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  • I have a ConnectException that isn't being caught for some reason

    - by aakbari1024
    I'm working on an Android application that uses sockets. I have a function called initializeStreams() which opens the socket and attempts a connection. This function throws a ConnectException if the connection could not be established. But for some reason, in the code that calls initializeStreams(), which has a catch block for ConnectException, the log prints out its own stack trace for the exception instead of going to the catch block. The catch block is never reached at all, even though the exact exception is being thrown. Here's the code: The try block: try { initializeStreams(); /* drivesList = new ArrayList<String>(); drivesList = enumerateDrives();*/ } catch (ConnectException e) { //Log.i(TAG, "caught connect exception"); /*loadingProgress.dismiss(); retryConnection();*/ } initializeStreams(): public void initializeStreams() throws ConnectException { try { Log.i(TAG, "Attempting to connect"); requestSocket = new Socket(SERVER_ADDR, PORT); /* other code */ } catch (IOException e) { e.printStackTrace(); } I can't figure this out, so any help would be much appreciated. }

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  • Is the "message" of an exception culturally independent?

    - by Ray Hayes
    In an application I'm developing, I have the need to handle a socket-timeout differently from a general socket exception. The problem is that many different issues result in a SocketException and I need to know what the cause was. There is no inner exception reported, so the only information I have to work with is the message: "A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond" This question has a general and specific part: is it acceptable to write conditional logic based upon the textual representation of an exception? Is there a way to avoid needing exception handling? Example code below... try { IPEndPoint endPoint = null; client.Client.ReceiveTimeout = 1000; bytes = client.Receive(ref endPoint); } catch( SocketException se ) { if ( se.Message.Contains("did not properly respond after a period of time") ) { // Handle timeout differently.. } }

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  • C++ code which is slower than its C equivalent?

    - by user997112
    Are there any aspects to the C++ programming language where the code is known to be slower than the equivalent C language? Obviously this would be excluding the OO features like virtual functions and vtable features etc. I am wondering whether, when you are programming in a latency-critical area (and you aren't worried about OO features) whether you could stick with basic C++ or would C be better?

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  • What's SimpleEditableListAppDelegate?

    - by Shawn
    I'm trying to follow the TableView programming guide, and I'm copying the code directly from the guide, but I get "SimpleEditableListAppDelegate undeclared" when I try to compile. Google returns nothing but the programming guide. What's SimpleEditableListAppDelegate, and how do I use it?

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  • What was the motivation for adding the IPV6_V6ONLY flag?

    - by Jeremy Friesner
    In IPv6 networking, the IPV6_V6ONLY flag is used to ensure that a socket will only use IPv6, and in particular that IPv4-to-IPv6 mapping won't be used for that socket. On many OS's, the IPV6_V6ONLY is not set by default, but on some OS's (e.g. Windows 7), it is set by default. My question is: What was the motivation for introducing this flag? Is there something about IPv4-to-IPv6 mapping that was causing problems, and thus people needed a way to disable it? It would seem to me that if someone didn't want to use IPv4-to-IPv6 mapping, they could simply not specify a IPv4-mapped IPv6 address. What am I missing here?

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  • Chat Server with sockets in C

    - by Andrew
    I'm trying to write a chat server in C that allows communication between two clients using POSIX sockets. I'm not sure I have a good grasp on this concept or how I should set up the communication protocol between the clients and the server. I know I need one socket to bind() the server port to so I can accept incoming connections from clients, but in order to have two clients connected at the same time do I need to create a socket for each of these clients when I accept() or should I accept() a client and then fork() so I can have another client accept? I'm not worried about concurrent chatting yet, it's more of a ping-pong approach where the clients need to wait for a recv() after they send() before they can type a new message.

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  • How to use #ifdef entities as part of functions in header files

    - by Crazyjavahacking
    I would like to ask if it is possible to use the entities defined in #ifdef block in header files. To be clear, I have following code: #ifdef #include <winsock2.h> #define SOCKET_HANDLE SOCKET #define CONNECTION_HANDLE SOCKET #endif SOCKET_HANDLE createServerSocket(const char* hostAddress, short port); I am Java developer and this seems completely fine for me. However compiler has a problem with this. Can you explain why is that code a problem? Also how can I force to compile it. (The idea is to have generic interface and conditional compilation to determine real types according to running platform at compile time.) Thanks

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  • execl doesn't work in a while(1) cicle, server side; C script

    - by Possa
    Hi guys, I have a problem with a little C script who should run as a server and launch a popup for every message arriving. The execl syntax is correct because if I try a little script with main() { execl(...); } it works. When I put it in a while(1) cicle it doesn't work. Everything else is working, like printf or string operation, but not the execl. Even if I fork it doesn't work. I really don't know what I can do ... can anyone help me? Thanks in advice for your help and sorry for my bad english. Here's the complete server C code. #include <arpa/inet.h> #include <netinet/in.h> #include <stdio.h> #include <stdlib.h> #include <sys/types.h> #include <sys/socket.h> #include <unistd.h> #include <string.h> #define BUFLEN 512 #define PORT 9930 void diep(char *s) { perror(s); exit(1); } int main() { struct sockaddr_in si_me, si_other; int s, i, slen=sizeof(si_other), broadcastPermission; char buf[100], zeni[BUFLEN]; if ((s=socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP))==-1) diep("socket"); broadcastPermission = 1; if (setsockopt(s, SOL_SOCKET, SO_BROADCAST, (void *) &broadcastPermission, sizeof(broadcastPermission)) < 0) diep("setsockopt() failed"); memset((char *) &si_me, 0, sizeof(si_me)); si_me.sin_family = AF_INET; si_me.sin_port = htons(PORT); si_me.sin_addr.s_addr = htonl(INADDR_ANY); if (bind(s, &si_me, sizeof(si_me))==-1) diep("bind"); while (1) { if (recvfrom(s, buf, BUFLEN, 0, &si_other, &slen)==-1) diep("recvfrom()"); //printf("Received packet from %s:%d\nData: %s\n", inet_ntoa(si_other.sin_addr), ntohs(si_other.sin_port), buf); strcpy(zeni, ""); strcat(zeni, "zenity --warning --title Hack!! --text "); strcat(zeni, buf); printf("cmd: %s\n", zeni); //system (zeni); execl("/usr/bin/zenity", "/usr/bin/zenity", "--warning", "--title", "Warn!", "--text", buf, (char *) NULL); } close(s); return 0; }

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  • is there a proper way to handle multiple errors/exceptions?

    - by toPeerOrNotToPeer
    in OO programming, is there some conceptual pattern, ideas, about handling multiple errors? for example, i have a method that performs some checks and should return an error message for each error found ['name is too short', 'name contains invalid unicode sequences', 'name is too long'] now, should i use an array of exceptions (not thrown exceptions)? or something like this is better: class MyExceptionList extends Exception{ public Void addException(Exception e){} public Array getExceptions(){} } any theory behind this argument will be appreciated! (this isn't a request about a specific programming language, but a pure theoretical one) thank you in advance

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  • Freeing a character pointer returns error

    - by Kraffs
    I'm trying to free a character pointer after having used it but it returns a strange error. The error says: "_CrtDbgREport: String too long or IO Error" The debugger itself returns no errors while compiling. The code currently looks like this: void RespondToUser(SOCKET client, SOCKET server) { char buffer[80]; char *temp = malloc(_scprintf("HTTP/1.1 200 OK\r\n%s\r\nServer: %s\r\nConnection: close\r\n\r\nHi!", buffer, SERVER_NAME)); sprintf(temp, "HTTP/1.1 200 OK\r\n%s\r\nServer: %s\r\nConnection: close\r\n\r\nHi!", buffer, SERVER_NAME); send(client, temp, strlen(temp), 0); closesocket(client); free(temp); ListenToUsers(server); } The problem only occurs when I try to free the temp pointer from the memory and not otherwise. What might be causing this?

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  • Lots of bugs in SourceForge, maybe?

    - by Delirium tremens
    http://sourceforge.net/develop/ - Project Finder - Programming Language - Python ( * 16596 * ) - even so, All Anys - Go - Programming Language - Python ( * 11,847 * ) - Desktop ( * 572 * ) - All Desktop Categories (7 + 1 + 67 + 35 + 286 = * 396 * ) Does anybody know what is going on there?

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  • C# Asynchronous Sockets questions.

    - by ccppjava
    Based on my reading and testing, with asynchronous sockets, the socket itself can be passed using state object (IAsyncResult result), also if store the socket as a private field, it would be captured by the callback methods. I am wondering how the IAysnResult is kepted between the BeginXXX and ReceiveXXX? It looks to me that after the BeginXXX call and the method ends, the state object would be disposed by GC if there is no reference to it. In the case of private field, how the private field is shared between threads? (As far as I know, a callback is executed using a thread from the default thread pool, which would be considered as a new thread.) Many thanks, hope the questions themselves are clear.

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  • What are all the concurrent things [data structure, algorithm, locking mechanism] missing in .Net 3.

    - by user49767
    First time I am bit disappointed in StackOverflow cause my http://stackoverflow.com/questions/2571727/c-concurrency-vs-java-concurrency-which-is-neatly-designed-which-is-better question was closed. My intension was just trying to gather knowledge from programming guru's who worked in both the programming technologies. Rather closing this question, please help me by discussing what is good, bad, and ugly in multi-threading part in both the platforms. It is also welcome, if someone would like to compare with .Net 4.0 with JDK 6 (or JDK 7)

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  • acts_as_ferret with multiple hosts

    - by Nick
    I've got everything working with ferret and acts_as_ferret for development (or localhost DRb), but I can't get my multiple host deployment working. All of the remote systems get ECONNREFUSED when accessing the port. On the ferret server, the daemon is listening on localhost only despite the configuration listing the FQDN as the host. I also tried switching to a UNIX socket to share data between the ferret DRb daemon and the app code but it too gets ECONNREFUSED. (The socket is available to all of the machines via an NFS mount). Is there a better way to do this or should I be looking for another search indexer? Thanks.

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  • Threaded application sleeps with other application

    - by DeeD
    I have a weird problem with my threaded software. I start 2 instances of the software. Each instance has 2 threads, one thread creates a socket to use, and the other one is uses the socket for communication. When one of the threads in one instance calls sleep(3), the other threads in the the other instance sleeps too. And the weirdest thing is that when I rebooted the computer, it works the first time, but after trying a second time, it sleeps like described. How is this possible? Is it using some shared resource?

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  • Current stock price by using sockets in java

    - by user2976396
    My program is to find the current stock price of a symbol ..this is the code which i m using `String yahoo = "finance.yahoo.com" ; final int httpd = 80; Socket sock = new Socket(yahoo,httpd); PrintWriter out = new PrintWriter( sock.getOutputStream(), true ); BufferedReader in =new BufferedReader(new InputStreamReader( sock.getInputStream() ) ); out.println( "GET http://finance.yahoo.com/q?s=ibm&f=1l HTTP/1.0\r\n\r\n " ); out.println(""); out.flush();` I am just getting the output as ibm .Can anyone please suggest how to get the price.

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  • Beginner's book

    - by Aymen
    Hi I'm wanna learn C++ and i'm going to buy one of these books : Accelerated C++ Programming: Principles and Practice Using C++ Wich one do you consider more appropriate for me ? And is it worth it that I buy both of them ? PS: I'm not new to programming, I already have a good experience with Java and Scala. Thank you !

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  • Developing Bots__Where can I start?

    - by user947659
    i have a pet programming goal: to develop a bot for a game. Now, this won't be anything malicious, and I just want to do this to further my knowledge in programming. Can anyone help me out by pointing to where i can start learning how to develop a bot? the type of bots i want to make are video game bots (online multiplayer, first person shooters, and offline games(like solitaire and such)). Thanks!

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  • Is it worth learning C# or Java in 2010

    - by Dhawal
    We are in web era standalone applications are almost gone everyone wants their internet application to run inside browser, programming languages like Ruby, Python and scala are becoming more and more mainstream. Sometimes I wonder what these programming language offer which make them top choice of IT companies, if I plan to become a freelance web developer is it worth learning C# or Java. I read beginner's book for both of them, but to master any of them require some time investment.

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  • Why is the Java VM so popular?

    - by sdudo
    There are more and more programming languages (Scala, Clojure,...) coming out that are made for the Java VM and are therefore compatible with the Java Byte-Code. I'm beginning to ask myself: Why the Java VM? What makes it so powerful or popular that there are new programming languages, which seem gaining popularity too, created for it? Why don't they write a new VM for a new language?

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  • Does a servlet-based stack have significant overheads?

    - by John
    I don't know if it's simply because page-loads take a little time, or the way servlets have an abstraction framework above the 'bare metal' of HTTP, or just because of the "Enterprise" in Jave-EE, but in my head I have the notion that a servlet-based app is inherently adding overhead compared to a Java app which simply deals with sockets directly. Forget web-pages, imagine instead a Java server app where you send it a question over an HTTP request and it looks up an answer from memory and returns the answer in the response. You can easily write a Java socket-based app which does this, you can also do a servlet approach and get away from the "bare metal" of sockets. Is there any measurable performance impact to be expected implementing the same approach using Servlets rather than a custom socket-based HTTP listening app? And yes, I am hazy on the exact data sent in HTTP requests and I know it's a vague question. It's really about whether servlet implementations have lots of layers of indirection or anything else that would add up to a significant overhead per call, where by significant I mean maybe an additional 0.1s or more.

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  • Fork a process and send data to it inside Rails

    - by taro
    I'm making a Rails application. In the one action I need to spawn a long running process. This is not a problem. I can fork new process using spawn gem or some other. But some time after process has been spawned, user must be able to pass additional data to that process. Sure, I can fork process which will listen a UNIX socket, store socket address in the HTTP session and communicate with that process using drb protocol when user will require to pass new data to process. But I think it is not best solution and it will be a problem to deploy an application to the hosting. What is the easy way to do that?

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  • New to PHP, need book recommendations

    - by bran
    Hey guys, I need few good book recommendations for PHP. I am trying to learn to develop webapps. I know there are other (arguably) better language out there that I should start with (ie, python). But I want to start with PHP and go from there. My programming knowledge is limited to html/css (I know they are not actually programming languages), and I have gone through half of a python book. Thanks! :)

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  • How the websocket bi-directional concept work?

    - by GMsoF
    I think the main difference between websocket and http streaming (I am not refering to polling and long polling) is websocket allows bi-directional communication which is similar to usual raw socket programming. (above is my understanding, could be wrong, feel free to correct me.) My question is how the web client (browser) continue to send another request in the already-opened websocket? Usual http request will treat another request as new socket connection, but websocket does not, that is why I am confused, how it achieve that? It should be handled in Server side or Client (browser) side?

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  • A non-blocking server with java.io

    - by Jon
    Everybody knows that java IO is blocking, and java NIO is non-blocking. In IO you will have to use the thread per client pattern, in NIO you can use one thread for all clients. Now my question follows: is it possible to make a non-blocking design using only the Java IO api. (not NIO) I was thinking about a pattern like this (obviously very simplified); List<Socket> li; for (Socket s : li) { InputStream in = s.getInputStream(); byte[] data = in.available(); in.read(data); // processData(data); (decoding packets, encoding outgoing packets } Also note that the client will always be ready for reading data. What are your opinions on this? Will this be suitable for a server that should at least hold a few hundred of clients without major performance issues?

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