsonRequestBehavior.AllowGet);   2. In Mvc if you have a controller base you could wrap the Json method with:         public new JsonResult Json(object data)         {             return Json(data, "application/json", JsonRequestBehavior.AllowGet);                    }   3. The most work would be to decorate your Actions with:         [AcceptVerbs(HttpVerbs.Get)]   4. Another tnat is also a lot of work that needs to be done to every ajax call returning Json is:                             msg = $.ajax({ url: $('#ajaxGetSampleUrl').val(), dataType: 'json', type: 'POST', async: false, data: { name: theClass }, success: function(data, result) { if (!result) alert('Failure to retrieve the Sample Data.'); } }).responseText;   This should cover all the issues you may run into when upgrading. Let me kow if you run into any other ones.

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• Simplifying C++11 optimal parameter passing when a copy is needed

  - by Mr.C64

  It seems to me that in C++11 lots of attention was made to simplify returning values from functions and methods, i.e.: with move semantics it's possible to simply return heavy-to-copy but cheap-to-move values (while in C++98/03 the general guideline was to use output parameters via non-const references or pointers), e.g.: // C++11 style vector<string> MakeAVeryBigStringList(); // C++98/03 style void MakeAVeryBigStringList(vector<string>& result); On the other side, it seems to me that more work should be done on input parameter passing, in particular when a copy of an input parameter is needed, e.g. in constructors and setters. My understanding is that the best technique in this case is to use templates and std::forward<>, e.g. (following the pattern of this answer on C++11 optimal parameter passing): class Person { std::string m_name; public: template <class T, class = typename std::enable_if < std::is_constructible<std::string, T>::value >::type> explicit Person(T&& name) : m_name(std::forward<T>(name)) { } ... }; A similar code could be written for setters. Frankly, this code seems boilerplate and complex, and doesn't scale up well when there are more parameters (e.g. if a surname attribute is added to the above class). Would it be possible to add a new feature to C++11 to simplify code like this (just like lambdas simplify C++98/03 code with functors in several cases)? I was thinking of a syntax with some special character, like @ (since introducing a &&& in addition to && would be too much typing :) e.g.: class Person { std::string m_name; public: /* Simplified syntax to produce boilerplate code like this: template <class T, class = typename std::enable_if < std::is_constructible<std::string, T>::value >::type> */ explicit Person(std::string@ name) : m_name(name) // implicit std::forward as well { } ... }; This would be very convenient also for more complex cases involving more parameters, e.g. Person(std::string@ name, std::string@ surname) : m_name(name), m_surname(surname) { } Would it be possible to add a simplified convenient syntax like this in C++? What would be the downsides of such a syntax?

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• Stuff I learned at Innovate 2011

  - by David Dorf

  After returning from the NRF Innovate 2011 conference, I picked up few nuggets I thought I'd share here.  These thoughts are a bit random, but I hope they're useful nonetheless.Kevin Kelly opened the conference with six verbs that represent the future.  They were Screening, Interacting, Sharing, Accessing, Flowing, and Generating.  It struck me that these are all ways in which we merge the digital and physical worlds.  The internet of things continues to gain momentum.Some buzzwords:  deal economy, subscription commerce, discovery (instead of search), curationThat last one, curation, came up over and over.  Retailers, especially those in fashion, are finding value in helping their customers organize and present their own collections.  Social media has made sharing such collections easy, and mobile lets them take those ideas into the stores.  Mannequins are becoming less relevant.I heard from both HauteLook and Gilt Groupe (flash sale retailers) that a large percentage of their visits come from mobile devices, and most of those are iOS devices.  I find it interesting that even though Android has passed iPhone in units shipped (and will eventually pass iOS as a whole), its still the Apple crowd that leads the way.RadioShack mentioned their Holiday Heroes campaigned was very successful.  They asked their Foursquare users to check-in at a gym, coffee shop, and transportation hub as part of being a hero.  For this feat, customers were awarded a special badge that was worth 20% off at their next store visit. They claim a 3.5x increase in ticket size vs. regular check-in customers, and a 5x increase vs those that don't check-in at all.I also learned of RadioShack's #28 campaign, which is apparently one of the largest Twitter trends ever.  Their partnership with LIVESTRONG has gotten them followers, impressions, and credit for supporting the fight against cancer.The guys at Invodo showed the importance of video to e-commerce.  They gave compelling examples of how video can show customers the value of products better than just words.The highlight of the show was Guy Kawasaki's talk on innovation, which was not only informative but also peppered with humor and personality.  Back in the early days of the internet boom, Guy turned down the CEO position at Yahoo! because the commute was too long.  By his calculation, that was a $2B mistake.There are other good accounts of the conference at the NRF Blog.

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• WebAPI and MVC4 and OData

  - by Aligned

  I was looking closer into WebAPI, specificially how to use OData to avoid writing GetCustomerByCustomerId(int id) methods all over the place. I had problems just returning IQueryable<T> as some sites suggested in the WebpAPI (Assembly System.Web.Http.dll, v4.0.0.0).  I think things changed in the release version and the blog posts are still out of date. There is no [Queraable] as the answer to this question suggests. Once I get WebAPI.Odata Nuget package, and added the [Queryable] to the method http://localhost:57146/api/values/?$filter=Id%20eq%201 worked (don’t forget the ‘$’). Now the main question is whether I should do this and how to stop logged in users from sniffing the url and getting data for other users. I John V. Peterson has a post on securing WebAPI with headers and intercepting the call at that point. He had an update to use HttpMessageHandlers instead. I think I’ll use this to force the call to contain some kind of unique code for the user, but I’m still thinking about this. I will not expose this to the public, just to my calls with-in my Forms Authentication areas. Other links: http://robbincremers.me/2012/02/16/building-and-consuming-rest-services-with-asp-net-web-api-and-odata-support/ ~lots of good information John V Peterson example: https://github.com/johnvpetersen/ASPWebAPIExample ~ all data access goes through the WebApi and the web client doesn’t have a connection string ~ There is code library for calling the WebApi from MVC using the HttpClient. It’s a great starting point http://blogs.msdn.com/b/alexj/archive/2012/08/15/odata-support-in-asp-net-web-api.aspx ~ Beta (9/18/2012) Nuget package to help with what I want to do? ~ has a sample code project with examples http://blogs.msdn.com/b/alexj/archive/2012/08/15/odata-support-in-asp-net-web-api.aspx http://blogs.msdn.com/b/alexj/archive/2012/08/21/web-api-queryable-current-support-and-tentative-roadmap.aspx http://stackoverflow.com/questions/10885868/asp-net-mvc4-rc-web-api-odata-filter-not-working-with-iqueryable JSON, pass the correct format in the header (Accept: application/json). $format=JSON doesn’t appear to be working. Async methods built into WebApi! Look for the GetAsync methods.

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• Deferred Shading - Toolkit

  - by AliveDevil

  I recently managed to get some lights rendered in a scene by using a buffer and a for-loop. The problem with this method is the performance drop if more lights are used. I tried to convert Deferred Rendering in XNA4.0 | ROY-T.NL but it is not working, because I am not using any models. I know I have to render color, normals and lights seperate but I don't know how I could get it working. For understanding my structure better I'm using a world-class which holds some chunks. These chunks are loading all vertices from their items. These items have a property which returns the vertices. The item is returning VertexPositionNormalTexture[]. The chunk loads these Vertices and combines them to one large array of VertexPositionNormalTexture via someList.AsParallel().SelectMany(m => m).ToArray()). m is a VertexPositionNormalTexture. someList is List<VertexPositionNormalTexture>. I got my own shader to draw these vertices how I want them to be drawn. The first thing I would try is setting up two RenderTarget2D for rendering the color and normal part. With two different shaders. Than I would have to render the lights and there's the problem: I don't know how. I set up a structure to simplify working with lights but it didn't really help. public struct Light { public Vector3 Position; public Color4 Color; public float Range; public float Intensity; public Light( Vector3 position, Color color, float range, float intensity ) : this() { this.Position = position; this.Color = color; this.Range = range; this.Intensity = intensity; } public float[] Definition { get { return new[] { Position.X, Position.Y, Position.Z, Color.Red, Color.Green, Color.Blue, Intensity, Range }; } } } The next part is equally different because I don't know how to combine the colorMap, normalMap and textureMap to one finalMap. Some information to the system: I'm using SharpDX (Nightly from some months ago) and the SharpDX.Toolkit (I don't want to mess up with Direct3DDevice and similar things). Can someone help me with this problem? If things are missing or I provided insufficient information tell me, I need to get deferred shading working. Things I'm not able to do: create a rendertarget which holds all lights, merge colorMap, normalMap and lightMap to one finalMap and presenting this to the user.

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• Particle System in XNA - cannot draw particle

  - by Dave Voyles

  I'm trying to implement a simple particle system in my XNA project. I'm going by RB Whitaker's tutorial, and it seems simple enough. I'm trying to draw particles within my menu screen. Below I've included the code which I think is applicable. I'm coming up with one error in my build, and it is stating that I need to create a new instance of the EmitterLocation from the particleEngine. When I hover over particleEngine.EmitterLocation = new Vector2(Mouse.GetState().X, Mouse.GetState().Y); it states that particleEngine is returning a null value. What could be causing this? /// <summary> /// Base class for screens that contain a menu of options. The user can /// move up and down to select an entry, or cancel to back out of the screen. /// </summary> abstract class MenuScreen : GameScreen ParticleEngine particleEngine; public void LoadContent(ContentManager content) { if (content == null) { content = new ContentManager(ScreenManager.Game.Services, "Content"); } base.LoadContent(); List<Texture2D> textures = new List<Texture2D>(); textures.Add(content.Load<Texture2D>(@"gfx/circle")); textures.Add(content.Load<Texture2D>(@"gfx/star")); textures.Add(content.Load<Texture2D>(@"gfx/diamond")); particleEngine = new ParticleEngine(textures, new Vector2(400, 240)); } public override void Update(GameTime gameTime, bool otherScreenHasFocus, bool coveredByOtherScreen) { base.Update(gameTime, otherScreenHasFocus, coveredByOtherScreen); // Update each nested MenuEntry object. for (int i = 0; i < menuEntries.Count; i++) { bool isSelected = IsActive && (i == selectedEntry); menuEntries[i].Update(this, isSelected, gameTime); } particleEngine.EmitterLocation = new Vector2(Mouse.GetState().X, Mouse.GetState().Y); particleEngine.Update(); } public override void Draw(GameTime gameTime) { // make sure our entries are in the right place before we draw them UpdateMenuEntryLocations(); GraphicsDevice graphics = ScreenManager.GraphicsDevice; SpriteBatch spriteBatch = ScreenManager.SpriteBatch; SpriteFont font = ScreenManager.Font; spriteBatch.Begin(); // Draw stuff logic spriteBatch.End(); particleEngine.Draw(spriteBatch); }

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• What layer to introduce human readable error messages?

  - by MrLane

  One of the things that I have never been happy with on any project I have worked on over the years and have really not been able to resolve myself is exactly at what tier in an application should human readable error information be retrieved for display to a user. A common approach that has worked well has been to return strongly typed/concrete "result objects" from the methods on the public surface of the business tier/API. A method on the interface may be: public ClearUserAccountsResult ClearUserAccounts(ClearUserAccountsParam param); And the result class implementation: public class ClearUserAccountsResult : IResult { public readonly List<Account> ClearedAccounts{get; set;} public readonly bool Success {get; set;} // Implements IResult public readonly string Message{get; set;} // Implements IResult, human readable // Constructor implemented here to set readonly properties... } This works great when the API needs to be exposed over WCF as the result object can be serialized. Again this is only done on the public surface of the API/business tier. The error message can also be looked up from the database, which means it can be changed and localized. However, it has always been suspect to me, this idea of returning human readable information from the business tier like this, partly because what constitutes the public surface of the API may change over time...and it may be the case that the API will need to be reused by other API components in the future that do not need the human readable string messages (and looking them up from a database would be an expensive waste). I am thinking a better approach is to keep the business objects free from such result objects and keep them simple and then retrieve human readable error strings somewhere closer to the UI layer or only in the UI itself, but I have two problems here: 1) The UI may be a remote client (Winforms/WPF/Silverlight) or an ASP.NET web application hosted on another server. In these cases the UI will have to fetch the error strings from the server. 2) Often there are multiple legitimate modes of failure. If the business tier becomes so vague and generic in the way it returns errors there may not be enough information exposed publicly to tell what the error actually was: i.e: if a method has 3 modes of legitimate failure but returns a boolean to indicate failure, you cannot work out what the appropriate message to display to the user should be. I have thought about using failure enums as a substitute, they can indicate a specific error that can be tested for and coded against. This is sometimes useful within the business tier itself as a way of passing via method returns the specifics of a failure rather than just a boolean, but it is not so good for serialization scenarios. Is there a well worn pattern for this? What do people think? Thanks.

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• Push-Based Events in a Services Oriented Architecture

  - by Colin Morelli

  I have come to a point, in building a services oriented architecture (on top of Thrift), that I need to expose events and allow listeners. My initial thought was, "create an EventService" to handle publishing and subscribing to events. That EventService can use whatever implementation it desires to actually distribute the events. My client automatically round-robins service requests to available service hosts which are determined using Zookeeper-based service discovery. So, I'd probably use JMS inside of EventService mainly for the purpose of persisting messages (in the event that a service host for EventService goes down before it can distribute the message to all of the available listeners). When I started considering this, I began looking into the differences between Queues and Topics. Topics unfortunately won't work for me, because (at least for now), all listeners must receive the message (even if they were down at the time the event was pushed, or hadn't made a subscription yet because they haven't completed startup (during deployment, for example) - messages should be queued until the service is available). However, I don't want EventService to be responsible for handling all of the events. I don't think it should have the code to react to events inside of it. Each of the services should do what it needs with a given event. This would indicate that each service would need a JMS connection, which questions the value of having EventService at all (as the services could individually publish and subscribe to JMS directly). However, it also couples all of the services to JMS (when I'd rather that there be a single service that's responsible for determining how to distribute events). What I had thought was to publish an event to EventService, which pulls a configuration of listeners from some configuration source (database, flat file, irrelevant for now). It replicates the message and pushes each one back into a queue with information specific to that listener (so, if there are 3 listeners, 1 event would become 3 events in JMS). Then, another thread in EventService (which is replicated, running on multiple hots) would be pulling from the queue, attempting to make the service call to the "listener", and returning the message to the queue (if the service is down), or discarding the message (if the listener completed successfully). tl;dr If I have an EventService that is responsible for receiving events and delegating service calls to "event listeners," (which are really just endpoints on other services), how should it know how to craft the service call? Should I create a generic "Event" object that is shared among all services? Then, the EventService can just construct this object and pass it to the service call. Or is there a better answer to this problem entirely?

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• Is there an API for determining congressional districts?

  - by ardavis

  I'm looking to determine the congressional district based on an address my user is providing. This will avoid having the user to look it up themselves. Does an API of this sort exist? Note Through my attempts to find one, I've only come across these: http://www.govtrack.us/developers/api (not sure how to submit an an address or zip code however) The following resources are available in the API ...Bills and resolutions in the U.S. Congress since 1973 (the 93rd Congress). ...A (bill, person) pair indicating cosponsorship, with join and withdrawn dates. ...Members of Congress and U.S. Presidents since the founding of the nation. ...Terms held in office by Members of Congress and U.S. Presidents. Each term corresponds with an election, meaning each term in the House covers two years (one 'Congress'), as President four years, and in the Senate six years (three 'Congresses'). ...Roll call votes in the U.S. Congress since 1789. How people voted is accessed through the Vote_voter API. ...How people voted on roll call votes in the U.S. Congress since 1789. See the Vote API. Filter on the vote field to get the results of a particular vote... http://www.opencongress.org/api (seems to be a way to find congress information, but not districts) This API provides programmers with structured access to all the data on OpenCongress, everything from official bill info to news and blog coverage to user-generated votes on bills and much more... This API defaults to returning XML. All queries can also return JSON... https://groups.google.com/forum/?fromgroups=#!topic/opendems-discuss/CeKyi_aANaE (similar question, no resolution) I've been looking over Open Dems, and seeing what's exposed at this point and what isn't. I work with Democrats Abroad, and am interested in using stuff from the lab for their sites. I quickly looked over the Precinct API, which does both more and less than what I'd need. An ideal resource would be any way of translating addresses into CD at the very least (getting state district data would be good as well), since that would make it easier for DA's membership to make a difference in races like last month's NY26 race... Update I'm looking at the source for the govtrack.us website and the 'doGeoCode' function may be useful. view-source:http://www.govtrack.us/congress/members If no one has any suggestions, I will try to go off of what they are doing.

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• Should a server "be lenient" in what it accepts and "discard faulty input silently"?

  - by romkyns

  I was under the impression that by now everyone agrees this maxim was a mistake. But I recently saw this answer which has a "be lenient" comment upvoted 137 times (as of today). In my opinion, the leniency in what browsers accept was the direct cause of the utter mess that HTML and some other web standards were a few years ago, and have only recently begun to properly crystallize out of that mess. The way I see it, being lenient in what you accept will lead to this. The second part of the maxim is "discard faulty input silently, without returning an error message unless this is required by the specification", and this feels borderline offensive. Any programmer who has banged their head on the wall when something fails silently will know what I mean. So, am I completely wrong about this? Should my program be lenient in what it accepts and swallow errors silently? Or am I mis-interpreting what this is supposed to mean? The original question said "program", and I take everyone's point about that. It can make sense for programs to be lenient. What I really meant, however, is APIs: interfaces exposed to other programs, rather than people. HTTP is an example. The protocol is an interface that only other programs use. People never directly provide the dates that go into headers like "If-Modified-Since". So, the question is: should the server implementing a standard be lenient and allow dates in several other formats, in addition to the one that's actually required by the standard? I believe the "be lenient" is supposed to apply to this situation, rather than human interfaces. If the server is lenient, it might seem like an overall improvement, but I think in practice it only leads to client implementations that end up relying on the leniency and thus failing to work with another server that's lenient in slightly different ways. So, should a server exposing some API be lenient or is that a very bad idea? Now onto lenient handling of user input. Consider YouTrack (a bug tracking software). It uses a language for text entry that is reminiscent of Markdown. Except that it's "lenient". For example, writing - foo - bar - baz is not a documented way of creating a bulleted list, and yet it worked. Consequently, it ended up being used a lot throughout our internal bugtracker. Next version comes out, and this lenient feature starts working slightly differently, breaking a bunch of lists that (mis)used this (non)feature. The documented way to create bulleted lists still works, of course. So, should my software be lenient in what user inputs it accepts?

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• C# 5: At last, async without the pain

  - by Alex.Davies

  For me, the best feature in Visual Studio 11 is the async and await keywords that come with C# 5. I am a big fan of asynchronous programming: it frees up resources, in particular the thread that a piece of code needs to run in. That lets that thread run something else, while waiting for your long-running operation to complete. That's really important if that thread is the UI thread, or if it's holding a lock because it accesses some data structure. Before C# 5, I think I was about the only person in the world who really cared about asynchronous programming. The trouble was that you had to go to extreme lengths to make code asynchronous. I would forever be writing methods that, instead of returning a value, accepted an extra argument that is a "continuation". Then, when calling the method, I'd have to pass a lambda in to it, which contained all the stuff that needed to happen after the method finished. Here is a real snippet of code that is in .NET Demon: m_BuildControl.FilterEnabledForBuilding(     projects,     enabledProjects = m_OutOfDateProjectFinder.FilterNeedsBuilding(         enabledProjects,         newDirtyProjects =         {             // Mark any currently broken projects as dirty             newDirtyProjects.UnionWith(m_BrokenProjects);             // Copy what we found into the set of dirty things             m_DirtyProjects = newDirtyProjects;             RunSomeBuilds();         })); It's just obtuse. Who puts a lambda inside a lambda like that? Well, me obviously. But surely enabledProjects should just be the return value of FilterEnabledForBuilding? And newDirtyProjects should just be the return value of FilterNeedsBuilding? C# 5 async/await lets you write asynchronous code without it looking so stupid. Here's what I plan to change that code to, once we upgrade to VS 11: var enabledProjects = await m_BuildControl.FilterEnabledForBuilding(projects); var newDirtyProjects = await m_OutOfDateProjectFinder.FilterNeedsBuilding(enabledProjects); // Mark any currently broken projects as dirty newDirtyProjects.UnionWith(m_BrokenProjects); // Copy what we found into the set of dirty things m_DirtyProjects = newDirtyProjects; RunSomeBuilds(); Much easier to read! But how is this the same code? If we were on the UI thread, doesn't the UI thread have to block while FilterEnabledForBuilding runs? No, it doesn't, and that's the magic of the await keyword! It cuts your method up into its constituent pieces, much like I did manually with lambdas before. When you run it, only the piece up to the first await actually runs. The rest is passed to FilterEnabledForBuilding as a continuation, which will get called back whenever that method is finished. In the meantime, our thread returns, and can go back to making the UI responsive, or whatever else threads do in their spare time. This is actually a massive simplification, and if you're interested in all the gory details, and speed hacks that the await keyword actually does for you, I recommend Jon Skeet's blog posts about it.

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• Use Expressions with LINQ to Entities

  - by EltonStoneman

  [Source: http://geekswithblogs.net/EltonStoneman] Recently I've been putting together a generic approach for paging the response from a WCF service. Paging changes the service signature, so it's not as simple as adding a behavior to an existing service in config, but the complexity of the paging is isolated in a generic base class. We're using the Entity Framework talking to SQL Server, so when we ask for a page using LINQ's .Take() method we get a nice efficient SQL query for just the rows we want, with minimal impact on SQL Server and network traffic. We use the maximum ID of the record returned as a high-water mark (rather than using .Skip() to go to the next record), so the approach caters for records being deleted between page requests. In the paged response we include a HasMorePages indicator, computed by comparing the max ID in the page of results to the max ID for the whole resultset - if the latter is bigger, then there are more pages. In some quick performance testing, the paged version of the service performed much more slowly than the unpaged version, which was unexpected. We narrowed it down to the code which gets the max ID for the full resultset - instead of building an efficient MAX() SQL query, EF was returning the whole resultset and then computing the max ID in the service layer. It's easy to reproduce - take this AdventureWorks query:             var context = new AdventureWorksEntities();             var query = from od in context.SalesOrderDetail                         where od.ModifiedDate >= modified                          && od.SalesOrderDetailID.CompareTo(id) > 0                         orderby od.SalesOrderDetailID                         select od;   We can find the maximum SalesOrderDetailID like this:             var maxIdEfficiently = query.Max(od => od.SalesOrderDetailID);   which produces our efficient MAX() SQL query. If we're doing this generically and we already have the ID function in a Func:             Func<SalesOrderDetail, int> idFunc = od => od.SalesOrderDetailID;             var maxIdInefficiently = query.Max(idFunc);   This fetches all the results from the query and then runs the Max() function in code. If you look at the difference in Reflector, the first call passes an Expression to the Max(), while the second call passes a Func. So it's an easy fix - wrap the Func in an Expression:             Expression<Func<SalesOrderDetail, int>> idExpression = od => od.SalesOrderDetailID;             var maxIdEfficientlyAgain = query.Max(idExpression);   - and we're back to running an efficient MAX() statement. Evidently the EF provider can dissect an Expression and build its equivalent in SQL, but it can't do that with Funcs.

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• Update in Certification Exam Score Report Access Process!

  - by Richard Lefebvre

  Please note that exam results for all Oracle Certification exams will be accessed through CertView, starting October 30th, 2012. Exam results will no longer be available at the test center, or on the Pearson VUE website. Candidates will receive an email from Oracle within 30 minutes of completing the exam to let them know that their exam results are available on CertView. Candidates must have an Oracle Web Account to access CertView. This new process applies to exam results for all Oracle Certification exams - proctored and non-proctored as well beta exams. CertView, Oracle's self-service certification portal will be the partners’ one stop source for all their certification and exam history! Other benefits of this change include: driving all candidates to have an Oracle Web Account which will lead to tighter integration with Oracle University records in the future, increased security around data privacy and a higher validity rate for candidate email addresses. Existing benefits of CertView include, self-service access to exam and certification records and logos, and access to Oracle's self service certification verification. Accessing Exam Results  Returning CertView Users ·         Click the link in the email sent by Oracle or go to certview.oracle.com ·         Select the See My New Exam Results Now link to view exam results ·         Select the Print My New Exam Results Now link to print exam results  New CertView Users - Who Have An Oracle Web Account ·         First time Users must authenticate their CertView account ·         Account Authentication requires the Oracle Testing ID and email address from your Pearson VUE profile ·         Click the link in the email sent by Oracle or go to certview.oracle.com and follow the Authenticate My CertView Account link.  New CertView Users - Who Do Not Have An Oracle Web Account ·         CertView users are required to have an Oracle Web Account ·         To create an Oracle Web Account, go to certview.oracle.com and select theCreate My Oracle Web Account Now link. Then follow the remaining instructions under I do not have an Oracle Web Account on that page.

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• Documenting sp_ssiscatalog

  - by jamiet

  What is the best way to document an API? Moreover, what is the best way to document a T-SQL API? Before I try to answer those questions I should explain what I mean by “a T-SQL API”. I think of an API as being a collection of well-defined, known, code modules that provide some notion of a service to whomever uses it; in T-SQL terms I tend to think of a collection of stored procedures and functions as a form of API. Its a loose definition, I admit, and in SQL Server circles we don’t tend to think of stored procedures collectively as an API but if you think about it that’s exactly what they are. The question of how to document a T-SQL API came to my mind as I worked on sp_ssiscatalog. How could I make it easy for people to learn about the capabilities of sp_ssiscatalog without forcing them to dig through the code and find out for themselves? My opening gambit was to write documentation pages on the wiki at http://ssisreportingpack.codeplex.com. That’s kinda useful but it does suffer the disadvantage that someone using sp_ssiscatalog needs to go visit a webpage to read it – I want the documentation to be available wherever the user is using sp_ssiscatalog. Moreover, maintaining the wiki is a real PITA. Intellisense works up to a point, I guess: but that only shows whatever SQL Server knows about the various parameters, which isn’t all that much! I wanted a better way for my API users to learn about its capabilities and so I hit upon the idea of simply using PRINT statements within the code itself to inform the user what options are available; hence I added such PRINT statements in the latest check-in. Now when you execute (for example): EXEC sp_ssiscatalog @operation_type='execs' you can hit F6 a few times to view the messages pane and you shall see something like this: Notice that I’m returning information about all the parameters that can be used to affect the results that just got returned. I really do think this will be very useful to anyone using sp_ssiscatalog; I myself am always forgetting what the parameters are and I wrote the damn thing so I can’t really expect anyone else to remember them. I have not yet made available a release that has these changes in it but when I do I’ll blog about it right here. At the time of writing the latest available release of sp_ssiscatalog is DB v1.0.1.0 but if you want to the latest and greatest simply download it straight from source. Feedback is welcome as always. @Jamiet

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