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  • Single-player pong game

    - by Jam
    I am just starting out learning pygame and livewires, and I'm trying to make a single-player pong game, where you just hit the ball, and it bounces around until it passes your paddle (located on the left side of the screen and controlled by the mouse), which makes you lose. However, I keep getting the error: "Cannot have more than on Screen object", which I can find no references to online really, and I can't make sense of it. I want to eventually make the game more complicated, but I need to make it work first. Help please! Here's the code so far: from livewires import games games.init(screen_width=640, screen_height=480, fps=50) class Paddle(games.Sprite): image=games.load_image("paddle.bmp") def __init__(self): super(Paddle, self).__init__(image=Paddle.image, y=games.mouse.y, left=0) self.score=games.Text(value=0, size=25, top=5, right=games.screen.width-10) games.screen.add(self.score) def update(self): self.y=games.mouse.y self.check_collide() def check_collide(self): for ball in self.overlapping_sprites: self.score.value+=1 self.score.right=games.screen.width-10 ball.handle_collide() class Ball(games.Sprite): image=games.load_image("ball.bmp") speed=1 def __init__(self, x, y=90): super(Ball, self).__init__(image=Ball.image, x=x, y=y, dx=Ball.speed, dy=Ball.speed) def update(self): if self.left<0: self.end_game() self.destroy() def handle_collide(self): if self.right>games.screen.width: self.dx=-self.dx if self.bottom>games.screen.height or self.top<0: self.dy=-self.dy def ball_destroy(self): self.destroy() def main(): background_image=games.load_image("background.bmp", transparent=False) games.screen.background=background_image the_ball=Ball() games.screen.add(the_ball) the_paddle=Paddle() games.screen.add(the_paddle) games.mouse.is_visible=False games.screen.event_grab=True games.screen.mainloop() main()

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  • 3D Web Sites and Applications

    - by Scott Evernden
    I have for the last several years been struggling to understand why the Internet has so few actually useful 3D web applications. It's 2009 and still everything looks like pages from a Sears catalog. You can turn on your TV and find flying logos every night. After that you can get nostalgic and flip on ol' N-64 and play some Zelda or Mario Kart. On the PC, Sims 2 is approaching 6 years old already.. And then there's WoW. Current generation of users - the Facebook crowd, let's say - has ~no~ problem dealing with multi-dimensional environments.. And yet, nothing really immersive seems to happen on the web. I've been hearing about VRML and X3D for at least 10 years and ... pffft .. - nothing earth shaking going on there. Java 3D ? .. cool ! .. but ...... Still .... waiting and waiting. Do you think it will take a killer-web app before people become accustomed-to or will seek to use what could more more engaging web experiences? I am not talking about Second Life and other dedicated downloaded applications. I probably am more focused on apps like Lively or SceneCaster or Hangout or a half dozen others that are delivered 'painlessly' directly into web pages. My own particular interest is in the domain of virtual stores and immersive shopping. Its been a challenge trying to understand why an average user would not want to browse and wander a changing mall-space - like in the real world -- entertained by unexpected discovery. Is the 3D web always going to be 5 years in the future ?

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  • java distributed cache for low latency, high availability

    - by Shahbaz
    I've never used distributed caches/DHTs like memcached, jboss cache, ehcache, etc. I'm wondering which, if any, is appropriate for my use. First, I'm not doing web applications (as most of these project seem to be geared towards web apps). I write servers (Order Management Systems actually) for financial trading firms. The servers themselves are not too complicated. They need to receive information (market data, orders, executions, etc.) rout them to their destination while possibly transforming some of these messages. I am looking at these products to solve the following problems: * Safe repository of the state of the server. I'd rather build the logic of my application as a bunch of transformers (similar to Apache Camel) and store the state in a 'safe' place * This repository should be distributed: in case one of these data stores crashes, one or two more should be up and I should be able to switch to them seamlessly * This repository should be fast. Single digits milliseconds count here, in other words, systems which consume/process this data are automated systems, not humans clicking on links. This system needs to have high-throughput and low latency. By sending my data outside the process, I am necessarily slowing performance, but I am trying to balance absolute raw speed and absolute protection of data. * This repository should be safe. Similar to the point about several on-line backups, this system needs to write data to disk (potentially more than one disk). I'd really like to stop writing my own 'transaction servers.' Am I correct to be looking into projects such as jboss cache, ehcache, etc.? Thanks

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  • C# PInvoke VerQueryValue returns back OutOfMemoryException?

    - by Bopha
    Hi, Below is the code sample which I got from online resource but it's suppose to work with fullframework, but when I try to build it using C# smart device, it throws exception saying it's out of memory. Does anybody know how can I fix it to use on compact? the out of memory exception when I make the second call to VerQueryValue which is the last one. thanks, [DllImport("coredll.dll")] public static extern bool VerQueryValue(byte[] buffer, string subblock, out IntPtr blockbuffer, out uint len); [DllImport("coredll.dll")] public static extern bool VerQueryValue(byte[] pBlock, string pSubBlock, out string pValue, out uint len); // private static void GetAssemblyVersion() { string filename = @"\Windows\MyLibrary.dll"; if (File.Exists(filename)) { try { int handle = 0; Int32 size = 0; size = GetFileVersionInfoSize(filename, out handle); if (size > 0) { bool retValue; byte[] buffer = new byte[size]; retValue = GetFileVersionInfo(filename, handle, size, buffer); if (retValue == true) { bool success = false; IntPtr blockbuffer = IntPtr.Zero; uint len = 0; //success = VerQueryValue(buffer, "\\", out blockbuffer, out len); success = VerQueryValue(buffer, @"\VarFileInfo\Translation", out blockbuffer, out len); if(success) { int p = (int)blockbuffer; //Reads a 16-bit signed integer from unmanaged memory int j = Marshal.ReadInt16((IntPtr)p); p += 2; //Reads a 16-bit signed integer from unmanaged memory int k = Marshal.ReadInt16((IntPtr)p); string sb = string.Format("{0:X4}{1:X4}", j, k); string spv = @"\StringFileInfo\" + sb + @"\ProductVersion"; string versionInfo; VerQueryValue(buffer, spv, out versionInfo, out len); } } } } catch (Exception err) { string error = err.Message; } } }

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  • How are you taking advantage of Multicore?

    - by tgamblin
    As someone in the world of HPC who came from the world of enterprise web development, I'm always curious to see how developers back in the "real world" are taking advantage of parallel computing. This is much more relevant now that all chips are going multicore, and it'll be even more relevant when there are thousands of cores on a chip instead of just a few. My questions are: How does this affect your software roadmap? I'm particularly interested in real stories about how multicore is affecting different software domains, so specify what kind of development you do in your answer (e.g. server side, client-side apps, scientific computing, etc). What are you doing with your existing code to take advantage of multicore machines, and what challenges have you faced? Are you using OpenMP, Erlang, Haskell, CUDA, TBB, UPC or something else? What do you plan to do as concurrency levels continue to increase, and how will you deal with hundreds or thousands of cores? If your domain doesn't easily benefit from parallel computation, then explaining why is interesting, too. Finally, I've framed this as a multicore question, but feel free to talk about other types of parallel computing. If you're porting part of your app to use MapReduce, or if MPI on large clusters is the paradigm for you, then definitely mention that, too. Update: If you do answer #5, mention whether you think things will change if there get to be more cores (100, 1000, etc) than you can feed with available memory bandwidth (seeing as how bandwidth is getting smaller and smaller per core). Can you still use the remaining cores for your application?

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  • Having trouble with extension methods for byte arrays

    - by Dave
    I'm working with a device that sends back an image, and when I request an image, there is some undocumented information that comes before the image data. I was only able to realize this by looking through the binary data and identifying the image header information inside. I've been able to make everything work fine by writing a method that takes a byte[] and returns another byte[] with all of this preamble "stuff" removed. However, what I really want is an extension method so I can write image_buffer.RemoveUpToByteArray(new byte[] { 0x42, 0x4D }); instead of byte[] new_buffer = RemoveUpToByteArray( image_buffer, new byte[] { 0x42, 0x4D }); I first tried to write it like everywhere else I've seen online: public static class MyExtensionMethods { public static void RemoveUpToByteArray(this byte[] buffer, byte[] header) { ... } } but then I get an error complaining that there isn't an extension method where the first parameter is a System.Array. Weird, everyone else seems to do it this way, but okay: public static class MyExtensionMethods { public static void RemoveUpToByteArray(this Array buffer, byte[] header) { ... } } Great, that takes now, but still doesn't compile. It doesn't compile because Array is an abstract class and my existing code that gets called after calling RemoveUpToByteArray used to work on byte arrays. I could rewrite my subsequent code to work with Array, but I am curious -- what am I doing wrong that prevents me from just using byte[] as the first parameter in my extension method?

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  • How do you word wrap a RichTextField for Blackberry

    - by Kai
    I've been trying to modify a rich text field to display correctly in its half of the horizontal field. The goal is this: --------------------------- | address is | ***********| | very long | ** IMAGE **| | state, zip | ***********| --------------------------- Where address is a single string separate from the city and zip. I am modifying the address field like this: RichTextField addrField = new RichTextField(address) { public int getPreferredWidth() { return 200; } protected void layout(int maxWidth,int maxHeight) { super.layout(getPreferredWidth(),maxHeight); setExtent(getPreferredWidth(), getHeight()); } }; The results look like this: ----------------------------- | address is ve| ***********| | state, zip | ** IMAGE **| | | ***********| ----------------------------- where clearly the address is just going under the image. Both horizontal fields are static 200 pixels wide. It's not like the system wouldn't know where to wrap the address. However, I have heard it is not easy to do this and is not done automatically. I have had no success finding a direct answer online. I have found people saying you need to do it in a custom layout manager, some refer to the RichTextField API, which is of no use. But nobody actually mentions how to do it. I understand that I may need to read character by character and set where the line breaks should happen. What I don't know is how exactly to do any of this. You can't just count characters and assume each is worth 5 pixels, and you shouldn't have to. Surely there must be some way to achieve this in a way that makes sense. Any suggestions?

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  • iPhone app: How to implement in-app purchased game levels

    - by Wonderflonium
    So, I understand that it's possible to set up in-app purchases for iPhone apps to purchase non-consumables like game levels. I understand the logic behind the purchase part, but what I don't understand is, how can I deliver the new game level. For example: I build an app that contains the first level and they purchase additional levels. Is it better to build all the other levels into the app and whenever they purchase the app, it unlocks it with a plist entry or something? That doesn't seem very update-able to me. Every time I come up with a new level, I'd have to update the app. So, what I don't understand then, is what is how do I package up a level and download it as a separate entity that can accessed by the game? Would the level just be some XML with images in a ZIP folder or something? How does the level get added to the game? What are best practices for this type of thing? I Googled and have found NOTHING about this. I'm a little bit confused by the concept and any help would be appreciated. I'm not looking for someone to write the game for me, I just need pointed in the right direction so I can develop it on my own.

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  • Auto switching databases from a rails app gracefully from the ApplicationController?

    - by Zaqintosh
    I've seen this post a few times, but haven't really found the answer to this specific question. I'd like to run a rails application that based on the detected request.host (imagine I have two subdomains points to the same rails app and server ip address: myapp1.domain.com and myapp2.domain.com). I'm trying to have myapp1 use the default "production" database, and myapp2 requests always use the alternative remote database. Here is an example of what I tried to do in Application controller that did not work: class ApplicationController < ActionController::Base helper :all before_filter :use_alternate_db private def use_alternate_db if request.host == 'myapp1.domain.com' regular_db elsif request.host == 'myapp2.domain.com' alternate_db end end def regular_db ActiveRecord::Base.establish_connection :production end def alternate_db ActiveRecord::Base.establish_connection( :adapter => 'mysql', :host => '...', :username => '...', :password => '...', :database => 'alternatedb' ) end end The problem is when it switches databases using this method, all connections (including valid sessions across the different subdomains get interrupted...). All examples online have people controlling database connectivity at the model level, but this would involve adding code all over my application. Is there some way to globally switch database connections on a per-request basis in the manner I'm suggesting above WITHOUT having to inject code all over my application? The added complexity here is I'm using Heroku as a hosting provider, so I have no control at the apache / rails application server level. I have looked at solutions like dbcharmer and magicmodels, but none seem to show examples of doing it in the manner that I'm trying to. Thanks for any help!

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  • Multiple Out-of-Browser Applications in One Application

    - by Otaku
    I'm looking at a scenario where I need to create a single "master" Silverlight application and then add "child" applications for an out-of-browser Silverlight application. The scenario is something like this. A user will visit a gameboard web site and choose a game to play. Let's call it Checkers. He likes it, so then he installs the out-of-browser app to his desktop. He then finds Chess, and installs that too. For both games, while played on the site, he has stats (games played, win/loss records, etc.). For each game on the site, he navigates to a different page. But now he wants to play offline and view his stats and other cross-games information. He wants to have a single app to launch to play either game. From his single out-of-browser app, he sees that Go is also available, and he places a checkmark against it to download on his next connection. Does anyone have any experience at developing multiple out-of-browser Silverlight apps that reside within a single master app? What considerations need to be had for this type of design? How would this work in terms of install experience from different web pages?

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  • Any way to identify a redirect when using jQuery's $.ajax() or $.getScript() methods?

    - by Bungle
    Within my company's online application, we've set up a JSONP-based API that returns some data that is used by a bookmarklet I'm developing. Here is a quick test page I set up that hits the API URL using jQuery's $.ajax() method: http://troy.onespot.com/static/3915/index.html If you look at the requests using Firebug's "Net" tab (or the like), you'll see that what's happening is that the URL is requested successfully, but since our app redirects any unauthorized users to a login page, the login page is also requested by the browser and seemingly interpreted as JavaScript. This inevitably causes an exception since the login page is HTML, not JavaScript. Basically, I'm looking for any sort of hook to determine when the request results in a redirect - some way to determine if the URL resolved to a JSONP response (which will execute a method I've predefined in the bookmarklet script) or if it resulted in a redirect. I tried wrapping the $.ajax() method in a try {} catch(e) {} block, but that doesn't trap the exception, I'm assuming because the requests were successful, just not the parsing of the login page as JavaScript. Is there anywhere I could use a try {} catch(e) {} block, or any property of $.ajax() that might allow me to hone in on the exception or otherwise determine that I've been redirected? I actually doubt this is possible, since $.getScript() (or the equivalent setup of $.ajax()) just loads a script dynamically, and can't inspect the response headers since it's cross-domain and not truly AJAX: http://api.jquery.com/jQuery.getScript/ My alternative would be to just fire off the $.ajax() for a period of time until I either get the JSONP callback or don't, and in the latter case, assume the user is not logged in and prompt them to do so. I don't like that method, though, since it would result in a lot of unnecessary requests to the app server, and would also pile up the JavaScript exceptions in the meantime. Thanks for any suggestions!

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  • iPhone SQLite Password Field Encryption

    - by Louis Russell
    Good Afternoon Guys and Girls, Hopefully this will be a quick and easy question. I am building an App that requires the user to input their login details for an online service that it links to. Multiple login details can be added and saved as the user may have several accounts that they would like to switch between. These details will be stored in an SQLite database and will contain their passwords. Now the questions are: 1: Should these passwords be encrypted in the database? My instinct would say yes but then I do not know how secure the device and system is and if this is necessary. 2: If they should be encrypted what should I use? I think encrypting the whole database file sounds a bit over-kill so should I just encrypt the password before saving it to the database? If this is case what could I use to achieve this? I have found reference to a "crypt(3)" but am having trouble finding much about it or how to implement it. I eagerly await your replies!

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  • Google Contacts Error: If-Match or If-None-Match header or entry etag attribute required

    - by Ali
    Hi guys I'm following the example code as defined on this website: http://www.ibm.com/developerworks/opensource/library/x-phpgooglecontact/index.html I want to be able to integrate with my google apps account and play around with teh contacts. However I get this error whenever I try to run the modify contacts code: If-Match or If-None-Match header or entry etag attribute required This is my code: Zend_Loader::loadClass('Zend_Gdata_ClientLogin'); Zend_Loader::loadClass('Zend_Http_Client'); Zend_Loader::loadClass('Zend_Gdata_Query'); Zend_Loader::loadClass('Zend_Gdata_Feed'); $client = getGoogleClient('cp'); // this is a function I made - its working fine $client->setHeaders('If-Match: *'); $gdata = new Zend_Gdata($client); $gdata->setMajorProtocolVersion(3); $query = new Zend_Gdata_Query($id);// id is the google reference $entry = $gdata->getEntry($query); $xml = simplexml_load_string($entry->getXML()); $xml->name->fullName = trim($contact->first_name).' '.trim($contact->last_name); $entryResult = $gdata->updateEntry($xml->saveXML(), $id);

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  • What Algorithm will Find New Longtail Keywords for *keyword* in PPC

    - by Becci
    I am looking for the algorithm (or combo) that would allow someone to find new longtail PPC search phrases based on say one corekeyword. Eg #1 word word corekeyword eg #2 word corekeyword word Google search tool allows a limited number vertically - mostly of eg#1 (https://adwords.google.com.au/select/KeywordToolExternal) I also know of other PPC apps that allow more volume than google adwords keyword tool, But I want to find other combos that mention the corekeyword & then naturally sort for the highest volume searched. Working example of exact match: corekeyword: copywriter (40,500 searches a month) google will serve up: become a copywriter (480 searches globally/month in english) But if I specifically look up: How to become a copywriter (720 searches a month) This exact longtail keyword phrase has 300 more searches than the 3 word version spat out by google. I want the algorithm to find any other highly search exact longtials like: how to become a copywriter Simply because it was save significant $ finding other longtail keywords after your campaign has been running an made google lots of money. I don't want a concantenation algorithm (I already have one of those), because hypothetically, I don't know what keywords will be that I want to find. Any gurus out there? Becci

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  • Using the MVVM Light Toolkit to make Blendable applications

    - by Dave
    A while ago, I posted a question regarding switching between a Blend-authored GUI and a Visual Studio-authored one. I got it to work okay by adding my Blend project to my VS2008 project and then changing the Startup Application and recompiling. This would result in two applications that had completely different GUIs, yet used the exact same ViewModel and Model code. I was pretty happy with that. Now that I've learned about the Laurent Bugnion's MVVM Light Toolkit, I would really like to leverage his efforts to make this process of supporting multiple GUIs for the same backend code possible. The question is, does the toolkit facilate this, or am I stuck doing it my previous way? I've watched his video from MIX10 and have read some of the articles about it online. However, I've yet to see something that indicates that there is a clean way to allow a user to either dynamically switch GUIs on the fly by loading a different DLL. There are MVVM templates for VS2008 and Blend 3, but am I supposed to create both types of projects for my application and then reference specific files from my VS2008 solution? UPDATE I re-read some information on Laurent's site, and seemed to have forgotten that the whole point of the template was to allow the same solution to be opened in VS2008 and Blend. So anyhow, with this new perspective it looks like the templates are actually intended to use a single GUI, most likely designed entirely in Blend (with the convenience of debugging through VS2008), and then be able to use two different ViewModels -- one for design-time, and one for runtime. So it seems to me like the answer to my question is that I want to use a combination of my previous solution, along with the MVVM Light Toolkit. The former will allow me to make multiple, distinct GUIs around my core code, while the latter will make designing fancy GUIs in Blend easier with the usage of a design-time ViewModel. Can anyone comment on this?

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  • adding stock data to amibroker using c#

    - by femi
    hello, I have had a hard time getting and answer to this and i would really , really appreciate some help on this. i have been on this for over 2 weeks without headway. i want to use c# to add a line of stock data to amibroker but i just cant find a CLEAR response on how to instantiate it in C#. In VB , I would do it something like; Dim AmiBroker = CreateObject("Broker.Application") sSymbol = ArrayRow(0).ToUpper Stock = AmiBroker.Stocks.Add(sSymbol) iDate = ArrayRow(1).ToLower quote = Stock.Quotations.Add(iDate) quote.Open = CSng(ArrayRow(2)) quote.High = CSng(ArrayRow(3)) quote.Low = CSng(ArrayRow(4)) quote.Close = CSng(ArrayRow(5)) quote.Volume = CLng(ArrayRow(6)) The problem is that CreateObject will not work in C# in this instance. I found the code below somewhere online but i cant seem to understand how to achieve the above. Type objClassType; objClassType = Type.GetTypeFromProgID("Broker.Application"); // Instantiate AmiBroker objApp = Activator.CreateInstance(objClassType); objStocks = objApp.GetType().InvokeMember("Stocks", BindingFlags.GetProperty,null, objApp, null); Can anyone help me here? Thanks

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  • Learning about the low level

    - by Anoners
    I'm interested in learning more about the PC from a lower (machine) level. I graduated from a school which taught us concepts using the Java language which abstracted out that level almost completely. As a result I only learned a bit from the one required assembly language course. In order to cram in ASM and quite a few details about architecture, it was hard to get a very deep picture of what is going on there. At work I focus on unix socket programming in C, so i'm much closer to the hardware now, but I feel I should learn a bit more about what streams really are, how memory management and paging works, what goes on when you call "paint()" on a graphics buffer, etc. I missed out on a lot of this and i'm looking for a good resource to get me started. I've heard a lot about the "Pink Book" by Peter Norton (Programmer's Guide to the IBM PC, Programmer's Guide to inside the PC, etc). It seems like this is on the right track, however the original is quite out dated and the newer ones have had conflicting reviews, with many people saying to stay away from it. I'm not sure what the SO crowd thinks about this book or if they have some suggestions for similar books, online resources, etc that may be good primers for this sort of thing. Any suggestions would be appreciated.

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  • Preventing Processes From Spawning Using .NET Code

    - by Matt
    I remember coming across an article on I think CodeProject quite some time ago regarding an antivirus or antimalware some guy was writing where he hooked into the Windows API to be able to catch whenever a new process was started and was prompting he user before allowing the process to start. I can no longer find the article, and would actually like to be able to implement something like this. Currently, we have a custom browser built on Gecko that we've integrated access restrictions to sites based on our internal employee security levels, etc. We prevent any other browser from running with a timer and a call to Process.GetProcessesByName() from a list of the browsers we don't allow. What we want to accomplish is, instead of just blocking these browsers, where there is a small delay between the other browser starting and it being killed by our service, we'd like to be able to display a dialog instead of the process launching at all, explaining that the program isn't in the allowed list. This way, we can generate a list of "allowed" processes and just block everything else (we haven't yet had a problem with outside apps being installed, but you can never be too careful). Unfortunately, we don't do much Windows API programming from C#, so I'm not sure where to begin looking for what calls we need to hook. Even just a starting point of what to read up on would be helpful.

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  • C# TCP Async EndReceive() throws InvalidOperationException ONLY on Windows XP 32-bit

    - by James Farmer
    I have a simple C# Async Client using a .NET socket that waits for timed messages from a local Java server used for automating commands. The messages come in asynchronously and is written to a ring buffer. This implementation seems to work fine on Windows Vista/7/8 and OSX, but will randomly throw this exception while it's receiving a message from the local Java server: Unhandled Exception: System.InvalidOperationException: EndReceive can only be called once for each asynchronous operation.     at System.Net.Sockets.Socket.EndReceive(IAsyncResult asyncResult, SocketError& errorCode)     at System.Net.Sockets.Socket.EndReceive(IAsyncResult asyncResult)     at SocketTest.Controller.RecvAsyncCallback(IAsyncResult ar)     at System.Net.LazyAsyncResult.Complete(IntPtr userToken)     ... I've looked online for this error, but have found nothing really helpful. This is the code where it seems to break: /// <summary> /// Callback to receive socket data /// </summary> /// <param name="ar">AsyncResult to pass to End</param> private void RecvAsyncCallback(IAsyncResult ar) { // The exception will randomly happen on this call int bytes = _socket.EndReceive(_recvAsyncResult); // check for connection closed if (bytes == 0) { return; } _ringBuffer.Write(_buffer, 0, bytes); // Checks buffer CheckBuffer(); _recvAsyncResult = _sock.BeginReceive(_buffer, 0, _buffer.Length, SocketFlags.None, RecvAsyncCallback, null); } The error doesn't happen on any particular moment except in the middle of receiving a message. The message itself can be any length for this to happen, and the exception can happen right away, or sometimes even up to a minute of perfect communication. I'm pretty new with sockets and network communication, and I feel I might be missing something here. I've tested on at least 8 different computers, and the only similarity with the computers that throw this exception is that their OS is Windows XP 32-bit.

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  • BackgroundWorker From ASP.Net Application

    - by Kevin
    We have an ASP.Net application that provides administrators to work with and perform operations on large sets of records. For example, we have a "Polish Data" task that an administrator can perform to clean up data for a record (e.g. reformat phone numbers, social security numbers, etc.) When performed on a small number of records, the task completes relatively quickly. However, when a user performs the task on a larger set of records, the task may take several minutes or longer to complete. So, we want to implement these kinds of tasks using some kind of asynchronous pattern. For example, we want to be able to launch the task, and then use AJAX polling to provide a progress bar and status information. I have been looking into using the BackgroundWorker class, but I have read some things online that make me pause. I would love to get some additional advice on this. For example, I understand that the BackgroundWorker will actually use the thread pool from the current application. In my case, the application is an ASP.Net web site. I have read that this can be a problem because when the application recycles, the background workers will be terminated. Some of the jobs I mentioned above may take 3 minutes, but others may take a few hours. Also, we may have several hundred administrators all performing similar operations during the day. Will the ASP.Net application thread pool be able to handle all of these background jobs efficiently while still performing it's normal request processing? So, I am trying to determine if using the BackgroundWorker class and approach is right for our needs. Should I be looking at an alternative approach? Thanks and sorry for such a long post! Kevin

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  • Can a single developer still make money with shareware?

    - by Wouter van Nifterick
    I'm wondering if the shareware concept is dead nowadays. Like most developers, I've built up quite a collection of self-made tools and code libraries that help me to be productive. Some examples to give you an idea of the type of thing I'm talking about: A self-learning program that renames and orders all my mp3 files and adds information to the id3 tags; A Delphi component that wraps the Google Maps API; A text-to-singing-voice converter for musical purposes; A program to control a music synthesizer; A Gps-log <- KML <- ESRI-shapefile converter; I've got one of these already freely downloadable on my website, and on average it gets downloaded about a 150 times per month. Let's say I'd start charging 15 euro's for it; would there actually be people who buy it? How many? What would it depend on? If I could get some money for some of these, I'd finish them up a bit and put them online, but without that, I probably won't bother. Maintaining a SourceForge project is not very rewarding by itself. Is there anyone who is making money with shareware? How much? Any tips?

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  • Can I use RegFree Com with an application written in Excel VBA?

    - by Steven
    I have an application that is written in Excel VBA, myApp.xls. Currently we use InstallShield to distribute the application. Since we are moving to Windows Vista, I need to be able to install the application as a standard user. This does not allow for me to update the registry during the install process. In addition to the excel application we also have several VB6 applications. In order to install those applications, I was able to use RegFree com and Make My Manifest (MMM) as suggested by people on this forum (I greatly appreciate the insight btw!). This process, although a bit tedious, worked well. I then packaged the output from MMM in a VS '05 installer project and removed the UAC prompt on the msi using msiinfo.exe. Now I am faced with installing an application that basically lives in an Excel file. I modified a manifest that MMM created for me for one of my VB6 apps and tried to run the excel file through that, but I did not have much luck. Does anybody know of a way to do this? Does RegFree com work with VBA? Any thoughts or suggestions would be much appreciated. Thanks, Steve

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  • Pros and cons of making database IDs consistent and "readable"

    - by gmale
    Question Is it a good rule of thumb for database IDs to be "meaningless?" Conversely, are there significant benefits from having IDs structured in a way where they can be recognized at a glance? What are the pros and cons? Background I just had a debate with my coworkers about the consistency of the IDs in our database. We have a data-driven application that leverages spring so that we rarely ever have to change code. That means, if there's a problem, a data change is usually the solution. My argument was that by making IDs consistent and readable, we save ourselves significant time and headaches, long term. Once the IDs are set, they don't have to change often and if done right, future changes won't be difficult. My coworkers position was that IDs should never matter. Encoding information into the ID violates DB design policies and keeping them orderly requires extra work that, "we don't have time for." I can't find anything online to support either position. So I'm turning to all the gurus here at SA! Example Imagine this simplified list of database records representing food in a grocery store, the first set represents data that has meaning encoded in the IDs, while the second does not: ID's with meaning: Type 1 Fruit 2 Veggie Product 101 Apple 102 Banana 103 Orange 201 Lettuce 202 Onion 203 Carrot Location 41 Aisle four top shelf 42 Aisle four bottom shelf 51 Aisle five top shelf 52 Aisle five bottom shelf ProductLocation 10141 Apple on aisle four top shelf 10241 Banana on aisle four top shelf //just by reading the ids, it's easy to recongnize that these are both Fruit on Aisle 4 ID's without meaning: Type 1 Fruit 2 Veggie Product 1 Apple 2 Banana 3 Orange 4 Lettuce 5 Onion 6 Carrot Location 1 Aisle four top shelf 2 Aisle four bottom shelf 3 Aisle five top shelf 4 Aisle five bottom shelf ProductLocation 1 Apple on aisle four top shelf 2 Banana on aisle four top shelf //given the IDs, it's harder to see that these are both fruit on aisle 4 Summary What are the pros and cons of keeping IDs readable and consistent? Which approach do you generally prefer and why? Is there an accepted industry best-practice?

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  • Multiplication algorithm for abritrary precision (bignum) integers.

    - by nn
    Hi, I'm writing a small bignum library for a homework project. I am to implement Karatsuba multiplication, but before that I would like to write a naive multiplication routine. I'm following a guide written by Paul Zimmerman titled "Modern Computer Arithmetic" which is freely available online. On page 4, there is a description of an algorithm titled BasecaseMultiply which performs gradeschool multiplication. I understand step 2, 3, where B^j is a digit shift of 1, j times. But I don't understand step 1 and 3, where we have A*b_j. How is this multiplication meant to be carried out if the bignum multiplication hasn't been defined yet? Would the operation "*" in this algorithm just be the repeated addition method? Here is the parts I have written thus far. I have unit tested them so they appear to be correct for the most part: The structure I use for my bignum is as follows: #define BIGNUM_DIGITS 2048 typedef uint32_t u_hw; // halfword typedef uint64_t u_w; // word typedef struct { unsigned int sign; // 0 or 1 unsigned int n_digits; u_hw digits[BIGNUM_DIGITS]; } bn; Currently available routines: bn *bn_add(bn *a, bn *b); // returns a+b as a newly allocated bn void bn_lshift(bn *b, int d); // shifts d digits to the left, retains sign int bn_cmp(bn *a, bn *b); // returns 1 if a>b, 0 if a=b, -1 if a<b

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  • Comet Jetty/Tomcat, having some browser issues with Firefox and Chrome

    - by ages04
    I am exploring the use of Comet for a project I am working on. I tried creating a test application first using Tomcat6 and CometProcessor API and then with Jetty7 Continuations. The application is kind of working on both but I am having some issues with the actual display of messages. I used the technique of creating an XMLHttpRequest Connection and keeping it open all the time so the server can continuously push data to all the clients connected whenever it is available. My client side code is something similar to this: function fn(){ var xhr = new XMLHttpRequest(); xhr.onreadystatechange = function(){ if (xhr.readyState==3){ document.getElementById('dv').innerHTML =(xhr.responseText); } if (xhr.readyState==4){ alert ('done'); } } xhr.open("GET", "First", true); xhr.send(null); } I found this thing of using readyState 3 somewhere online. I am facing 2 problems currently: In Firefox this code works perfectly. But if I open a new tab or even a new browser window, it does not make a new connection to the server and nothing shows up on the new tab or window, only the first tab/window gets the display. I used wireshark to check this and its shows only 1 connection even after the 2nd tab is opened. I am unable to understand why this would happen. I have read about the 2 connection limit, but here there is only one connection. Secondly in Chrome, the above code does not work, and the callback is not invoked for readystate of 3, only when the connection is closed by the server i get the output. I would also like to ask which is the best way/framework for doing Comet with Java. I am currently using jQuery on the client side. Any suggestions would be greatly appreciated!! Thanks

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