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• How do I make a web interface for a socket server

  - by mgroat

  I've got a socket server running (it's something that's basically like a chat server). Users can telnet into it, but I'd like to make a web interface. This is the first time I've ever done something like this, so I'm not really sure where to start. A few thoughts I've had: Have some server-side Python (or PHP) on my webserver, which accesses the socket server. I think I know enough about sockets to have Python interact with the server, but how do I go about getting the website that the user sees to update in real time? Should I just have the website refresh few seconds? I would prefer to do things this way if I can figure out how. Write a Java applet that interacts with the socket server, and embed the applet in the website. I would have to re-learn a language that I haven't touched in years, but my main goal here is learning -- so that wouldn't be such a bad thing. The main problem I have with this is that it requires end users to have Java installed on their computers, which I'd rather not do. Is one of these two solutions the right way to go? Anybody know where I can find a good tutorial to get started? Edit: There's no real security concerns with exposing the server to the internet.

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• Difference in regex between Python and Rubular?

  - by Rosarch

  In Rubular, I have created a regular expression: (Prerequisite|Recommended): (\w|-| )* It matches the bolded: Recommended: good comfort level with computers and some of the arts. Summer. 2 credits. Prerequisite: pre-freshman standing or permission of instructor. Credit may not be applied toward engineering degree. S-U grades only. Here is a use of the regex in Python: note_re = re.compile(r'(Prerequisite|Recommended): (\w|-| )*', re.IGNORECASE) def prereqs_of_note(note): match = note_re.match(note) if not match: return None return match.group(0) Unfortunately, the code returns None instead of a match: >>> import prereqs >>> result = prereqs.prereqs_of_note("Summer. 2 credits. Prerequisite: pre-fres hman standing or permission of instructor. Credit may not be applied toward engi neering degree. S-U grades only.") >>> print result None What am I doing wrong here?

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• Python, Ruby, and C#: Use cases?

  - by thaorius

  Hi everyone. For as long as I can remember, I've always had a "favorite" language, which I use for most projects, until, for some particular reason, there is no way/point on using it for project XYZ. At that point, I find myself rusty (and sometimes outdated) on other languages+libraries+toolchains. So I decided, I would just use some languages/libs/tools for some things, and some for other, effectively keeping them fresh (there would obviously be exceptions, I'm not looking for an arbitrary rule set, but some guidelines). I wanted an opinion on what would be your standard use cases (new projects) for Python, Ruby, and C# (Mono). At the moment, I have time like this:Languages: C#: Mid-Large Sized Projects (mainly server-side daemons) High Performance (I hardly ever need C's performance, but Python just doesn't cut it) Relatively Low Footprint (vs the JVM, for example) Ruby: Web Applications Python: General Use Scripts (automation, system config, etc) Small-Mid Sized Projects Prototyping Web Applications About Ruby, I have no idea what to use it for that I can't use Python for (specially considering Python is more easily found installed by default). And I like both languages (though I'm really new to Ruby), which makes things even worse. As for C#, I have not used a Windows powered computer in a few years, I don't make things for Windows computers, and I don't mind waiting for Mono to implement some new features. That being said, I haven't found many people on the internet using it for server-sided *nix programming (not web related). I would appreciate some insight on this too. Thanks for your time.

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• Facebook IFrame Application issues for certain users

  - by Kon

  We have a strange issue with running an Facebook IFrame application (using MVC 2). When I run my app and log into Facebook, I get to the application just fine. But when my coworker does it, she gets the following error: API Error Code: 100 API Error Description: Invalid parameter Error Message: Requires valid next URL. Typically this error is resolved by updating the "New Data Permissions" setting of the Facebook application. However, in this case it doesn't help. We've also tried logging in with our accounts from different computers and it seems that neither computer nor which one the MVC ASP.NET app is running from matters. The only difference is who is logged into Facebook. We've looked at our Facebook account settings, but couldn't find any obvious differences. We both have Developer access to the FB application and we both can edit its settings. However, only one of us can actually run the application without getting the above mentioned error message. Any idea what could be happening here?

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• What makes people think that NNs have more computational power than existing models?

  - by Bubba88

  I've read in Wikipedia that neural-network functions defined on a field of arbitrary real/rational numbers (along with algorithmic schemas, and the speculative `transrecursive' models) have more computational power than the computers we use today. Of course it was a page of russian wikipedia (ru.wikipedia.org) and that may be not properly proven, but that's not the only source of such.. rumors Now, the thing that I really do not understand is: How can a string-rewriting machine (NNs are exactly string-rewriting machines just as Turing machines are; only programming language is different) be more powerful than a universally capable U-machine? Yes, the descriptive instrument is really different, but the fact is that any function of such class can be (easily or not) turned to be a legal Turing-machine. Am I wrong? Do I miss something important? What is the cause of people saying that? I do know that the fenomenum of undecidability is widely accepted today (though not consistently proven according to what I've read), but I do not really see a smallest chance of NNs being able to solve that particular problem. Add-in: Not consistently proven according to what I've read - I meant that you might want to take a look at A. Zenkin's (russian mathematician) papers after mid-90-s where he persuasively postulates the wrongness of G. Cantor's concepts, including transfinite sets, uncountable sets, diagonalization method (method used in the proof of undecidability by Turing) and maybe others. Even Goedel's incompletness theorems were proven in right way in only 21-st century.. That's all just to plug Zenkin's work to the post cause I don't know how widespread that knowledge is in CS community so forgive me if that did look stupid. Thank you!

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• Memorystream and Large Object Heap

  - by Flo

  I have to transfer large files between computers on via unreliable connections using WCF. Because I want to be able to resume the file and I don't want to be limited in my filesize by WCF, I am chunking the files into 1MB pieces. These "chunk" are transported as stream. Which works quite nice, so far. My steps are: open filestream read chunk from file into byet[] and create memorystream transfer chunk back to 2. until the whole file is sent My problem is in step 2. I assume that when I create a memory stream from a byte array, it will end up on the LOH and ultimately cause an outofmemory exception. I could not actually create this error, maybe I am wrong in my assumption. Now, I don't want to send the byte[] in the message, as WCF will tell me the array size is too big. I can change the max allowed array size and/or the size of my chunk, but I hope there is another solution. My actual question(s): Will my current solution create objects on the LOH and will that cause me problem? Is there a better way to solve this? Btw.: On the receiving side I simple read smaller chunks from the arriving stream and write them directly into the file, so no large byte arrays involved.

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• CORBA on MacOS X (Cocoa)

  - by user8472

  I am currently looking into different ways to support distributed model objects (i.e., a computational model that runs on several different computers) in a project that initially focuses on MacOS X (using Cocoa). As far as I know there is the possibility to use the class cluster around NSProxy. But there also seem to be implementations of CORBA around with Objective-C support. At a later time there may be the need to also support/include Windows machines. In that case I would need to use something like Gnustep on the Windows side (which may be an option, if it works well) or come up with a combination of both technologies. Or write something manually (which is, of course, the least desirable option). My questions are: If you have experience with both technologies (Cocoa native infrastructure vs. CORBA) can you point out some key features/issues of either approach? Is it possible to use Gnustep with Cocoa in the way explained above? Is it possible (and reasonably feasible, i.e. simpler than writing a network layer manually) to communicate among all MacOS clients using Cocoa's technology and with Windows clients through CORBA?

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• JQuery UI drag and drop doesn't notice DOM changes happening during the dragging ?

  - by user315677

  Hi everybody, I have a html table in which each line (<tr>) represents a group of client computers. Each line can be expanded to show the clients belonging to the group. The <tr> containing the clients are always generated but hidden and showed when clicking the plus button at the beginning of each line. The clients themselves (they are <div>) can be dragged and dropped in another group as long as this group is already expanded. So far it works fine. What I am trying to achieve now is that the client can be dragged to a collapsed group and after a second or so hovering the group it will be expanded and the client can be dropped amongst the other clients of the group. I programmed the hover using the in and outevents of the droppable and it expands the group all right, but (and now it starts to be hard to explain with words ;) the behavior of the droppable (the client) is still as if the table line that appeared were not there : the in out and drop events of the droppable are fired on the old position of the elements, and the in out and drop events of the newly appeared <tr> are never fired. It looks as if JQuery memorizes the position, size etc. of the elements when the drag starts, and these values are not updated if there is a change in the DOM before the drop happens... Can someone confirm this behavior is normal, or can it be caused by another problem in my own code ? Any workaround ? (the question is quite bloated already so I don't include any code but I'll gladly upload it if required)

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• Is there a mechanism to distribute an app with its own JRE?

  - by user179997

  These fine folks are my users: http://www.youtube.com/watch?v=o4MwTvtyrUQ If you don't want to enjoy the video here is the gist: my users can't tell between a file and a folder, between a browser and a web site. I need to create a Java web app (Tomcat or Jetty) and deploy it in as many of their computers, Windows and Mac. The question is: Is there a mechanism to distribute an app with its own JRE? (in the Tcl world there are starpacks and starkits, in the Python world there's py2exe and others, that's the idea). And also, is it legal? I know the VM is open source but I'm not clear about the libraries, and I know about GNU Classpath but I don't know if all the packages are there. I don't want to depend on the installed JRE or on the user having enough privileges to install one. On the Mac I don't want to depend on Apple (I had to switch from Tiger to Snow Leopard just to have Java 1.6, I can't put my users in that position) Any info greatly appreciated. Thanks! jb edit: I'm wondering if I can just paste the JRE folder under my app folder. Is that allowed?

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• why do we need advanced knowledge of mathematics & physics for programming?

  - by Sumeet

  Guys, I have been very good in mathematics and physics in my schools and colleges. Right now I am a programmer. Even in the colleges I have to engrossed my self into computers and programming things all the time. As I used to like it very much. But I have always felt the lack of advanced mathematics and physics in all the work I have done (Programs). Programming never asked me any advanced mathematics and physics knowledge in what I was very good. It always ask u some optimized loops, and different programming technologies which has never been covered in advanced mathematics and physics. Even at the time of selection in big College , such a kind of advanced knowledge is required. Time by time I got out of touch of all that facts and concepts (advanced mathematics and physics). And now after, 5 years in job I found it hard to resolve Differentiations and integrations from Trigonometry. Which sometimes make me feel like I have wasted time in those concepts because they are never used. (At that time I knew that I am going to be a programmer) If one need to be a programmer why do all this advanced knowledge is required. One can go with elementry knowledge a bit more. You never got to think like scientists and R&D person in your Schols and colleges for being a programmer? Just think and let me know your thoughts. I must be wrong somewhere in what I think , but not able to figure that out..? Regards Sumeet

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• Very strange client/browser issue

  - by Jeriko

  One of our clients has logged a very strange issue with us- We launched a preview for their website, but when it's viewed on their main PC, peculiar things start to happen... At first, the stylesheet wasn't being found, and so accessing any page resulted in one void of all styles. We sent them a direct link to the stylesheet, which was viewable from all our computers in the office - but gave a "File Not Found" error on their side. I then deleted the file, and replaced it with a new blank file, which he could then access. Copy-pasted screen.css contents into this file, and he could then view it fine, and stylesheets magically worked on the site again. Now, he can view styles, but not the referenced header images. The strange thing is that this problem doesn't exist on any other PC we've tested, or on any other site on the problem computer, but obviously we'd like our client's site to work for them. The strange thing is, they can view other sites of ours, hosted on the same server, built on top of the same CMS (and so most of the files are the same) without problem - but are getting 404s for files that most definitely do exist. Stylesheets are not turned off, nor is anything specifically deactivated on their browser (as other sites are fine) Reloading with CTRL+F5 doesn't help The client is using the latest version of firefox Any ideas here on what to try / how to narrow the problem down?

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• How would I code a complex formula parser manually?

  - by StormianRootSolver

  Hm, this is language - agnostic, I would prefer doing it in C# or F#, but I'm more interested this time in the question "how would that work anyway". What I want to accomplish ist: a) I want to LEARN it - it's about my ego this time, it's for a fun project where I want to show myself that I'm a really good at this stuff b) I know a tiny little bit about EBNF (although I don't know yet, how operator precedence works in EBNF - Irony.NET does it right, I checked the examples, but this is a bit ominous to me) c) My parser should be able to take this: 5 * (3 + (2 - 9 * (5 / 7)) + 9) for example and give me the right results d) To be quite frankly, this seems to be the biggest problem in writing a compiler or even an interpreter for me. I would have no problem generating even 64 bit assembler code (I CAN write assembler manually), but the formula parser... e) Another thought: even simple computers (like my old Sharp 1246S with only about 2kB of RAM) can do that... it can't be THAT hard, right? And even very, very old programming languages have formula evaluation... BASIC is from 1964 and they already could calculate the kind of formula I presented as an example f) A few ideas, a few inspirations would be really enough - I just have no clue how to do operator precedence and the parentheses - I DO, however, know that it involves an AST and that many people use a stack So, what do you think?

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• Random-access archive for Unix use

  - by tylerl

  I'm looking for a good format for archiving entire file-systems of old Linux computers. TAR.GZ The tar.gz format is great for archiving files with UNIX-style attributes, but since the compression is applied across the entire archive, the design precludes random-access. Instead, if you want to access a file at the end of the archive, you have to start at the beginning and decompress the whole file (which could be several hundred GB) up to the point where you find the entry you're looking for. ZIP Conversely, one selling point of the ZIP format is that it stores an index of the archive: filenames are stored separately with pointers to the location within the archive were to find the data. If I want to extract a file at the end, I look up the position of that file by name, seek to the location, and extract the data. However, it doesn't store file attributes such as ownership, permissions, symbolic links, etc. Other options? I've tried using squashfs, but it's not really designed for this purpose. The file format is not consistent between versions, and building the archive takes a lot of time and space. What other options might suit this purpose better?

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• Opening my application when a usb device is inserted on Windows using WMI

  - by rsteckly

  Hi, I'm trying to launch an event when someone plugs in a usb device. For now, I'm content to simply print something to the console (in the finished product, it will launch an application). This code is very loosely adapted from: http://serverfault.com/questions/115496/use-wmi-to-detect-a-usb-drive-was-connected-regardless-of-whether-it-was-mounted There's two problems: 1) I need to pass the argument to Management scope dynamically because this will be installed on computers I don't use or whose name I don't know. 2) I'm getting an invalid namespace exception when I call w.Start(); Any ideas what I'm doing wrong? static ManagementEventWatcher w=null; static void Main(string[] args) { AddInstUSBHandler(); for(;;); } public static void USBRemoved(object sneder, EventArgs e) { Console.WriteLine("A USB device inserted"); } static void AddInstUSBHandler() { WqlEventQuery q; ManagementScope scope = new ManagementScope("HQ\\DEV1"); scope.Options.EnablePrivileges=true; q=new WqlEventQuery(); q.EventClassName+="_InstanceCreationEvent"; q.WithinInterval=new TimeSpan(0,0,3); q.Condition=@"TargetInstance ISA 'Win32_USBControllerdevice'"; w=new ManagementEventWatcher(scope,q); w.EventArrived+=new EventArrivedEventHandler(USBRemoved); w.Start(); }

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• How does Amazon's Statistically Improbable Phrases work?

  - by ??iu

  How does something like Statistically Improbable Phrases work? According to amazon: Amazon.com's Statistically Improbable Phrases, or "SIPs", are the most distinctive phrases in the text of books in the Search Inside!™ program. To identify SIPs, our computers scan the text of all books in the Search Inside! program. If they find a phrase that occurs a large number of times in a particular book relative to all Search Inside! books, that phrase is a SIP in that book. SIPs are not necessarily improbable within a particular book, but they are improbable relative to all books in Search Inside!. For example, most SIPs for a book on taxes are tax related. But because we display SIPs in order of their improbability score, the first SIPs will be on tax topics that this book mentions more often than other tax books. For works of fiction, SIPs tend to be distinctive word combinations that often hint at important plot elements. For instance, for Joel's first book, the SIPs are: leaky abstractions, antialiased text, own dog food, bug count, daily builds, bug database, software schedules One interesting complication is that these are phrases of either 2 or 3 words. This makes things a little more interesting because these phrases can overlap with or contain each other.

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• Document management, SCM ?

  - by tsunade

  Hello, This might not be a hard core programming question, but it's related to some of the tools used by programmers I suspect. So we're a bunch of people each with a bunch of documents and a bunch of different computers on a bunch of operating systems (well, only 2, linux and windows). The best way these documents can be stored/managed is if they were available offline (the laptop might not always be online) but also synchronized between all the machines. Having a server with extra reliable storage be a "base repository" seems like a good idea to me. Using a SCM comes to my mind and I've tried Subversion, and it seems to be a good thing that it uses a centralized repository - but: When checking out the total size of the checkout is roughly double the original size. Big files or big repositories seem to slow it down. Also I've tried rsync, which might work - but it's a bit rough when it comes to the potential conflict. Finally I've tried Unison (which is a wrapping of rsync, I think) and while it works it becomes horribly slow for the big directories we have here since it has to scan everything. So the question is - is there a SCM tool out there that is actually practial to use for a big bunch of both small and big files? If thats a NO - does anyone know other tools that do this job? Thanks for reading :)

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• Time with and without OpenMP

  - by was

  I have a question.. I tried to improve a well known program algorithm in C, FOX algorithm for matrix multiplication.. relative link without openMP: (http://web.mst.edu/~ercal/387/MPI/ppmpi_c/chap07/fox.c). The initial program had only MPI and I tried to insert openMP in the matrix multiplication method, in order to improve the time of computation: (This program runs in a cluster and computers have 2 cores, thus I created 2 threads.) The problem is that there is no difference of time, with and without openMP. I observed that using openMP sometimes, time is equivalent or greater than the time without openMP. I tried to multiply two 600x600 matrices. void Local_matrix_multiply( LOCAL_MATRIX_T* local_A /* in */, LOCAL_MATRIX_T* local_B /* in */, LOCAL_MATRIX_T* local_C /* out */) { int i, j, k; chunk = CHUNKSIZE; // 100 #pragma omp parallel shared(local_A, local_B, local_C, chunk, nthreads) private(i,j,k,tid) num_threads(2) { /* tid = omp_get_thread_num(); if(tid == 0){ nthreads = omp_get_num_threads(); printf("O Pollaplasiamos pinakwn ksekina me %d threads\n", nthreads); } printf("Thread %d use the matrix: \n", tid); */ #pragma omp for schedule(static, chunk) for (i = 0; i < Order(local_A); i++) for (j = 0; j < Order(local_A); j++) for (k = 0; k < Order(local_B); k++) Entry(local_C,i,j) = Entry(local_C,i,j) + Entry(local_A,i,k)*Entry(local_B,k,j); } //end pragma omp parallel } /* Local_matrix_multiply */

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• vlcj not displaying the video

  - by Cássio Eudardo

  I'm using vlcj to play video, but the video doesn't display on some computers(i tested in 4 and worked on 2, all windows), on 1 it displays the button but not the video and on the other it just display a gray background without the button. I tested .wmv and .avi files. I'm using the following code: public class Video extends JFrame implements WindowListener{ private JPanel contentPane; private JButton btnClose; private Dimension size; private float aspectRatio; private EmbeddedMediaPlayer mediaPlayer; public Video() { try { size = Toolkit.getDefaultToolkit().getScreenSize(); aspectRatio = (float)size.width/size.height; String file = "..."; btnClose = new JButton("X"); btnClose.addActionListener(new ActionListener() {...}); btnClose.setBounds(640 - 50, 10, 40, 40); setBounds(size.width/2 - 320, (int)(size.height - 40*aspectRatio) - 250, 640, 200); contentPane = new JPanel(); contentPane.setLayout(null); setContentPane(contentPane); WindowsCanvas surface = new WindowsCanvas(); contentPane.setBounds(0, 0, 640, 200); surface.setBounds(0, 0, 640, 200); MediaPlayerFactory factory = new MediaPlayerFactory(new String("--no-video-title-show")); mediaPlayer = factory.newEmbeddedMediaPlayer(); surface.addMouseListener(new MouseListener() {...}); contentPane.add(btnClose); contentPane.add(surface); setVisible(true); mediaPlayer.setVideoSurface(factory.newVideoSurface(surface)); mediaPlayer.setRepeat(true); mediaPlayer.playMedia(file); } catch(Exception e) { } }}

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• Secure Copy File from remote server via scp and os module in Python

  - by user1063572

  I'm pretty new to Python and programming. I'm trying to copy a file between two computers via a python script. However the code os.system("ssh " + hostname + " scp " + filepath + " " + user + "@" + localhost + ":" cwd) won't work. I think it needs a password, as descriped in How do I copy a file to a remote server in python using scp or ssh?. I didn't get any error logs, the file just won't show in my current working directory. However every other command with os.system("ssh " + hostname + "command") or os.popen("ssh " + hostname + "command") does work. - command = e.g. ls When I try ssh hostname scp file user@local:directory in the commandline it works without entering a password. I tried to combine os.popen commands with getpass and pxssh module to establish a ssh connection to the remote server and use it to send commands directly (I only tested it for an easy command): import pxssh import getpass ssh = pxssh.pxssh() ssh.force_password = True hostname = raw_input("Hostname: ") user = raw_input("Username: ") password = getpass.getpass("Password: ") ssh.login(hostname, user, password) test = os.popen("hostname") print test But I'm not able to put commands through to the remote server (print test shows, that hostname = local and not the remote server), however I'm sure, the conection is established. I thought it would be easier to establish a connection than always use "ssh " + hostname in the bash commands. I also tried some of the workarounds in How do I copy a file to a remote server in python using scp or ssh?, but I must admit due to lack of expirience I didn't get them to work. Thanks a lot for helping me.

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• ReWriteRule is redirecting rather rewriting

  - by James Doc

  At the moment I have two machines that I do web development on; an iMac for work at the office and a MacBook for when I have to work on the move. They both running OS X 10.6 have the same version of PHP, Apache, etc running on them. Both computers have the same files of the website, including the .htaccess file (see below). On the MacBook the URLs are rewritten nicely, masking the URL they are pointing to (eg site/page/page-name), however on the iMac they simply redirect to the page (eg site/index.php?method=page&value=page-name) which is making switching back and forth between machines a bit of a pain! I'm sure it must be a config setting somewhere, but I can't for the life of me find it. Has anyone got a remedy? Many thanks. I'm fairly convinced there is a much nice way of writing this htaccess file without loosing access several key folders as well! Options +FollowSymlinks RewriteEngine on RewriteBase /In%20Progress/Vila%20Maninga/ RewriteRule ^page/([a-z|0-9_&;=-]+) index.php?method=page&value=$1 [NC] RewriteRule ^tag/([a-z|0-9_]+) index.php?method=tag&value=$1 [NC] RewriteRule ^search/([a-z|0-9_"]+) index.php?method=search&value=$1 [NC] RewriteRule ^modpage/([con0-9-]+) index.php?method=modpage&value=$1 [NC] RewriteRule ^login index.php?method=login [NC] RewriteRule ^logout index.php?method=logout [NC] RewriteRule ^useraccounts index.php?method=useraccounts [NC]

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• Tips for Using Multiple Development Systems

  - by Tim Lytle

  When I travel, I don't pack up the desktop I use in the office and take it with me. Maybe I should, but I don't. However, since I'm a contract programmer I like to be able to work wherever I am: I'm mostly thinking of web development here. Version Control goes a long way in keeping sane and working on multiple projects on multiple systems (two or three computers); however, there are the issues of: IDE settings - different display sizes mean the IDE settings can't be completely synced, if at all. Database - if the database is 'external' (even if it's running on the same system, it's not in version control), how do you maintain the needed syncs of structure. Development Stack - Some projects need non-standard extensions, libraries, etc installed. Just an overview of some of the hassle involved with developing on multiple systems. I'll probably end up asking some specific questions, but I thought a CW style tips might reveal some things I would even think to ask about. Update: I guess this would also address tips to make upgrading/replacing your development system easier (something I've just done). So, one tip per answer please, so the 'top' tips are easy to find. How do you make it easier to develop on multiple systems, or to transfer work after upgrading/replaceing a development system?

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• Multi-reader IPC solution?

  - by gct

  I'm working on a framework in C++ (just for fun for now), that lets the user write plugins that use a standard API to stream data between each other. There's going to be three basic transport mechanisms for the data: files, sockets, and some kind of IPC piping system. The system is set up so that for the non-file transport, each stream can have multiple readers. IE once a server socket it setup, multiple computers can connect and stream the data. I'm a little stuck at the multi-reader IPC system though. All my plugins run in threads so they live in the same address space, so some kind of shared memory system would work fine, I was thinking I'd write my own circular buffer with a write pointer and read pointers chassing it around the buffer, but I have my doubts that I can achieve the same performance as something like linux pipes. I'm curious what people would suggest for a multi-reader solution to something like this? Is the overhead for pipes or domain sockets low enough that I could just open a connection to each reader and issue separate writes to each reader? This is intended to be significant volumes of data (tens of mega-samples/sec), so performance is a must.

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• Accurately and securely measure the time spent viewing a web page

  - by balpha

  Suppose the following: You have a web page that presents a simple game to a user (e.g. a quiz, a puzzle, etc). The user solves the puzzle, submits the result, and you want to measure as precisely as possible how long they took to solve it. Assume it's quite simple, so we're talking seconds, not hours. Also assume JavaScript is required anyway, so there's no need to think of JS-disabled browsers. Finally, assume we don't want to use anything like Flash, Silverlight, or the like. I can think of several techniques: Simply take the time between the points when the data was sent from the server and when the submission arrives. Since this is exclusively server-side, there's no chance for cheating. However, issues like network latency and page rendering time might make this unfair for users with slow computers / browsers / internet connections. On the first request, just send the page without the actual game data. When everything is loaded so far, retrieve the game data through an AJAX call and populate it into the page. This is similar to 1., but reduces some of the caveats introduced through time spent on overhead. Have the time measured on the client side using JavaScript and submitted alongside with the solution. This would theoretically be the most accurate, but it introduces the possibility of cheating, because you're relying on client data. Use the request time headers of a "ready to play" AJAX call and the result submission request. Same caveat as 3., as it is still client data. A combination of server side and client side measuring with some kind of plausibility analysis. I can't think of a good way, but maybe you can. Thoughts? Other ideas?

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• Inconsistent GWT behavior in IE 8

  - by Don Branson

  All, I have a web site that's built with GWT at https://penwag.com/penwag/. If you just hit the site and see the main page, there's supposed to be a login/registration area that displays, along with a teaser for the site. I've tried the site with most of the main browsers - FF 3 & 3.5, IE 6 & 8, Safari, and Chrome, and all appears well to me. However, I have a non-geek user that has visited the site from both work and home. The work computer can see the intro page fine, but the home computer shows only the static content, and non of the javascript-based portion, that is the login/registration and teaser. Both computers are using IE 8. He checked the computer where the site fails, and scripting is enabled. Can anyone else see the problem? (You don't have to register to see the problem, just hit the main page.) Anything else I should check or have him try? Thanks! Edit: The site is implemented using GWT 1.7.0. I'll have to find out about the OS versions. Edit: The one that works is running Windows XT, the failing one is running Windows Vista. (There's a shocker!) I myself have viewed it successfully with both OSs. Edit: I've since completely re-structured the site, and documented the changes here: http://penwag.blogspot.com/2010/04/april-penwag-update.html So, the site is no longer the same as when I asked this question.

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• Cross-platform general purpose C++ RPC library

  - by iUm

  Here's the task: Imagine, we have an applications and a plug-in for it (dynamic library). Interface between the application and the plug-in is completely defined. Now I need to run the application and the plug-in on different computers. I wrote a stub for the plug-in on a computer where the real applications is running. And the application loads it and calls its functions like if it were a native plug-in. On the other computer there's a stub instead of the real application, which loads the native plug-in. Now I need to organize RPCs between my stubs over the network, regardless the very transport. Usually, it's not difficult. But there're some restrictions: Application-plug-in interaction can be reenterable (e.g. application calls f1() from plug-in, in f1() plug-in calls g1() from application, in g1() application calls f2() from plug-in and so on...) Any such reenteration should be executed exactly by the same thread, which started the sequence Where can I find a cross-platform C++ RPC library with such features?

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