diff --git a/dune-project b/dune-project
index ff2150c..4035343 100644
--- a/dune-project
+++ b/dune-project
@@ -20,9 +20,14 @@
  (synopsis "Tiny event loop abstraction")
  (depends ocaml dune base-unix)
  (depopts
-  (trace (>= 0.7))
+  (trace
+   (>= 0.7))
+  (iostream
+   (>= 0.3))
   (picos
-   (and (>= 0.5) (< 0.7))))
+   (and
+    (>= 0.5)
+    (< 0.7))))
  (tags
   (unix select async)))
 
@@ -40,9 +45,12 @@
   ocaml
   dune
   nanoev
-  (picos (>= 0.6))
+  (picos
+   (>= 0.6))
   picos_std
-  (tiny_httpd (>= 0.17)))
- (tags (nanoev http)))
+  (tiny_httpd
+   (>= 0.17)))
+ (tags
+  (nanoev http)))
 
 ; See the complete stanza docs at https://dune.readthedocs.io/en/stable/reference/dune-project/index.html
diff --git a/nanoev.opam b/nanoev.opam
index 9fa7ba9..9aeadaa 100644
--- a/nanoev.opam
+++ b/nanoev.opam
@@ -15,6 +15,7 @@ depends: [
 ]
 depopts: [
   "trace" {>= "0.7"}
+  "iostream" {>= "0.3"}
   "picos" {>= "0.5" & < "0.7"}
 ]
 build: [
diff --git a/src/picos/IO_in.ml b/src/picos/IO_in.ml
new file mode 100644
index 0000000..6184eba
--- /dev/null
+++ b/src/picos/IO_in.ml
@@ -0,0 +1,152 @@
+open Common_
+
+class type t = object
+  method input : bytes -> int -> int -> int
+  (** Read into the slice. Returns [0] only if the stream is closed. *)
+
+  method close : unit -> unit
+  (** Close the input. Must be idempotent. *)
+end
+
+let create ?(close = ignore) ~input () : t =
+  object
+    method close = close
+    method input = input
+  end
+
+let empty : t =
+  object
+    method close () = ()
+    method input _ _ _ = 0
+  end
+
+let of_bytes ?(off = 0) ?len (b : bytes) : t =
+  (* i: current position in [b] *)
+  let i = ref off in
+
+  let len =
+    match len with
+    | Some n ->
+      if n > Bytes.length b - off then invalid_arg "Iostream.In.of_bytes";
+      n
+    | None -> Bytes.length b - off
+  in
+  let end_ = off + len in
+
+  object
+    method input b_out i_out len_out =
+      let n = min (end_ - !i) len_out in
+      Bytes.blit b !i b_out i_out n;
+      i := !i + n;
+      n
+
+    method close () = i := end_
+  end
+
+let of_string ?off ?len s : t = of_bytes ?off ?len (Bytes.unsafe_of_string s)
+
+(** Read into the given slice.
+    @return the number of bytes read, [0] means end of input. *)
+let[@inline] input (self : #t) buf i len = self#input buf i len
+
+(** Close the channel. *)
+let[@inline] close self : unit = self#close ()
+
+let rec really_input (self : #t) buf i len =
+  if len > 0 then (
+    let n = input self buf i len in
+    if n = 0 then raise End_of_file;
+    (really_input [@tailrec]) self buf (i + n) (len - n)
+  )
+
+let really_input_string self n : string =
+  let buf = Bytes.create n in
+  really_input self buf 0 n;
+  Bytes.unsafe_to_string buf
+
+let copy_into ?(buf = Bytes.create _default_buf_size) (ic : #t) (oc : IO_out.t)
+    : unit =
+  let continue = ref true in
+  while !continue do
+    let len = input ic buf 0 (Bytes.length buf) in
+    if len = 0 then
+      continue := false
+    else
+      IO_out.output oc buf 0 len
+  done
+
+let concat (l0 : t list) : t =
+  let l = ref l0 in
+  let rec input b i len : int =
+    match !l with
+    | [] -> 0
+    | ic :: tl ->
+      let n = ic#input b i len in
+      if n > 0 then
+        n
+      else (
+        l := tl;
+        input b i len
+      )
+  in
+  let close () = List.iter close l0 in
+  create ~close ~input ()
+
+let input_all ?(buf = Bytes.create 128) (self : #t) : string =
+  let buf = ref buf in
+  let i = ref 0 in
+
+  let[@inline] full_ () = !i = Bytes.length !buf in
+
+  let grow_ () =
+    let old_size = Bytes.length !buf in
+    let new_size = min Sys.max_string_length (old_size + (old_size / 4) + 10) in
+    if old_size = new_size then
+      failwith "input_all: maximum input size exceeded";
+    let new_buf = Bytes.extend !buf 0 (new_size - old_size) in
+    buf := new_buf
+  in
+
+  let rec loop () =
+    if full_ () then grow_ ();
+    let available = Bytes.length !buf - !i in
+    let n = input self !buf !i available in
+    if n > 0 then (
+      i := !i + n;
+      (loop [@tailrec]) ()
+    )
+  in
+  loop ();
+
+  if full_ () then
+    Bytes.unsafe_to_string !buf
+  else
+    Bytes.sub_string !buf 0 !i
+
+let of_unix_fd ?(close_noerr = false) ?(buf = Bytes.create _default_buf_size)
+    (fd : Unix.file_descr) : t =
+  let buf_len = ref 0 in
+  let buf_off = ref 0 in
+
+  let refill () =
+    buf_off := 0;
+    buf_len := Base.read fd buf 0 (Bytes.length buf)
+  in
+
+  object
+    method input b i len : int =
+      if !buf_len = 0 then refill ();
+      let n = min len !buf_len in
+      if n > 0 then (
+        Bytes.blit buf !buf_off b i n;
+        buf_off := !buf_off + n;
+        buf_len := !buf_len - n
+      );
+      n
+
+    method close () =
+      if close_noerr then (
+        try Unix.close fd with _ -> ()
+      ) else
+        Unix.close fd
+  end
diff --git a/src/picos/IO_out.ml b/src/picos/IO_out.ml
new file mode 100644
index 0000000..b98525f
--- /dev/null
+++ b/src/picos/IO_out.ml
@@ -0,0 +1,118 @@
+open Common_
+
+class type t = object
+  method output_char : char -> unit
+  method output : bytes -> int -> int -> unit
+  method flush : unit -> unit
+  method close : unit -> unit
+end
+
+let create ?(flush = ignore) ?(close = ignore) ~output_char ~output () : t =
+  object
+    method flush () = flush ()
+    method close () = close ()
+    method output_char c = output_char c
+    method output bs i len = output bs i len
+  end
+
+let dummy : t =
+  object
+    method flush () = ()
+    method close () = ()
+    method output_char _ = ()
+    method output _ _ _ = ()
+  end
+
+let of_unix_fd ?(close_noerr = false) ?(buf = Bytes.create _default_buf_size) fd
+    : t =
+  let buf_off = ref 0 in
+
+  let[@inline] is_full () = !buf_off = Bytes.length buf in
+
+  let flush () =
+    if !buf_off > 0 then (
+      Base.write fd buf 0 !buf_off;
+      buf_off := 0
+    )
+  in
+
+  object
+    method output_char c =
+      if is_full () then flush ();
+      Bytes.set buf !buf_off c;
+      incr buf_off
+
+    method output bs i len : unit =
+      let i = ref i in
+      let len = ref len in
+
+      while !len > 0 do
+        (* make space *)
+        if is_full () then flush ();
+
+        let n = min !len (Bytes.length buf - !buf_off) in
+        Bytes.blit bs !i buf !buf_off n;
+        buf_off := !buf_off + n;
+        i := !i + n;
+        len := !len - n
+      done;
+      (* if full, write eagerly *)
+      if is_full () then flush ()
+
+    method close () =
+      if close_noerr then (
+        try
+          flush ();
+          Unix.close fd
+        with _ -> ()
+      ) else (
+        flush ();
+        Unix.close fd
+      )
+
+    method flush = flush
+  end
+
+let of_buffer (buf : Buffer.t) : t =
+  object
+    method close () = ()
+    method flush () = ()
+    method output_char c = Buffer.add_char buf c
+    method output bs i len = Buffer.add_subbytes buf bs i len
+  end
+
+(** Output the buffer slice into this channel *)
+let[@inline] output_char (self : #t) c : unit = self#output_char c
+
+(** Output the buffer slice into this channel *)
+let[@inline] output (self : #t) buf i len : unit = self#output buf i len
+
+let[@inline] output_string (self : #t) (str : string) : unit =
+  self#output (Bytes.unsafe_of_string str) 0 (String.length str)
+
+let output_line (self : #t) (str : string) : unit =
+  output_string self str;
+  output_char self '\n'
+
+(** Close the channel. *)
+let[@inline] close self : unit = self#close ()
+
+(** Flush (ie. force write) any buffered bytes. *)
+let[@inline] flush self : unit = self#flush ()
+
+let output_int self i =
+  let s = string_of_int i in
+  output_string self s
+
+let output_lines self seq = Seq.iter (output_line self) seq
+
+let tee (l : t list) : t =
+  match l with
+  | [] -> dummy
+  | [ oc ] -> oc
+  | _ ->
+    let output bs i len = List.iter (fun oc -> output oc bs i len) l in
+    let output_char c = List.iter (fun oc -> output_char oc c) l in
+    let close () = List.iter close l in
+    let flush () = List.iter flush l in
+    create ~flush ~close ~output ~output_char ()
diff --git a/src/picos/background_thread.ml b/src/picos/background_thread.ml
new file mode 100644
index 0000000..261daad
--- /dev/null
+++ b/src/picos/background_thread.ml
@@ -0,0 +1,7 @@
+let is_setup = Global_.has_bg_thread
+let setup = Global_.setup_bg_thread
+let shutdown = Global_.shutdown_bg_thread
+
+let with_setup ev f =
+  setup ev;
+  Fun.protect ~finally:shutdown f
diff --git a/src/picos/background_thread.mli b/src/picos/background_thread.mli
new file mode 100644
index 0000000..6e4a531
--- /dev/null
+++ b/src/picos/background_thread.mli
@@ -0,0 +1,10 @@
+val setup : Nanoev.t -> unit
+(** Install this event loop in a background thread *)
+
+val shutdown : unit -> unit
+(** Shutdown background thread, assuming {! is_setup} returns [true] *)
+
+val with_setup : Nanoev.t -> (unit -> 'a) -> 'a
+
+val is_setup : unit -> bool
+(** [is_setup()] is [true] iff a background thread is running a nanoev loop *)
diff --git a/src/picos/base.ml b/src/picos/base.ml
new file mode 100644
index 0000000..a34577f
--- /dev/null
+++ b/src/picos/base.ml
@@ -0,0 +1,96 @@
+open Common_
+
+let[@inline] get_loop_exn_ () : Nanoev.t =
+  match Atomic.get Global_.st with
+  | None -> failwith "No nanoev loop installed."
+  | Some st -> st.nanoev
+
+let[@inline] unwrap_ = function
+  | None -> ()
+  | Some (exn, bt) -> Printexc.raise_with_backtrace exn bt
+
+let[@unroll 1] rec retry_read_ fd f =
+  match f () with
+  | res -> res
+  | exception
+      Unix.Unix_error ((Unix.EAGAIN | Unix.EWOULDBLOCK | Unix.EINTR), _, _) ->
+    (* Trace_.message "read must wait"; *)
+    let trigger = Picos.Trigger.create () in
+    let closed_r = ref false in
+    let ev = get_loop_exn_ () in
+    Nanoev.on_readable ev fd trigger closed_r (fun ~closed trigger closed_r ->
+        closed_r := closed;
+        Picos.Trigger.signal trigger);
+    Picos.Trigger.await trigger |> unwrap_;
+    if !closed_r then raise Closed;
+    retry_read_ fd f
+
+let[@unroll 1] rec retry_write_ fd f =
+  match f () with
+  | res -> res
+  | exception
+      Unix.Unix_error ((Unix.EAGAIN | Unix.EWOULDBLOCK | Unix.EINTR), _, _) ->
+    (* Trace_.message "write must wait"; *)
+    let ev = get_loop_exn_ () in
+    let trigger = Picos.Trigger.create () in
+    let closed_r = ref false in
+    Nanoev.on_writable ev fd trigger closed_r (fun ~closed trigger closed_r ->
+        closed_r := closed;
+        Picos.Trigger.signal trigger);
+    Picos.Trigger.await trigger |> unwrap_;
+    if !closed_r then raise Closed;
+    retry_write_ fd f
+
+let read fd buf i len : int =
+  try
+    retry_read_ fd (fun () ->
+        (* Trace_.message "read"; *)
+        Unix.read fd buf i len)
+  with Closed -> 0
+
+let close fd =
+  Unix.close fd;
+  let ev = get_loop_exn_ () in
+  Nanoev.close ev fd
+
+let accept fd =
+  try
+    retry_read_ fd (fun () ->
+        (* Trace_.message "accept"; *)
+        Unix.accept fd)
+  with Unix.Unix_error ((Unix.ESHUTDOWN | Unix.ECONNABORTED), _, _) ->
+    raise Closed
+
+let write_once fd buf i len : int =
+  try
+    retry_write_ fd (fun () ->
+        (* Trace_.message "write"; *)
+        Unix.write fd buf i len)
+  with Closed -> 0
+
+let rec write fd buf i len =
+  if len > 0 then (
+    let n = write_once fd buf i len in
+    if n < len then write fd buf (i + n) (len - n)
+  )
+
+let connect fd addr = retry_write_ fd (fun () -> Unix.connect fd addr)
+
+let[@inline] max_fds () =
+  match Atomic.get Global_.st with
+  | None -> 1024
+  | Some st -> Nanoev.max_fds st.nanoev
+
+let sleep t =
+  if t > 0. then (
+    let ev = get_loop_exn_ () in
+    let trigger = Picos.Trigger.create () in
+    Nanoev.run_after_s ev t trigger () (fun trigger () ->
+        Picos.Trigger.signal trigger);
+    Picos.Trigger.await trigger |> unwrap_
+  )
+
+module Raw = struct
+  let retry_read = retry_read_
+  let retry_write = retry_write_
+end
diff --git a/src/picos/base.mli b/src/picos/base.mli
new file mode 100644
index 0000000..7b949e9
--- /dev/null
+++ b/src/picos/base.mli
@@ -0,0 +1,37 @@
+val read : Unix.file_descr -> bytes -> int -> int -> int
+(** Read from the non blocking FD.
+    @raise Nanoev.Closed if the FD is closed
+    @raise Unix.Unix_error for other errors *)
+
+val write_once : Unix.file_descr -> bytes -> int -> int -> int
+(** Write into the non blocking FD.
+    @raise Nanoev.Closed if the FD is closed
+    @raise Unix.Unix_error for other errors *)
+
+val write : Unix.file_descr -> bytes -> int -> int -> unit
+
+val close : Unix.file_descr -> unit
+(** Close the file descriptor
+    @raise Unix.Unix_error when it fails *)
+
+val connect : Unix.file_descr -> Unix.sockaddr -> unit
+(** Connect this FD to the remote address.
+    @raise Nanoev.Closed if the FD is closed.
+    @raise Unix.Unix_error for other errors *)
+
+val accept : Unix.file_descr -> Unix.file_descr * Unix.sockaddr
+(** Accept a connection on this fd.
+    @raise Nanoev.Closed if the FD is closed.
+    @raise Unix.Unix_error for other errors *)
+
+val max_fds : unit -> int
+(** Maximum number of file descriptors one can await on. See {!Nanoev.max_fds}
+*)
+
+val sleep : float -> unit
+(** Suspend current fiber for [n] seconds *)
+
+module Raw : sig
+  val retry_read : Unix.file_descr -> (unit -> 'a) -> 'a
+  val retry_write : Unix.file_descr -> (unit -> 'a) -> 'a
+end
diff --git a/src/picos/common_.ml b/src/picos/common_.ml
new file mode 100644
index 0000000..d35dd22
--- /dev/null
+++ b/src/picos/common_.ml
@@ -0,0 +1,6 @@
+module Trace_ = Nanoev.Trace_
+
+let ( let@ ) = ( @@ )
+let _default_buf_size = 4 * 1024
+
+exception Closed = Nanoev.Closed
diff --git a/src/picos/dune b/src/picos/dune
index db9792d..fb37e29 100644
--- a/src/picos/dune
+++ b/src/picos/dune
@@ -2,4 +2,4 @@
  (name nanoev_picos)
  (public_name nanoev.picos)
  (optional) ; picos
- (libraries threads picos nanoev))
+ (libraries threads picos iostream nanoev))
diff --git a/src/picos/global_.ml b/src/picos/global_.ml
new file mode 100644
index 0000000..2e590b8
--- /dev/null
+++ b/src/picos/global_.ml
@@ -0,0 +1,59 @@
+open Common_
+
+type st =
+  | None
+  | Some of {
+      active: bool Atomic.t;
+      nanoev: Nanoev.t;
+      th: Thread.t;
+    }
+
+let st : st Atomic.t = Atomic.make None
+let lock = Mutex.create ()
+
+let with_lock lock f =
+  Mutex.lock lock;
+  match f () with
+  | exception e ->
+    Mutex.unlock lock;
+    raise e
+  | x ->
+    Mutex.unlock lock;
+    x
+
+let bg_thread_ ~active ~evloop () : unit =
+  Trace_.set_thread_name "nanoev.picos.bg-thread";
+  while Atomic.get active do
+    Nanoev.step evloop
+  done
+
+let[@inline] has_bg_thread () = Atomic.get st <> None
+
+let setup_bg_thread (ev : Nanoev.t) : unit =
+  let@ () = with_lock lock in
+  (* shutdown existing thread, if any *)
+  (match Atomic.get st with
+  | Some st ->
+    Atomic.set st.active false;
+    Nanoev.wakeup_from_outside st.nanoev;
+    Thread.join st.th
+  | None -> ());
+
+  (* start new bg thread *)
+  let active = Atomic.make true in
+  Atomic.set st
+  @@ Some
+       {
+         active;
+         nanoev = ev;
+         th = Thread.create (bg_thread_ ~active ~evloop:ev) ();
+       }
+
+let shutdown_bg_thread () =
+  let@ () = with_lock lock in
+  match Atomic.exchange st None with
+  | None -> ()
+  | Some st ->
+    Atomic.set st.active false;
+    Nanoev.wakeup_from_outside st.nanoev;
+    Thread.join st.th
diff --git a/src/picos/nanoev_picos.ml b/src/picos/nanoev_picos.ml
index a11c89f..8029fda 100644
--- a/src/picos/nanoev_picos.ml
+++ b/src/picos/nanoev_picos.ml
@@ -1,161 +1,7 @@
-open struct
-  module Trace_ = Nanoev.Trace_
-
-  let ( let@ ) = ( @@ )
-end
-
-exception Closed = Nanoev.Closed
-
-module Global_ = struct
-  type st =
-    | None
-    | Some of {
-        active: bool Atomic.t;
-        nanoev: Nanoev.t;
-        th: Thread.t;
-      }
-
-  let st : st Atomic.t = Atomic.make None
-  let lock = Mutex.create ()
-
-  let with_lock lock f =
-    Mutex.lock lock;
-    match f () with
-    | exception e ->
-      Mutex.unlock lock;
-      raise e
-    | x ->
-      Mutex.unlock lock;
-      x
-
-  let bg_thread_ ~active ~evloop () : unit =
-    Trace_.set_thread_name "nanoev.picos.bg-thread";
-    while Atomic.get active do
-      Nanoev.step evloop
-    done
-
-  let[@inline] has_bg_thread () = Atomic.get st <> None
-
-  let setup_bg_thread (ev : Nanoev.t) : unit =
-    let@ () = with_lock lock in
-    (* shutdown existing thread, if any *)
-    (match Atomic.get st with
-    | Some st ->
-      Atomic.set st.active false;
-      Nanoev.wakeup_from_outside st.nanoev;
-      Thread.join st.th
-    | None -> ());
-
-    (* start new bg thread *)
-    let active = Atomic.make true in
-    Atomic.set st
-    @@ Some
-         {
-           active;
-           nanoev = ev;
-           th = Thread.create (bg_thread_ ~active ~evloop:ev) ();
-         }
-
-  let shutdown_bg_thread () =
-    let@ () = with_lock lock in
-    match Atomic.exchange st None with
-    | None -> ()
-    | Some st ->
-      Atomic.set st.active false;
-      Nanoev.wakeup_from_outside st.nanoev;
-      Thread.join st.th
-end
-
-module Background_thread = struct
-  let is_setup = Global_.has_bg_thread
-  let setup = Global_.setup_bg_thread
-  let shutdown = Global_.shutdown_bg_thread
-
-  let with_setup ev f =
-    setup ev;
-    Fun.protect ~finally:shutdown f
-end
-
-let[@inline] get_loop_exn_ () : Nanoev.t =
-  match Atomic.get Global_.st with
-  | None -> failwith "No nanoev loop installed."
-  | Some st -> st.nanoev
-
-let[@inline] unwrap_ = function
-  | None -> ()
-  | Some (exn, bt) -> Printexc.raise_with_backtrace exn bt
-
-let[@unroll 1] rec retry_read_ fd f =
-  match f () with
-  | res -> res
-  | exception
-      Unix.Unix_error ((Unix.EAGAIN | Unix.EWOULDBLOCK | Unix.EINTR), _, _) ->
-    (* Trace_.message "read must wait"; *)
-    let trigger = Picos.Trigger.create () in
-    let closed_r = ref false in
-    let ev = get_loop_exn_ () in
-    Nanoev.on_readable ev fd trigger closed_r (fun ~closed trigger closed_r ->
-        closed_r := closed;
-        Picos.Trigger.signal trigger);
-    Picos.Trigger.await trigger |> unwrap_;
-    if !closed_r then raise Closed;
-    retry_read_ fd f
-
-let[@unroll 1] rec retry_write_ fd f =
-  match f () with
-  | res -> res
-  | exception
-      Unix.Unix_error ((Unix.EAGAIN | Unix.EWOULDBLOCK | Unix.EINTR), _, _) ->
-    (* Trace_.message "write must wait"; *)
-    let ev = get_loop_exn_ () in
-    let trigger = Picos.Trigger.create () in
-    let closed_r = ref false in
-    Nanoev.on_writable ev fd trigger closed_r (fun ~closed trigger closed_r ->
-        closed_r := closed;
-        Picos.Trigger.signal trigger);
-    Picos.Trigger.await trigger |> unwrap_;
-    if !closed_r then raise Closed;
-    retry_write_ fd f
-
-let read fd buf i len : int =
-  try
-    retry_read_ fd (fun () ->
-        (* Trace_.message "read"; *)
-        Unix.read fd buf i len)
-  with Closed -> 0
-
-let close fd =
-  Unix.close fd;
-  let ev = get_loop_exn_ () in
-  Nanoev.close ev fd
-
-let accept fd =
-  try
-    retry_read_ fd (fun () ->
-        (* Trace_.message "accept"; *)
-        Unix.accept fd)
-  with Unix.Unix_error ((Unix.ESHUTDOWN | Unix.ECONNABORTED), _, _) ->
-    raise Closed
-
-let write fd buf i len : int =
-  try
-    retry_write_ fd (fun () ->
-        (* Trace_.message "write"; *)
-        Unix.write fd buf i len)
-  with Closed -> 0
-
-let connect fd addr = retry_write_ fd (fun () -> Unix.connect fd addr)
-
-let[@inline] max_fds () =
-  match Atomic.get Global_.st with
-  | None -> 1024
-  | Some st -> Nanoev.max_fds st.nanoev
-
-let sleep t =
-  if t > 0. then (
-    let ev = get_loop_exn_ () in
-    let trigger = Picos.Trigger.create () in
-    Nanoev.run_after_s ev t trigger () (fun trigger () ->
-        Picos.Trigger.signal trigger);
-    Picos.Trigger.await trigger |> unwrap_
-  )
+module Background_thread = Background_thread
+module Base = Base
+include Base
+module IO_in = IO_in
+module IO_out = IO_out
+module Net_client = Net_client
+module Net_server = Net_server
diff --git a/src/picos/nanoev_picos.mli b/src/picos/nanoev_picos.mli
index 27310dc..c89e3a5 100644
--- a/src/picos/nanoev_picos.mli
+++ b/src/picos/nanoev_picos.mli
@@ -1,47 +1,18 @@
 (** Basic interface with picos *)
 
-module Background_thread : sig
-  val setup : Nanoev.t -> unit
-  (** Install this event loop in a background thread *)
-
-  val shutdown : unit -> unit
-  (** Shutdown background thread, assuming {! is_setup} returns [true] *)
-
-  val with_setup : Nanoev.t -> (unit -> 'a) -> 'a
-
-  val is_setup : unit -> bool
-  (** [is_setup()] is [true] iff a background thread is running a nanoev loop *)
-end
+module Background_thread = Background_thread
 
 (** {2 Non blocking IO primitives} *)
 
-val read : Unix.file_descr -> bytes -> int -> int -> int
-(** Read from the non blocking FD.
-    @raise Nanoev.Closed if the FD is closed
-    @raise Unix.Unix_error for other errors *)
+module Base = Base
 
-val write : Unix.file_descr -> bytes -> int -> int -> int
-(** Write into the non blocking FD.
-    @raise Nanoev.Closed if the FD is closed
-    @raise Unix.Unix_error for other errors *)
+include module type of struct
+  include Base
+end
 
-val close : Unix.file_descr -> unit
-(** Close the file descriptor
-    @raise Unix.Unix_error when it fails *)
+(** {2 Building blocks on top of {!Base}} *)
 
-val connect : Unix.file_descr -> Unix.sockaddr -> unit
-(** Connect this FD to the remote address.
-    @raise Nanoev.Closed if the FD is closed.
-    @raise Unix.Unix_error for other errors *)
-
-val accept : Unix.file_descr -> Unix.file_descr * Unix.sockaddr
-(** Accept a connection on this fd.
-    @raise Nanoev.Closed if the FD is closed.
-    @raise Unix.Unix_error for other errors *)
-
-val max_fds : unit -> int
-(** Maximum number of file descriptors one can await on. See {!Nanoev.max_fds}
-*)
-
-val sleep : float -> unit
-(** Suspend current fiber for [n] seconds *)
+module IO_in = IO_in
+module IO_out = IO_out
+module Net_client = Net_client
+module Net_server = Net_server
diff --git a/src/picos/net_client.ml b/src/picos/net_client.ml
new file mode 100644
index 0000000..1bb3cf5
--- /dev/null
+++ b/src/picos/net_client.ml
@@ -0,0 +1,20 @@
+open Common_
+
+let connect addr : Unix.file_descr =
+  let sock = Unix.socket (Unix.domain_of_sockaddr addr) Unix.SOCK_STREAM 0 in
+  Unix.set_nonblock sock;
+  (try Unix.setsockopt sock Unix.TCP_NODELAY true with _ -> ());
+
+  (* connect asynchronously *)
+  Base.Raw.retry_write sock (fun () -> Unix.connect sock addr);
+  sock
+
+let with_connect addr (f : IO_in.t -> IO_out.t -> 'a) : 'a =
+  let sock = connect addr in
+
+  let ic = IO_in.of_unix_fd sock in
+  let oc = IO_out.of_unix_fd sock in
+
+  let finally () = try Unix.close sock with _ -> () in
+  let@ () = Fun.protect ~finally in
+  f ic oc
diff --git a/src/picos/net_server.ml b/src/picos/net_server.ml
new file mode 100644
index 0000000..8c91799
--- /dev/null
+++ b/src/picos/net_server.ml
@@ -0,0 +1,48 @@
+type client_handler = Unix.sockaddr -> IO_in.t -> IO_out.t -> unit
+
+type t = {
+  active: bool Atomic.t;
+  sock: Unix.file_descr;
+  client_handler: client_handler;
+  spawn: (unit -> unit) -> unit Picos.Computation.t;
+  mutable running: unit Picos.Computation.t option;
+}
+
+let shutdown (self : t) =
+  if Atomic.exchange self.active false then
+    Option.iter Picos.Computation.await self.running
+
+open struct
+  let run (self : t) () : unit =
+    while Atomic.get self.active do
+      let client_sock, client_addr = Base.accept self.sock in
+      let comp =
+        self.spawn (fun () ->
+            let ic = IO_in.of_unix_fd client_sock in
+            let oc = IO_out.of_unix_fd client_sock in
+            self.client_handler client_addr ic oc)
+      in
+      ignore (comp : _ Picos.Computation.t)
+    done
+end
+
+let establish ?(backlog = 32) ~spawn ~(client_handler : client_handler) addr : t
+    =
+  let domain = Unix.domain_of_sockaddr addr in
+  let sock = Unix.socket domain Unix.SOCK_STREAM 0 in
+  Unix.bind sock addr;
+  Unix.listen sock backlog;
+  Unix.set_nonblock sock;
+  Unix.setsockopt sock Unix.SO_REUSEADDR true;
+  (try Unix.setsockopt sock Unix.TCP_NODELAY true with _ -> ());
+
+  let server =
+    { active = Atomic.make true; spawn; sock; client_handler; running = None }
+  in
+
+  server.running <- Some (spawn (run server));
+  server
+
+let with_ ?backlog ~spawn ~client_handler addr f =
+  let server = establish ?backlog ~spawn ~client_handler addr in
+  Fun.protect ~finally:(fun () -> shutdown server) (fun () -> f server)
diff --git a/src/picos/net_server.mli b/src/picos/net_server.mli
new file mode 100644
index 0000000..7432335
--- /dev/null
+++ b/src/picos/net_server.mli
@@ -0,0 +1,19 @@
+type client_handler = Unix.sockaddr -> IO_in.t -> IO_out.t -> unit
+type t
+
+val shutdown : t -> unit
+
+val establish :
+  ?backlog:int ->
+  spawn:((unit -> unit) -> unit Picos.Computation.t) ->
+  client_handler:client_handler ->
+  Unix.sockaddr ->
+  t
+
+val with_ :
+  ?backlog:int ->
+  spawn:((unit -> unit) -> unit Picos.Computation.t) ->
+  client_handler:client_handler ->
+  Unix.sockaddr ->
+  (t -> 'a) ->
+  'a
diff --git a/src/tiny_httpd/nanoev_tiny_httpd.ml b/src/tiny_httpd/nanoev_tiny_httpd.ml
index 46314e8..b637122 100644
--- a/src/tiny_httpd/nanoev_tiny_httpd.ml
+++ b/src/tiny_httpd/nanoev_tiny_httpd.ml
@@ -23,7 +23,7 @@ module Out = struct
         let i = ref i in
         let len = ref len0 in
         while !len > 0 do
-          match EV.write fd bs !i !len with
+          match EV.write_once fd bs !i !len with
           | 0 -> failwith "write failed"
           | n ->
             i := !i + n;