diff --git a/Cargo.toml b/Cargo.toml
index 55e2863..d7c7f47 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -9,7 +9,7 @@ readme = "README.md"
 homepage = "https://github.com/snapview/tungstenite-rs"
 documentation = "https://docs.rs/tungstenite/0.2.4"
 repository = "https://github.com/snapview/tungstenite-rs"
-version = "0.3.0"
+version = "0.4.0"
 
 [features]
 default = ["tls"]
diff --git a/README.md b/README.md
index 0811262..cf917c4 100644
--- a/README.md
+++ b/README.md
@@ -8,15 +8,21 @@ Lightweight stream-based WebSocket implementation for [Rust](http://www.rust-lan
 let server = TcpListener::bind("127.0.0.1:9001").unwrap();
 for stream in server.incoming() {
     spawn (move || {
-        let mut websocket = accept(stream.unwrap()).unwrap();
+        let mut websocket = accept(stream.unwrap(), None).unwrap();
         loop {
             let msg = websocket.read_message().unwrap();
-            websocket.write_message(msg).unwrap();
+
+            // We do not want to send back ping/pong messages.
+            if msg.is_binary() || msg.is_text() {
+                websocket.write_message(msg).unwrap();
+            }
         }
     });
 }
 ```
 
+Take a look at the examples section to see how to write a simple client/server.
+
 [![MIT licensed](https://img.shields.io/badge/License-MIT-blue.svg)](./LICENSE-MIT)
 [![Apache-2.0 licensed](https://img.shields.io/badge/License-Apache%202.0-blue.svg)](./LICENSE-APACHE)
 [![Crates.io](https://img.shields.io/crates/v/tungstenite.svg?maxAge=2592000)](https://crates.io/crates/tungstenite)
diff --git a/examples/autobahn-client.rs b/examples/autobahn-client.rs
index 700e2d7..8a08e4b 100644
--- a/examples/autobahn-client.rs
+++ b/examples/autobahn-client.rs
@@ -10,7 +10,7 @@ use tungstenite::{connect, Error, Result, Message};
 const AGENT: &'static str = "Tungstenite";
 
 fn get_case_count() -> Result<u32> {
-    let mut socket = connect(
+    let (mut socket, _) = connect(
         Url::parse("ws://localhost:9001/getCaseCount").unwrap()
     )?;
     let msg = socket.read_message()?;
@@ -19,7 +19,7 @@ fn get_case_count() -> Result<u32> {
 }
 
 fn update_reports() -> Result<()> {
-    let mut socket = connect(
+    let (mut socket, _) = connect(
         Url::parse(&format!("ws://localhost:9001/updateReports?agent={}", AGENT)).unwrap()
     )?;
     socket.close(None)?;
@@ -31,7 +31,7 @@ fn run_test(case: u32) -> Result<()> {
     let case_url = Url::parse(
         &format!("ws://localhost:9001/runCase?case={}&agent={}", case, AGENT)
     ).unwrap();
-    let mut socket = connect(case_url)?;
+    let (mut socket, _) = connect(case_url)?;
     loop {
         match socket.read_message()? {
             msg @ Message::Text(_) |
diff --git a/examples/autobahn-server.rs b/examples/autobahn-server.rs
index 458fa26..79fb5e2 100644
--- a/examples/autobahn-server.rs
+++ b/examples/autobahn-server.rs
@@ -6,8 +6,9 @@ use std::net::{TcpListener, TcpStream};
 use std::thread::spawn;
 
 use tungstenite::{accept, HandshakeError, Error, Result, Message};
+use tungstenite::handshake::HandshakeRole;
 
-fn must_not_block<Stream, Role>(err: HandshakeError<Stream, Role>) -> Error {
+fn must_not_block<Role: HandshakeRole>(err: HandshakeError<Role>) -> Error {
     match err {
         HandshakeError::Interrupted(_) => panic!("Bug: blocking socket would block"),
         HandshakeError::Failure(f) => f,
@@ -15,7 +16,7 @@ fn must_not_block<Stream, Role>(err: HandshakeError<Stream, Role>) -> Error {
 }
 
 fn handle_client(stream: TcpStream) -> Result<()> {
-    let mut socket = accept(stream).map_err(must_not_block)?;
+    let mut socket = accept(stream, None).map_err(must_not_block)?;
     loop {
         match socket.read_message()? {
             msg @ Message::Text(_) |
diff --git a/examples/client.rs b/examples/client.rs
index 1c97aba..8e11038 100644
--- a/examples/client.rs
+++ b/examples/client.rs
@@ -8,9 +8,16 @@ use tungstenite::{Message, connect};
 fn main() {
     env_logger::init().unwrap();
 
-    let mut socket = connect(Url::parse("ws://localhost:3012/socket").unwrap())
+    let (mut socket, response) = connect(Url::parse("ws://localhost:3012/socket").unwrap())
         .expect("Can't connect");
 
+    println!("Connected to the server");
+    println!("Response HTTP code: {}", response.code);
+    println!("Response contains the following headers:");
+    for &(ref header, _ /*value*/) in response.headers.iter() {
+        println!("* {}", header);
+    }
+
     socket.write_message(Message::Text("Hello WebSocket".into())).unwrap();
     loop {
         let msg = socket.read_message().expect("Error reading message");
diff --git a/examples/server.rs b/examples/server.rs
new file mode 100644
index 0000000..5b6bfee
--- /dev/null
+++ b/examples/server.rs
@@ -0,0 +1,38 @@
+extern crate tungstenite;
+
+use std::thread::spawn;
+use std::net::TcpListener;
+
+use tungstenite::accept;
+use tungstenite::handshake::server::Request;
+
+fn main() {
+    let server = TcpListener::bind("127.0.0.1:3012").unwrap();
+    for stream in server.incoming() {
+        spawn(move || {
+            let callback = |req: &Request| {
+                println!("Received a new ws handshake");
+                println!("The request's path is: {}", req.path);
+                println!("The request's headers are:");
+                for &(ref header, _ /* value */) in req.headers.iter() {
+                    println!("* {}", header);
+                }
+
+                // Let's add an additional header to our response to the client.
+                let extra_headers = vec![
+                    (String::from("MyCustomHeader"), String::from(":)")),
+                    (String::from("SOME_TUNGSTENITE_HEADER"), String::from("header_value")),
+                ];
+                Ok(Some(extra_headers))
+            };
+            let mut websocket = accept(stream.unwrap(), Some(Box::new(callback))).unwrap();
+
+            loop {
+                let msg = websocket.read_message().unwrap();
+                if msg.is_binary() || msg.is_text() {
+                    websocket.write_message(msg).unwrap();
+                }
+            }
+        });
+    }
+}
diff --git a/src/client.rs b/src/client.rs
index 3274ad0..2326ac7 100644
--- a/src/client.rs
+++ b/src/client.rs
@@ -6,6 +6,8 @@ use std::io::{Read, Write};
 
 use url::Url;
 
+use handshake::client::Response;
+
 #[cfg(feature="tls")]
 mod encryption {
     use std::net::TcpStream;
@@ -75,7 +77,9 @@ use error::{Error, Result};
 /// This function uses `native_tls` to do TLS. If you want to use other TLS libraries,
 /// use `client` instead. There is no need to enable the "tls" feature if you don't call
 /// `connect` since it's the only function that uses native_tls.
-pub fn connect<'t, Req: Into<Request<'t>>>(request: Req) -> Result<WebSocket<AutoStream>> {
+pub fn connect<'t, Req: Into<Request<'t>>>(request: Req)
+    -> Result<(WebSocket<AutoStream>, Response)>
+{
     let request: Request = request.into();
     let mode = url_mode(&request.url)?;
     let addrs = request.url.to_socket_addrs()?;
@@ -120,10 +124,13 @@ pub fn url_mode(url: &Url) -> Result<Mode> {
 /// Use this function if you need a nonblocking handshake support or if you
 /// want to use a custom stream like `mio::tcp::TcpStream` or `openssl::ssl::SslStream`.
 /// Any stream supporting `Read + Write` will do.
-pub fn client<'t, Stream, Req>(request: Req, stream: Stream)
-    -> StdResult<WebSocket<Stream>, HandshakeError<Stream, ClientHandshake>>
-where Stream: Read + Write,
-      Req: Into<Request<'t>>,
+pub fn client<'t, Stream, Req>(
+    request: Req,
+    stream: Stream
+    ) -> StdResult<(WebSocket<Stream>, Response), HandshakeError<ClientHandshake<Stream>>>
+where
+    Stream: Read + Write,
+    Req: Into<Request<'t>>,
 {
     ClientHandshake::start(stream, request.into()).handshake()
 }
diff --git a/src/handshake/client.rs b/src/handshake/client.rs
index ff07d37..cd5e6d0 100644
--- a/src/handshake/client.rs
+++ b/src/handshake/client.rs
@@ -1,18 +1,19 @@
 //! Client handshake machine.
 
+use std::io::{Read, Write};
+use std::marker::PhantomData;
+
 use base64;
-use rand;
-use httparse;
 use httparse::Status;
-use std::io::Write;
+use httparse;
+use rand;
 use url::Url;
 
 use error::{Error, Result};
 use protocol::{WebSocket, Role};
-
 use super::headers::{Headers, FromHttparse, MAX_HEADERS};
-use super::{MidHandshake, HandshakeRole, ProcessingResult, convert_key};
 use super::machine::{HandshakeMachine, StageResult, TryParse};
+use super::{MidHandshake, HandshakeRole, ProcessingResult, convert_key};
 
 /// Client request.
 pub struct Request<'t> {
@@ -52,13 +53,14 @@ impl From<Url> for Request<'static> {
 }
 
 /// Client handshake role.
-pub struct ClientHandshake {
+pub struct ClientHandshake<S> {
     verify_data: VerifyData,
+    _marker: PhantomData<S>,
 }
 
-impl ClientHandshake {
+impl<S: Read + Write> ClientHandshake<S> {
     /// Initiate a client handshake.
-    pub fn start<Stream>(stream: Stream, request: Request) -> MidHandshake<Stream, Self> {
+    pub fn start(stream: S, request: Request) -> MidHandshake<Self> {
         let key = generate_key();
 
         let machine = {
@@ -83,9 +85,8 @@ impl ClientHandshake {
         let client = {
             let accept_key = convert_key(key.as_ref()).unwrap();
             ClientHandshake {
-                verify_data: VerifyData {
-                    accept_key: accept_key,
-                },
+                verify_data: VerifyData { accept_key },
+                _marker: PhantomData,
             }
         };
 
@@ -94,10 +95,12 @@ impl ClientHandshake {
     }
 }
 
-impl HandshakeRole for ClientHandshake {
+impl<S: Read + Write> HandshakeRole for ClientHandshake<S> {
     type IncomingData = Response;
-    fn stage_finished<Stream>(&self, finish: StageResult<Self::IncomingData, Stream>)
-        -> Result<ProcessingResult<Stream>>
+    type InternalStream = S;
+    type FinalResult = (WebSocket<S>, Response);
+    fn stage_finished(&mut self, finish: StageResult<Self::IncomingData, Self::InternalStream>)
+        -> Result<ProcessingResult<Self::InternalStream, Self::FinalResult>>
     {
         Ok(match finish {
             StageResult::DoneWriting(stream) => {
@@ -106,7 +109,8 @@ impl HandshakeRole for ClientHandshake {
             StageResult::DoneReading { stream, result, tail, } => {
                 self.verify_data.verify_response(&result)?;
                 debug!("Client handshake done.");
-                ProcessingResult::Done(WebSocket::from_partially_read(stream, tail, Role::Client))
+                ProcessingResult::Done((WebSocket::from_partially_read(stream, tail, Role::Client),
+                                       result))
             }
         })
     }
@@ -166,8 +170,10 @@ impl VerifyData {
 
 /// Server response.
 pub struct Response {
-    code: u16,
-    headers: Headers,
+    /// HTTP response code of the response.
+    pub code: u16,
+    /// Received headers.
+    pub headers: Headers,
 }
 
 impl TryParse for Response {
@@ -203,7 +209,6 @@ fn generate_key() -> String {
 
 #[cfg(test)]
 mod tests {
-
     use super::{Response, generate_key};
     use super::super::machine::TryParse;
 
@@ -230,5 +235,4 @@ mod tests {
         assert_eq!(resp.code, 200);
         assert_eq!(resp.headers.find_first("Content-Type"), Some(&b"text/html"[..]));
     }
-
 }
diff --git a/src/handshake/headers.rs b/src/handshake/headers.rs
index c9e6bee..b5a9f62 100644
--- a/src/handshake/headers.rs
+++ b/src/handshake/headers.rs
@@ -49,6 +49,11 @@ impl Headers {
             .unwrap_or(false)
     }
 
+    /// Allows to iterate over available headers.
+    pub fn iter(&self) -> slice::Iter<(String, Box<[u8]>)> {
+        self.data.iter()
+    }
+
 }
 
 /// The iterator over headers.
diff --git a/src/handshake/mod.rs b/src/handshake/mod.rs
index 64d31f1..a6d9192 100644
--- a/src/handshake/mod.rs
+++ b/src/handshake/mod.rs
@@ -14,30 +14,17 @@ use base64;
 use sha1::Sha1;
 
 use error::Error;
-use protocol::WebSocket;
-
 use self::machine::{HandshakeMachine, RoundResult, StageResult, TryParse};
 
 /// A WebSocket handshake.
-pub struct MidHandshake<Stream, Role> {
+pub struct MidHandshake<Role: HandshakeRole> {
     role: Role,
-    machine: HandshakeMachine<Stream>,
-}
-
-impl<Stream, Role> MidHandshake<Stream, Role> {
-    /// Returns a shared reference to the inner stream.
-    pub fn get_ref(&self) -> &Stream {
-        self.machine.get_ref()
-    }
-    /// Returns a mutable reference to the inner stream.
-    pub fn get_mut(&mut self) -> &mut Stream {
-        self.machine.get_mut()
-    }
+    machine: HandshakeMachine<Role::InternalStream>,
 }
 
-impl<Stream: Read + Write, Role: HandshakeRole> MidHandshake<Stream, Role> {
+impl<Role: HandshakeRole> MidHandshake<Role> {
     /// Restarts the handshake process.
-    pub fn handshake(self) -> Result<WebSocket<Stream>, HandshakeError<Stream, Role>> {
+    pub fn handshake(mut self) -> Result<Role::FinalResult, HandshakeError<Role>> {
         let mut mach = self.machine;
         loop {
             mach = match mach.single_round()? {
@@ -48,7 +35,7 @@ impl<Stream: Read + Write, Role: HandshakeRole> MidHandshake<Stream, Role> {
                 RoundResult::StageFinished(s) => {
                     match self.role.stage_finished(s)? {
                         ProcessingResult::Continue(m) => m,
-                        ProcessingResult::Done(ws) => return Ok(ws),
+                        ProcessingResult::Done(result) => return Ok(result),
                     }
                 }
             }
@@ -57,14 +44,14 @@ impl<Stream: Read + Write, Role: HandshakeRole> MidHandshake<Stream, Role> {
 }
 
 /// A handshake result.
-pub enum HandshakeError<Stream, Role> {
+pub enum HandshakeError<Role: HandshakeRole> {
     /// Handshake was interrupted (would block).
-    Interrupted(MidHandshake<Stream, Role>),
+    Interrupted(MidHandshake<Role>),
     /// Handshake failed.
     Failure(Error),
 }
 
-impl<Stream, Role> fmt::Debug for HandshakeError<Stream, Role> {
+impl<Role: HandshakeRole> fmt::Debug for HandshakeError<Role> {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         match *self {
             HandshakeError::Interrupted(_) => write!(f, "HandshakeError::Interrupted(...)"),
@@ -73,7 +60,7 @@ impl<Stream, Role> fmt::Debug for HandshakeError<Stream, Role> {
     }
 }
 
-impl<Stream, Role> fmt::Display for HandshakeError<Stream, Role> {
+impl<Role: HandshakeRole> fmt::Display for HandshakeError<Role> {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         match *self {
             HandshakeError::Interrupted(_) => write!(f, "Interrupted handshake (WouldBlock)"),
@@ -82,7 +69,7 @@ impl<Stream, Role> fmt::Display for HandshakeError<Stream, Role> {
     }
 }
 
-impl<Stream, Role> ErrorTrait for HandshakeError<Stream, Role> {
+impl<Role: HandshakeRole> ErrorTrait for HandshakeError<Role> {
     fn description(&self) -> &str {
         match *self {
             HandshakeError::Interrupted(_) => "Interrupted handshake",
@@ -91,7 +78,7 @@ impl<Stream, Role> ErrorTrait for HandshakeError<Stream, Role> {
     }
 }
 
-impl<Stream, Role> From<Error> for HandshakeError<Stream, Role> {
+impl<Role: HandshakeRole> From<Error> for HandshakeError<Role> {
     fn from(err: Error) -> Self {
         HandshakeError::Failure(err)
     }
@@ -102,15 +89,19 @@ pub trait HandshakeRole {
     #[doc(hidden)]
     type IncomingData: TryParse;
     #[doc(hidden)]
-    fn stage_finished<Stream>(&self, finish: StageResult<Self::IncomingData, Stream>)
-        -> Result<ProcessingResult<Stream>, Error>;
+    type InternalStream: Read + Write;
+    #[doc(hidden)]
+    type FinalResult;
+    #[doc(hidden)]
+    fn stage_finished(&mut self, finish: StageResult<Self::IncomingData, Self::InternalStream>)
+        -> Result<ProcessingResult<Self::InternalStream, Self::FinalResult>, Error>;
 }
 
 /// Stage processing result.
 #[doc(hidden)]
-pub enum ProcessingResult<Stream> {
+pub enum ProcessingResult<Stream, FinalResult> {
     Continue(HandshakeMachine<Stream>),
-    Done(WebSocket<Stream>),
+    Done(FinalResult),
 }
 
 /// Turns a Sec-WebSocket-Key into a Sec-WebSocket-Accept.
@@ -126,7 +117,6 @@ fn convert_key(input: &[u8]) -> Result<String, Error> {
 
 #[cfg(test)]
 mod tests {
-
     use super::convert_key;
 
     #[test]
diff --git a/src/handshake/server.rs b/src/handshake/server.rs
index a3a5fab..510126c 100644
--- a/src/handshake/server.rs
+++ b/src/handshake/server.rs
@@ -1,5 +1,10 @@
 //! Server handshake machine.
 
+use std::fmt::Write as FmtWrite;
+use std::io::{Read, Write};
+use std::marker::PhantomData;
+use std::mem::replace;
+
 use httparse;
 use httparse::Status;
 
@@ -19,15 +24,23 @@ pub struct Request {
 
 impl Request {
     /// Reply to the response.
-    pub fn reply(&self) -> Result<Vec<u8>> {
+    pub fn reply(&self, extra_headers: Option<Vec<(String, String)>>) -> Result<Vec<u8>> {
         let key = self.headers.find_first("Sec-WebSocket-Key")
             .ok_or_else(|| Error::Protocol("Missing Sec-WebSocket-Key".into()))?;
-        let reply = format!("\
-        HTTP/1.1 101 Switching Protocols\r\n\
-        Connection: Upgrade\r\n\
-        Upgrade: websocket\r\n\
-        Sec-WebSocket-Accept: {}\r\n\
-        \r\n", convert_key(key)?);
+        let mut reply = format!(
+            "\
+            HTTP/1.1 101 Switching Protocols\r\n\
+            Connection: Upgrade\r\n\
+            Upgrade: websocket\r\n\
+            Sec-WebSocket-Accept: {}\r\n",
+            convert_key(key)?
+        );
+        if let Some(eh) = extra_headers {
+            for (k, v) in eh {
+                write!(reply, "{}: {}\r\n", k, v).unwrap();
+            }
+        }
+        write!(reply, "\r\n").unwrap();
         Ok(reply.into())
     }
 }
@@ -58,32 +71,63 @@ impl<'h, 'b: 'h> FromHttparse<httparse::Request<'h, 'b>> for Request {
     }
 }
 
+/// The callback type, the callback is called when the server receives an incoming WebSocket
+/// handshake request from the client, specifying a callback allows you to analyze incoming headers
+/// and add additional headers to the response that server sends to the client and/or reject the
+/// connection based on the incoming headers. Due to usability problems which are caused by a
+/// static dispatch when using callbacks in such places, the callback is boxed.
+///
+/// The type uses `FnMut` instead of `FnOnce` as it is impossible to box `FnOnce` in the current
+/// Rust version, `FnBox` is still unstable, this code has to be updated for `FnBox` when it gets
+/// stable.
+pub type Callback = Box<FnMut(&Request) -> Result<Option<Vec<(String, String)>>>>;
+
 /// Server handshake role.
 #[allow(missing_copy_implementations)]
-pub struct ServerHandshake;
+pub struct ServerHandshake<S> {
+    /// Callback which is called whenever the server read the request from the client and is ready
+    /// to reply to it. The callback returns an optional headers which will be added to the reply
+    /// which the server sends to the user.
+    callback: Option<Callback>,
+    /// Internal stream type.
+    _marker: PhantomData<S>,
+}
 
-impl ServerHandshake {
-    /// Start server handshake.
-    pub fn start<Stream>(stream: Stream) -> MidHandshake<Stream, Self> {
+impl<S: Read + Write> ServerHandshake<S> {
+    /// Start server handshake. `callback` specifies a custom callback which the user can pass to
+    /// the handshake, this callback will be called when the a websocket client connnects to the
+    /// server, you can specify the callback if you want to add additional header to the client
+    /// upon join based on the incoming headers.
+    pub fn start(stream: S, callback: Option<Callback>) -> MidHandshake<Self> {
         trace!("Server handshake initiated.");
         MidHandshake {
             machine: HandshakeMachine::start_read(stream),
-            role: ServerHandshake,
+            role: ServerHandshake { callback, _marker: PhantomData },
         }
     }
 }
 
-impl HandshakeRole for ServerHandshake {
+impl<S: Read + Write> HandshakeRole for ServerHandshake<S> {
     type IncomingData = Request;
-    fn stage_finished<Stream>(&self, finish: StageResult<Self::IncomingData, Stream>)
-        -> Result<ProcessingResult<Stream>>
+    type InternalStream = S;
+    type FinalResult = WebSocket<S>;
+
+    fn stage_finished(&mut self, finish: StageResult<Self::IncomingData, Self::InternalStream>)
+        -> Result<ProcessingResult<Self::InternalStream, Self::FinalResult>>
     {
         Ok(match finish {
             StageResult::DoneReading { stream, result, tail } => {
-                if ! tail.is_empty() {
+                if !tail.is_empty() {
                     return Err(Error::Protocol("Junk after client request".into()))
                 }
-                let response = result.reply()?;
+                let extra_headers = {
+                    if let Some(mut callback) = replace(&mut self.callback, None) {
+                        callback(&result)?
+                    } else {
+                        None
+                    }
+                };
+                let response = result.reply(extra_headers)?;
                 ProcessingResult::Continue(HandshakeMachine::start_write(stream, response))
             }
             StageResult::DoneWriting(stream) => {
@@ -96,9 +140,9 @@ impl HandshakeRole for ServerHandshake {
 
 #[cfg(test)]
 mod tests {
-
     use super::Request;
     use super::super::machine::TryParse;
+    use super::super::client::Response;
 
     #[test]
     fn request_parsing() {
@@ -119,7 +163,15 @@ mod tests {
             Sec-WebSocket-Key: dGhlIHNhbXBsZSBub25jZQ==\r\n\
             \r\n";
         let (_, req) = Request::try_parse(DATA).unwrap().unwrap();
-        let _ = req.reply().unwrap();
-    }
+        let _ = req.reply(None).unwrap();
 
+        let extra_headers = Some(vec![(String::from("MyCustomHeader"),
+                                       String::from("MyCustomValue")),
+                                       (String::from("MyVersion"),
+                                        String::from("LOL"))]);
+        let reply = req.reply(extra_headers).unwrap();
+        let (_, req) = Response::try_parse(&reply).unwrap().unwrap();
+        assert_eq!(req.headers.find_first("MyCustomHeader"), Some(b"MyCustomValue".as_ref()));
+        assert_eq!(req.headers.find_first("MyVersion"), Some(b"LOL".as_ref()));
+    }
 }
diff --git a/src/server.rs b/src/server.rs
index 3217006..b0d191d 100644
--- a/src/server.rs
+++ b/src/server.rs
@@ -3,6 +3,7 @@
 pub use handshake::server::ServerHandshake;
 
 use handshake::HandshakeError;
+use handshake::server::Callback;
 use protocol::WebSocket;
 
 use std::io::{Read, Write};
@@ -12,9 +13,10 @@ use std::io::{Read, Write};
 /// This function starts a server WebSocket handshake over the given stream.
 /// If you want TLS support, use `native_tls::TlsStream` or `openssl::ssl::SslStream`
 /// for the stream here. Any `Read + Write` streams are supported, including
-/// those from `Mio` and others.
-pub fn accept<Stream: Read + Write>(stream: Stream)
-    -> Result<WebSocket<Stream>, HandshakeError<Stream, ServerHandshake>>
+/// those from `Mio` and others. You can also pass an optional `callback` which will
+/// be called when the websocket request is received from an incoming client.
+pub fn accept<S: Read + Write>(stream: S, callback: Option<Callback>)
+    -> Result<WebSocket<S>, HandshakeError<ServerHandshake<S>>>
 {
-    ServerHandshake::start(stream).handshake()
+    ServerHandshake::start(stream, callback).handshake()
 }