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##### websocket::stream::async_write

Write a complete message asynchronously.

###### Synopsis

    template<
        class ConstBufferSequence,
        class WriteHandler>
    async_write(
        ConstBufferSequence const& buffers,
        WriteHandler&& handler);

###### Description

This function is used to asynchronously write a complete message. This call always returns immediately. The asynchronous operation will continue until one of the following conditions is true:

- The complete message is written.
- An error occurs.

The algorithm, known as a composed asynchronous operation, is implemented in terms of calls to the next layer's `async_write_some` function. The program must ensure that no other calls to `websocket::stream::write`, `websocket::stream::write_some`, `websocket::stream::async_write`, or `websocket::stream::async_write_some` are performed until this operation completes. The current setting of the `websocket::stream::binary` option controls whether the message opcode is set to text or binary. If the `websocket::stream::auto_fragment` option is set, the message will be split into one or more frames as necessary. The actual payload contents sent may be transformed as per the WebSocket protocol settings.

###### Parameters

Name | Description
--- | ---
`buffers` | A buffer sequence containing the entire message payload. The implementation will make copies of this object as needed, but ownership of the underlying memory is not transferred. The caller is responsible for ensuring that the memory locations pointed to by buffers remains valid until the completion handler is called.
`handler` | The completion handler to invoke when the operation completes. The implementation takes ownership of the handler by performing a decay-copy. The equivalent function signature of the handler must be:
    void handler(
        error_code const& ec,           // Result of operation
        std::size_t bytes_transferred   // Number of bytes sent from the
                                        // buffers. If an error occurred,
                                        // this will be less than the buffer_size.
    );
Regardless of whether the asynchronous operation completes immediately or not, the handler will not be invoked from within this function. Invocation of the handler will be performed in a manner equivalent to using `net::post`.