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###### websocket::stream::accept_ex (3 of 6 overloads)

Read and respond to a WebSocket HTTP Upgrade request.

Synopsis

    template<
        class ConstBufferSequence,
        class ResponseDecorator>
    void
    accept_ex(
        ConstBufferSequence const& buffers,
        ResponseDecorator const& decorator);

Description

This function is used to synchronously read an HTTP WebSocket Upgrade request and send the HTTP response. The call blocks until one of the following conditions is true:

- The request is received and the response finishes sending.
- An error occurs on the stream.

This function is implemented in terms of one or more calls to the next layer's `read_some` and `write_some` functions.

If the stream receives a valid HTTP WebSocket Upgrade request, an HTTP response is sent back indicating a successful upgrade. When this call returns, the stream is then ready to send and receive WebSocket protocol frames and messages. If the HTTP Upgrade request is invalid or cannot be satisfied, an HTTP response is sent indicating the reason and status code (typically 400, "Bad Request"). This counts as a failure.

The implementation uses fixed size internal storage to receive the request. If the request is too large, the error `websocket::buffer_overflow` will be indicated. Applications that wish to receive larger requests should first read the request using their own buffer and a suitable overload of `http::read` or `http::async_read`, then call `websocket::stream::accept` or `websocket::stream::async_accept` with the request.

Parameters

Name | Description
--- | ---
`buffers` | Caller provided data that has already been received on the stream. The implementation will copy the caller provided data before the function returns.
`decorator` | A function object which will be called to modify the HTTP response object delivered by the implementation. This could be used to set the Server field, subprotocols, or other application or HTTP specific fields. The object will be called with this equivalent signature:
     void decorator(
        response_type& res
    );

Exceptions

Type | Thrown On
--- | ---
`system_error` | Thrown on failure.