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• What is faster with PictureBox? Many small redraws or complete redraw.

  - by kornelijepetak

  I have a PictureBox (WinMobile 6 WinForm) on which I draw some images. There is a background image that goes in the background and it does not change. However objects that are drawn on the picturebox are moving during the application so I need to refresh the background. Since items that are redrawn fill from 50% to 80% of the surface, the question is which of the two is faster: 1) Redraw only parts of the background image that have been changed (previous+next location of the moving object). 2) Redraw complete background and then draw all the objects in their current position. Now, the reason for asking is because I am not sure how much of processor power is needed for a single drawImage operation and what are the time consuming factors. I am aware if there is almost complete coverage of the background, it would be stupid to redraw portions of it, because by drawing portions I will have drawn the complete picture. But since sometimes only half of the image had changed (some objects remained in their old position), it may (perhaps) be benefitial to redraw only those regions. But I need your insight on this... Thanks.

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• Javascript Object.Watch for all browsers?

  - by SeanW

  Hey all, I was looking for an easy way to monitor an object or variable for changes, and I found Object.Watch that's supported in Mozilla browsers, but not IE. So I started searching around to see if anyone had written some sort of equivalent. About the only thing I've found has been a jQuery plugin (http://plugins.jquery.com/files/jquery-watch.js.txt), but I'm not sure if that's the best way to go. I certainly use jQuery in most of my projects, so I'm not worried about the jQuery aspect... Anyway, the question: can someone show me a working example of that jQuery plugin? I'm having problems making it work... Or, does anyone know of any better alternatives that would work cross browser? Thanks! Update after answers: Thanks everyone for the responses! I tried out the code posted here: http://webreflection.blogspot.com/2009/01/internet-explorer-object-watch.html But I couldn't seem to make it work with IE. The code below works fine in FireFox, but does nothing in IE. In Firefox, each time watcher.status is changed, the document.write in watcher.watch is called and you can see the output on the page. In IE, that doesn't happen, but I can see that watcher.status is updating the value, because the last document.write shows the correct value (in both IE and FF). But, if the callback function isn't called, then that's kind of pointless... :) Am I missing something? var options = {'status': 'no status'}, watcher = createWatcher(options); watcher.watch("status", function(prop, oldValue, newValue) { document.write("old: " + oldValue + ", new: " + newValue + "<br>"); return newValue; }); watcher.status = 'asdf'; watcher.status = '1234'; document.write(watcher.status + "<br>");

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• Netty options for real-time distribution of small messages to a large number of clients?

  - by user439407

  I am designing a (near) real-time Netty server to distribute a large number of very small messages to a large number of clients across the internet. In internal, go as fast as you can testing, I found that I could do 10k clients no sweat, but now that we are trying to go across the internet, where the latency, bandwidth etc varies pretty wildly we are running into the dreaded outOfMemory issues, even with 2 gigs of RAM. I have tried various workarounds(setting the socket stack sizes smaller, setting high and low water marks, cancelling things that are too old), and they help a little, but they seem to only help a little bit. What would some good ways to optimize Netty for sending large #s of small messages without significant delays? Also, the bulk of the message only consists of one kind of message that I don't particularly care if it doesn't arrive. I would use UDP but because we don't control the client, thats not really a possibility. Is it possible to set a separate timeout solely for this kind of message without affecting the other messages? Any insight you could offer would be greatly appreciated.

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• How to create extensible dynamic array in Java without using pre-made classes?

  - by AndrejaKo

  Yeah, it's a homework question, so givemetehkodezplsthx! :) Anyway, here's what I need to do: I need to have a class which will have among its attributes array of objects of another class. The proper way to do this in my opinion would be to use something like LinkedList, Vector or similar. Unfortunately, last time I did that, I got fire and brimstone from my professor, because according to his belief I was using advanced stuff without understanding basics. Now next obvious solution would be to create array with fixed number of elements and add checks to get and set which will see if the array is full. If it is full, they'd create new bigger array, copy older array's data to the new array and return the new array to the caller. If it's mostly empty, they'd create new smaller array and move data from old array to new. To me this looks a bit stupid. For my homework, there probably won't be more that 3 elements in an array, but I'd like to make a scalable solution without manually calculating statistics about how often is array filled, what is the average number of new elements added, then using results of calculation to calculate number of elements in new array and so on. By the way, there is no need to remove elements from the middle of the array. Any tips?

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• How to define Module and use it in dojo with AMD?

  - by Devdatta Tengshe

  I am maintaining and extending an old project which was pre-AMD. I wish to add an Chart to the application. for this, I have created a js file as follows: define(["dojox/charting/Chart",...."dijit/Dialog","dojo/dom-construct"], function (Chart) { function showDailyChart(data){ //code to show the chart in a dialog } return customModules.singleChart; }); I have saved this file as /customModules/singleChart.js In My main HTML Page, I have added it to the packages as follows: var dojoConfig = { parseOnLoad: true, packages: [....,{"name":"customModules", "location":location.pathname.replace(/\/[^/]+$/, "")+"/modules" } ]}; The function from which I want to call it, is pre-AMD. So I am calling it as follows: dojo.require("customModules.singleChart"); . . . customModules.singleChart.showDailyChart(data); I can see that /customModules/singleChart.js is loaded in the Firebug console as well as Net Tab. However there is no customModules.singleChart object. Strangely enough there is no error either. I have tested this in Firebug, as well as Google Chrome's developer tools. What is the correct way to call an AMD Module using dojo.require? Or is there a better way to do what I need?

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• How do I write unescaped XML outside of a CDATA

  - by kazanaki

  Hello I am trying to write XML data using Stax where the content itself is HTML If I try xtw.writeStartElement("contents"); xtw.writeCharacters("<b>here</b>"); xtw.writeEndElement(); I get this <contents>&lt;b&gt;here&lt;/b&gt;</contents> Then I notice the CDATA method and change my code to: xtw.writeStartElement("contents"); xtw.writeCData("<b>here</b>"); xtw.writeEndElement(); and this time the result is <contents><![CDATA[<b>here</b>]]></contents> which is still not good. What I really want is <contents><b>here</b></contents> So is there an XML API/Library that allows me to write raw text without being in a CDATA section? So far I have looked at Stax and JDom and they do not seem to offer this. In the end I might resort to good old StringBuilder but this would not be elegant. Update I agree mostly with the answers so far. However instead of <b>here</b> I could have a 1MB HTML document that I want to embed in a bigger XML document. What you suggest means that I have to parse this HTML document in order to understand its structure. I would like to avoid this if possible.

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• How to structure applications as multiple projects an name the packages in Java

  - by lostiniceland

  Hello Everyone I would like to know how you set up your projects in Java For example, in my current work-project, a six year old J2EE app with approximately 2 million LoC, we only have one project in Eclipse. The package structure is split into tiers and then domains, so it follows guidelines from Sun/Oracle. A huge ant-script is building different jars out of this one source-folder Personally I think it would be better to have multiple projects, at least for each tier. Recently I was playing around with a projects-structure like this: Domainproject (contains only annotated pojos, needed by all other projects) Datalayer (only persistence) Businesslogic (services) Presenter View This way, it should be easier to exchange components and when using a build tool like Maven I can have everything in a repository so when only working on the frontend I can get the rest as a dependecy in my classpath. Does this makes sense to you? Do you use different approaches and how do they look like? Furthermore I am struggeling how to name my packages/projects correctly. Right now, the above project-structure reflects in the names of the packages, eg. de.myapp.view and it continues with some technical subfolders like internal or interfaces. What I am missing here, and I dont know how to do this properly, is the distinction to a certain domain. When the project gets bigger it would be nice to recognise a particular domain but also the technical details to navigate more easily within the project. This leads to my second question: how do you name your projects and packages?

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• What is SSIS order of data transformation component method calls

  - by Ron Ruble

  I am working on a custom data transformation component. I'm using NUnit and NMock2 to test as I code. Testing and getting the custom UI and other features right is a huge pain, in part because I can't find any documentation about the order in which SSIS invokes methods on the component at design time as well as runtime. I can correct the issues readily enough, but it's tedious and time consuming to unregister the old version, register the new version, fire up the test ssis package, try to display the UI, get an obscure error message, backtrace it, modify the component and continue. One of the big issues involves the UI component needing access to the componentmetadata and buffermanager properties of the component at design time, and what I need to provide for to support properties that won't be initialized until after the user enters them in the UI. I can work through it; but if someone knows of some docs or tips that would speed me up, I'd greatly appreciate it. The samples I've found havn't been much use; they seem to be directed to showing off cool stuff (Twitter, weather.com) rather than actual work. Thanks in advance.

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• Why would I be seeing execution timeouts when setting $_SESSION values?

  - by Kev

  I'm seeing the following errors in my PHP error logs: PHP Fatal error: Maximum execution time of 60 seconds exceeded in D:\sites\s105504\www\index.php on line 3 PHP Fatal error: Maximum execution time of 60 seconds exceeded in D:\sites\s105504\www\search.php on line 4 The lines in question are: index.php: 01 <?php 02 session_start(); 03 ob_start(); 04 error_reporting(E_All); 05 $_SESSION['nav'] = "range"; // <-- Error generated here search.php 01 <?php 02 03 session_start(); 04 $_SESSION['nav'] = "range"; 05 $_SESSION['navselected'] = 21; // <-- Error generated here Would it really take as long as 60+ seconds to assign a $_SESSION[] value? The platform is: Windows 2003 SP2 + IIS6 FastCGI for Windows 2003 (original RTM build) PHP 5.2.6 Non thread-safe build There aren't any issues with session data files being cleared up on the server as sessions expire. The oldest sess_XXXXXXXXXXXXXX file I'm seeing is around 2 hours old. There are no disk timeouts evident in the event logs or other such disk health issues that might suggest difficulty creating session data files. The site is also on a server that isn't under heavy load. The site is busy but not being hammered and is very responsive. It's just that we get these errors, three or four in a row, every three or four hours. I should also add that I'm not the original developer of this code and that it belongs to a customer who's developer has long since departed.

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• InstallExecuteSequence cache interferes with custom action operation

  - by Dima G

  I need to upgrade a product that could be installed in per-user context to a new version that is always in per-machine context. The requirements are: Whether the old version was installed in a Per-User (no matter who) or Per-Machine context should be completely seamless to an administrator user that performs the upgrade. The MSI upgrade should succeed without the need to know the password of the user that originally installed the previous version of the product in a Per-User context. The installation should be performed from a single .msi file (no setup.exe is allowed). The installation should be able to run in a silent (non-UI) mode. No reboots are allowed during installation. My strategy is to find in the beginning of the installation whether the product is already installed in per-user context, and if so, to transform the registry keys manually to Per-Machine context (I checked: no additional changes such as file system changes etc. are needed except this transform). I figured out how to move all appropriate keys in the registry from the user settings to the machine settings (pre-loaded appropriate user hive in case it didn't appear in HKEY_USERS) and created custom action that does it - and it does work when I run it as a stand-alone executable before running the MSI. The problem, however, is that when Windows Installer runs InstallExecuteSequence it first creates a 'cached product context' for all products. So when my custom action runs in the course of InstallExecuteSequence, this cache has already been created. Thus FindRelatedProducts action that determines if older product with same upgrade code exists looks on that cache and ignores the changes that my custom action applied. If before running the MSI the previous product was in per-user context, FindRelatedProducts will look at the cache and not apply the upgrade and remove the previous version, because the new product is in per-machine context, even though the previous product version is already configured to per-machine context in the registry by that time by my custom action. What can be done to solve this problem without violating the requirements stated above?

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• Unit tests - The benefit from unit tests with contract changes?

  - by Stefan Hendriks

  Recently I had an interesting discussion with a colleague about unit tests. We where discussing when maintaining unit tests became less productive, when your contracts change. Perhaps anyone can enlight me how to approach this problem. Let me elaborate: So lets say there is a class which does some nifty calculations. The contract says that it should calculate a number, or it returns -1 when it fails for some reason. I have contract tests who test that. And in all my other tests I stub this nifty calculator thingy. So now I change the contract, whenever it cannot calculate it will throw a CannotCalculateException. My contract tests will fail, and I will fix them accordingly. But, all my mocked/stubbed objects will still use the old contract rules. These tests will succeed, while they should not! The question that rises, is that with this faith in unit testing, how much faith can be placed in such changes... The unit tests succeed, but bugs will occur when testing the application. The tests using this calculator will need to be fixed, which costs time and may even be stubbed/mocked a lot of times... How do you think about this case? I never thought about it thourougly. In my opinion, these changes to unit tests would be acceptable. If I do not use unit tests, I would also see such bugs arise within test phase (by testers). Yet I am not confident enough to point out what will cost more time (or less). Any thoughts?

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• Toggling between instances of NiftyPlayer on a page - won't stop playing when hidden on IE

  - by Ashley

  Hi, i've got a page with links to MP3s, when the link is clicked I use javascript to show a small Flash player (NiftyPlayer) under the link. When a different link is clicked, the old player is hidden and the new player is revealed. The player auto-starts when the element is shown, and auto-stops when hidden - in Firefox. In IE it will only auto-start and NOT auto-stop. This is what I would like to solve. This is an example HTML with link and player <a href="Beat The Radar - Misunderstood What You Said.mp3" onclick="toggle_visibility('player662431');return false;" class="mp3caption">Misunderstood What You Said</a> <div id="player662431" class="playerhide"><embed src="http://www.xxx.com/shop/flash/player.swf?file=/mp3/Beat The Radar - Misunderstood What You Said.mp3&as=1" quality="high" bgcolor="#000000" width="161" height="13" name="niftyPlayer662431" align="" type="application/x-shockwave-flash" swLiveConnect="true" pluginspage="http://www.macromedia.com/go/getflashplayer"></embed> Here is the javascript (i've got jquery installed to let me hide all the open players on this page apart from the new one) function toggle_visibility(id) { $('.playerhide').hide(); var e = document.getElementById(id); e.style.display = 'block'; } I think what I need to do is start the player manually with javascript (rather than using the autostart as=1 function in the URL string) There is some javascript that comes with NiftyPlayer to allow this EG niftyplayer('niftyPlayer1').play() there is also a stop method. I need some help with javascript - how do I add this call to play into my toggle_visibility function (it has the same unique ID number added to the name of the player as the ID of the div that's being shown, but I don't know how to pull this ID number out of one thing and put it in another) I also would like to be able to do niftyplayer('niftyPlayer1').stop() to stop the audio of the previously running player. Is it possible to store the current ID number somewhere and call it back when needed? Thanks for the help, i'm a PHP programmer who needs some support with Javascript - I know what I want to achieve, just don't know the commands to do it! Thanks

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• Loader.php trying to load Doctrine classes, but we use Propel!

  - by kewpiedoll99

  We are finding cases where we get the following 500 error: File xyz.php does not exist or class "xyz" was not found in the file at () in SF_ROOT_DIR/lib/vendor/Zend/Loader.php line 107 ... where xyz == Memcache (when trying to use symfony cc on the command line) or sfDoctrineAdminGenerator (when using an old-ish AdminGenerator-generated CMS page). We use Propel, but Loader.php is trying to load classes used only for Doctrine. Currently I am using a filthy hack where I request Loader.php to check if the file is either of these two cases, and if so simply return rather than trying to load it. Obviously, this is unacceptable longer term. Has anybody encountered this, and how did you solve it? Edited to add: We have: class ProjectConfiguration extends sfProjectConfiguration { public function setup() { // for compatibility / remove and enable only the plugins you want $this->enableAllPluginsExcept(array('sfDoctrinePlugin')); } } And we have a propel.ini file in our top level config directory. This has only started in the past four weeks or so, and we've had a stable build for over a year now. I'm pretty sure Doctrine is totally disabled.

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• Convert asp.net webforms logic to asp.net MVC

  - by gmcalab

  I had this code in an old asp.net webforms app to take a MemoryStream and pass it as the Response showing a PDF as the response. I am now working with an asp.net MVC application and looking to do this this same thing, but how should I go about showing the MemoryStream as PDF using MVC? Here's my asp.net webforms code: private void ShowPDF(MemoryStream ms) { try { //get byte array of pdf in memory byte[] fileArray = ms.ToArray(); //send file to the user Page.Response.Cache.SetCacheability(HttpCacheability.NoCache); Page.Response.Buffer = true; Response.Clear(); Response.ClearContent(); Response.ClearHeaders(); Response.Charset = string.Empty; Response.ContentType = "application/pdf"; Response.AddHeader("content-length", fileArray.Length.ToString()); Response.AddHeader("Content-Disposition", "attachment;filename=TID.pdf;"); Response.BinaryWrite(fileArray); Response.Flush(); Response.Close(); } catch { // and boom goes the dynamite... } }

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• Protecting an Application's Memory From Tampering

  - by Changeling

  We are adding AES 256 bit encryption to our server and client applications for encrypting the TCP/IP traffic containing sensitive information. We will be rotating the keys daily. Because of that, the keys will be stored in memory with the applications. Key distribution process: Each server and client will have a list of initial Key Encryption Key's (KEK) by day If the client has just started up or the server has just started up, the client will request the daily key from the server using the initial key. The server will respond with the daily key, encrypted with the initial key. The daily key is a randomly generated set of alphanumeric characters. We are using AES 256 bit encryption. All subsequent communications will be encrypted using that daily key. Nightly, the client will request the new daily key from the server using the current daily key as the current KEK. After the client gets the new key, the new daily key will replace the old daily key. Is it possible for another bad application to gain access to this memory illegally or is this protected in Windows? The key will not be written to a file, only stored in a variable in memory. If an application can access the memory illegally, how can you protect the memory from tampering? We are using C++ and XP (Vista/7 may be an option in the future so I don't know if that changes the answer).

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• Ajax function partially fails when alert removed

  - by YsoL8

  Hello. I have a problem in the following code: //quesry the db for image information function queryDB (parameters) { var parameters = "p="+parameters; alert ("hello"); if (window.XMLHttpRequest) {// code for IE7+, Firefox, Chrome, Opera, Safari xmlhttp=new XMLHttpRequest(); } else {// code for IE6, IE5 xmlhttp=new ActiveXObject("Microsoft.XMLHTTP"); } xmlhttp.onreadystatechange=function() { if (xmlhttp.readyState==4 && xmlhttp.status==200) { // use the info alert (xmlhttp.responseText); } } xmlhttp.open("POST", "js/imagelist.php", true); //Send the proper header information along with the request xmlhttp.setRequestHeader("Content-type", "application/x-www-form-urlencoded"); xmlhttp.setRequestHeader("Content-length", parameters.length); xmlhttp.setRequestHeader("Connection", "close"); xmlhttp.send(parameters); } When I remove the alert statement 4 lines down I hit problems. This function is being called by a loop, and without the alert, I only get results for the last value sent to the statement. With it, I get everything I was expecting and really I'm at a loss to know why. I've heard that this may be a timing issue as I'm sending new requests before the old one is finished. I also heard polling being mentioned, but I can't find any information detailed enough. I'm new to synchronous services and I'm not really aware of the issues.

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• Managing large binary files with git

  - by pi

  Hi there. I am looking for opinions of how to handle large binary files on which my source code (web application) is dependent. We are currently discussing several alternatives: Copy the binary files by hand. Pro: Not sure. Contra: I am strongly against this, as it increases the likelihood of errors when setting up a new site/migrating the old one. Builds up another hurdle to take. Manage them all with git. Pro: Removes the possibility to 'forget' to copy a important file Contra: Bloats the repository and decreases flexibility to manage the code-base and checkouts/clones/etc will take quite a while. Separate repositories. Pro: Checking out/cloning the source code is fast as ever, and the images are properly archived in their own repository. Contra: Removes the simpleness of having the one and only git repository on the project. Surely introduces some other things I haven't thought about. What are your experiences/thoughts regarding this? Also: Does anybody have experience with multiple git repositories and managing them in one project? Update: The files are images for a program which generates PDFs with those files in it. The files will not change very often(as in years) but are very relevant to a program. The program will not work without the files. Update2: I found a really nice screencast on using git-submodule at GitCasts.

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• iPhone application update (using Core Data on Sqlite)

  - by owen

  I have an app which is using Core Data on Sqlite, Now I have a update which has some DB structure changes say adding a new table I know when an app get updated, it updates the app binary only, nothing on document directory will be changed. When the app gets updated and launchs at the first time and run [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:[self managedObjectModel]]; It will find the difference between the data model and DB structure in Sqlite and will throw an exception and quit. Error: "The model used to open the store is incompatible with the one used to create the store" So, can anyone here give me some idea how to update an app when there is a DB structure change? I think we can run a DB script to create that new table when it launchs the update at the first time. But if there are other changes like changing the type of some fields or deleting some fields, and we need to migrate the old data, this is really a headache. In this case, Is the only way to do is creating a new app? Is there anyone tried something similar like this?

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• Implementing scroll view that is much larger than the screen view with random images

  - by pulegium

  What I'm trying to do is to implement something like the fruit machine scroll view. Basically I have a sequence of images (randomly generated on the fly) and I want to allow the users to scroll through this line. There can fit approx 10 images on the screen, but the line is virtually unlimited. My question is what would be the best approach in implementing this? So far I've thought of having a UIImageView going across the screen (with width equal to the sum of 10 images) and the image associated with it would be a combination of 12 or so images, with two images falling out of the visible area, this would allow for smooth scrolling. If the user scrolls further, then I would reconstruct the image associated with the view so the new images are appended and the old one's are discarded. This image reconstruction business sounds bit complicated, so I was wondering if there's a more logical way to implement this. There's one more thing, I want to have two lines crossing each other with images, bit like conveyor belts crossing. If that makes any sense... Bit like below: V1 V2 H1 H2 H3 H4 H5 V4 V5 So if the vertical belt is moved it'd be like: V2 H3 H1 H2 V4 H4 H5 V5 V6 H1-H5, V1-V6 being automatically generated images. I'm not asking for the implementation code, just the thoughts on the principles how to implement this. Thanks!! :)

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• C Run-Time library part 2

  - by b-gen-jack-o-neill

  Hi, I was suggested when I have some further questions on my older ones, to create newer Question and reffer to old one. So, this is the original question: What is the C runtime library? OK, from your answers, I now get thet statically linked libraries are Microsoft implementation of C standart functions. Now: If I get it right, the scheme would be as follow: I want to use printf(), so I must include which just tels compiler there us functio printf() with these parameters. Now, when I compile code, becouse printf() is defined in C Standart Library, and becouse Microsoft decided to name it C Run Time library, it gets automatically statically linked from libcmt.lib (if libcmt.lib is set in compiler) at compile time. I ask, becouse on wikipedia, in article about runtime library there is that runtime library is linked in runtime, but .lib files are linked at compile time, am I right? Now, what confuses me. There is .dll version of C standart library. But I thought that to link .dll file, you must actually call winapi program to load that library. So, how can be these functions dynamically linked, if there is no static library to provide code to tell Windows to load desired functions from dll? And really last question on this subject - are C Standart library functions also calls to winapi even they are not .dll files like more advanced WinAPI functions? I mean, in the end to access framebuffer and print something you must tell Windows to do it, since OS cannot let you directly manipulate HW. I think of it like the OS must be written to support all C standart library functions same way across similiar versions, since they are statically linked, and can differently support more complex WinAPI calls becouse new version of OS can have adjustements in the .dll file.

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• Can I interrupt javascript code and then continue on a keystroke?

  - by Brian Ramsay

  I am porting an old game from C to Javascript. I have run into an issue with display code where I would like to have the main game code call display methods without having to worry about how those status messages are displayed. In the original code, if the message is too long, the program just waits for the player to toggle through the messages with the spacebar and then continues. This doesn't work in javascript, because while I wait for an event, all of the other program code continues. I had thought to use a callback so that further code can execute when the player hits the designated key, but I can't see how that will be viable with a lot of calls to display.update(msg) scattered throughout the code. Can I architect things differently so the event-based, asynchronous model works, or is there some other solution that would allow me to implement a more traditional event loop? Am I making sense? Example: // this is what the original code does, but obviously doesn't work in Javascript display = { update : function(msg) { // if msg is too long // wait for user input // ok, we've got input, continue } }; // this is more javascript-y... display = { update : function(msg, when_finished) { // show part of the message $(document).addEvent('keydown', function(e) { // display the rest of the message when_finished(); }); } }; // but makes for amazingly nasty game code do_something(param, function() { // in case do_something calls display I have to // provide a callback for everything afterwards // this happens next, but what if do_the_next_thing needs to call display? // I have to wait again do_the_next_thing(param, function() { // now I have to do this again, ad infinitum } }

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• Getting a nicely formatted timestamp without lots of overhead?

  - by Brad Hein

  In my app I have a textView which contains real-time messages from my app, as things happen, messages get printed to this text box. Each message is time-stamped with HH:MM:SS. Up to now, I had also been chasing what seemed to be a memory leak, but as it turns out, it's just my time-stamp formatting method (see below), It apparently produces thousands of objects that later get gc'd. For 1-10 messages per second, I was seeing 500k-2MB of garbage collected every second by the GC while this method was in place. After removing it, no more garbage problem (its back to a nice interval of about 30 seconds, and only a few k of junk typically) So I'm looking for a new, more lightweight method for producing a HH:MM:SS timestamp string :) Old code: /** * Returns a string containing the current time stamp. * @return - a string. */ public static String currentTimeStamp() { String ret = ""; Date d = new Date(); SimpleDateFormat timeStampFormatter = new SimpleDateFormat("hh:mm:ss"); ret = timeStampFormatter.format(d); return ret; }

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• How does the socket API accept() function work?

  - by Eli Bendersky

  The socket API is the de-facto standard for TCP/IP and UDP/IP communications (that is, networking code as we know it). However, one of its core functions, accept() is a bit magical. To borrow a semi-formal definition: accept() is used on the server side. It accepts a received incoming attempt to create a new TCP connection from the remote client, and creates a new socket associated with the socket address pair of this connection. In other words, accept returns a new socket through which the server can communicate with the newly connected client. The old socket (on which accept was called) stays open, on the same port, listening for new connections. How does accept work? How is it implemented? There's a lot of confusion on this topic. Many people claim accept opens a new port and you communicate with the client through it. But this obviously isn't true, as no new port is opened. You actually can communicate through the same port with different clients, but how? When several threads call recv on the same port, how does the data know where to go? I guess it's something along the lines of the client's address being associated with a socket descriptor, and whenever data comes through recv it's routed to the correct socket, but I'm not sure. It'd be great to get a thorough explanation of the inner-workings of this mechanism.

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• How to hand-over a TCP listening socket with minimal downtime?

  - by Shtééf

  While this question is tagged EventMachine, generic BSD-socket solutions in any language are much appreciated too. Some background: I have an application listening on a TCP socket. It is started and shut down with a regular System V style init script. My problem is that it needs some time to start up before it is ready to service the TCP socket. It's not too long, perhaps only 5 seconds, but that's 5 seconds too long when a restart needs to be performed during a workday. It's also crucial that existing connections remain open and are finished normally. Reasons for a restart of the application are patches, upgrades, and the like. I unfortunately find myself in the position that, every once in a while, I need to do this kind of thing in production. The question: I'm looking for a way to do a neat hand-over of the TCP listening socket, from one process to another, and as a result get only a split second of downtime. I'd like existing connections / sockets to remain open and finish processing in the old process, while the new process starts servicing new connectinos. Is there some proven method of doing this using BSD-sockets? (Bonus points for an EventMachine solution.) Are there perhaps open-source libraries out there implementing this, that I can use as is, or use as a reference? (Again, non-Ruby and non-EventMachine solutions are appreciated too!)

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• How do I setup Linq to SQL and WCF

  - by Jisaak

  So I'm venturing out into the world of Linq and WCF web services and I can't seem to make the magic happen. I have a VERY basic WCF web service going and I can get my old SqlConnection calls to work and return a DataSet. But I can't/don't know how to get the Linq to SQL queries to work. I'm guessing it might be a permissions problem since I need to connect to the SQL Database with a specific set of credentials but I don't know how I can test if that is the issue. I've tried using both of these connection strings and neither seem to give me a different result. <add name="GeoDataConnectionString" connectionString="Data Source=SQLSERVER;Initial Catalog=GeoData;Integrated Security=True" providerName="System.Data.SqlClient" /> <add name="GeoDataConnectionString" connectionString="Data Source=SQLSERVER;Initial Catalog=GeoData;User ID=domain\userName; Password=blahblah; Trusted_Connection=true" providerName="System.Data.SqlClient" /> Here is the function in my service that does the query and I have the interface add the [OperationContract] public string GetCity(int cityId) { GeoDataContext db = new GeoDataContext(); var city = from c in db.Cities where c.CITY_ID == 30429 select c.DESCRIPTION; return city.ToString(); } The GeoData.dbml only has one simple table in it with a list of city id's and city names. I have also changed the "Serialization Mode" on the DataContext to "Unidirectional" which from what I've read needs to be done for WCF. When I run the service I get this as the return: SELECT [t0].[DESCRIPTION] FROM [dbo].[Cities] AS [t0] WHERE [t0].[CITY_ID] = @p0 Dang, so as I'm writing this I realize that maybe my query is all messed up?

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