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  • [C++][Boost] Acceptor and Problems with Async_Accept

    - by bobber205
    See code. :P I am able to receive new connections before async_accept() has been called. My delegate function is also never called so I can't manage any connections I receive, rendering the new connections useless. ;) So here's my question. Is there a way to prevent the Boost ASIO acceptor from getting new connections on its own and only getting connections from async_accept()? Thanks! bool AlexSocket::StartListening(int port) { bool didStart = false; if (!this->listening) { //try to listen acceptor = new tcp::acceptor(this->myService); boost::asio::ip::tcp::endpoint endpoint(boost::asio::ip::tcp::v4(), port); acceptor->open(endpoint.protocol()); acceptor->set_option(boost::asio::ip::tcp::acceptor::reuse_address(true)); acceptor->bind(endpoint); //CAN GET NEW CONNECTIONS HERE (before async_accept is called) acceptor->listen(); didStart = true; //probably change? tcp::socket* tempNewSocket = new tcp::socket(this->myService); acceptor->async_accept(*tempNewSocket, boost::bind(&AlexSocket::NewConnection, this, tempNewSocket, boost::asio::placeholders::error) ); } else //already started! return false; this->listening = didStart; return didStart; } //this function is never called :( void AlexSocket::NewConnection(tcp::socket* s, const boost::system::error_code& error) { cout << "New Connection Made" << endl; //Start new accept async tcp::socket* tempNewSocket = new tcp::socket(this->myService); acceptor->async_accept(*tempNewSocket, boost::bind(&AlexSocket::NewConnection, this, tempNewSocket, boost::asio::placeholders::error) ); }

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  • c windows connect() fails. error 10049

    - by Joshua Moore
    The following two pieces of code compile, but I get a connect() failed error on the client side. (compiled with MinGW). Client Code: // thanks to cs.baylor.edu/~donahoo/practical/CSockets/code/TCPEchoClientWS.c #include <stdio.h> #include <winsock.h> #include <stdlib.h> #define RCVBUFSIZE 32 // size of receive buffer void DieWithError(char *errorMessage); int main(int argc, char* argv[]) { int sock; struct sockaddr_in echoServAddr; unsigned short echoServPort; char *servIP; char *echoString; char echoBuffer[RCVBUFSIZE]; int echoStringLen; int bytesRcvd, totalBytesRcvd; WSAData wsaData; if((argc < 3) || (argc > 4)){ fprintf(stderr, "Usage: %s <Sever IP> <Echo Word> [<Echo Port>]\n", argv[0]); exit(1); } if (argc==4) echoServPort = atoi(argv[3]); // use given port if any else echoServPort = 7; // echo is well-known port for echo service if(WSAStartup(MAKEWORD(2, 0), &wsaData) != 0){ // load winsock 2.0 dll fprintf(stderr, "WSAStartup() failed"); exit(1); } // create reliable, stream socket using tcp if((sock=socket(PF_INET, SOCK_STREAM, IPPROTO_TCP)) < 0) DieWithError("socket() failed"); // construct the server address structure memset(&echoServAddr, 0, sizeof(echoServAddr)); echoServAddr.sin_family = AF_INET; echoServAddr.sin_addr.s_addr = inet_addr(servIP); // server IP address echoServAddr.sin_port = htons(echoServPort); // establish connection to the echo server if(connect(sock, (struct sockaddr*)&echoServAddr, sizeof(echoServAddr)) < 0) DieWithError("connect() failed"); echoStringLen = strlen(echoString); // determine input length // send the string, includeing the null terminator to the server if(send(sock, echoString, echoStringLen, 0)!= echoStringLen) DieWithError("send() sent a different number of bytes than expected"); totalBytesRcvd = 0; printf("Received: "); // setup to print the echoed string while(totalBytesRcvd < echoStringLen){ // receive up to the buffer size (minus 1 to leave space for a null terminator) bytes from the sender if(bytesRcvd = recv(sock, echoBuffer, RCVBUFSIZE-1, 0) <= 0) DieWithError("recv() failed or connection closed prematurely"); totalBytesRcvd += bytesRcvd; // keep tally of total bytes echoBuffer[bytesRcvd] = '\0'; printf("%s", echoBuffer); // print the echo buffer } printf("\n"); closesocket(sock); WSACleanup(); exit(0); } void DieWithError(char *errorMessage) { fprintf(stderr, "%s: %d\n", errorMessage, WSAGetLastError()); exit(1); } Server Code: // thanks cs.baylor.edu/~donahoo/practical/CSockets/code/TCPEchoServerWS.c #include <stdio.h> #include <winsock.h> #include <stdlib.h> #define MAXPENDING 5 // maximum outstanding connection requests #define RCVBUFSIZE 1000 void DieWithError(char *errorMessage); void HandleTCPClient(int clntSocket); // tcp client handling function int main(int argc, char **argv) { int serverSock; int clientSock; struct sockaddr_in echoServerAddr; struct sockaddr_in echoClientAddr; unsigned short echoServerPort; int clientLen; // length of client address data structure WSAData wsaData; if (argc!=2){ fprintf(stderr, "Usage: %s <Server Port>\n", argv[0]); exit(1); } echoServerPort = atoi(argv[1]); if(WSAStartup(MAKEWORD(2, 0), &wsaData)!=0){ fprintf(stderr, "WSAStartup() failed"); exit(1); } // create socket for incoming connections if((serverSock=socket(PF_INET, SOCK_STREAM, IPPROTO_TCP))<0) DieWithError("socket() failed"); // construct local address structure memset(&echoServerAddr, 0, sizeof(echoServerAddr)); echoServerAddr.sin_family = AF_INET; echoServerAddr.sin_addr.s_addr = htonl(INADDR_ANY); // any incoming interface echoServerAddr.sin_port = htons(echoServerPort); // local port // bind to the local address if(bind(serverSock, (struct sockaddr*)&echoServerAddr, sizeof(echoServerAddr) )<0) DieWithError("bind() failed"); // mark the socket so it will listen for incoming connections if(listen(serverSock, MAXPENDING)<0) DieWithError("listen() failed"); for (;;){ // run forever // set the size of the in-out parameter clientLen = sizeof(echoClientAddr); // wait for a client to connect if((clientSock = accept(serverSock, (struct sockaddr*)&echoClientAddr, &clientLen)) < 0) DieWithError("accept() failed"); // clientSock is connected to a client printf("Handling client %s\n", inet_ntoa(echoClientAddr.sin_addr)); HandleTCPClient(clientSock); } // NOT REACHED } void DieWithError(char *errorMessage) { fprintf(stderr, "%s: %d\n", errorMessage, WSAGetLastError()); exit(1); } void HandleTCPClient(int clientSocket) { char echoBuffer[RCVBUFSIZE]; // buffer for echostring int recvMsgSize; // size of received message // receive message from client if((recvMsgSize = recv(clientSocket, echoBuffer, RCVBUFSIZE, 0) <0)) DieWithError("recv() failed"); // send received string and receive again until end of transmission while(recvMsgSize > 0){ // echo message back to client if(send(clientSocket, echoBuffer, recvMsgSize, 0)!=recvMsgSize) DieWithError("send() failed"); // see if there's more data to receive if((recvMsgSize = recv(clientSocket, echoBuffer, RCVBUFSIZE, 0)) <0) DieWithError("recv() failed"); } closesocket(clientSocket); // close client socket } How can I fix this?

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  • Analyzing Python Code: Modulus Operator

    - by Bhubhu Hbuhdbus
    I was looking at some code in Python (I know nothing about Python) and I came across this portion: def do_req(body): global host, req data = "" s = socket.socket(socket.AF_INET, socket.SOCK_STREAM) s.connect((host, 80)) s.sendall(req % (len(body), body)) tmpdata = s.recv(8192) while len(tmpdata) > 0: data += tmpdata tmpdata = s.recv(8192) s.close() return data This is then called later on with body of huge size, as in over 500,000 bytes. This is sent to an Apache server that has the max request size on the default 8190 bytes. My question is what is happening at the "s.sendall()" part? Obviously the entire body cannot be sent at once and I'm guessing it is reduced by way of the modulus operator. I don't know how it works in Python, though. Can anyone explain? Thanks.

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  • ZeroMQ REQ/REP on ipc:// and concurrency

    - by Metiu
    I implemented a JSON-RPC server using a REQ/REP 0MQ ipc:// socket and I'm experiencing strange behavior which I suspect is due to the fact that the ipc:// underlying unix socket is not a real socket, but rather a single pipe. From the documentation, one has to enforce strict zmq_send()/zmq_recv() alternation, otherwise the out-of-order zmq_send() will return an error. However, I expected the enforcement to be per-client, not per-socket. Of course with a Unix socket there is just one pipeline from multiple clients to the server, so the server won't know who it is talking with. Two clients could zmq_send() simultaneously and the server would see this as an alternation violation. The sequence could be: ClientA: zmq_send() ClientB: zmq_send() : will it block until the other send/receive completes? will it return -1? (I suspect it will with ipc:// due to inherent low-level problems, but with TCP it could distinguish the two clients) ClientA: zmq_recv() ClientB: zmq_recv() so what about tcp:// sockets? Will it work concurrently? Should I use some other locking mechanism to work around this?

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  • Compiling linux library for mingw32

    - by TheFuzz
    I have been using a socket library for C++. Some other info: 32 bit Linux, Codelite and GCC toolset. I want to be able to compile my program for Windows using the windows edition of Codelite. The socket library I have been using doesn’t have a mingw32 build of the library, but it’s open source. So how can I make a mingw32 build of the socket library so I can make a windows build using the source provided?

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  • How to hide helper functions from public API in c

    - by emge
    I'm working on a project and I need to create an API. I am using sockets to communicate between the server (my application) and the clients (the other applications using my API). This project is in c not C++ I come from a linux background and this is my first project using Windows, Visual Studio 2008, and dll libraries. I have communication working between the client and server, but I have some that is duplicated on both projects. I would like to create a library (probably a dll file), that both projects can link to so I don't have to maintain extra code. I also have to create the library that has the API that I need to make available for my clients. Within the API functions that I want public are the calls to these helper functions that are "duplicated code", I don't want to expose these functions to my client, but I do want my server to be able to use those functions. How can I do this? I will try to clarify with an example. This is what I started with. Server Project: int Server_GetPacket(SOCKET sd); int ReceiveAll(SOCKET sd, char *buf, int len); int VerifyLen(char *buf); Client Project: int Client_SendCommand(int command); int Client_GetData(int command, char *buf, int len); int ReceiveAll(SOCKET sd, char *buf, int len); int VerifyLen(char *buf); This is kind of what I would like to end up with: //Server Project: int Server_GetPacket(SOCKET sd); // library with public and private types // private API (not exposed to my client) int ReceiveAll(SOCKET sd, char *buf, int len); int VerifyLen(char *buf); // public API (header file available for client) int Client_SendCommand(int command); int Client_GetData(int command, char *buf, int len); Thanks any help would be appreciated.

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  • Code only runs properly if debugging step-by-step

    - by Cornwell
    Hello, I'm making a webserver and I've come up with some very strange problems. My server was running as expected yesterday when I turned off my laptop, but today it only sends the http headers (I didn't change anything) When a user requests a file, if I send them using the following code, it works perfectly: while ((n = fread(data, 1, sizeof(data), file)) > 0) send(ts, data, n, 0); but if I change it to this, it only sends ~2% of the file. And that's not a random number, it actually only sends about 2% of the file. while ((n = fread(data, 1, sizeof(data), file)) > 0) web.Send(data); int WEB::Send(string data) { return send(TempSocket, data.c_str(), data.size(), 0); } changing string to char* doesn't solve the problem. I'm using visual studio2010. If I run my code step-by-step, I am able to solve problem #1, everything gets sent. And that is my main problem. I do not understand why it happens. Hopefully someone can explain it to me. Thanks in advance. EDIT: int APIENTRY WinMain( HINSTANCE hInstance, HINSTANCE hPrev, LPSTR lpCmd,int nShow) { SOCKET MainSocket=0; MSG msg; RedirectIOToConsole(); CreateThread(NULL, NULL, ListenThread, NULL, NULL, NULL); while (GetMessage(&msg, NULL, 0, 0)) { TranslateMessage(&msg); DispatchMessage(&msg); } WSACleanup(); closesocket(MainSocket); MainSocket = INVALID_SOCKET; return msg.wParam; } DWORD WINAPI ListenThread(LPVOID lparam) { SOCKET MainSocket; WSADATA wsaData; SOCKET tmpsock; struct sockaddr_in local, from; int fromlen=sizeof(from); WSAStartup(MAKEWORD(2, 2), &wsaData); local.sin_family=AF_INET; local.sin_addr.s_addr=INADDR_ANY; local.sin_port=htons(PORT); MainSocket=socket(AF_INET,SOCK_STREAM,0); if(MainSocket==INVALID_SOCKET) { return 0; } if(bind(MainSocket,(struct sockaddr*)&local,sizeof(local))!=0) { return 0; } if(listen(MainSocket,10)!=0) { return 0; } while(1) { tmpsock = accept(MainSocket,(struct sockaddr*)&from,&fromlen); CreateThread(NULL, NULL, SlaveThread, (LPVOID)tmpsock, NULL, NULL); } } DWORD WINAPI SlaveThread(LPVOID lparam) { SOCKET ts = (SOCKET)lparam;//temporary socket ...... char data[4096]; int n; unsigned long int length = statbuf.st_size; web.SendHeaders(200, "OK", format("Content-Disposition: attachment; filename=\"%s\"", FileName.c_str()).c_str(), web.GetMimeType(ReqPath.c_str()), length, statbuf.st_mtime); unsigned long int i=0,d=0; while ((n = fread(data, 1, sizeof(data), file)) > 0) { d+=send(ts, data, n, 0); i+=n; } printf("%i=%i=%i\n", length,i,d); fclose(file);

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  • C++ MFC server app with sockets crashes and I cannot find the fault, help!

    - by usermeister
    My program has one dialog and two sockets. Both sockets are derived from CAsyncSocket, one is for listening, other is for receiving data from client. My program crashes when client tries to connect to server application and server needs to initialize receiving socket. This is my MFC dialog class. class CFileTransferServerDlg : public CDialog { ... ListeningSocket ListenSock; ReceivingSocket* RecvSock; void OnAccept(); // called when ListenSock gets connection attempt ... }; This is my derived socket class for receiving data that calls parent dialogs method when event is signaled. class ReceivingSocket : public CAsyncSocket { CFileTransferServerDlg* m_pDlg; // for accessing parent dialogs controls virtual void OnReceive(int nErrorCode); } ReceivingSocket::ReceivingSocket() { } This is dialogs function that handles incoming connection attempt when listening socket gets event notification. This is where the crash happens. void CFileTransferServerDlg::OnAccept() { RecvSock = new ReceivingSocket; /* CRASH */ } OR void CFileTransferServerDlg::OnAccept() { ReceivingSocket* tmpSock = new ReceivingSocket; tmpSock->SetParentDlg(this); CString message; if( ListenSock.Accept(*tmpSock) ) /* CRASH */ { message.LoadStringW(IDS_CLIENT_CONNECTED); m_txtStatus.SetWindowTextW(message); RecvSock = tmpSock; } } My program crashes when I try to create a socket for receiving file sent from client application. OnAccept starts when Listening socket signals incoming connection attempt, but my application then crashes. I've tried running it on another computer and connection attempt was succesful. What could be wrong? Error in debug mode: Unhandled exception at 0x009c30e1 in FileTransferServer.exe: 0xC0000005: Access violation reading location 0xccccce58.

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  • Where to begin with multi-threaded programming with c++?

    - by zoke
    I'm trying to implement my own IRC client as a personal proejct and I realized I needed a way to read and write from the socket at the same time. I realized I could have a reading thread which reads from the socket in the background and puts data in a queue and I could have another thread which writes data from a queue to the socket. However I have no idea on how to start with multithreaded programing or how to do it with c++. Where do I go from here?

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  • Splitting Code into Headers/Source files

    - by cam
    I took the following code from the examples page on Asio class tcp_connection : public boost::enable_shared_from_this<tcp_connection> { public: typedef boost::shared_ptr<tcp_connection> pointer; static pointer create(boost::asio::io_service& io_service) { return pointer(new tcp_connection(io_service)); } tcp::socket& socket() { return socket_; } void start() { message_ = make_daytime_string(); boost::asio::async_write(socket_, boost::asio::buffer(message_), boost::bind(&tcp_connection::handle_write, shared_from_this(), boost::asio::placeholders::error, boost::asio::placeholders::bytes_transferred)); } private: tcp_connection(boost::asio::io_service& io_service) : socket_(io_service) { } void handle_write(const boost::system::error_code& /*error*/, size_t /*bytes_transferred*/) { } tcp::socket socket_; std::string message_; }; I'm relatively new to C++ (from a C# background), and from what I understand, most people would split this into header and source files (declaration/implementation, respectively). Is there any reason I can't just leave it in the header file if I'm going to use it across many source files? If so, are there any tools that will automatically convert it to declaration/implementation for me? Can someone show me what this would look like split into header/source file for an example (or just part of it, anyway)? I get confused around weird stuff like thistypedef boost::shared_ptr<tcp_connection> pointer; Do I include this in the header or the source? Same with tcp::socket& socket() I've read many tutorials, but this has always been something that has confused me about C++.

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  • How Do Sockets Work in C?

    - by kaybenleroll
    I am a bit confused about socket programming in C. You create a socket, bind it to an interface and an IP address and get it to listen. I found a couple of web resources on that, and understood it fine. In particular, I found an article Network programming under Unix systems to be very informative. What confuses me is the timing of data arriving on the socket. How can you tell when packets arrive, and how big the packet is, do you have to do all the heavy lifting yourself? My basic assumption here is that packets can be of variable length, so once binary data starts appearing down the socket, how do you begin to construct packets from that?

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  • Problems with Asynchronous UDP Sockets

    - by ihatenetworkcoding
    Hi, I'm struggling a bit with socket programming (something I'm not at all familiar with) and I can't find anything which helps from google or MSDN (awful). Apologies for the length of this. Basically I have an existing service which recieves and responds to requests over UDP. I can't change this at all. I also have a client within my webapp which dispatches and listens for responses to that service. The existing client I've been given is a singleton which creates a socket and an array of response slots, and then creates a background thread with an infinite looping method that makes "sock.Receive()" calls and pushes the data received into the slot array. All kinds of things about this seem wrong to me and the infinite thread breaks my unit testing so I'm trying to replace this service with one which makes it's it's send/receives asynchronously instead. Point 1: Is this the right approach? I want a non-blocking, scalable, thread-safe service. My first attempt is roughly like this, which sort of worked but the data I got back was always shorter than expected (i.e. the buffer did not have the number of bytes requested) and seemed to throw exceptions when processed. private Socket MyPreConfiguredSocket; public object Query() { //build a request this.MyPreConfiguredSocket.SendTo(MYREQUEST, packet.Length, SocketFlags.Multicast, this._target); IAsyncResult h = this._sock.BeginReceiveFrom(response, 0, BUFFER_SIZE, SocketFlags.None, ref this._target, new AsyncCallback(ARecieve), this._sock); if (!h.AsyncWaitHandle.WaitOne(TIMEOUT)) { throw new Exception("Timed out"); } //process response data (always shortened) } private void ARecieve (IAsyncResult result) { int bytesreceived = (result as Socket).EndReceiveFrom(result, ref this._target); } My second attempt was based on more google trawling and this recursive pattern I frequently saw, but this version always times out! It never gets to ARecieve. public object Query() { //build a request this.MyPreConfiguredSocket.SendTo(MYREQUEST, packet.Length, SocketFlags.Multicast, this._target); State s = new State(this.MyPreConfiguredSocket); this.MyPreConfiguredSocket.BeginReceiveFrom(s.Buffer, 0, BUFFER_SIZE, SocketFlags.None, ref this._target, new AsyncCallback(ARecieve), s); if (!s.Flag.WaitOne(10000)) { throw new Exception("Timed out"); } //always thrown //process response data } private void ARecieve (IAsyncResult result) { //never gets here! State s = (result as State); int bytesreceived = s.Sock.EndReceiveFrom(result, ref this._target); if (bytesreceived > 0) { s.Received += bytesreceived; this._sock.BeginReceiveFrom(s.Buffer, s.Received, BUFFER_SIZE, SocketFlags.None, ref this._target, new AsyncCallback(ARecieve), s); } else { s.Flag.Set(); } } private class State { public State(Socket sock) { this._sock = sock; this._buffer = new byte[BUFFER_SIZE]; this._buffer.Initialize(); } public Socket Sock; public byte[] Buffer; public ManualResetEvent Flag = new ManualResetEvent(false); public int Received = 0; } Point 2: So clearly I'm getting something quite wrong. Point 3: I'm not sure if I'm going about this right. How does the data coming from the remote service even get to the right listening thread? Do I need to create a socket per request? Out of my comfort zone here. Need help.

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  • Detecting TCP dropout over an unreliable network

    - by yx
    I am doing some experimentation over an unreliable radio network (home brewed) using very rudimentary java socket programming to transfer messages back and forth between the end nodes. The setup is as follows: Node A --- Relay Node --- Node B One problem I am constantly running into is that somehow the connection drops out and neither Node A or B knows that the link is dead, and yet continues to transmit data. The TCP connection does not time out either. I have added in a heartbeat message that causes a timeout after a while, but I still would like to know what is the underlying cause of why TCP does not time out. Here are the options I am enabling when setting up a socket: channel.socket().setKeepAlive(false); channel.socket().setTrafficClass(0x08); // for max throughput This behavior is strange since it is totally different than when I have a wired network. On a wired network, I can simulate a disconnected connection by pulling out the ethernet cord, however, once I plug the cord back in, the connection becomes restablished and messages begin to be passed through once more. On the radio network, the connection is never reestablished and once it silently dies, the messages never resume. Is there some other unknown java implentation or setting for a socket that I can use, also, why am I seeing this behavior in the first place? And yes, before anyone says anything, I know TCP is not the preffered choice over an unreliable network, but in this case I wanted to ensure no packet loss.

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  • TDD, Unit Test and architectural changes

    - by Leandro
    I'm writing an RPC middleware in C++. I have a class named RPCClientProxy that contains a socket client inside: class RPCClientProxy { ... private: Socket* pSocket; ... } The constructor: RPCClientProxy::RPCClientProxy(host, port) { pSocket = new Socket(host, port); } As you can see, I don't need to tell the user that I have a socket inside. Although, to make unit tests for my proxies it would be necessary to create mocks for sockets and pass them to the proxies, and to do so I must use a setter or pass a factory to the sockets in the proxies's constructors. My question: According to TDD, is it acceptable to do it ONLY because the tests? As you can see, these changes would change the way the library is used by a programmer.

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  • BluetoothChat doesn't work

    - by jes
    Hello I want to make conversation between android devices. I use BluetoothChat to do this but it doesn't work I can't read correctly data from another device. Conversation is : Me: privet Device: p Device: rivet Can you help me? private class ConnectedThread extends Thread { private final InputStream mmInStream; private final OutputStream mmOutStream; public ConnectedThread(BluetoothSocket socket) { Log.d(TAG, "create ConnectedThread"); mmSocket = socket; //InputStream tmpIn = null; OutputStream tmpOut = null; BufferedInputStream tmpIn=null; int INPUT_BUFFER_SIZE=32; // Get the BluetoothSocket input and output streams try { //tmpIn = socket.getInputStream(); tmpOut = socket.getOutputStream(); tmpIn = new BufferedInputStream(socket.getInputStream(),INPUT_BUFFER_SIZE); } catch (IOException e) { Log.e(TAG, "temp sockets not created", e); } mmInStream = tmpIn; mmOutStream = tmpOut; } public void run() { Log.i(TAG, "BEGIN mConnectedThread"); byte[] buffer = new byte[1024]; int bytes; // Keep listening to the InputStream while connected while (true) { try { // Read from the InputStream bytes = mmInStream.read(buffer); // Send the obtained bytes to the UI Activity mHandler.obtainMessage(BluetoothChat.MESSAGE_READ, bytes, -1, buffer) .sendToTarget(); } catch (IOException e) { Log.e(TAG, "disconnected", e); connectionLost(); break; } } }

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  • Joel Spolsky Retires From Blogging in 3 Days

    - by andyleonard
    No it's not 1 Apr. Joel Spolsky ( Blog - @spolsky ) announced recently he is retiring from blogging 17 Mar 2010 . Reading Joel on Software always makes me think. Mr. Spolsky pioneered a writing style. Along the way he empowered developers, encouraging them to speak up about the manifold misconceptions of our trade. I will miss Mr. Spolsky's writings. I wish him well in all his endeavors. :{| Andy Share this post: email it! | bookmark it! | digg it! | reddit! | kick it! | live it!...(read more)

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  • Faceted search with Solr on Windows

    - by Dr.NETjes
    With over 10 million hits a day, funda.nl is probably the largest ASP.NET website which uses Solr on a Windows platform. While all our data (i.e. real estate properties) is stored in SQL Server, we're using Solr 1.4.1 to return the faceted search results as fast as we can.And yes, Solr is very fast. We did do some heavy stress testing on our Solr service, which allowed us to do over 1,000 req/sec on a single 64-bits Solr instance; and that's including converting search-url's to Solr http-queries and deserializing Solr's result-XML back to .NET objects! Let me tell you about faceted search and how to integrate Solr in a .NET/Windows environment. I'll bet it's easier than you think :-) What is faceted search? Faceted search is the clustering of search results into categories, allowing users to drill into search results. By showing the number of hits for each facet category, users can easily see how many results match that category. If you're still a bit confused, this example from CNET explains it all: The SQL solution for faceted search Our ("pre-Solr") solution for faceted search was done by adding a lot of redundant columns to our SQL tables and doing a COUNT(...) for each of those columns:   So if a user was searching for real estate properties in the city 'Amsterdam', our facet-query would be something like: SELECT COUNT(hasGarden), COUNT(has2Bathrooms), COUNT(has3Bathrooms), COUNT(etc...) FROM Houses WHERE city = 'Amsterdam' While this solution worked fine for a couple of years, it wasn't very easy for developers to add new facets. And also, performing COUNT's on all matched rows only performs well if you have a limited amount of rows in a table (i.e. less than a million). Enter Solr "Solr is an open source enterprise search server based on the Lucene Java search library, with XML/HTTP and JSON APIs, hit highlighting, faceted search, caching, replication, and a web administration interface." (quoted from Wikipedia's page on Solr) Solr isn't a database, it's more like a big index. Every time you upload data to Solr, it will analyze the data and create an inverted index from it (like the index-pages of a book). This way Solr can lookup data very quickly. To explain the inner workings of Solr is beyond the scope of this post, but if you want to learn more, please visit the Solr Wiki pages. Getting faceted search results from Solr is very easy; first let me show you how to send a http-query to Solr:    http://localhost:8983/solr/select?q=city:Amsterdam This will return an XML document containing the search results (in this example only three houses in the city of Amsterdam):    <response>     <result name="response" numFound="3" start="0">         <doc>            <long name="id">3203</long>            <str name="city">Amsterdam</str>            <str name="steet">Keizersgracht</str>            <int name="numberOfBathrooms">2</int>        </doc>         <doc>             <long name="id">3205</long>             <str name="city">Amsterdam</str>             <str name="steet">Vondelstraat</str>             <int name="numberOfBathrooms">3</int>          </doc>          <doc>             <long name="id">4293</long>             <str name="city">Amsterdam</str>             <str name="steet">Wibautstraat</str>             <int name="numberOfBathrooms">2</int>          </doc>       </result>   </response> By adding a facet-querypart for the field "numberOfBathrooms", Solr will return the facets for this particular field. We will see that there's one house in Amsterdam with three bathrooms and two houses with two bathrooms.    http://localhost:8983/solr/select?q=city:Amsterdam&facet=true&facet.field=numberOfBathrooms The complete XML response from Solr now looks like:    <response>      <result name="response" numFound="3" start="0">         <doc>            <long name="id">3203</long>            <str name="city">Amsterdam</str>            <str name="steet">Keizersgracht</str>            <int name="numberOfBathrooms">2</int>         </doc>         <doc>            <long name="id">3205</long>            <str name="city">Amsterdam</str>            <str name="steet">Vondelstraat</str>            <int name="numberOfBathrooms">3</int>         </doc>         <doc>            <long name="id">4293</long>            <str name="city">Amsterdam</str>            <str name="steet">Wibautstraat</str>            <int name="numberOfBathrooms">2</int>         </doc>      </result>      <lst name="facet_fields">         <lst name="numberOfBathrooms">            <int name="2">2</int>            <int name="3">1</int>         </lst>      </lst>   </response> Trying Solr for yourself To run Solr on your local machine and experiment with it, you should read the Solr tutorial. This tutorial really only takes 1 hour, in which you install Solr, upload sample data and get some query results. And yes, it works on Windows without a problem. Note that in the Solr tutorial, you're using Jetty as a Java Servlet Container (that's why you must start it using "java -jar start.jar"). In our environment we prefer to use Apache Tomcat to host Solr, which installs like a Windows service and works more like .NET developers expect. See the SolrTomcat page.Some best practices for running Solr on Windows: Use the 64-bits version of Tomcat. In our tests, this doubled the req/sec we were able to handle!Use a .NET XmlReader to convert Solr's XML output-stream to .NET objects. Don't use XPath; it won't scale well.Use filter queries ("fq" parameter) instead of the normal "q" parameter where possible. Filter queries are cached by Solr and will speed up Solr's response time (see FilterQueryGuidance)In my next post I’ll talk about how to keep Solr's indexed data in sync with the data in your SQL tables. Timestamps / rowversions will help you out here!

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  • Fixing /etc/shadow with md5 passwords to sha512 passwords

    - by dr jimbob
    I recently upgraded an ubuntu server with many users to a recent version from a version from 2008. The server used to use md5 password hashes (e.g., the shadow passwords began with $1$) and now is configured to use sha512. I'd prefer to keep using sha512, but would like the old users to be able to partially login once with their old password and then be forced to update their password (even if its the same password) generating a sha512. Right now, the old md5-based passwords in /etc/shadow won't let the user login at all (and just appear to be incorrect passwords). This seems like plenty of people should have had to do this before; yet I can't see how to do it, looking in the common places like /etc/pam.d/common-password nad /etc/login.defs. Also users will be logging in via ssh; and I do not have everyone's contact info (email or otherwise); and some login fairly rarely. Any help? (Googling doesn't seem to give any good solutions).

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  • Open source engagement as a professional reference

    - by Martin
    if one commits his or her time to an open source project, he or she may be invest a substantial amount of time without getting paid. As much as altruism is appreciable, I wonder whether it "counts" as an activity which can be shown and is valued in job applications. If the company is worth your time and working power, which it should be in my honest opinion. So I wonder whether there is something like a common practice in open source projects for this matters. Say, something like Mr. Martin has been working on our project for five years and has contributed this and that,[...] I we wish him very best for his future. Mr. ChiefofProject I think this is a just concern. Do have experiences you can share?

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  • Is there a LibreOffice equivalent to microsofts office themes?

    - by Dr. Mike
    I've used MS office for many years now. Especially powerpoint. One of the strengths is that it defines and separates the concepts of template and theme. A theme can be saved and contains fonts, colours, and a set of images that can be reused every time you create a new presentation. This ensures that everyone in your organization uses exactly the same colours and fonts all the time. Now I know that you can download templates for LibreOffice, but I have not seen anything similar to the theme concept. The file extensions used in MS office are the following for the two concepts mentioned: Example Powerpoint template file name: mytemplate.potx Example Powerpoint theme file name: mytheme.thmx Now back to my question: Do these concepts and their separation exist in LibreOffice or OpenOffice? If so, how do I create them?

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  • Suitable Ubuntu distribution

    - by Dr AMD
    I need help choosing a suitable distrbution for my PC. I am using an HP d530 CMT with: ?• CPU Type: Intel Pentium 4, 3000 MHz (15 x 200) ?• Motherboard Chipset: Intel Springdale-G i865G ?• System Memory: 1015 MB (PC3200 DDR SDRAM) ?• Video Adapter: Intel(R) 82865G Graphics Controller (96 MB) ?• 3D Accelerator: Intel Extreme Graphics 2 ?• Audio Adapter: Analog Devices AD1981B(L) @ Intel 82801EB ICH5 - AC'97 Audio Controller ?• Network Adapter: Broadcom NetXtreme Gigabit Ethernet I have tried to install Ubuntu 13.10 and 12.04 LTS. Everything is OK on Ubuntu 12.04 except, that the video card was not recognized and the media player, YouTube,etc. did not work properly.

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  • CloudFlare DNS: Downtime failover host

    - by Dr. McKay
    My company uses CloudFlare for its DNS, but as our site is HTTPS-secured and we're on the free plan, we can't utilize CloudFlare's CDN services. Our host has fairly rare but not insignificant downtime. We can't migrate servers just yet, and I'd like to be able to either have the main domain redirect to the status domain, or simply resolve to the alternative status host in the event of downtime so users will stop bugging me asking if the site is down. Is this possible to do automatically using the free CloudFlare plan, or will I have to manually edit my DNS every time the site goes down?

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  • Why is my partition claiming to be out of space?

    - by Dr C
    My file system claims to only have 4.5 GB left. While my OS (a folder with in file system) still has 75.2 GB left. I put something near 130 GB on my Ubuntu partition, it should have enough space. I confirmed that I can put things in OS that exceed the space in available file systems, but that makes no sense, OS is listed as a folder inside of file system, why would it have more space than it's parent folder? What is going on? Here is the output of df: Filesystem 1K-blocks Used Available Use% Mounted on /dev/sda5 113773200 103741440 4252408 97% / udev 2004600 4 2004596 1% /dev tmpfs 804756 848 803908 1% /run none 5120 0 5120 0% /run/lock none 2011884 436 2011448 1% /run/shm /dev/sda2 127526908 54045584 73481324 43% /media/OS /dev/sda3 39144708 89016 39055692 1% /media/DATA`

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  • Screensaver + lock double login problem after Maverick upgrade

    - by dr Hannibal Lecter
    Just found something strange after updating from 10.04 to 10.10. I've set up my screensaver to lock the account when activated. When I log back in, I see my desktop for a second and then the screensaver starts again and I have to re-login. I checked my process list in gnome system monitor, and I have two gnome-screensaver processes(!?), one started as /usr/bin/gnome-screensaver and other simply as gnome-screensaver. And no, I did not start one manually. Where do I look for a way to switch off one of those (supposing that's the problem)? I did not find anything in my startup applications.

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