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#### websocket::is_upgrade

Returns `true` if the specified HTTP request is a WebSocket Upgrade.

##### Synopsis

Defined in header `<boost/beast/websocket/rfc6455.hpp>`

    template<
        class Allocator>
    bool
    is_upgrade(
        beast::http::header< true, http::basic_fields< Allocator > > const& req);

##### Description

This function returns `true` when the passed HTTP Request indicates a WebSocket Upgrade. It does not validate the contents of the fields: it just trivially accepts requests which could only possibly be a valid or invalid WebSocket Upgrade message.

Callers who wish to manually read HTTP requests in their server implementation can use this function to determine if the request should be routed to an instance of `websocket::stream`.

##### Example

    void handle_connection(net::ip::tcp::socket& sock)
    {
        boost::beast::flat_buffer buffer;
        boost::beast::http::request<boost::beast::http::string_body> req;
        boost::beast::http::read(sock, buffer, req);
        if (boost::beast::websocket::is_upgrade(req))
        {
            boost::beast::websocket::stream< decltype (sock)> ws{std::move(sock)};
            ws.accept(req);
        }
    }

##### Parameters

Name | Description
--- | ---
`req` | The HTTP Request object to check.

##### Return Value

`true` if the request is a WebSocket Upgrade.