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• Cant finish upgrade from 11.10 to 12 on VPS based on Parallels Virtuozzo Containers, due to libc6

  - by Carmageddon

  I was stuck with this problem near the end of an upgrade: WARNING: this version of the GNU libc requires kernel version 2.6.24 or later. Please upgrade your kernel before installing glibc. The installation of a 2.6 kernel could ask you to install a new libc first, this is NOT a bug, and should NOT be reported. In that case, please add lenny sources to your /etc/apt/sources.list and run: apt-get install -t lenny linux-image-2.6 Their suggested stepds dont work on VPS, and after googling, I came up to this: Why did my upgrade to 12.04 fail with "glibc not found" or "libc6" or "requires kernel 2.6.24" error? There is comment by izx which explains my problem and proposes a workaround (might take a while to convince the guys to upgrade the kernel..). However, when I follow his instructions, I get error: # apt-get -f install Reading package lists... Done Building dependency tree Reading state information... Done Correcting dependencies... Done The following extra packages will be installed: libc-dev-bin libc6 libc6-dev libnih1 Suggested packages: glibc-doc The following packages will be upgraded: libc-dev-bin libc6 libc6-dev libnih1 4 upgraded, 0 newly installed, 0 to remove and 394 not upgraded. 1 not fully installed or removed. Need to get 0 B/7737 kB of archives. After this operation, 233 kB disk space will be freed. Do you want to continue [Y/n]? y locale: /lib/x86_64-linux-gnu/libc.so.6: version `GLIBC_2.15' not found (required by locale) locale: /lib/x86_64-linux-gnu/libc.so.6: version `GLIBC_2.14' not found (required by locale) Preconfiguring packages ... (Reading database ... 35175 files and directories currently installed.) Preparing to replace libc6-dev 2.13-20ubuntu5.2 (using .../libc6-dev_2.15-0ubuntu10.3_amd64.deb) ... Unpacking replacement libc6-dev ... Preparing to replace libc-dev-bin 2.13-20ubuntu5.2 (using .../libc-dev-bin_2.15-0ubuntu10.3_amd64.deb) ... Unpacking replacement libc-dev-bin ... Preparing to replace libc6 2.13-20ubuntu5.2 (using .../libc6_2.15-0ubuntu10.3_amd64.deb) ... locale: /lib/x86_64-linux-gnu/libc.so.6: version `GLIBC_2.15' not found (required by locale) locale: /lib/x86_64-linux-gnu/libc.so.6: version `GLIBC_2.14' not found (required by locale) Checking for services that may need to be restarted... Checking init scripts... runlevel:/var/run/utmp: No such file or directory Checking for services that may need to be restarted... Checking init scripts... runlevel:/var/run/utmp: No such file or directory WARNING: init script for samba not found. Stopping some services possibly affected by the upgrade (will be restarted later): cron: stopping...done. WARNING: this version of the GNU libc requires kernel version 2.6.24 or later. Please upgrade your kernel before installing glibc. The installation of a 2.6 kernel _could_ ask you to install a new libc first, this is NOT a bug, and should *NOT* be reported. In that case, please add lenny sources to your /etc/apt/sources.list and run: apt-get install -t lenny linux-image-2.6 Then reboot into this new kernel, and proceed with your upgrade dpkg: error processing /var/cache/apt/archives/libc6_2.15-0ubuntu10.3_amd64.deb (--unpack): subprocess new pre-installation script returned error exit status 1 Processing triggers for man-db ... locale: /lib/x86_64-linux-gnu/libc.so.6: version `GLIBC_2.15' not found (required by locale) locale: /lib/x86_64-linux-gnu/libc.so.6: version `GLIBC_2.14' not found (required by locale) Errors were encountered while processing: /var/cache/apt/archives/libc6_2.15-0ubuntu10.3_amd64.deb E: Sub-process /usr/bin/dpkg returned an error code (1) I also attempted to manually grab the .deb package and install it using dpkg -i, but getting: locale: /lib/x86_64-linux-gnu/libc.so.6: version `GLIBC_2.15' not found (required by locale) Even though the file is: libc-bin_2.15-0ubuntu10+openvz0_amd64.deb

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• Do you want to learn about developing Web, Mobile and beyond Oracle based applications? Join our online virtual event on November 26th

  - by JuergenKress

  Learn about the latest innovations in Oracle ADF. Our virtual event provides sessions that range from introductory to deep dive, covering Oracle’s strategic framework for developing multi-channel enterprise applications for the Oracle platforms. Multiple tracks cover every interest and every level and include live online Q&A chats with Oracle’s technical staff. For details please visit our registration page. WebLogic Partner Community For regular information become a member in the WebLogic Partner Community please visit: http://www.oracle.com/partners/goto/wls-emea ( OPN account required). If you need support with your account please contact the Oracle Partner Business Center. Blog Twitter LinkedIn Mix Forum Wiki Technorati Tags: ADF,ADF mobile,education,training,Oracle OpenWorld,WebLogic,WebLogic Community,Oracle,OPN,Jürgen Kress

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• Should I still consider using Appcelerator Titanium for building mobile apps if I don't have any web dev skills?

  - by BeachRunnerJoe

  Hello, I'm an experienced desktop developer who's recently begun writing iOS apps and would like to venture into Android development as well. I've been hearing a lot of talk surrounding the Appcelerator Titanium framework lately, but I'm not sure I fully understand it's purpose. As I understand it, it's a framework for building native mobile apps using web technologies. If I don't have any web dev skills, are there any ways that using Appcelerator Titanium would benefit me? Thanks for your thoughts, I'm going to continue researching this right now.

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• WampServer 2.1.a est disponible, la plateforme de développement et de test d'applications Web met à jour ses outils

  WampServer 2.1.a est disponible La plateforme de développement et de tests d'applications Web est de retour Alter Way annonce la disponibilité de la nouvelle version de son outil WampServer. WampServer permet de développer et de tester des applications Web, dynamiques, en local sous Windows, à l'aide du serveur Apache, du langage de scripts PHP et d'une base de données MySQL. La plate-forme possède également PHPMyAdmin pour gérer plus facilement les bases de données. « Contrairement aux autres solutions, WampServer permet de reproduire fidèlement son serveur de production », se félicite l'éditeur. La version 2.1.a inclue ...

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• How to shift a vector based on the rotation of another vector?

  - by bpierre

  I’m learning 2D programming, so excuse my approximations, and please, don’t hesitate to correct me. I am just trying to fire a bullet from a player. I’m using HTML canvas (top left origin). Here is a representation of my problem: The black vector represent the position of the player (the grey square). The green vector represent its direction. The red disc represents the target. The red vector represents the direction of a bullet, which will move in the direction of the target (red and dotted line). The blue cross represents the point from where I really want to fire the bullet (and the blue and dotted line represents its movement). This is how I draw the player (this is the player object. Position, direction and dimensions are 2D vectors): ctx.save(); ctx.translate(this.position.x, this.position.y); ctx.rotate(this.direction.getAngle()); ctx.drawImage(this.image, Math.round(-this.dimensions.x/2), Math.round(-this.dimensions.y/2), this.dimensions.x, this.dimensions.y); ctx.restore(); This is how I instanciate a new bullet: var bulletPosition = playerPosition.clone(); // Copy of the player position var bulletDirection = Vector2D.substract(targetPosition, playerPosition).normalize(); // Difference between the player and the target, normalized new Bullet(bulletPosition, bulletDirection); This is how I move the bullet (this is the bullet object): var speed = 5; this.position.add(Vector2D.multiply(this.direction, speed)); And this is how I draw the bullet (this is the bullet object): ctx.save(); ctx.translate(this.position.x, this.position.y); ctx.rotate(this.direction.getAngle()); ctx.fillRect(0, 0, 3, 3); ctx.restore(); How can I change the direction and position vectors of the bullet to ensure it is on the blue dotted line? I think I should represent the shift with a vector, but I can’t see how to use it.

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• How to handle fine grained field-based ACL permissions in a RESTful service?

  - by Jason McClellan

  I've been trying to design a RESTful API and have had most of my questions answered, but there is one aspect of permissions that I'm struggling with. Different roles may have different permissions and different representations of a resource. For example, an Admin or the user himself may see more fields in his own User representation vs another less-privileged user. This is achieved simply by changing the representation on the backend, ie: deciding whether or not to include those fields. Additionally, some actions may be taken on a resource by some users and not by others. This is achieved by deciding whether or not to include those action items as links, eg: edit and delete links. A user who does not have edit permissions will not have an edit link. That covers nearly all of my permission use cases, but there is one that I've not quite figured out. There are some scenarios whereby for a given representation of an object, all fields are visible for two or more roles, but only a subset of those roles my edit certain fields. An example: { "person": { "id": 1, "name": "Bob", "age": 25, "occupation": "software developer", "phone": "555-555-5555", "description": "Could use some sunlight.." } } Given 3 users: an Admin, a regular User, and Bob himself (also a regular User), I need to be able to convey to the front end that: Admins may edit all fields, Bob himself may edit all fields, but a regular User, while they can view all fields, can only edit the description field. I certainly don't want the client to have to make the determination (or even, for that matter, to have any notion of the roles involved) but I do need a way for the backend to convey to the client which fields are editable. I can't simply use a combination of representation (the fields returned for viewing) and links (whether or not an edit link is availble) in this scenario since it's more finely grained. Has anyone solved this elegantly without adding the logic directly to the client?

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• Install a i386 printer driver into an amd64 distribution or how can I find a good printer based on features?

  - by Yanick Rochon

  Hi, I just bought a Lexmark Interpret S408 all-in-one printer. The box said that it supported Ubuntu 8.04, but I told myself it should work with Lucid... well no. The only driver I have found is for i386 while I have a amd64 image installed; the architecture is incompatible. So, the quesiton is : Is it possible to install that driver anyway, somehow? Or do I need to take that printer back to the store and buy another one? If the latter is the only alternative, I need a printer that has wireless connection capability can do color printing is of good price (less than $200 CAD) Thank you for your answers, help, and tips. ** UPDATE ** The driver was given in the form of deb package (for Debian distributions) and I managed to extract the actual deb package driver out of the install program. I ran sudo dpkg -i --force-all lexmark-inkjet-09-driver-1.5-1.i386.deb and the driver installed, and I was able to print something out. But that pretty much ends there; I cannot access anymore of the printer settings, etc. (i.g. scanner, fax, wifi settings, etc.) I should suffice for now as I'm satisfied with the printer's features (and size, and prince), but if I could have a full-linux-supported printer like that one, I would return this one in exchange for the other.

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• Is there a way I can filter traffic by page-type based upon URL structure in Google-Analytics or Google Webmaster Tools?

  - by Felix

  I have a local business directory site. I'm trying to segment my incoming traffic by page-type such that I can find out what percentage of traffic is going to zip code pages exclusively and what percentage is going to city/state level pages. I basically want to filter by URL structure to find out what percentage of total traffic zip code pages account for. The reason for doing this is to find out if Google Tag Manager can help with this? Here are the two URL paths: http://www.example.com/ny/new-york/10011/ http://www.example.com/ny/new-york

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• Is it possible to mod_rewrite BASED on the existence of a file/directory and uniqueID?

  - by JM4

  My site currently forces all non www. pages to use www. Ultimately, I am able to handle all unique subdomains and parse correctly but I am trying to achieve the following: (ideally with mod_rewrite): when a consumer visits www.site.com/john4, the server processes that request as: www.site.com?Agent=john4 Our requirements are: The URL should continue to show www.site.com/john4 even though it was redirected to www.site.com?index.php?Agent=john4 If a file (of any extension OR a directory) exists with the name, the entire process stops an it tries to pull that file instead: for example: www.site.com/file would pull up (www.site.com/file.php if file.php existed on the server. www.site.com/pages would go to www.site.com/pages/index.php if the pages directory exists). Thank you ahead of time. I am completely at a crapshot right now.

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• How do I install Adobe Acrobat Pro From Web Premium CS4,....?

  - by RedBunny

  I am Running the new Ubuntu 12.04 Beta 2, and am looking to install Adobe Acrobat Pro from My CS4 Web Premium CD. Whenever I try and install the setup.exe I get the following error: Internal Error - invalid parameters recieved. in a Wine Program Crash box. I am running wine 1.5 and have tried 1.4 also. I have used winetricks and PlayOnLinux, and cannot get it to install with either program. Any help would be appreciated,.... Also If I cant get it installed does anyone know any programs that can link .PDF files to MySql databases in Linux ,....? I really need this to be able to host some web forms for work. Thanx in Advance,..... ~RedBunny

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• What is a good method for coloring textures based on a palette in XNA?

  - by Bob

  I've been trying to work on a game with the look of an 8-bit game using XNA, specifically using the NES as a guide. The NES has a very specific palette and each sprite can use up to 4 colors from that palette. How could I emulate this? The current way I accomplish this is I have a texture with defined values which act as indexes to an array of colors I pass to the GPU. I imagine there must be a better way than this, but maybe this is the best way? I don't want to simply make sure I draw every sprite with the right colors because I want to be able to dynamically alter the palette. I'd also prefer not to alter the texture directly using the CPU.

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• How do I get my RTL8192ce based wireless device working properly?

  - by JonnyTruelove

  I am using the rtl8192cu chipset (on a Belkin wireless USB adapter N300) combined with 64 bit architecture and the 3.8 kernel. Some of you may know that this doesn't work. I tried this fix - RTL8188CU USB Network Adaptor on ubuntu 13.04 and now my internet is super slow. I am totally new to Ubuntu and I am concerned I do not have the right driver. The "stock" driver was the RTL8192cu, but it didn't connect 99% of the time and if it did the upload speed was higher than the download. Right now I am connecting through my laptop with a crossover cable, so my internet connection is just fine in my apartment. Relevant output from lsusb is here: Bus 002 Device 002: ID 050d:2103 Belkin Components F7D2102 802.11n N300 Micro Wireless Adapter v3000 [Realtek RTL8192CU] (bonus question: is that [050d:2103] the actual physical address straight from the hardware? Or does it change when I put different drivers on it? I am concerned I do not have the right driver)

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• Can emsripten compile down to Canvas-based Js instead of WebGL?

  - by Sebastian Scholle

  I understand that emscripten compiles down LLVM to JS and it converts OpenGL Calls to WebGL. Thats a fairly simple translation. Is there a way to tell emscripten to use some other graphics Library ( for example Pixi JS ) for its rendering code translations? Is the compiled JS code easy to update or would it be better to merge in your own Graphics API that handles WebGL/Canvas calls. IE: can we use a C++ Graphics Wrapper Library that when compiles to JS, will simply plug into our own JS Graphics Wrapper Library? Im assuming YES, but has anyone tried this? And if So, what would be your technique, as my C++ skills are basic.

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• Can web applications running on IIS7 Windows Server 2008 R2 be forced to immediately detect changes to hosts file?

  - by Brenda Bell

  We have several web applications running on several load-balanced servers. We want to have our web applications communicate with each other without first traversing outside the load balancer. For example: http://appA.example.com is running on 192.0.2.1 and 192.0.2.2 http://appB.example.com is also running on 192.0.2.1 and 192.0.2.2 The load balancer's public IP address is 198.51.100.3 By default, when appA on 192.0.2.1 makes a call to a WCF service hosted in appB, the HTTP request is routed to 192.51.100.3; this establishes a new session and the load balancer will direct the call to either of the two servers We want the call to be routed to the instance of appB running on the same server so we add 192.0.2.1 appB.example.com to the hosts file on 192.0.2.1. This eventually works, but we either have to wait for the app pool to naturally recycle or do a manual reset before appA sees the new address. Is there any way to have the change automatically detected without having to recycle the app pool?

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• How can I spawn a sprite based on a condition after the game starts?

  - by teddyweedy

  How do I spawn a sprite anytime later in the game when the game starts? I'm using FlashDevelop with Flixel. I did try it in override public function create(): void. It works only in the beginning. I try it using if (FlxG.score == 1) but it doesn't work. I also tried it in override public function update(): void. It works and it is moving but it leaves a sprite making it a multi-sprite. I also did try FlxGroup but to no avail.

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• How to react to an office harassment based on my profession ? [closed]

  - by bob from jersey

  A lot of my co-workers (not developers, people from the other departments) who are framing me in the classical "nerd" stereotype, and with that acting disturbing towards me. Of course they are not aggressive or anything, since we are in a work environment having rules on it's own, plus we are all grownups now, but they are on a "quite war" against me (not particularly against me, they are against all developers, but I am the only one who dares to speak about it). I hear names, "nerd", "geek", "cyborg", "outsider" and so on, it's really inappropriate. Of course, nothing is said in our faces, but, you know, "you hear things over". Also this general feeling of "them not liking us at all" can be sensed in the air all the time. And while it is not a problem for a few weeks, a larger duration of constant office harassment (going for months now), can be really annoying and can cause a serious drop in the development performance, which will (inevitably) lead to problems with the management (maybe getting me fired). I want to know, should I continue with my current defensive strategy (passively ignoring their inappropriate labels) or should I switch into a more aggressive maneuvers, like giving them logical reasons why their antisocial behavior should be banned?

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• How do functional languages handle a mocking situation when using Interface based design?

  - by Programmin Tool

  Typically in C# I use dependency injection to help with mocking; public void UserService { public UserService(IUserQuery userQuery, IUserCommunicator userCommunicator, IUserValidator userValidator) { UserQuery = userQuery; UserValidator = userValidator; UserCommunicator = userCommunicator; } ... public UserResponseModel UpdateAUserName(int userId, string userName) { var result = UserValidator.ValidateUserName(userName) if(result.Success) { var user = UserQuery.GetUserById(userId); if(user == null) { throw new ArgumentException(); user.UserName = userName; UserCommunicator.UpdateUser(user); } } ... } ... } public class WhenGettingAUser { public void AndTheUserDoesNotExistThrowAnException() { var userQuery = Substitute.For<IUserQuery>(); userQuery.GetUserById(Arg.Any<int>).Returns(null); var userService = new UserService(userQuery); AssertionExtensions.ShouldThrow<ArgumentException>(() => userService.GetUserById(-121)); } } Now in something like F#: if I don't go down the hybrid path, how would I test workflow situations like above that normally would touch the persistence layer without using Interfaces/Mocks? I realize that every step above would be tested on its own and would be kept as atomic as possible. Problem is that at some point they all have to be called in line, and I'll want to make sure everything is called correctly.

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• Opinion : les frameworks Web sont-ils une mauvaise idée ? Partagez-vous l'avis de ce développeur PHP ?

  Opinion : les framework web sont-ils synonymes du mal ? J'ai récemment remarqué que personne n'a pris de recul sur les frameworks dédiés au langage PHP. Ils sont utilisés partout, ils sont devenus critères numéro un dans les recrutements de projets, ils sont l'équivalent d'une mode, etc. Bref, le framework est devenu le crucifix du développeur web. Mais un framework, est-ce vraiment que du bien? Non. En rassemblant une certaine quantité d'information trouvée sur quelques débats à propos de ceux-ci, j'ai décidé d'exprimer mon opinion sur l'utilisation d'un framework. Je trouve qu'un framework peut s'avérer être au sens propre le synonyme du mal. Avons-nous des statistiques sur l'utilisation des framewor...

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• New Success Story: McGrath RentCorp Improves Business Reporting and Analytics Capabilities with Cloud-based Business Intelligence Solution

  - by LanaProut

  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";} 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";} McGrath RentCorp worked with Jade Global, an Oracle Platinum Partner, to scope, design, and execute the deployment, using its Oracle Accelerate solution to jumpstart the process and accelerate the time to value. Click here to view the full story.

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• Is the structure used for these web pages a design pattern?

  - by aspdotnetuser

  I want to know if the structure for an ASP.NET website I'm working on uses a design pattern for it's web pages. If it is a design pattern, what is it called? The web pages have the following structure: UserDetails page (UserDetails.aspx) - includes UserDetailsController.ascx user control. UserDetailsController.ascx includes sub user controls like UserAccountDetails.ascx and UserLoginDetails.ascx etc Each sub user control contains a small amount of code/logic, the 'controller' user controls that host these sub user controls (i.e UserDetailsController.ascx) appear to call the business rules code and pass the data to the sub user controls. Is this a design pattern? What is it called?

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• Amazon Web Services : mise à jour de l'environnement Linux, avec les dernières versions de MySQL, Python, Ruby et le Kernel 3.2

  Amazon Web Services : mise à jour de l'environnement Linux avec les dernières versions de MySQL, Python, Ruby et le Kernel Linux 3.2 Amazon Web Services (AWS) vient de procéder à une mise à jour majeure d'Amazon Linux AMI. L'image du système d'exploitation Linux qui s'exécute sur la plateforme intègre désormais les versions les plus récentes de TomCat, MySQL, Python, GCC, Ruby, etc. Cette version a été construite avec pour objectif principal de permettre aux entreprises de migrer ou de rester sur les anciennes versions des outils. Ainsi, les organismes peuvent exécuter différentes versions majeures des applications et langages de programmation. Ceci permet au code qui s'appuie su...

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• In a 2D tile-based game, how should NPCs and tiles reference each other?

  - by lezebulon

  I'm making a tile engine for 2D games (seen from the top). Basically the world is composed of a grid of tiles. Now I want to put for instance NPCs that can move on the map. What do you think is best: 1) each tile has a pointer to the NPC that is on its tile, or a NULL pointer 2) having a list of NPCs, and they have the coordinates of the tile they are on. 3) something else? 1) is faster for collision detection but it would use much more memory space and it is slower to find all NPCs in a map. 2) is the opposite. thanks

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• I need help with a timer for a text based game, i need to include a mysql query to it, but not sure how.

  - by Hijumper

  i would like to add a mysql query somewhere in my timer code so that everytime it restarts then 1 item would be added to the database, i can get it to show how many items you have gotten since the timer has been running, but im not quite sure how to add it into a mysql database, any help would be appreciated :D heres my timer code thus far: <head> <script type="text/javascript"> var c=10; var mineCount = 0; var t; var timer_is_on=0; function timedCount() { document.getElementById('txt').value = c; c = c - 1; if (c <= -1) { mineCount++; var _message = "You have mined " + mineCount + " iron ore" + (((mineCount > 1) ? "s" : "") + "!"); document.getElementById('message').innerHTML = _message; startover(); } } function startover() { c = 10; clearTimeout(t); timer_is_on=0; doMining(); } function doMining() { if (!timer_is_on) { timer_is_on = true; t = setInterval(function () { timedCount(); }, 1000); } } </script> <SPAN STYLE="float:left"> <form> <input type="button" value="Mining" onClick="doMining()"> <input type="text" id="txt"> </form> </SPAN> <html> <center> <div id='message'></div>

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• How can I locate the frames of a spritesheet PNG based on this PLIST data?

  - by kitsune

  Someone asked me to reskin a certain game. Now he only sent me the whole sprite PNG and PLIST files of the sprites. He instructed me to rename each sprite with the same name corresponding to each original sprite. The problem is, he gave me the whole sprite sheet instead of each individual sprite and the PLIST. Now yes, I can read the PNG filenames from the PLIST, but I cannot rename the reskin sprites I did because I'm not sure which sprite is boy_gun_3_3.png; there are multiple guns, I don't know which is which. Is there a way to extract individual accurately named individual PNG files from the single sprite sheet using the PLIST?

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• How to avoid oscillation by async event based systems?

  - by inf3rno

  Imagine a system where there are data sources which need to be kept in sync. A simple example is model - view data binding by MVC. Now I intend to describe these kind of systems with data sources and hubs. Data sources are publishing and subscribing for events and hubs are relaying events to data sources. By handling an event a data source will change it state described in the event. By publishing an event the data source puts its current state to the event, so other data sources can use that information to change their state accordingly. The only problem with this system, that events can be reflected from the hub or from the other data sources, and that can put the system into an infinite oscillation (by async or infinite loop by sync). For example A -- data source B -- data source H -- hub A -> H -> A -- reflection from the hub A -> H -> B -> H -> A -- reflection from another data source By sync it is relatively easy to solve this issue. You can compare the current state with the event, and if they are equal, you don't change the state and raise the same event again. By async I could not find a solution yet. The state comparison does not work by async event handling because there is eventual consistency, and new events can be published in an inconsistent state causing the same oscillation. For example: A(*->x) -> H -> B(y->x) -- can go parallel with B(*->y) -> H -> A(x->y) -- so first A changes to x state while B changes to y state -- then B changes to x state while A changes to y state -- and so on for eternity... What do you think is there an algorithm to solve this problem? If there is a solution, is it possible to extend it to prevent oscillation caused by multiple hubs, multiple different events, etc... ? update: I don't think I can make this work without a lot of effort. I think this problem is just the same as we have by syncing multiple databases in a distributed system. So I think what I really need is constraints if I want to prevent this problem in an automatic way. What constraints do you suggest?

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