Search Results

Search found 14213 results on 569 pages for 'distributed programming'.

facebook twitter digg google delicious technorati stumbleupon myspace wordpress linkedin gmail igoogle windows live tumblr viadeo yahoo buzz yahoo mail yahoo bookmarks favorites email print

Page 163/569 | < Previous Page | 159 160 161 162 163 164 165 166 167 168 169 170  | Next Page >

  • Cartesian product in Scheme

    - by John Retallack
    I've been trying to do a function that returns the Cartesian Product of n sets,in Dr Scheme,the sets are given as a list of lists,I've been stuck at this all day,I would like a few guidelines as where to start,I've wrote a pice of code but it dosen't work. (define cart-n(?(l) (if (null? l) '(()) (map (?(lst) (cons (car ( car(l))) lst)) (cart-n (cdr l) )))))

    Read the article

  • Polygon packing 2D

    - by Ilnur
    Hi! I have problem of packing 2 arbitrary polygons. I.e. we have 2 arbitrary polygons. We are to find such placement of this polygons (we could make rotations and movements), when rectangle, which circumscribes this polygons has minimal area. I know, that this is a NP-complete problem. I want to choose an efficient algorithm for solving this problem. I' looking for No-Fit-Polygon approach. But I could't find anywhere the simple and clear algorithm for finding the NFP of two arbitrary polygons.

    Read the article

  • Haskell Parsec Numeration

    - by Martin
    I'm using Text.ParserCombinators.Parsec and Text.XHtml to parse an input like this: - First type A\n -- First type B\n - Second type A\n -- First type B\n --Second type B\n And my output should be: <h11 First type A\n</h1 <h21.1 First type B\n</h2 <h12 Second type A\n</h2 <h22.1 First type B\n</h2 <h22.2 Second type B\n</h2 I have come to this part, but I cannot get any further: title1= do{ ;(count 1 (char '-')) ;s <- many1 anyChar newline ;return (h1 << s) } title2= do{ ;(count 2 (char '--')) ;s <- many1 anyChar newline ;return (h1 << s) } text=do { ;many (choice [try(title1),try(title2)]) } main :: IO () main = do t putStr "Error: " print err Right x - putStrLn $ prettyHtml x This is ok, but it does not include the numbering. Any ideas? Thanks!

    Read the article

  • When to use closure?

    - by shahkalpesh
    I have seen samples of closure from - http://stackoverflow.com/questions/36636/what-is-a-closure Can anyone provide simple example of when to use closure? Specifically, scenarios in which closure makes sense? Lets assume that the language doesn't have closure support, how would one still achieve similar thing? Not to offend anyone, please post code samples in a language like c#, python, javascript, ruby etc. I am sorry, I do not understand functional languages yet.

    Read the article

  • Reference for proper handling of PID file on Unix

    - by bignose
    Where can I find a well-respected reference that details the proper handling of PID files on Unix? On Unix operating systems, it is common practice to “lock” a program (often a daemon) by use of a special lock file: the PID file. This is a file in a predictable location, often ‘/var/run/foo.pid’. The program is supposed to check when it starts up whether the PID file exists and, if the file does exist, exit with an error. So it's a kind of advisory, collaborative locking mechanism. The file contains a single line of text, being the numeric process ID (hence the name “PID file”) of the process that currently holds the lock; this allows an easy way to automate sending a signal to the process that holds the lock. What I can't find is a good reference on expected or “best practice” behaviour for handling PID files. There are various nuances: how to actually lock the file (don't bother? use the kernel? what about platform incompatibilities?), handling stale locks (silently delete them? when to check?), when exactly to acquire and release the lock, and so forth. Where can I find a respected, most-authoritative reference (ideally on the level of W. Richard Stevens) for this small topic?

    Read the article

  • OT: US Banks: Bank Routing Number and BIC/SWIFT

    - by Konerak
    I know it is a bit offtopic, but I've been having a hard time finding more information to this question, and since this site is visited by a lot of people from the United States, you guys might know/find the answer more easily. Banks in europe each have a SWIFT Number, while US Banks use Routing Numbers. This leads to following questions: Does each bank in the US also carry a BIC number? (SWIFT) Is there a 1-1 relationship between BIC and SWIFT? Is there a list of these numbers somewhere? (background information: we're adding international payments to our bookkeeping application. Users can add international suppliers, but my boss prefered not to change the current supplier table but to have the ROUTING NUMBER in another table, with as PK the BIC. I'm wondering if BIC is a valid choice, or if it should just be BANK ACCOUNT NUMBER.)

    Read the article

  • Bad File descriptor

    - by Luke
    Does anyone see a problem with this, its not working saying bad file descriptor not sure why? pipe(pipefd[0]); if ((opid = fork()) == 0) { dup2(pipefd[0][1],1);/*send to output*/ close(pipefd[0][0]); close(pipefd[0][1]); execlp("ls","ls","-al",NULL); } if((cpid = fork())==0){ dup2(pipefd[0][1],0);/*read from input*/ close(pipefd[0][0]); close(pipefd[1][1]); execlp("grep","grep",".bak",NULL); } close(pipefd[0][0]); close(pipefd[0][1]);

    Read the article

  • Can I ran 2 or more Tcp Sever applications on one computer?

    - by Samvel Siradeghyan
    Hi all. I have a client-server Silverlight application, which is use Socets. I have server appliaction on may computer(Win Form application) and client applucation as web site(Silverlight application). I use policy server which open port 943. Everything works fine on this application. But now I need to write another client-server application. Server for that application olso use port 943 for policy connection. When I try to run this 2 server applications on the same compyeter an excepten is thrown which says that only one application can work on port 943. How can I solve this problem? Thanks.

    Read the article

  • 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!

    Read the article

  • Storing VMware virtual machines in external harddisk

    - by Jeffery Ang
    Any issue with that? I recently setup ubunutu virtual machine on my external harddisk. Once i accidentally removed the external harddisk usb connection then when i try to startup the ubuntu virtual machine again i get kernel panic. I thinking of writing a cron script to backup everyday to another location to prevent this issue

    Read the article

  • How does a portable Thread Specific Storage Mechanism's Naming Scheme Generate Thread Relative Uniqu

    - by Hassan Syed
    A portable thread specific storage reference/identity mechanism, of which boost/thread/tss.hpp is an instance, needs a way to generate a unique keys for itself. This key is unique in the scope of a thread, and is subsequently used to retrieve the object it references. This mechanism is used in code written in a thread neutral manner. Since boost is a portable example of this concept, how specifically does such a mechanism work ?

    Read the article

  • What are your recommended tools and frameworks for network development on Linux?

    - by Vivek Sharma
    What are your favourite network-tools, which you use to troubleshoot or design (as in conceptualize) your network-application code. Ethereal/Wireshark Nmap any particular simulators (e.g. ns) any special purpose sniffer any particular frameworks, (e.g. iptables) I am looking at must have, and good/advantage to have tools/framework in ones profile/skill set. I think Wireshark and Nmap are must haves.

    Read the article

  • What are the Open Source alternatives to WPF/XAML?

    - by Evan Plaice
    If we've learned anything from HTML/CSS it's that, declarative languages (like XML) work best to describe User Interfaces because: It's easy to build code preprocessors that can template the code effectively. The code is in a well defined well structured (ideally) format so it's easy to parse. The technology to effectively parse or crawl an XML based source file already exists. The UIs scripted code becomes much simpler and easier to understand. It simple enough that designers are able to design the interface themselves. Programmers suck at creating UIs so it should be made easy enough for designers. I recently took a look at the meat of a WPF application (ie. the XAML) and it looks surprisingly familiar to the declarative language style used in HTML. It's apparent to me that the current state of desktop UI development is largely fractionalized, otherwise there wouldn't be so much duplicated effort in the domain of graphical user interface design (IE. GTK, XUL, Qt, Winforms, WPF, etc). There are 45 GUI platforms for Python alone It's seems reasonable to me that there should be a general purpose, open source, standardized, platform independent, markup language for designing desktop GUIs. Much like what the W3C made HTML/CSS into. WPF, or more specifically XAML seems like a pretty likely step in the right direction. Now that the 'browser wars' are over should we look forward to a future of 'desktop gui wars?' Note: This topic is relatively subjective in the attempt to be 'future-thinking.' I think that desktop GUI development in its current state sucks ((really)hard) and, even though WPF is still in it's infancy, it presents a likely solution to the problem. Update: Thanks a lot for the info, keep it comin'. Here's are the options I've gathered from the comments and answers. GladeXML Editor: Glade Interface Designer OS Platforms: All GUI Platform: GTK+ Languages: C (libglade), C++, C# (Glade#), Python, Ada, Pike, Perl, PHP, Eiffel, Ruby XRC (XML Resource) Editors: wxGlade, XRCed, wxDesigner, DialogBlocks (non-free) OS Platforms: All GUI Platform: wxWidgets Languages: C++, Python (wxPython), Perl (wxPerl), .NET (wx.NET) XML based formats that are either not free, not cross-platform, or language specific XUL Editor: Any basic text editor OS Platforms: Any OS running a browser that supports XUL GUI Platform: Gecko Engine? Languages: C++, Python, Ruby as plugin languages not base languages Note: I'm not sure if XUL deserves mentioning in this list because it's less of a desktop GUI language and more of a make-webapps-run-on-the-desktop language. Plus, it requires a browser to run. IE, it's 'DHTML for the desktop.' CookSwing Editor: Eclipse via WindowBuilder, NetBeans 5.0 (non-free) via Swing GUI Builder aka Matisse OS Platforms: All GUI Platform: Java Languages: Java only XAML (Moonlight) Editor: MonoDevelop OS Platforms: Linux and other Unix/X11 based OSes only GUI Platforms: GTK+ Languages: .NET Note: XAML is not a pure Open Source format because Microsoft controls its terms of use including the right to change the terms at any time. Moonlight can not legally be made to run on Windows or Mac. In addition, the only platform that is exempt from legal action is Novell. See this for a full description of what I mean.

    Read the article

  • Receiving broadcast messages

    - by Prasad
    Hi, I'm trying to receive broadcast messages using C# code in an ISDN network with BRI interface at my end. I see the packets sent to the broadcast ip address (239.255.255.255) on some ports using Comm View tool. But when I try to listen to this IP address, it says the address is not in a valid context. But when I send broadcast messages to 255.255.255.255 on a port, I can receive those messages with the below code.. What could be the problem with this ip address - 239.255.255.255 ? The code I use to listen to broadcast messages is.. UdpClient udp = new UdpClient(); IPEndPoint receiveEndPoint = new IPEndPoint(IPAddress.Any, 8013); // If I use IPAddress.Parse("239.255.255.255") to listen to, // it says "the address is not in a valid // context." udp.Client.Bind(receiveEndPoint); udp.BeginReceive(_Callback, udp); static private void _Callback(IAsyncResult iar) { try { UdpClient client = (UdpClient)iar.AsyncState; client.BeginReceive(_Callback, client); IPEndPoint ipRemote = new IPEndPoint(IPAddress.Any, 8013); byte[] rgb = client.EndReceive(iar, ref ipRemote); Console.WriteLine("Received {0} bytes: \"{1}\"", rgb.Length.ToString(), Encoding.UTF8.GetString(rgb)); } catch (ObjectDisposedException) { Console.WriteLine("closing listening socket"); } catch (Exception exc) { Console.WriteLine("Listening socket error: \"" + exc.Message + "\""); } } There are packets sent to the broadcast ipaddress (239.255.255.255) which I can see in Commview tool, but can't receive them from the code... Can anybody help me out please? Thanking you in advance, Prasad Kancharla.

    Read the article

  • Linq Query Performance , comparing Compiled query vs Non-Compiled.

    - by AG.
    Hello Guys, I was wondering if i extract the common where clause query into a common expression would it make my query much faster, if i have say something like 10 linq queries on a collection with exact same 1st part of the where clause. I have done a small example to explain a bit more . public class Person { public string First { get; set; } public string Last { get; set; } public int Age { get; set; } public String Born { get; set; } public string Living { get; set; } } public sealed class PersonDetails : List<Person> { } PersonDetails d = new PersonDetails(); d.Add(new Person() {Age = 29, Born = "Timbuk Tu", First = "Joe", Last = "Bloggs", Living = "London"}); d.Add(new Person() { Age = 29, Born = "Timbuk Tu", First = "Foo", Last = "Bar", Living = "NewYork" }); Expression<Func<Person, bool>> exp = (a) => a.Age == 29; Func<Person, bool> commonQuery = exp.Compile(); var lx = from y in d where commonQuery.Invoke(y) && y.Living == "London" select y; var bx = from y in d where y.Age == 29 && y.Living == "NewYork" select y; Console.WriteLine("All Details {0}, {1}, {2}, {3}, {4}", lx.Single().Age, lx.Single().First , lx.Single().Last, lx.Single().Living, lx.Single().Born ); Console.WriteLine("All Details {0}, {1}, {2}, {3}, {4}", bx.Single().Age, bx.Single().First, bx.Single().Last, bx.Single().Living, bx.Single().Born); So can some of the guru's here give me some advice if it would be a good practice to write query like var lx = "Linq Expression " or var bx = "Linq Expression" ? Any inputs would be highly appreciated. Thanks, AG

    Read the article

  • How to solve a deallocated connection in iPhone SDK 3.1.3? - Streams - CFSockets

    - by Christian
    Hi everyone, Debugging my implementation I found a memory leak issue. I know where is the issue, I tried to solve it but sadly without success. I will try to explain you, maybe someone of you can help with this. First I have two classes involved in the issue, the publish class (where publishing the service and socket configuration is done) and the connection (where the socket binding and the streams configuration is done). The main issue is in the connection via native socket. In the 'publish' class the "server" accepts a connection with a callback. The callback has the native-socket information. Then, a connection with native-socket information is created. Next, the socket binding and the streams configuration is done. When those actions are successful the instance of the connection is saved in a mutable array. Thus, the connection is established. static void AcceptCallback(CFSocketRef socket, CFSocketCallBackType type, CFDataRef address, const void *data, void *info) { Publish *rePoint = (Publish *)info; if ( type != kCFSocketAcceptCallBack) { return; } CFSocketNativeHandle nativeSocketHandle = *((CFSocketNativeHandle *)data); NSLog(@"The AcceptCallback was called, a connection request arrived to the server"); [rePoint handleNewNativeSocket:nativeSocketHandle]; } - (void)handleNewNativeSocket:(CFSocketNativeHandle)nativeSocketHandle{ Connection *connection = [[[Connection alloc] initWithNativeSocketHandle:nativeSocketHandle] autorelease]; // Create the connection if (connection == nil) { close(nativeSocketHandle); return; } NSLog(@"The connection from the server was created now try to connect"); if ( ! [connection connect]) { [connection close]; return; } [clients addObject:connection]; //save the connection trying to avoid the deallocation } The next step is receive the information from the client, thus a read-stream callback is triggered with the information of the established connection. But when the callback-handler tries to use this connection the error occurs, it says that such connection is deallocated. The issue here is that I don't know where/when the connection is deallocated and how to know it. I am using the debugger, but after some trials, I don't see more info. void myReadStreamCallBack (CFReadStreamRef stream, CFStreamEventType eventType, void *info) { NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init]; Connection *handlerEv = [[(Connection *)info retain] autorelease]; // The error -[Connection retain]: message sent to deallocated instance 0x1f5ef0 (Where 0x1f5ef0 is the reference to the established connection) [handlerEv readStreamHandleEvent:stream andEvent:eventType]; [pool drain]; } void myWriteStreamCallBack (CFWriteStreamRef stream, CFStreamEventType eventType, void *info){ NSAutoreleasePool *p = [[NSAutoreleasePool alloc] init]; Connection *handlerEv = [[(Connection *)info retain] autorelease]; //Sometimes the error also happens here, I tried without the pool, but it doesn't help neither. [handlerEv writeStreamHandleEvent:eventType]; [p drain]; } Something strange is that when I run the debugger(with breakpoints) everything goes well, the connection is not deallocated and the callbacks work fine and the server is able to receive the message. I will appreciate any hint!

    Read the article

  • perl multiple tasks problem

    - by Alice Wozownik
    I have finished my earlier multithreaded program that uses perl threads and it works on my system. The problem is that on some systems that it needs to run on, thread support is not compiled into perl and I cannot install additional packages. I therefore need to use something other than threads, and I am moving my code to using fork(). This works on my windows system in starting the subtasks. A few problems: How to determine when the child process exits? I created new threads when the thread count was below a certain value, I need to keep track of how many threads are running. For processes, how do I know when one exits so I can keep track of how many exist at the time, incrementing a counter when one is created and decrementing when one exits? Is file I/O using handles obtained with OPEN when opened by the parent process safe in the child process? I need to append to a file for each of the child processes, is this safe on unix as well. Is there any alternative to fork and threads? I tried use Parallel::ForkManager, but that isn't installed on my system (use Parallel::ForkManager; gave an error) and I absolutely require that my perl script work on all unix/windows systems without installing any additional modules.

    Read the article

  • Choosing a non microsoft language for web development?

    - by Luke Lowrey
    I am resonably experienced with asp.net and would like to learn a new language with a focus on web development. Licensing and hosting costs are why I would like to use something not reliant on microsoft so something based on open source technologies is a plus. I have had a tiny bit of experience with php and did not like it but I guess I could be convinced otherwise. Basically I'd like to know peoples opinion on the the best language for future web development with regards to longivity, resources, frameworks, hosting etc.

    Read the article

  • What is the sequence followed by the Linux kernel to configure a device?

    - by Jaime Soriano
    As I understood after reading the chapter related to The Linux Device Model in the Linux Device Drivers 3rd Edition, when a new device is configured, the kernel follows more or less this sequence: The Device is registered in the driver core (device_register(), what includes device initialization) A kobject is registered in the device model It provokes a hotplug event Bus and drivers are checked to see which one matches with the device Probe Device is binded to the driver My main doubt is, in step 1, when is device_register() called and what info should be yet in the device struct? Is it called by the bus to which the device is connected? Any example in the code? Have I misunderstood something? :)

    Read the article

  • Corrupted version of WordPad [closed]

    - by Mike GH
    Somehow in trying to cleanup my computer's hard drive, I have inadvertently corrupted WordPad, which I have long used for viewing many types of files, including logs (i.e., log4j). Now when I right click one of these files and choose "open with" & WordPad, I get an error (fn is not a valid Win32 application). I've researched this issue, tried reinstalling wordpad.exe; bbut I still get the same error. Any suggestions would be appreciated.

    Read the article

  • Linux Kernel - Red/Black Trees

    - by CodeRanger
    I'm trying to implement a red/black tree in Linux per task_struct using code from linux/rbtree.h. I can get a red/black tree inserting properly in a standalone space in the kernel such as a module but when I try to get the same code to function with the rb_root declared in either task_struct or task_struct-files_struct, I get a SEGFAULT everytime I try an insert. Here's some code: In task_struct I create a rb_root struct for my tree (not a pointer). In init_task.h, macro INIT_TASK(tsk), I set this equal to RB_ROOT. To do an insert, I use this code: rb_insert(&(current-fd_tree), &rbnode); This is where the issue occurs. My insert command is the standard insert that is documented in all RBTree documentation for the kernel: int my_insert(struct rb_root *root, struct mytype *data) { struct rb_node **new = &(root->rb_node), *parent = NULL; /* Figure out where to put new node */ while (*new) { struct mytype *this = container_of(*new, struct mytype, node); int result = strcmp(data->keystring, this->keystring); parent = *new; if (result < 0) new = &((*new)->rb_left); else if (result > 0) new = &((*new)->rb_right); else return FALSE; } /* Add new node and rebalance tree. */ rb_link_node(&data->node, parent, new); rb_insert_color(&data->node, root); return TRUE; } Is there something I'm missing? Some reason this would work fine if I made a tree root outside of task_struct? If I make rb_root inside of a module this insert works fine. But once I put the actual tree root in the task_struct or even in the task_struct-files_struct, I get a SEGFAULT. Can a root node not be added in these structs? Any tips are greatly appreciated. I've tried nearly everything I can think of.

    Read the article

facebook twitter digg google delicious technorati stumbleupon myspace wordpress linkedin gmail igoogle windows live tumblr viadeo yahoo buzz yahoo mail yahoo bookmarks favorites email print

< Previous Page | 159 160 161 162 163 164 165 166 167 168 169 170  | Next Page >