diff --git a/Cargo.toml b/Cargo.toml
index 377e09d..5b1cadc 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -16,8 +16,8 @@ name = "netapp"
 
 [features]
 default = []
-basalt = ["lru", "rand"]
-telemetry = ["opentelemetry", "opentelemetry-contrib", "rand"]
+basalt = ["lru"]
+telemetry = ["opentelemetry", "opentelemetry-contrib"]
 
 [dependencies]
 futures = "0.3.17"
@@ -30,7 +30,7 @@ serde = { version = "1.0", default-features = false, features = ["derive", "rc"]
 rmp-serde = "0.14.3"
 hex = "0.4.2"
 
-rand = { version = "0.5.5", optional = true }
+rand = { version = "0.5.5" }
 
 log = "0.4.8"
 arc-swap = "1.1"
diff --git a/src/bytes_buf.rs b/src/bytes_buf.rs
index 46c7039..857be9d 100644
--- a/src/bytes_buf.rs
+++ b/src/bytes_buf.rs
@@ -146,7 +146,10 @@ mod test {
 		assert!(buf.len() == 23);
 		assert!(!buf.is_empty());
 
-		assert_eq!(buf.take_all(), Bytes::from(b"Hello, world!1234567890".to_vec()));
+		assert_eq!(
+			buf.take_all(),
+			Bytes::from(b"Hello, world!1234567890".to_vec())
+		);
 		assert!(buf.len() == 0);
 		assert!(buf.is_empty());
 
@@ -160,7 +163,10 @@ mod test {
 
 		assert_eq!(buf.take_exact(12), None);
 		assert!(buf.len() == 11);
-		assert_eq!(buf.take_exact(11), Some(Bytes::from(b"llo, world!".to_vec())));
+		assert_eq!(
+			buf.take_exact(11),
+			Some(Bytes::from(b"llo, world!".to_vec()))
+		);
 		assert!(buf.len() == 0);
 		assert!(buf.is_empty());
 	}
diff --git a/src/client.rs b/src/client.rs
index 0dcbdf1..aef7bbb 100644
--- a/src/client.rs
+++ b/src/client.rs
@@ -35,7 +35,7 @@ pub(crate) struct ClientConn {
 	pub(crate) remote_addr: SocketAddr,
 	pub(crate) peer_id: NodeID,
 
-	query_send: ArcSwapOption<mpsc::UnboundedSender<(RequestID, RequestPriority, ByteStream)>>,
+	query_send: ArcSwapOption<mpsc::UnboundedSender<SendStream>>,
 
 	next_query_number: AtomicU32,
 	inflight: Mutex<HashMap<RequestID, oneshot::Sender<ByteStream>>>,
@@ -165,7 +165,7 @@ impl ClientConn {
 		// Encode request
 		let req_enc = req.into_enc(prio, path.as_bytes().to_vec().into(), telemetry_id);
 		let req_msg_len = req_enc.msg.len();
-		let req_stream = req_enc.encode();
+		let (req_stream, req_order) = req_enc.encode();
 
 		// Send request through
 		let (resp_send, resp_recv) = oneshot::channel();
@@ -175,7 +175,10 @@ impl ClientConn {
 				"Too many inflight requests! RequestID collision. Interrupting previous request."
 			);
 			let _ = old_ch.send(Box::pin(futures::stream::once(async move {
-				Err(std::io::Error::new(std::io::ErrorKind::Other, "RequestID collision, too many inflight requests"))
+				Err(std::io::Error::new(
+					std::io::ErrorKind::Other,
+					"RequestID collision, too many inflight requests",
+				))
 			})));
 		}
 
diff --git a/src/error.rs b/src/error.rs
index 2fa4594..c0aeeac 100644
--- a/src/error.rs
+++ b/src/error.rs
@@ -28,6 +28,9 @@ pub enum Error {
 	#[error(display = "Framing protocol error")]
 	Framing,
 
+	#[error(display = "Remote error ({:?}): {}", _0, _1)]
+	Remote(io::ErrorKind, String),
+
 	#[error(display = "Request ID collision")]
 	IdCollision,
 
@@ -42,30 +45,6 @@ pub enum Error {
 
 	#[error(display = "Version mismatch: {}", _0)]
 	VersionMismatch(String),
-
-	#[error(display = "Remote error {}: {}", _0, _1)]
-	Remote(u8, String),
-}
-
-impl Error {
-	pub fn code(&self) -> u8 {
-		match self {
-			Self::Io(_) => 100,
-			Self::TokioJoin(_) => 110,
-			Self::OneshotRecv(_) => 111,
-			Self::RMPEncode(_) => 10,
-			Self::RMPDecode(_) => 11,
-			Self::UTF8(_) => 12,
-			Self::Framing => 13,
-			Self::NoHandler => 20,
-			Self::ConnectionClosed => 21,
-			Self::IdCollision => 22,
-			Self::Handshake(_) => 30,
-			Self::VersionMismatch(_) => 31,
-			Self::Remote(c, _) => *c,
-			Self::Message(_) => 99,
-		}
-	}
 }
 
 impl<T> From<tokio::sync::watch::error::SendError<T>> for Error {
diff --git a/src/lib.rs b/src/lib.rs
index 18091c8..8e30e40 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -13,10 +13,10 @@
 //! about message priorization.
 //! Also check out the examples to learn how to use this crate.
 
+pub mod bytes_buf;
 pub mod error;
 pub mod stream;
 pub mod util;
-pub mod bytes_buf;
 
 pub mod endpoint;
 pub mod message;
diff --git a/src/message.rs b/src/message.rs
index 61d01d0..ca68cac 100644
--- a/src/message.rs
+++ b/src/message.rs
@@ -3,6 +3,7 @@ use std::marker::PhantomData;
 use std::sync::Arc;
 
 use bytes::{BufMut, Bytes, BytesMut};
+use rand::prelude::*;
 use serde::{Deserialize, Serialize};
 
 use futures::stream::StreamExt;
@@ -40,6 +41,24 @@ pub const PRIO_SECONDARY: RequestPriority = 0x01;
 
 // ----
 
+#[derive(Clone, Copy)]
+pub struct OrderTagStream(u64);
+#[derive(Clone, Copy, Serialize, Deserialize, Debug)]
+pub struct OrderTag(u64, u64);
+
+impl OrderTag {
+	pub fn stream() -> OrderTagStream {
+		OrderTagStream(thread_rng().gen())
+	}
+}
+impl OrderTagStream {
+	pub fn order(&self, order: u64) -> OrderTag {
+		OrderTag(self.0, order)
+	}
+}
+
+// ----
+
 /// This trait should be implemented by all messages your application
 /// wants to handle
 pub trait Message: Serialize + for<'de> Deserialize<'de> + Send + Sync + 'static {
@@ -56,6 +75,7 @@ pub struct Req<M: Message> {
 	pub(crate) msg: Arc<M>,
 	pub(crate) msg_ser: Option<Bytes>,
 	pub(crate) stream: AttachedStream,
+	pub(crate) order_tag: Option<OrderTag>,
 }
 
 impl<M: Message> Req<M> {
@@ -77,6 +97,13 @@ impl<M: Message> Req<M> {
 		}
 	}
 
+	pub fn with_order_tag(self, order_tag: OrderTag) -> Self {
+		Self {
+			order_tag: Some(order_tag),
+			..self
+		}
+	}
+
 	pub fn msg(&self) -> &M {
 		&self.msg
 	}
@@ -97,6 +124,7 @@ impl<M: Message> Req<M> {
 			telemetry_id,
 			msg: self.msg_ser.unwrap(),
 			stream: self.stream.into_stream(),
+			order_tag: self.order_tag,
 		}
 	}
 
@@ -109,6 +137,7 @@ impl<M: Message> Req<M> {
 				.stream
 				.map(AttachedStream::Stream)
 				.unwrap_or(AttachedStream::None),
+			order_tag: enc.order_tag,
 		})
 	}
 }
@@ -125,6 +154,7 @@ impl<M: Message> IntoReq<M> for M {
 			msg: Arc::new(self),
 			msg_ser: Some(Bytes::from(msg_ser)),
 			stream: AttachedStream::None,
+			order_tag: None,
 		})
 	}
 	fn into_req_local(self) -> Req<M> {
@@ -132,6 +162,7 @@ impl<M: Message> IntoReq<M> for M {
 			msg: Arc::new(self),
 			msg_ser: None,
 			stream: AttachedStream::None,
+			order_tag: None,
 		}
 	}
 }
@@ -158,6 +189,7 @@ impl<M: Message> Clone for Req<M> {
 			msg: self.msg.clone(),
 			msg_ser: self.msg_ser.clone(),
 			stream,
+			order_tag: self.order_tag,
 		}
 	}
 }
@@ -184,6 +216,7 @@ pub struct Resp<M: Message> {
 	pub(crate) _phantom: PhantomData<M>,
 	pub(crate) msg: M::Response,
 	pub(crate) stream: AttachedStream,
+	pub(crate) order_tag: Option<OrderTag>,
 }
 
 impl<M: Message> Resp<M> {
@@ -192,6 +225,7 @@ impl<M: Message> Resp<M> {
 			_phantom: Default::default(),
 			msg: v,
 			stream: AttachedStream::None,
+			order_tag: None,
 		}
 	}
 
@@ -209,6 +243,13 @@ impl<M: Message> Resp<M> {
 		}
 	}
 
+	pub fn with_order_tag(self, order_tag: OrderTag) -> Self {
+		Self {
+			order_tag: Some(order_tag),
+			..self
+		}
+	}
+
 	pub fn msg(&self) -> &M::Response {
 		&self.msg
 	}
@@ -222,26 +263,24 @@ impl<M: Message> Resp<M> {
 	}
 
 	pub(crate) fn into_enc(self) -> Result<RespEnc, rmp_serde::encode::Error> {
-		Ok(RespEnc::Success {
+		Ok(RespEnc {
 			msg: rmp_to_vec_all_named(&self.msg)?.into(),
 			stream: self.stream.into_stream(),
+			order_tag: self.order_tag,
 		})
 	}
 
 	pub(crate) fn from_enc(enc: RespEnc) -> Result<Self, Error> {
-		match enc {
-			RespEnc::Success { msg, stream } => {
-				let msg = rmp_serde::decode::from_read_ref(&msg)?;
-				Ok(Self {
-					_phantom: Default::default(),
-					msg,
-					stream: stream
-						.map(AttachedStream::Stream)
-						.unwrap_or(AttachedStream::None),
-				})
-			}
-			RespEnc::Error { code, message } => Err(Error::Remote(code, message)),
-		}
+		let msg = rmp_serde::decode::from_read_ref(&enc.msg)?;
+		Ok(Self {
+			_phantom: Default::default(),
+			msg,
+			stream: enc
+				.stream
+				.map(AttachedStream::Stream)
+				.unwrap_or(AttachedStream::None),
+			order_tag: enc.order_tag,
+		})
 	}
 }
 
@@ -295,10 +334,11 @@ pub(crate) struct ReqEnc {
 	pub(crate) telemetry_id: Bytes,
 	pub(crate) msg: Bytes,
 	pub(crate) stream: Option<ByteStream>,
+	pub(crate) order_tag: Option<OrderTag>,
 }
 
 impl ReqEnc {
-	pub(crate) fn encode(self) -> ByteStream {
+	pub(crate) fn encode(self) -> (ByteStream, Option<OrderTag>) {
 		let mut buf = BytesMut::with_capacity(
 			self.path.len() + self.telemetry_id.len() + self.msg.len() + 16,
 		);
@@ -315,15 +355,18 @@ impl ReqEnc {
 
 		let header = buf.freeze();
 
-		if let Some(stream) = self.stream {
+		let res_stream: ByteStream = if let Some(stream) = self.stream {
 			Box::pin(futures::stream::iter([Ok(header), Ok(self.msg)]).chain(stream))
 		} else {
 			Box::pin(futures::stream::iter([Ok(header), Ok(self.msg)]))
-		}
+		};
+		(res_stream, self.order_tag)
 	}
 
 	pub(crate) async fn decode(stream: ByteStream) -> Result<Self, Error> {
-		Self::decode_aux(stream).await.map_err(|_| Error::Framing)
+		Self::decode_aux(stream)
+			.await
+			.map_err(read_exact_error_to_error)
 	}
 
 	async fn decode_aux(stream: ByteStream) -> Result<Self, ReadExactError> {
@@ -346,6 +389,7 @@ impl ReqEnc {
 			telemetry_id,
 			msg,
 			stream: Some(reader.into_stream()),
+			order_tag: None,
 		})
 	}
 }
@@ -360,74 +404,67 @@ impl ReqEnc {
 /// - message length + 1: u8
 /// - error code: u8
 /// - message: [u8; message_length]
-pub(crate) enum RespEnc {
-	Error {
-		code: u8,
-		message: String,
-	},
-	Success {
-		msg: Bytes,
-		stream: Option<ByteStream>,
-	},
+pub(crate) struct RespEnc {
+	msg: Bytes,
+	stream: Option<ByteStream>,
+	order_tag: Option<OrderTag>,
 }
 
 impl RespEnc {
-	pub(crate) fn from_err(e: Error) -> Self {
-		RespEnc::Error {
-			code: e.code(),
-			message: format!("{}", e),
-		}
-	}
-
-	pub(crate) fn encode(self) -> ByteStream {
-		match self {
-			RespEnc::Success { msg, stream } => {
-				let mut buf = BytesMut::with_capacity(msg.len() + 8);
-
-				buf.put_u8(0);
+	pub(crate) fn encode(resp: Result<Self, Error>) -> (ByteStream, Option<OrderTag>) {
+		match resp {
+			Ok(Self {
+				msg,
+				stream,
+				order_tag,
+			}) => {
+				let mut buf = BytesMut::with_capacity(4);
 				buf.put_u32(msg.len() as u32);
-
 				let header = buf.freeze();
 
-				if let Some(stream) = stream {
+				let res_stream: ByteStream = if let Some(stream) = stream {
 					Box::pin(futures::stream::iter([Ok(header), Ok(msg)]).chain(stream))
 				} else {
 					Box::pin(futures::stream::iter([Ok(header), Ok(msg)]))
-				}
+				};
+				(res_stream, order_tag)
 			}
-			RespEnc::Error { code, message } => {
-				let mut buf = BytesMut::with_capacity(message.len() + 8);
-				buf.put_u8(1 + message.len() as u8);
-				buf.put_u8(code);
-				buf.put(message.as_bytes());
-				let header = buf.freeze();
-				Box::pin(futures::stream::once(async move { Ok(header) }))
+			Err(err) => {
+				let err = std::io::Error::new(
+					std::io::ErrorKind::Other,
+					format!("netapp error: {}", err),
+				);
+				(
+					Box::pin(futures::stream::once(async move { Err(err) })),
+					None,
+				)
 			}
 		}
 	}
 
 	pub(crate) async fn decode(stream: ByteStream) -> Result<Self, Error> {
-		Self::decode_aux(stream).await.map_err(|_| Error::Framing)
+		Self::decode_aux(stream)
+			.await
+			.map_err(read_exact_error_to_error)
 	}
 
 	async fn decode_aux(stream: ByteStream) -> Result<Self, ReadExactError> {
 		let mut reader = ByteStreamReader::new(stream);
 
-		let is_err = reader.read_u8().await?;
+		let msg_len = reader.read_u32().await?;
+		let msg = reader.read_exact(msg_len as usize).await?;
 
-		if is_err > 0 {
-			let code = reader.read_u8().await?;
-			let message = reader.read_exact(is_err as usize - 1).await?;
-			let message = String::from_utf8(message.to_vec()).unwrap_or_default();
-			Ok(RespEnc::Error { code, message })
-		} else {
-			let msg_len = reader.read_u32().await?;
-			let msg = reader.read_exact(msg_len as usize).await?;
-
-			Ok(RespEnc::Success {
-				msg,
-				stream: Some(reader.into_stream()),
-			})
-		}
+		Ok(Self {
+			msg,
+			stream: Some(reader.into_stream()),
+			order_tag: None,
+		})
+	}
+}
+
+fn read_exact_error_to_error(e: ReadExactError) -> Error {
+	match e {
+		ReadExactError::Stream(err) => Error::Remote(err.kind(), err.to_string()),
+		ReadExactError::UnexpectedEos => Error::Framing,
 	}
 }
diff --git a/src/recv.rs b/src/recv.rs
index f8606f3..b5289fb 100644
--- a/src/recv.rs
+++ b/src/recv.rs
@@ -35,7 +35,10 @@ impl Sender {
 impl Drop for Sender {
 	fn drop(&mut self) {
 		if let Some(inner) = self.inner.take() {
-			let _ = inner.send(Err(std::io::Error::new(std::io::ErrorKind::BrokenPipe, "Netapp connection dropped before end of stream")));
+			let _ = inner.send(Err(std::io::Error::new(
+				std::io::ErrorKind::BrokenPipe,
+				"Netapp connection dropped before end of stream",
+			)));
 		}
 	}
 }
@@ -82,7 +85,8 @@ pub(crate) trait RecvLoop: Sync + 'static {
 
 			let packet = if is_error {
 				let kind = u8_to_io_errorkind(next_slice[0]);
-				let msg = std::str::from_utf8(&next_slice[1..]).unwrap_or("<invalid utf8 error message>");
+				let msg =
+					std::str::from_utf8(&next_slice[1..]).unwrap_or("<invalid utf8 error message>");
 				debug!("recv_loop: got id {}, error {:?}: {}", id, kind, msg);
 				Some(Err(std::io::Error::new(kind, msg.to_string())))
 			} else {
diff --git a/src/send.rs b/src/send.rs
index 287fe40..c40787f 100644
--- a/src/send.rs
+++ b/src/send.rs
@@ -4,7 +4,7 @@ use std::sync::Arc;
 use std::task::{Context, Poll};
 
 use async_trait::async_trait;
-use bytes::{Bytes, BytesMut, BufMut};
+use bytes::{BufMut, Bytes, BytesMut};
 use log::*;
 
 use futures::AsyncWriteExt;
@@ -36,6 +36,8 @@ pub(crate) const ERROR_MARKER: ChunkLength = 0x4000;
 pub(crate) const CHUNK_HAS_CONTINUATION: ChunkLength = 0x8000;
 pub(crate) const CHUNK_LENGTH_MASK: ChunkLength = 0x3FFF;
 
+pub(crate) type SendStream = (RequestID, RequestPriority, ByteStream);
+
 struct SendQueue {
 	items: Vec<(u8, VecDeque<SendQueueItem>)>,
 }
@@ -184,7 +186,7 @@ impl DataFrame {
 pub(crate) trait SendLoop: Sync {
 	async fn send_loop<W>(
 		self: Arc<Self>,
-		msg_recv: mpsc::UnboundedReceiver<(RequestID, RequestPriority, ByteStream)>,
+		msg_recv: mpsc::UnboundedReceiver<SendStream>,
 		mut write: BoxStreamWrite<W>,
 	) -> Result<(), Error>
 	where
diff --git a/src/server.rs b/src/server.rs
index 57062d8..c23c9e4 100644
--- a/src/server.rs
+++ b/src/server.rs
@@ -53,7 +53,7 @@ pub(crate) struct ServerConn {
 
 	netapp: Arc<NetApp>,
 
-	resp_send: ArcSwapOption<mpsc::UnboundedSender<(RequestID, RequestPriority, ByteStream)>>,
+	resp_send: ArcSwapOption<mpsc::UnboundedSender<SendStream>>,
 }
 
 impl ServerConn {
@@ -177,26 +177,16 @@ impl RecvLoop for ServerConn {
 		tokio::spawn(async move {
 			debug!("server: recv_handler got {}", id);
 
-			let (prio, resp_enc) = match ReqEnc::decode(stream).await {
-				Ok(req_enc) => {
-					let prio = req_enc.prio;
-					let resp = self2.recv_handler_aux(req_enc).await;
-
-					(
-						prio,
-						match resp {
-							Ok(resp_enc) => resp_enc,
-							Err(e) => RespEnc::from_err(e),
-						},
-					)
-				}
-				Err(e) => (PRIO_NORMAL, RespEnc::from_err(e)),
+			let (prio, resp_enc_result) = match ReqEnc::decode(stream).await {
+				Ok(req_enc) => (req_enc.prio, self2.recv_handler_aux(req_enc).await),
+				Err(e) => (PRIO_HIGH, Err(e)),
 			};
 
 			debug!("server: sending response to {}", id);
 
+			let (resp_stream, resp_order) = RespEnc::encode(resp_enc_result);
 			resp_send
-				.send((id, prio, resp_enc.encode()))
+				.send((id, prio, resp_stream))
 				.log_err("ServerConn recv_handler send resp bytes");
 			Ok::<_, Error>(())
 		});
diff --git a/src/stream.rs b/src/stream.rs
index 6e00e5f..efa0ebc 100644
--- a/src/stream.rs
+++ b/src/stream.rs
@@ -150,7 +150,6 @@ impl<'a> Future for ByteStreamReadExact<'a> {
 
 // ----
 
-
 pub fn asyncread_stream<R: AsyncRead + Send + Sync + 'static>(reader: R) -> ByteStream {
 	Box::pin(tokio_util::io::ReaderStream::new(reader))
 }