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  • Replace low level web-service reference call transport with custom one

    - by hoodoos
    I'm not sure if title sounds right actually, so I will give more explanation here. I will begin from very beginning :) I'm using c# and .net for my development. I have an application that makes requests to some soap web-service and for each user request it produces 3 to 10 requests for web-service, they should all run async to finish in one time, so I use Async method of the web-service generated reference and then wait for result on callback. But it seems like it starts a thread (or takes it from pool) for every async call I make, so if I have 10 clients I got to spawn 30 to 100 threads and it sounds terrible even for my 16 cores server :) So i wanted to replace low level transport implementation with my own which uses non-blocking sockets and can handle at least 50 sockets run parallel in one thread with not much overhead. But I actually dunno where to put my override best. I analyzed System.Web.Services.Protocols.SoapHttpClientProtocol class and see that it has some GetWebRequest method which I actually could use. If only I could somehow interupt the object it creates and get a http request with all headers and body from there and then send it with my own sockets.. Any ideas what approach to use? Or maybe there's something built in the framework I can use?

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  • Forward local port or socket file to remote socket file

    - by Ninefingers
    Hi All, Quick question - I run two linux boxes, one my own desktop and the other my VPS. For security reasons on the VPS end I opted for socket connections to MySQL (/var/run/mysqld/mysql.sock). I know I can tunnel like this: ssh -L 3307:127.0.0.1:3306 [email protected] if I set up the remote sql server to listen on some port, but what I want to know is can I do something like: ssh -L /path/to/myremotesqlserver.sock:/var/run/mysqld/mysql.sock thereby tunnelling two sockets, as opposed to two ports? A perfectly acceptable solution would also be to forward a local port to the remote socket file, but where possible I'm trying not to have tcp servers running on the remote box. (and yes, I know tcp would be easier). Thanks all, Nf.

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  • Raw socket sendto() failure in OS X

    - by user37278
    When I open a raw socket is OS X, construct my own udp packet (headers and data), and call sendto(), I get the error "Invalid Argument". Here is a sample program "rawudp.c" from the web site http://www.tenouk.com/Module43a.html that demonstrates this problem. The program (after adding string and stdlib #includes) runs under Fedora 10 but fails with "Invalid Argument" under OS X. Can anyone suggest why this fails in OS X? I have looked and looked and looked at the sendto() call, but all the parameters look good. I'm running the code as root, etc. Is there perhaps a kernel setting that prevents even uid 0 executables from sending packets through raw sockets in OS X Snow Leopard? Thanks.

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  • Using mod_wsgi with mpm_itk: socket permission issue

    - by djechelon
    I'm using mod_itk as MPM for increased security in shared environment. I also have a Firefox Sync Server within one of the VHosts I host. That vhost is restricted to a certain user via AssignUserId user group. The problem is that the socket /var/run/wsgi...whatever.sock is chmodded srwx------ and owned by Apache's wwwrun. While I configured the vhost with WSGIProcessGroup sync WSGIDaemonProcess sync user=djechelon group=djechelon processes=1 threads=5 I still get the error that Apache wants to access a socket that is not accessible and because of this gets an error. Is it possible to configure mod_wsgi in order to create different sockets with different owners for different applications or to chmod its socket in a different way (less secure)? Currently, I'm running Firefox Sync as the only WSGI application. Moving it to a vhost that doesn't AssignUserId could solve this problem but will force me to change URL (and buy an additional SSL certificate), so I wouldn't consider this

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  • How to set up memcached to use unix socket?

    - by alfish
    While I could use memcached on Debian to use the default 11211 port, but I've had great difficulty setting up unix socket, Form what I'v read, I know that I need to create a memcache.socket and add -s /path/to/memcache.socket -a 0766 To /etc/memcached.conf and comment out the default connection port and IP, i.e. -p 11211 -l 127.0.0.1 However, when I restart memcached I get internal server errors on Drupal site. I'm trying to implement unix sockets to avoid TCP/IP overhead and boost overal memcached performance, however not sure how much performance gain one can expect of this tweak. I appreciate your hints or possibly configs to to resolve this.

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  • How to configure LAMP server for iOS social/chat app?

    - by andufo
    I'm on the last developing phase of a social networking app for iOS that has a chat module. Right now I'm trying to figure out the best way to achieve these features: Send message instantly to another user. If other user is online, delivery should be instantly. If user reads the message, the remitent should be notified of that action. If a user visits my profile, I should be notified instantly. What would be, in your opinion, the best approach to achieve that experience? The server is CentOS 5.6. I've previously reviewed XMPP, sockets, but I'm still unsure on what the best approach is. Any opinions and resources will be much appreciated.

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  • How can 2 or more instances of the same program to communicate in local network?

    - by user1981437
    I want to create program which will be in use for few computers connected in local network. Basically the program aim is to keep track of all tables in a bar ( lets say ), which are reserved. When some user book a table as reserved the program should broadcast the table number to all other Pc's and mark the table as reserved. Since all computers use the same program, how is possible to create communication between all of them ? Should i use sockets to achieve this? If it matters, all of the computers have installed Linux OS,and the app will be developed in ruby,perl or php. Thank you.

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  • socket connection failed, telnet OK

    - by cf16
    my problem is that I can't connect two comps through socket (windows xp and windows7) although the server created with socket is listening and I can telnet it. It receives then information and does what should be done, but if I run the corresponding socket client I get error 10061. Moreover I am behind firewall - these two comps are running within my LAN, the windows firewalls are turned off, comp1: 192.168.1.2 port 12345 comp1: 192.168.1.6 port 12345 router: 192.168.1.1 Maybe port forwarding could help? But most important for me is to answer why Sockets fail if telnet works fine. client: int main(){ // Initialize Winsock. WSADATA wsaData; int iResult = WSAStartup(MAKEWORD(2,2), &wsaData); if (iResult != NO_ERROR) printf("Client: Error at WSAStartup().\n"); else printf("Client: WSAStartup() is OK.\n"); // Create a socket. SOCKET m_socket; m_socket = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP); if (m_socket == INVALID_SOCKET){ printf("Client: socket() - Error at socket(): %ld\n", WSAGetLastError()); WSACleanup(); return 7; }else printf("Client: socket() is OK.\n"); // Connect to a server. sockaddr_in clientService; clientService.sin_family = AF_INET; //clientService.sin_addr.s_addr = inet_addr("77.64.240.156"); clientService.sin_addr.s_addr = inet_addr("192.168.1.5"); //clientService.sin_addr.s_addr = inet_addr("87.207.222.5"); clientService.sin_port = htons(12345); if (connect(m_socket, (SOCKADDR*)&clientService, sizeof(clientService)) == SOCKET_ERROR){ printf("Client: connect() - Failed to connect.\n"); wprintf(L"connect function failed with error: %ld\n", WSAGetLastError()); iResult = closesocket(m_socket); if (iResult == SOCKET_ERROR) wprintf(L"closesocket function failed with error: %ld\n", WSAGetLastError()); WSACleanup(); return 6; } // Send and receive data int bytesSent; int bytesRecv = SOCKET_ERROR; // Be careful with the array bound, provide some checking mechanism char sendbuf[200] = "Client: Sending some test string to server..."; char recvbuf[200] = ""; bytesSent = send(m_socket, sendbuf, strlen(sendbuf), 0); printf("Client: send() - Bytes Sent: %ld\n", bytesSent); while(bytesRecv == SOCKET_ERROR){ bytesRecv = recv(m_socket, recvbuf, 32, 0); if (bytesRecv == 0 || bytesRecv == WSAECONNRESET){ printf("Client: Connection Closed.\n"); break; }else printf("Client: recv() is OK.\n"); if (bytesRecv < 0) return 0; else printf("Client: Bytes received - %ld.\n", bytesRecv); } system("pause"); return 0; } server: int main(){ WORD wVersionRequested; WSADATA wsaData={0}; int wsaerr; // Using MAKEWORD macro, Winsock version request 2.2 wVersionRequested = MAKEWORD(2, 2); wsaerr = WSAStartup(wVersionRequested, &wsaData); if (wsaerr != 0){ /* Tell the user that we could not find a usable WinSock DLL.*/ printf("Server: The Winsock dll not found!\n"); return 0; }else{ printf("Server: The Winsock dll found!\n"); printf("Server: The status: %s.\n", wsaData.szSystemStatus); } /* Confirm that the WinSock DLL supports 2.2.*/ /* Note that if the DLL supports versions greater */ /* than 2.2 in addition to 2.2, it will still return */ /* 2.2 in wVersion since that is the version we */ /* requested. */ if (LOBYTE(wsaData.wVersion) != 2 || HIBYTE(wsaData.wVersion) != 2 ){ /* Tell the user that we could not find a usable WinSock DLL.*/ printf("Server: The dll do not support the Winsock version %u.%u!\n", LOBYTE(wsaData.wVersion), HIBYTE(wsaData.wVersion)); WSACleanup(); return 0; }else{ printf("Server: The dll supports the Winsock version %u.%u!\n", LOBYTE(wsaData.wVersion), HIBYTE(wsaData.wVersion)); printf("Server: The highest version this dll can support: %u.%u\n", LOBYTE(wsaData.wHighVersion), HIBYTE(wsaData.wHighVersion)); } //////////Create a socket//////////////////////// //Create a SOCKET object called m_socket. SOCKET m_socket; // Call the socket function and return its value to the m_socket variable. // For this application, use the Internet address family, streaming sockets, and the TCP/IP protocol. // using AF_INET family, TCP socket type and protocol of the AF_INET - IPv4 m_socket = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP); // Check for errors to ensure that the socket is a valid socket. if (m_socket == INVALID_SOCKET){ printf("Server: Error at socket(): %ld\n", WSAGetLastError()); WSACleanup(); //return 0; }else{ printf("Server: socket() is OK!\n"); } ////////////////bind////////////////////////////// // Create a sockaddr_in object and set its values. sockaddr_in service; // AF_INET is the Internet address family. service.sin_family = AF_INET; // "127.0.0.1" is the local IP address to which the socket will be bound. service.sin_addr.s_addr = htons(INADDR_ANY);//inet_addr("127.0.0.1");//htons(INADDR_ANY); //inet_addr("192.168.1.2"); // 55555 is the port number to which the socket will be bound. // using the htons for big-endian service.sin_port = htons(12345); // Call the bind function, passing the created socket and the sockaddr_in structure as parameters. // Check for general errors. if (bind(m_socket, (SOCKADDR*)&service, sizeof(service)) == SOCKET_ERROR){ printf("Server: bind() failed: %ld.\n", WSAGetLastError()); closesocket(m_socket); //return 0; }else{ printf("Server: bind() is OK!\n"); } // Call the listen function, passing the created socket and the maximum number of allowed // connections to accept as parameters. Check for general errors. if (listen(m_socket, 1) == SOCKET_ERROR) printf("Server: listen(): Error listening on socket %ld.\n", WSAGetLastError()); else{ printf("Server: listen() is OK, I'm waiting for connections...\n"); } // Create a temporary SOCKET object called AcceptSocket for accepting connections. SOCKET AcceptSocket; // Create a continuous loop that checks for connections requests. If a connection // request occurs, call the accept function to handle the request. printf("Server: Waiting for a client to connect...\n"); printf("***Hint: Server is ready...run your client program...***\n"); // Do some verification... while (1){ AcceptSocket = SOCKET_ERROR; while (AcceptSocket == SOCKET_ERROR){ AcceptSocket = accept(m_socket, NULL, NULL); } // else, accept the connection... note: now it is wrong implementation !!!!!!!! !! !! (only 1 char) // When the client connection has been accepted, transfer control from the // temporary socket to the original socket and stop checking for new connections. printf("Server: Client Connected! Mammamija. \n"); m_socket = AcceptSocket; char recvBuf[200]=""; char * rc=recvBuf; int bytesRecv=recv(m_socket,recvBuf,64,0); if(bytesRecv==0 || bytesRecv==WSAECONNRESET){ cout<<"server: connection closed.\n"; }else{ cout<<"server: recv() is OK.\n"; if(bytesRecv<0){ return 0; }else{ printf("server: bytes received: %ld.\n",recvBuf); } }

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  • Remote Socket Read In Multi-Threaded Application Returns Zero Bytes or EINTR (104)

    - by user39891
    Hi. Am a c-coder for a while now - neither a newbie nor an expert. Now, I have a certain daemoned application in C on a PPC Linux. I use PHP's socket_connect as a client to connect to this service locally. The server uses epoll for multiplexing connections via a Unix socket. A user submitted string is parsed for certain characters/words using strstr() and if found, spawns 4 joinable threads to different websites simultaneously. I use socket, connect, write and read, to interact with the said webservers via TCP on their port 80 in each thread. All connections and writes seems successful. Reads to the webserver sockets fail however, with either (A) all 3 threads seem to hang, and only one thread returns -1 and errno is set to 104. The responding thread takes like 10 minutes - an eternity long:-(. *I read somewhere that the 104 (is EINTR?), which in the network context suggests that ...'the connection was reset by peer'; or (B) 0 bytes from 3 threads, and only 1 of the 4 threads actually returns some data. Isn't the socket read/write thread-safe? I use thread-safe (and reentrant) libc functions such as strtok_r, gethostbyname_r, etc. *I doubt that the said webhosts are actually resetting the connection, because when I run a single-threaded standalone (everything else equal) all things works perfectly right, but of course in series not parallel. There's a second problem too (oops), I can't write back to the client who connect to my epoll-ed Unix socket. My daemon application will hang and hog CPU 100% for ever. Yet nothing is written to the clients end. Am sure the client (a very typical PHP socket application) hasn't closed the connection whenever this is happening - no error(s) detected either. Any ideas? I cannot figure-out whatever is wrong even with Valgrind, GDB or much logging. Kindly help where you can.

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  • Faye private pub web sockets Errno::ECONNREFUSED: Connection refused - connect(2)

    - by Rubytastic
    Faye private pub has issues connecting. It works from rails console and from inside application. It fails when called from background process like delayed_job or sidekiq. I have been unable to resolve this issue for some time now, does anyone know why this happens? Errno::ECONNREFUSED: Connection refused - connect(2) /Users/jordan/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/2.0.0/resolv-replace.rb:23:in initialize' /Users/jordan/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/2.0.0/resolv-replace.rb:23:in initialize' /Users/jordan/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/2.0.0/net/http.rb:878:in open' /Users/jordan/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/2.0.0/net/http.rb:878:in block in connect' /Users/jordan/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/2.0.0/timeout.rb:52:in timeout' /Users/jordan/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/2.0.0/net/http.rb:877:in connect' /Users/jordan/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/2.0.0/net/http.rb:862:in do_start' /Users/jordan/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/2.0.0/net/http.rb:851:in start' /Users/jordan/.rvm/gems/ruby-2.0.0-p247@books/gems/private_pub-1.0.3/lib/private_pub.rb:42:in publish_message' /Users/jordan/.rvm/gems/ruby-2.0.0-p247@books/gems/private_pub-1.0.3/lib/private_pub.rb:29:in publish_to' /srv/books/app/workers/session_reload.rb:16:in perform' /Users/jordan/.rvm/gems/ruby-2.0.0-p247@books/gems/sidekiq-2.16.0/lib/sidekiq/processor.rb:48:in block (3 levels) in process' /Users/jordan/.rvm/gems/ruby-2.0.0-p247@books/gems/sidekiq-2.16.0/lib/sidekiq/middleware/chain.rb:119:in call' /Users/jordan/.rvm/gems/ruby-2.0.0-p247@books/gems/sidekiq-2.16.0/lib/sidekiq/middleware/chain.rb:119:inblock in invoke' /Users/jordan/.rvm/gems/ruby-2.0.0-p247@books/gems/newrelic_rpm-3.6.8.168/lib/new_relic/agent/instrumentation/sidekiq.rb:25:in block in call' /Users/jordan/.rvm/gems/ruby-2.0.0-p247@books/gems/newrelic_rpm-3.6.8.168/lib/new_relic/agent/instrumentation/controller_instrumentation.rb:324:in perform_action_with_newrelic_trace' /Users/jordan/.rvm/gems/ruby-2.0.0-p247@books/gems/newrelic_rpm-3.6.8.168/lib/new_relic/agent/instrumentation/sidekiq.rb:21:in call' /Users/jordan/.rvm/gems/ruby-2.0.0-p247@books/gems/sidekiq-2.16.0/lib/sidekiq/middleware/chain.rb:121:inblock in invoke' /Users/jordan/.rvm/gems/ruby-2.0.0-p247@books/gems/sidekiq-failures-0.2.2/lib/sidekiq/failures/middleware.rb:10:in call' /Users/jordan/.rvm/gems/ruby-2.0.0-p247@books/gems/sidekiq-2.16.0/lib/sidekiq/middleware/chain.rb:121:inblock in invoke' /Users/jordan/.rvm/gems/ruby-2.0.0-p247@books/gems/sidekiq-2.16.0/lib/sidekiq/middleware/server/active_record.rb:6:in call' /Users/jordan/.rvm/gems/ruby-2.0.0-p247@books/gems/sidekiq-2.16.0/lib/sidekiq/middleware/chain.rb:121:inblock in invoke' /Users/jordan/.rvm/gems/ruby-2.0.0-p247@books/gems/sidekiq-2.16.0/lib/sidekiq/middleware/server/retry_jobs.rb:62:in call' /Users/jordan/.rvm/gems/ruby-2.0.0-p247@books/gems/sidekiq-2.16.0/lib/sidekiq/middleware/chain.rb:121:inblock in invoke' /Users/jordan/.rvm/gems/ruby-2.0.0-p247@books/gems/sidekiq-2.16.0/lib/sidekiq/middleware/server/logging.rb:11:in block in call' /Users/jordan/.rvm/gems/ruby-2.0.0-p247@books/gems/sidekiq-2.16.0/lib/sidekiq/logging.rb:22:in with_context' /Users/jordan/.rvm/gems/ruby-2.0.0-p247@books/gems/sidekiq-2.16.0/lib/sidekiq/middleware/server/logging.rb:7:in call' /Users/jordan/.rvm/gems/ruby-2.0.0-p247@books/gems/sidekiq-2.16.0/lib/sidekiq/middleware/chain.rb:121:inblock in invoke' /Users/jordan/.rvm/gems/ruby-2.0.0-p247@books/gems/sidekiq-2.16.0/lib/sidekiq/middleware/chain.rb:124:in call' /Users/jordan/.rvm/gems/ruby-2.0.0-p247@books/gems/sidekiq-2.16.0/lib/sidekiq/middleware/chain.rb:124:ininvoke' /Users/jordan/.rvm/gems/ruby-2.0.0-p247@books/gems/sidekiq-2.16.0/lib/sidekiq/processor.rb:47:in block (2 levels) in process' /Users/jordan/.rvm/gems/ruby-2.0.0-p247@books/gems/sidekiq-2.16.0/lib/sidekiq/processor.rb:102:in stats' /Users/jordan/.rvm/gems/ruby-2.0.0-p247@books/gems/sidekiq-2.16.0/lib/sidekiq/processor.rb:46:in block in process' /Users/jordan/.rvm/gems/ruby-2.0.0-p247@books/gems/sidekiq-2.16.0/lib/sidekiq/processor.rb:83:in do_defer' /Users/jordan/.rvm/gems/ruby-2.0.0-p247@books/gems/sidekiq-2.16.0/lib/sidekiq/processor.rb:37:in process' /Users/jordan/.rvm/gems/ruby-2.0.0-p247@books/gems/celluloid-0.15.2/lib/celluloid/calls.rb:25:in public_send' /Users/jordan/.rvm/gems/ruby-2.0.0-p247@books/gems/celluloid-0.15.2/lib/celluloid/calls.rb:25:in dispatch' /Users/jordan/.rvm/gems/ruby-2.0.0-p247@books/gems/celluloid-0.15.2/lib/celluloid/calls.rb:122:in dispatch' /Users/jordan/.rvm/gems/ruby-2.0.0-p247@books/gems/celluloid-0.15.2/lib/celluloid/actor.rb:322:in block in handle_message' /Users/jordan/.rvm/gems/ruby-2.0.0-p247@books/gems/celluloid-0.15.2/lib/celluloid/actor.rb:416:in block in task' /Users/jordan/.rvm/gems/ruby-2.0.0-p247@books/gems/celluloid-0.15.2/lib/celluloid/tasks.rb:55:in block in initialize' /Users/jordan/.rvm/gems/ruby-2.0.0-p247@books/gems/celluloid-0.15.2/lib/celluloid/tasks/task_fiber.rb:13:in block in create' Processor: dev-air.local:db67c04914cdef80c501043115298f6d-70211452597260

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  • python blocking sockets, send returns immediately

    - by Mark
    Hi, I am writing a multithreaded socket application in Python using the socket module. the server listens for connections and when it gets one it spawns a thread for that socket. the server thread sends some data to the client. but the client is not yet ready to receive it. I thought this would have caused the server to wait until the client starts recv but instead returns immediately the client then calls recv which is blocking and no data is ever received. client socket constructor self.__clientSocket = socket.socket(socket.AF_INET, socket.SOCK_STREAM) self.__clientSocket.connect((server, port)) server socket constructor self.servSock = socket.socket(socket.AF_INET, socket.SOCK_STREAM) self.servSock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1) #self.servSock.settimeout(None) self.servSock.setblocking(1) self.servSock.bind((self.addr,self.port)) self.servSock.listen(5) listening accept thread try: (cs, address) = self.servSock.accept() except socket.timeout: return threadName = '\r\nClient %s:%s\r\n' % (cs, address) print threadName clientSocketHandler = ClientSocket() clientSocketHandler.setClientSocket(cs) self.clients.newThread(self.clientFunc, {clientSocketHandler : "1"}, threadName).start() server and clients send/rec methods from inside ClientSocket receivedData = self.__clientSocket.recv(1024*1024) self.__clientSocket.send(s) any ideas why send() is returning straight away?

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  • What is the best way to send structs containing enum values via sockets in C.

    - by Axel
    I've lots of different structs containing enum members that I have to transmit via TCP/IP. While the communication endpoints are on different operating systems (Windows XP and Linux) meaning different compilers (gcc 4.x.x and MSVC 2008) both program parts share the same header files with type declarations. For performance reasons, the structures should be transmitted directly (see code sample below) without expensively serializing or streaming the members inside. So the question is how to ensure that both compilers use the same internal memory representation for the enumeration members (i.e. both use 32-bit unsigned integers). Or if there is a better way to solve this problem... //type and enum declaration typedef enum { A = 1, B = 2, C = 3 } eParameter; typedef enum { READY = 400, RUNNING = 401, BLOCKED = 402 FINISHED = 403 } eState; #pragma pack(push,1) typedef struct { eParameter mParameter; eState mState; int32_t miSomeValue; uint8_t miAnotherValue; ... } tStateMessage; #pragma pack(pop) //... send via socket tStateMessage msg; send(iSocketFD,(void*)(&msg),sizeof(tStateMessage)); //... receive message on the other side tStateMessage msg_received; recv(iSocketFD,(void*)(&msg_received),sizeof(tStateMessage)); Additionally... Since both endpoints are little endian maschines, endianess is not a problem here. And the pack #pragma solves alignment issues satisfactorily. Thx for your answers, Axel

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  • Web Services vs Persistent Sockets

    - by dsquires
    I plan on doing a little benchmarking around this question, myself. But I thought it would be good to get some initial feedback from "the community". Has anyone out there done any analysis regarding the pros and cons of these two technologies? My thoughts: Opening and closing TCP/IP connections for web service calls is relatively expensive compared to persistent connections. Dealing with intermittent connection errors and state, etc... would be easier with a web service based framework. You don't see World of Warcraft using web services. One question that I can't seem to find much of answer for anywhere (even on here)... are the limits on the # of persistent connections a single network card can support, etc?

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  • Returning from dll (Asynchronous sockets)

    - by Juha
    I am trying to do a simple http-server in (c++) dll-file that I can use from managed (C#) application with P/Invoke. I was trying to do this with asynchronous functions (WSAAsyncSelect() and stuff), so that I could manage server by calling functions inside dll whenever needed and after that it would return to my main program. Now I'm not sure if that is even possible. It seems that "main function" in dll, the function that starts the server, has to include message loop or something and since it's a loop, it doesn't return from dll ever. Could I somehow do this message stuff in my managed application and call some function in dll when there is something to do? Or is it even possible to do this stuff in one thred? I would really like to avoid all concurrency stuff. The dll looks now basicly the same as here, main function is the one that I call from managed C# program and would like to return to there after calling the function. http://www.winsocketdotnetworkprogramming.com/winsock2programming/winsock2advancediomethod5b.html I'm quite noob in windows programming, and never even heard of this message-queue or message-loop.

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  • C# UDP decoding datagrams fails randomly

    - by Tom Frey
    Hi, I'm experiencing an issue in a multi threaded application and have been debugging it for the last 3 days but for the life of it can not figure it out. I'm writing this, hoping that I either have a DUH moment when typing this or somebody sees something obvious in the code snippets I provide. Here's what's going on: I've been working on a new UDP networking library and have a data producer that multicasts UDP datagrams to several receiver applications. The sender sends on two different sockets that are bound to separate UDP multicast addresses and separate ports. The receiver application also creates two sockets and binds each one to one of the sender's multicast address/port. When the receiver receives the datagram, it copies it from the the buffer in a MemoryStream which is then put onto a thread safe queue, where another thread reads from it and decodes the data out of the MemoryStream. Both sockets have their own queues. What happens now is really weird, it happens randomly, non-reproducible and when I run multiple receiver applications, it only happens randomly on one of them every now and then. Basically, the thread that reads the MemoryStream out of the queue, reads it via a BinaryReader like ReadInt32(), etc. and thereby decodes the data. Every now and then however when it reads the data, the data it reads from it is incorrect, e.g. a negative integer number which the sender never would encode. However, as mentioned before, the decoding only fails in one of the receiver applications, in the other ones the datagram decodes fine. Now you might be saying, well, probably the UDP datagram has a byte corruption or something but I've logged every single datagram that's coming in and compared them on all receivers and the datagrams every application receives are absolutely identical. Now it gets even weirder, when I dump the datagram that failed to decode to disk and write a unit test that reads it and runs it through the decoder, it decodes just fine. Also when I wrap a try/catch around the decoder, reset the MemoryStream position in the catch and run it through the decoder again, it decodes just fine. To make it even weirder, this also only happens when I bind both sockets to read data from the sender, if I only bind one, it doesn't happen or at least I wasn't able to reproduce it. Here are is some corresponding code to what's going on: This is the receive callback for the socket: private void ReceiveCompleted(object sender, SocketAsyncEventArgs args) { if (args.SocketError != SocketError.Success) { InternalShutdown(args.SocketError); return; } if (args.BytesTransferred > SequencedUnitHeader.UNIT_HEADER_SIZE) { DataChunk chunk = new DataChunk(args.BytesTransferred); Buffer.BlockCopy(args.Buffer, 0, chunk.Buffer, 0, args.BytesTransferred); chunk.MemoryStream = new MemoryStream(chunk.Buffer); chunk.BinaryReader = new BinaryReader(chunk.MemoryStream); chunk.SequencedUnitHeader.SequenceID = chunk.BinaryReader.ReadUInt32(); chunk.SequencedUnitHeader.Count = chunk.BinaryReader.ReadByte(); if (prevSequenceID + 1 != chunk.SequencedUnitHeader.SequenceID) { log.Error("UdpDatagramGap\tName:{0}\tExpected:{1}\tReceived:{2}", unitName, prevSequenceID + 1, chunk.SequencedUnitHeader.SequenceID); } else if (chunk.SequencedUnitHeader.SequenceID < prevSequenceID) { log.Error("UdpOutOfSequence\tName:{0}\tExpected:{1}\tReceived:{2}", unitName, prevSequenceID + 1, chunk.SequencedUnitHeader.SequenceID); } prevSequenceID = chunk.SequencedUnitHeader.SequenceID; messagePump.Produce(chunk); } else UdpStatistics.FramesRxDiscarded++; Socket.InvokeAsyncMethod(Socket.ReceiveAsync, ReceiveCompleted, asyncReceiveArgs); } Here's some stub code that decodes the data: public static void OnDataChunk(DataChunk dataChunk) { try { for (int i = 0; i < dataChunk.SequencedUnitHeader.Count; i++) { int val = dataChunk.BinaryReader.ReadInt32(); if(val < 0) throw new Exception("EncodingException"); // do something with that value } } catch (Exception ex) { writer.WriteLine("ID:" + dataChunk.SequencedUnitHeader.SequenceID + " Count:" + dataChunk.SequencedUnitHeader.Count + " " + BitConverter.ToString(dataChunk.Buffer, 0, dataChunk.Size)); writer.Flush(); log.ErrorException("OnDataChunk", ex); log.Info("RETRY FRAME:{0} Data:{1}", dataChunk.SequencedUnitHeader.SequenceID, BitConverter.ToString(dataChunk.Buffer, 0, dataChunk.Size)); dataChunk.MemoryStream.Position = 0; dataChunk.SequencedUnitHeader.SequenceID = dataChunk.BinaryReader.ReadUInt32(); dataChunk.SequencedUnitHeader.Count = dataChunk.BinaryReader.ReadByte(); OnDataChunk(dataChunk); } } You see in the catch{} part I simply reset the MemoryStream.Position to 0 and call the same method again and it works just fine that next time? I'm really out of ideas at this point and unfortunately had no DUH moment writing this. Anybody have any kind of idea what might be going on or what else I could do to troubleshoot this? Thanks, Tom

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  • Sockets with Silverlight 4

    - by AngryHacker
    I need to implement a persistent socket connection from my in-browser Silverlight 4 app to a device on the network. I need the following: Connect to it and keep a persistent connection Send and Receive data Get some type of event or notification (or detect it) when the connection drops. Is this possible with Silverlight 4? If so, can someone point me to some examples? All I am finding are some attempts at it with Silverlight 2.

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  • When binding a client TCP socket to a specific local port with Winsock, SO_REUSEADDR does not have a

    - by Checkers
    I'm binding a client TCP socket to a specific local port. To handle the situation where the socket remains in TIME_WAIT state for some time, I use setsockopt() with SO_REUSEADDR on a socket. It works on Linux, but does not work on Windows, I get WSAEADDRINUSE on connect() call when the previous connection is still in TIME_WAIT. MSDN is not exactly clear what should happen with client sockets: [...] For server applications that need to bind multiple sockets to the same port number, consider using setsockopt (SO_REUSEADDR). Client applications usually need not call bind at all—connect chooses an unused port automatically. [...] How do I avoid this?

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  • Swing code in sockets

    - by asb
    I am learning swings for making GUI. I was thinking which is the best possible way in case of socket with swings. 1. The whole swing code goes in the server file. All the handlers and logic in on server side. Client only create socket. 2. The server have logic part. The code for the swing to display interface goes on client side. Client Creates stream to send / rec. data from server. Whch is the good way out of 2 ?

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  • How to make an existing socket fail?

    - by Huckphin
    OK. So, this is exactly the opposite of what everyone asks about in network programming. Usually, people ask how to make a broken socket work. I, on the other hand am looking for the opposite. I currently have sockets working fine, and want them to break to re-create this problem we are seeing. I am not sure how to go about intentionally making the socket fail by having a bad read. The trick is this: The socket needs to be a working, established connection, and then it must fail for whatever reason. I'm writing this in C and the drivers are running on a Linux system. The sockets are handled by a non-IP Level 3 protocol in Linux by a Linux Device Driver. I have full access to all of the code-base, I just need to find a way to tease it out so that it can fail. Any ideas?

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  • Fast way to test if a port is in use using Python

    - by directedition
    I have a python server that listens on a couple sockets. At startup, I try to connect to these sockets before listening, so I can be sure that nothing else is already using that port. This adds about three seconds to my server's startup (which is about .54 seconds without the test) and I'd like to trim it down. Since I'm only testing localhost, I think a timeout of about 50 milliseconds is more than ample for that. Unfortunately, the socket.setdefaulttimeout(50) method doesn't seem to work for some reason. How I can trim this down?

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  • programmatically controlling power sockets in the UK

    - by cartoonfox
    It's very simple. I want to plug a lamp into the UK mains supply. I want to be able to power it on and off from software - say from serial port commands, or by running a command-line or something I can get to from ruby or Java. I see lots written about how to do this with X10 with American power systems - but has anybody actually tried doing this in the UK? If you got this working: 1) Exactly what hardware did you use? 2) How do you control it from software? Thanks!

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  • how to learn winsock or raw sockets? (c++)

    - by blood
    i have been googleing trying to find a Winsock book or something about networking but all i can find is out of date books or nothing at all :( so does anyone know a book i can buy to learn about networking in VC++ 2008? i really would like a book i could hold because i learn better when it's in my hand.

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  • problem with closing sockets

    - by Samantha
    Hi, I'm trying to write a client/server program with threads. I close the socket once the connexion is finished. The servers gets plenty of new connexions, and the socket number (file descriptor) increases very quickly: after 5 minutes running I was already at around file descriptor number 800! Is this a normal thing? Do threads share file descriptors? When I do close(sockfd); is the number released immediatly or after a some time? PS: I used to do with fork(), and I didn't have this issue. Thanks

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  • Getting "Illegal Seek" error after calling accept()

    - by Bilthon
    Well.. it's pretty much that, I seem to be getting a "Illegal Seek" error when checking my errno variable. The problem is that I have no idea of what that can mean. I know sockets are treated like files in unix, but I can't see how can this be related to sockets. What I'm doing exactly is: int sck = ::accept(m_socket, (struct sockaddr*)&client_address, (socklen_t*)&address_len); Then I get sck = -1 and errno = ESPIPE And the weird thing is that it happens randomly. I mean, sometimes the code works fine, and sometimes it just thows an exception. I'm working with threads so that's understandable. But I just would like to know what kind of behaviour makes the accept() call to set errno as ESPIPE so I could check the paramethers for instance. Thanks Nelson R. Pérez

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