Re: [Boost-users] How to upload a file with ASIO

On Tuesday 03 November 2009 05:36:50 pm Ramon F Herrera wrote:

Benjamin Sobotta wrote:

...

Hello,

It would be interesting to know *how* you exactly transfer the information at hand and then build a solution from there.

Anyways, I use ASIO in conjunction with boost::serialization. There is an example on the ASIO website. I found that combination extremely handy. With this approach one could easily transfer any kind of data, for example in a std::vector.

hth,

Benjamin

Hi Benjamin,

Find below the relevant snippets of the client and the server code. As you can see, I keep on sending parameters, separated by newlines. Two consecutive newlines denote end of input. This obviously does not scale to a more complex transfer (i.e., a complete binary file).

Thanks for your kind assistance,

-Ramon

---------------------------------------- Client:

// stream boost::asio::streambuf buf; std::ostream net_out(&buf);

// Display the arguments

if (debug()) cout << "client pushing " << argc - 1 << " arguments" << endl;

for (int i = 1; i < argc; i++) { net_out << argv[i] << endl; if (debug()) cout << "arg[" << i << "], " << argv[i] << " was pushed" << endl; }

net_out << endl;

boost::asio::write(socket, buf);

while (true) {

boost::array buf; 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.

cout.write(buf.data(), len); }

---------------------------------------- Server:

while (true) {

tcp::socket socket(io_service); acceptor.accept(socket);

/////////////////////////////////////////////////////////////////////////// ////////

boost::asio::streambuf buf; boost::system::error_code error;

// read till end-of-args marker boost::asio::read_until(socket, buf, "\n\n");

// extract args from buf std::istream net_in(&buf);

while (getline(net_in, next_line)) {

if (next_line.length()) client_argv.push_back(next_line); }

if (debug()) cout << client_argv.size() << " arguments received by server" << endl;

/////////////////////////////////////////////////////////////////////////// ////////

ostringstream response;

it_takes_two_to_tango(client_argv, tx, db, response); client_argv.clear();

string message = response.str();

// if (debug()) cout << "Deliver to server:" << endl << message << endl;

boost::system::error_code ignored_error; boost::asio::write(socket, boost::asio::buffer(message), boost::asio::transfer_all(), ignored_error); } }

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Hello! Sorry, that my reply took so long as I was very busy. I think the way too transfer binary data is to first send, say, an unsigned integer indicating the number of bytes to come. Here a little snippet of code: Say your binary data is contained in a std::string data, then I would try something like the following: unsigned int outbound_message_size = data.size(); std::vectorboost::asio::const_buffer buffers; buffers.push_back(boost::asio::buffer((char*)(&outbound_message_size), sizeof(unsigned int))); buffers.push_back(boost::asio::buffer(data, outbound_message_size)); boost::system::error_code ignored_error; boost::asio::write(socket, buffers, boost::asio::transfer_all(), ignored_error); Then, on the receiving side you always read sizeof(unsigned int) bytes first and see how much data is waiting. Btw, I have to point out that I'm also new to ASIO and there maybe more elegant solutions for the problem. HTH, Ben