forked from boostorg/beast
78 lines
2.2 KiB
Plaintext
78 lines
2.2 KiB
Plaintext
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Copyright (c) 2013-2017 Vinnie Falco (vinnie dot falco at gmail dot com)
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Distributed under the Boost Software License, Version 1.0. (See accompanying
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file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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]
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[section:messages Send and Receive Messages]
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After the WebSocket handshake is accomplished, callers may send and receive
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messages using the message oriented interface. This interface requires that
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all of the buffers representing the message are known ahead of time:
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```
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template<class NextLayer>
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void echo(websocket::stream<NextLayer>& ws)
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{
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multi_buffer b;
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websocket::opcode::value op;
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ws.read(op, b);
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ws.set_option(websocket::message_type{op});
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ws.write(b.data());
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b.consume(b.size());
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}
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```
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[important
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Calls to [link beast.ref.websocket__stream.set_option `set_option`]
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must be made from the same implicit or explicit strand as that used
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to perform other operations.
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]
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[heading Frames]
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Some use-cases make it impractical or impossible to buffer the entire
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message ahead of time:
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* Streaming multimedia to an endpoint.
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* Sending a message that does not fit in memory at once.
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* Providing incremental results as they become available.
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For these cases, the frame oriented interface may be used. This
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example reads and echoes a complete message using this interface:
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```
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template<class NextLayer>
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void echo(websocket::stream<NextLayer>& ws)
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{
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multi_buffer b;
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websocket::frame_info fi;
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for(;;)
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{
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ws.read_frame(fi, b);
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if(fi.fin)
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break;
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}
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ws.set_option(websocket::message_type{fi.op});
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consuming_buffers<
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multi_buffer::const_buffers_type> cb{b.data()};
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for(;;)
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{
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using boost::asio::buffer_size;
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std::size_t size = std::min(buffer_size(cb));
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if(size > 512)
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{
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ws.write_frame(false, prepare_buffers(512, cb));
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cb.consume(512);
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}
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else
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{
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ws.write_frame(true, cb);
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break;
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}
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}
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}
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```
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[endsect]
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