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• How to asynchronously read to std::string using Boost::asio?

  - by SpyBot

  Hello. I'm learning Boost::asio and all that async stuff. How can I asynchronously read to variable user_ of type std::string? Boost::asio::buffer(user_) works only with async_write(), but not with async_read(). It works with vector, so what is the reason for it not to work with string? Is there another way to do that besides declaring char user_[max_len] and using Boost::asio::buffer(user_, max_len)? Also, what's the point of inheriting from boost::enable_shared_from_this<Connection> and using shared_from_this() instead of this in async_read() and async_write()? I've seen that a lot in the examples. Here is a part of my code: class Connection { public: Connection(tcp::acceptor &acceptor) : acceptor_(acceptor), socket_(acceptor.get_io_service(), tcp::v4()) { } void start() { acceptor_.get_io_service().post( boost::bind(&Connection::start_accept, this)); } private: void start_accept() { acceptor_.async_accept(socket_, boost::bind(&Connection::handle_accept, this, placeholders::error)); } void handle_accept(const boost::system::error_code& err) { if (err) { disconnect(); } else { async_read(socket_, boost::asio::buffer(user_), boost::bind(&Connection::handle_user_read, this, placeholders::error, placeholders::bytes_transferred)); } } void handle_user_read(const boost::system::error_code& err, std::size_t bytes_transferred) { if ( err or (bytes_transferred != sizeof(user_)) ) { disconnect(); } else { ... } } ... void disconnect() { socket_.shutdown(tcp::socket::shutdown_both); socket_.close(); socket_.open(tcp::v4()); start_accept(); } tcp::acceptor &acceptor_; tcp::socket socket_; std::string user_; std::string pass_; ... };

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• Using T[1] instead of T for functions overloaded for T(&)[N]

  - by Abyx

  The asio::buffer function has (void*, size_t) and (PodType(&)[N]) overloads. I didn't want to write ugly C-style (&x, sizeof(x)) code, so I wrote this: SomePacket packet[1]; // SomePacket is POD read(socket, asio::buffer(packet)); foo = packet->foo; But that packet-> looks kinda weird - the packet is an array after all. (And packet[0]. doesn't look better.) Now, I think if it was a good idea to write such code. Maybe I should stick to unsafe C-style code with void* and sizeof? Upd: here is another example, for writing a packet: SomePacket packet[1]; // SomePacket is POD packet->id = SomePacket::ID; packet->foo = foo; write(socket, asio::buffer(packet));

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• For distributed applications, which to use, ASIO vs. MPI?

  - by Rhubarb

  I am a bit confused about this. If you're building a distributed application, which in some cases may perform parallel operations (although not necessarily mathematical), should you use ASIO or something like MPI? I take it MPI is a higher level than ASIO, but it's not clear where in the stack one would begin.

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• Creative software leftovers - ASIO error message

  - by Tony Patriarche

  I temporarily installed an old Creative Audigy 2 soundboard on my Vista x64 Home Premium computer. Bad idea! I uninstalled the board & all software visible on the control panel. Now, with one particular app. (Sibelius) I keep getting a start-up message "CTASIO Warning: Creative ASIO: there are no Creative audio products installed on the system that support ASIO". I offer this as a candidate for "Most useless message", but that's beside the point. I used a commercial registry cleaner (PC-Tools Registry Mechanic) and then edited the registry looking for "creative", "audigy" and "ASIO". After removing everything I could find, I still get the message. Any suggestions?

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• How to create a simple server/client application using boost.asio?

  - by the_drow

  I was going over the examples of boost.asio and I am wondering why there isn't an example of a simple server/client example that prints a string on the server and then returns a response to the client. I tried to modify the echo server but I can't really figure out what I'm doing at all. Can anyone find me a template of a client and a template of a server? I would like to eventually create a server/client application that receives binary data and just returns an acknowledgment back to the client that the data is received.

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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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• Boost program will not working on Linux

  - by Martin Lauridsen

  Hi SOF, I have this program which uses Boost::Asio for sockets. I pretty much altered some code from the Boost examples. The program compiles and runs just like it should on Windows in VS. However, when I compile the program on Linux and run it, I get a Segmentation fault. I posted the code here The command I use to compile it is this: c++ -I/appl/htopopt/Linux_x86_64/NTL-5.4.2/include -I/appl/htopopt/Linux_x86_64/boost_1_43_0/include mpqs.cpp mpqs_polynomial.cpp mpqs_host.cpp -o mpqs_host -L/appl/htopopt/Linux_x86_64/NTL-5.4.2/lib -lntl -L/appl/htopopt/Linux_x86_64/gmp-4.2.1/lib -lgmp -lm -L/appl/htopopt/Linux_x86_64/boost_1_43_0/lib -lboost_system -lboost_thread -static -lpthread By commenting out code, I have found out that I get the Segmentation fault due to the following line: boost::asio::io_service io_service; Can anyone provide any assistance, as to what may be the problem (and the solution)? Thanks! Edit: I tried changing the program to a minimal example, using no other libraries or headers, just boost/asio.hpp: #define DEBUG 0 #include <boost/asio.hpp> int main(int argc, char* argv[]) { boost::asio::io_service io_service; return 0; } I also removed other library inclusions and linking on compilation, however this minimal example still gives me a segmentation fault.

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• Memory fragmentation @ boost::asio ?

  - by Poni

  I'm pretty much stuck with a question I never got an answer for, a question which addresses an extremely important issue; memory fragmentation at boost::asio. Found nothing at the documentation nor here at SO. The functions at boost::asio, for example async_write() & async_read_some() always allocate something. (in my case it's 144 & 96 bytes respectively, in VC9 Debug build). How do I know about it? I connect a client to the "echo server" example provided with this library. I put a breakpoint at "new.cpp" at the code of "operator new(size_t size)". Then I send "123". Breakpoint is hit! Now using the stack trace I can clearly see that the root to the "new" call is coming from the async_write() & async_read_some() calls I make in the function handlers. So memory fragmentation will come sooner or later, thus I can't use ASIO, and I wish I could! Any idea? Any helpful code example?

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• Boost ASIO read X bytes synchroniously into a vector

  - by xeross

  Hey, I've been attempting to write a client/server app with boost now, so far it sends and receives but I can't seem to just read X bytes into a vector. If I use the following code vector<uint8_t> buf; for (;;) { buf.resize(4); boost::system::error_code error; size_t len = socket.read_some(boost::asio::buffer(buf), error); if (error == boost::asio::error::eof) break; // Connection closed cleanly by peer. else if (error) throw boost::system::system_error(error); // Some other error. } And the packet is bigger then 4 bytes then it seems it keeps writing into those 4 bytes until the entire packet has been received, however I want it to fetch 4 bytes, then allow me to parse them, and then get the rest of the packet. Can anyone provide me with a working example, or at least a pointer on how to make it work properly ? Regards, Xeross

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• Binding a member signal to a function

  - by the_drow

  This line of code compiles correctly without a problem: boost::bind(boost::ref(connected_), boost::dynamic_pointer_cast<session<version> >(shared_from_this()), boost::asio::placeholders::error); However when assigning it to a boost::function or as a callback like this: socket_->async_connect(connection_->remote_endpoint(), boost::bind(boost::ref(connected_), boost::dynamic_pointer_cast<session<version> >(shared_from_this()), boost::asio::placeholders::error)); I'm getting a whole bunch of incomprehensible errors (linked since it's too long to fit here). On the other hand I have succeeded binding a free signal to a boost::function like this: void print(const boost::system::error_code& error) { cout << "session connected"; } int main() { boost::signal<void(const boost::system::error_code &)> connected_; connected_.connect(boost::bind(&print, boost::asio::placeholders::error)); client<>::connection_t::socket_ptr socket_(new client<>::connection_t::socket_t(conn->service())); // shared_ptr of a tcp socket socket_->async_connect(conn->remote_endpoint(), boost::bind(boost::ref(connected_), boost::asio::placeholders::error)); conn->service().run(); // io_service.run() return 0; } This works and prints session connected correctly. What am I doing wrong here?

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• what is the best mid/high-end class audio/music creation audio sound card?

  - by Chris

  Hello, I have a computershop myself, and I repair computers. But one of the things I really don't know (yet) is the performace od audio cards for music creation with midi. I have searched and searched and came up with some good reviews, but after browsing for a couple of hours I could't see the trees trough the forrest :-D (it's a dutch expression) At one moment I thought the M-Audio - Delta 1010LT would be a good PCIe card, later on I read that this card was released years ago. (but that could be false information) Also any personal expierence would be great, but not necessairy. I have searched a few cards, and I hope someone can help me make a choice for a friend of mine. He's buget is between $100 and $350 I know there are audio cards from $ 500 - $1850,- this is just too expensive. The following specs are crucial: ASIO Midi Mic in minimal 5.1, 7.1 recommended it's not for airplay, but just to compose music at home. using Ableton and midi keyboard. 1. M-Audio - Delta 1010LT: 8 x 8 analog I/O 2 mic preamps or line inputs S/PDIF digital I/O (coaxial) with 2-channel PCM SCMS copy protection control digital I/O supports surround-encoded AC-3 and DTS pass-through 1 x 1 MIDI I/O directly drive up to 7.1 surround (bass management software included) software controlled 36-bit internal DSP digital mixing/routing +4dbu/-10dBV operation individually switched in software word clock I/O for sample accurate device synchronization 2. RME HDSP 9632: * Stereo Analog Ein- und Ausgang, symmetrisch*, 24-Bit/192kHz, > 110 dB SNR * Optionale Erweiterungsboards mit je 4 symmetrischen Ein- und Ausgängen * Alle analogen I/Os voll 192 kHz-fähig, also keine Reduzierung der Kanalzahl * 1 x ADAT Digital In/Out, 96 kHz-fähig (S/MUX) * 1 x SPDIF Digital In/Out, 192 kHz-fähig * 1 x Breakout Kabel für koaxialen SPDIF-Betrieb* * Also bis zu 16 Ein-und Ausgänge gleichzeitig nutzbar! * 1 x Stereo Kopfhörerausgang, parallel zum analogen Ausgang, aber eigene Pegelanpassung * 1 x MIDI I/O für 16 Kanäle Hi-Speed MIDI über Breakout Kabel * DIGICheck, RMEs einzigartiges Meter- und Analysetool mit Spectral Analyser, Professionelle Level Meter 2/8/16-Kanalig, Vector Audio Scope und diversen weiteren Analysefunktionen * HDSP Meter Bridge: Frei skalierbare Levelmeter mit Peak- und RMS Berechnung in Hardware * TotalMix: 512-Kanal Mischer mit 40 Bit interner Auflösung 3. EMU 1212M (1212 M) PCIe: * Top kwaliteit convertors 24-bit/192kHz convertors. * Hardware gestuurde effecten. * DSP zero-latency hardware mixen en monitoring. * Analoge en digitale I/O plus MIDI. * EMU Production Tools Software Bundle - Cakewalk SONAR , Steinberg Cubase LE, Ableton Live E-MU Edition **EMU 1212M PCI-e inputs/outputs:** * 2 balanced jack inputs. * 2 balanced jack outputs. * 24-bit/192kHz ADAT I/O. * 24-bit/192kHz Coaxiale S/PDif I/O switchable to AES/EBU. * MIDI I/O. 4. M-Audio Audiophile 192: - Up to 24-bit/192kHz audio - 2 balanced analog inputs (1/4” TRS) - 2 balanced analog outputs (1/4” TRS) - S/PDIF digital I/O (coaxial RCA connectors) with 2-channel PCM - SCMS copy protection control - Digital I/O supports surround-encoded AC-3 and DTS pass-through - Direct hardware input monitoring via separate balanced 1/4” TRS monitor outputs - Software routing of inputs and outputs - Digital I/O can be routed to/from external effects - 16-channel MIDI I/O - ASIO, WDM, GSIF 2 and Core Audio driver support for compatibility with most applications - 64-bit driver support for Windows - PCI 2.2 compatibility - Apple G5 compatible - Incompatible exceptions - Includes Ableton Live Lite music production software, so you can make music right away - Works with other Delta cards Technical Specifcations: - Compatibility - ASIO - WDM - GSIF 2 - Core Audio

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• What is wrong with this attempt of sending a break-signal?

  - by Jook

  I have quite a headache about this seemingly easy task: send a break signal to my device, like the wxTerm (or any similar Terminal application) does. This signal has to be 125ms long, according to my tests and the devices specification. It should result in a specific response, but what I get is a longer response than expected, and the transmitted date is false. e.g.: what it should respond 08 00 81 00 00 01 07 00 what it does respond 08 01 0A 0C 10 40 40 07 00 7F What really boggles me is, that after I have used wxTerm to look at my available com-ports (without connecting or sending anything), my code starts to work! I can send then as many breaks as I like, I get my response right from then on. I have to reset my PC in order to try it again. What the heck is going on here?! Here is my code for a reset through a break-signal: minicom_client(boost::asio::io_service& io_service, unsigned int baud, const string& device) : active_(true), io_service_(io_service), serialPort(io_service, device) { if (!serialPort.is_open()) { cerr << "Failed to open serial port\n"; return; } boost::asio::serial_port_base::flow_control FLOW( boost::asio::serial_port_base::flow_control::hardware ); boost::asio::serial_port_base::baud_rate baud_option(baud); serialPort.set_option(FLOW); serialPort.set_option(baud_option); read_start(); std::cout << SetCommBreak(serialPort.native_handle()) << std::endl; std::cout << GetLastError() << std::endl; boost::posix_time::ptime mst1 = boost::posix_time::microsec_clock::local_time(); boost::this_thread::sleep(boost::posix_time::millisec(125)); boost::posix_time::ptime mst2 = boost::posix_time::microsec_clock::local_time(); std::cout << ClearCommBreak(serialPort.native_handle()) << std::endl; std::cout << GetLastError() << std::endl; boost::posix_time::time_duration msdiff = mst2 - mst1; std::cout << msdiff.total_milliseconds() << std::endl; } Edit: It was only necessary to look at the combo-box selection of com-ports of wxTerm - no active connection was needed to be established in order to make my code work. I am guessing, that there is some sort of initialisation missing, which is done, when wxTerm is creating the list for the serial-port combo-box.

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• Using boost::asio::async_read with stdin?

  - by yeus

  hi poeple.. short question: I have a realtime-simulation which is running as a backround process and is connected with pipes to the calling pogramm. I want to send commands to that process using stdin to get certain information from it via stdout. Now because it is a real-time process, it has to be a non blocking input. Is boost::asio::async_read in conjunction with iostream::cin a good idea for this task? how would I use that function if it is feasible? Any more suggestions?

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• C++: Best text accumulator

  - by MInner

  Text gets accumulates piecemeal before being sent to client. Now we use own class that allocates memory for each piece as char massive. (Anyway, works like char[][] + std::list<char*>). Then we build the whole string, convert it into std::sting and then create boost::asio::streambuf using it. That's slow enough, I assume. Correct me if I'm wrong. I know, in many cases simple FILE type from stdio.h is used. How does it works? Allocates memory at every write into it. So, is it faster and is there any way to read into boost::asio::streambuf from FILE?

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• Boost.Asio: The difference between async_read and async_recieve

  - by wowus

  What's the difference between async_read and async_receive?

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• Compatibility between Qt and Boost sockets libraries

  - by cake

  Hello In my work, I'm developing a Viewer client for a Offshore simulation server, using sockets to send the simulation data from the Simulator to de Viewer. But, the server uses Boost.asio as it's sockets library. As the client uses Qt for it's GUI, I was wondering if there is any problem in using de Qt Networking library for handling the sockets. Is there any compatibility issues? Thanks in advance, and sorry for my bad english.

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• How to raise a boost::signal whenever a packet is recieved?

  - by the_drow

  I know that boost.asio has a mechanism that calls a callback function whenever a packet is received but is there an option to emit a signal instead? Do I have to write a function that emits the signal? If it is so, why?

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• No network packets sent immediately after quick physical disconnect and reconnect.

  - by Hans

  I am using Boost's ASIO libraries to establish a UDP connection to a remote server. To make sure the connection is active, every second a keep-alive message is sent to the server. I have noticed that if I unplug the network cable and reinsert it quickly, the first 2 or 3 keep-alive messages after the reinsert are never sent. I tested this by running wire-shark on the server. I have seen it take up to 5 seconds before the client starts sending out network traffic again. The client is running under Linux (2.6.2), if that helps.

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• Writing a filter for incoming connections

  - by Kornel Kisielewicz

  I'm using C++/boost::asio under Win7. I'm trying to "sniff" trafic over a given TCP/IP port. Hence, I'd like to listen on that port, receive messages, analyze them, but also immidately allow them to flow further, as if I never intercepted them. I want them to sink into the program that normally listens and connects on that port. Imagine a transparent proxy, but not for HTTP. I'd rather find a code-based solution, but barring that, maybe you would suggest a tool?

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• How to program a connection pool?

  - by the_drow

  Is there a known algorithm for implementing a connection pool? If not what are the known algorithms and what are their trade-offs? What design patterns are common when designing and programming a connection pool? Are there any code examples implement a connection pool using boost.asio? Is it a good idea to use a connection pool for presisting connections (not http)? How is threading related to connection pooling? When do you need a new thread?

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• C++ Multithreaded server help

  - by kisplit

  Hello all, I'm working on a multithreaded server in c++ using boost-asio. Currently a design problem I'm running into deals with erasing a connection. I have a single server instance which holds a vector of connection objects. These connections receive commands which I parse. One command in particular deals with sending data to ALL connections in my vector. Now when a connection disconnects I'm currently erasing this connection from the vector and calling the destructor. It seems like I'm going to run into problems when someone 'SendAll' at the same time someone 'Disconnect'. Could anyone recommend a better design or just point me in the right direction? Any help greatly appreciated. Thanks

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• TCP 30 small packets per second polutes connection with server

  - by Denis Ermolin

  I'm testing connection with flash client and cloud server(boost::asio for software) over TCP connection. My connection with server already is really poor - 120 ms ping in average. I found when i start to send packets with 2 bytes size (without tcp header) with speed 30 packets/s ping grow to 170-200 average. I think that it's really bad and my bad connection and bad cloud provider is reason for this high ping without any load. What do you think? (I tested my software and can compute about 50k packets/s so software is not a problem).

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• cannot receive UDP broadcast packets

  - by user292792

  Hello I have 2 boxes: - an embedded device (ARM Omap with linux) which I'll call "Omap". - a PC (can either be Windows or linux). Scenario 1 Both boxes are in the same network (example: my office). The Omap gets its address from a DHCP server (ex: 192.168.10.110). The PC has always the same address (ex. 192.168.10.104). I can successfully exchange UDP broadcast packets on any port. Success. Scenario 2 The 2 boxes are in a network withOUT a DHCP server. The PC has a static IP address (example: 10.10.10.20). The Omap boots, looks for a DHCP server, doesn't find it, and is in what I call "bad IP address" state. Now... Broadcasting UDP packets from the Omap works: the PC can see them. The opposite doesn't work: UDP packets broadcasted by the PC are not seen by the Omap. I am using Wireshark on another PC to verify that the packets are being sent. Failure. I tried to change the Omap ip address (with ifconfig)... no luck. What am I missing? To complete the picture, when the Omap is in Scenario 2, if I run udhcpc ... it can communicate with the DHCP server and get an IP address. I also see the packets with Wireshark. So this means that the DHCP client is able to broadcast UDP packets. (Yes, I tried to use DHCP ports 67/68 but it doesn't work). I am using Boost C++ Asio UDP sockets. Specifically, I took the multicast examples and changed them to do broadcasting. Any help is appreciated. Thanks, Benedetto

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• C++ socket protocol design issue (ring inclusion)

  - by Martin Lauridsen

  So I have these two classes, mpqs_client and client_protocol. The mpqs_client class handles a Boost socket connection to a server (sending and receiving messages with some specific format. Upon receiving a message, it calls a static method, parse_message(..), in the class client_protocol, and this method should analyse the message received and perform some corresponding action. Given some specific input, the parse_message method needs to send some data back to the server. As mentioned, this happens through the class mpqs_client. So I could, from mpqs_client, pass "this" to parse_message(..) in client_protocol. However, this leads to a two-way association relationship between the two classes. Something which I reckon is not desireable. Also, to implement this, I would need to include the other in each one, and this gives me a terrible pain. I am thinking this is more of a design issue. What is the best solution here? Code is posted below. Class mpqs_client: #include "mpqs_client.h" mpqs_client::mpqs_client(boost::asio::io_service& io_service, tcp::resolver::iterator endpoint_iterator) : io_service_(io_service), socket_(io_service) { ... } ... void mpqs_client::write(const network_message& msg) { io_service_.post(boost::bind(&mpqs_client::do_write, this, msg)); } Class client_protocol: #include "../network_message.hpp" #include "../protocol_consts.h" class client_protocol { public: static void parse_message(network_message& msg, mpqs_sieve **instance_, mpqs_client &client_) { ... switch (type) { case MPQS_DATA: ... break; case POLYNOMIAL_DATA: ... break; default: break; } }

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• boost thread pool

  - by Dtag

  I need a threadpool for my application, and I'd like to rely on standard (C++11 or boost) stuff as much as possible. I realize there is an unofficial(!) boost thread pool class, which basically solves what I need, however I'd rather avoid it because it is not in the boost library itself -- why is it still not in the core library after so many years? In some posts on this page and elsewhere, people suggested using boost::asio to achieve a threadpool like behavior. At first sight, that looked like what I wanted to do, however I found out that all implementations I have seen have no means to join on the currently active tasks, which makes it useless for my application. To perform a join, they send stop signal to all the threads and subsequently join them. However, that completely nullifies the advantage of threadpools in my use case, because that makes new tasks require the creation of a new thread. What I want to do is: ThreadPool pool(4); for (...) { for (int i=0;i<something;i++) pool.pushTask(...); pool.join(); // do something with the results } Can anyone suggest a solution (except for using the existing unofficial thread pool on sourceforge)? Is there anything in C++11 or core boost that can help me here? Thanks a lot

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