diff --git a/crates/gen_lsp_server/src/lib.rs b/crates/gen_lsp_server/src/lib.rs
index a31e90f35d..b47db0df42 100644
--- a/crates/gen_lsp_server/src/lib.rs
+++ b/crates/gen_lsp_server/src/lib.rs
@@ -21,7 +21,7 @@ use languageserver_types::{
 
 pub type Result<T> = ::std::result::Result<T, failure::Error>;
 pub use {
-    msg::{RawMessage, RawRequest, RawResponse, RawResponseError, RawNotification},
+    msg::{RawMessage, RawRequest, RawResponse, RawResponseError, RawNotification, ErrorCode},
     stdio::{stdio_transport, Threads},
 };
 
diff --git a/crates/gen_lsp_server/src/msg.rs b/crates/gen_lsp_server/src/msg.rs
index 9426e98ec7..533d7da3ec 100644
--- a/crates/gen_lsp_server/src/msg.rs
+++ b/crates/gen_lsp_server/src/msg.rs
@@ -120,6 +120,16 @@ impl RawResponse {
 }
 
 impl RawNotification {
+    pub fn new<N>(params: N::Params) -> RawNotification
+    where
+        N: Notification,
+        N::Params: Serialize,
+    {
+        RawNotification {
+            method: N::METHOD.to_string(),
+            params: to_value(&params).unwrap(),
+        }
+    }
     pub fn cast<N>(self) -> ::std::result::Result<N::Params, RawNotification>
     where
         N: Notification,
diff --git a/crates/server/Cargo.toml b/crates/server/Cargo.toml
index 35ced91ac7..32c1219e1d 100644
--- a/crates/server/Cargo.toml
+++ b/crates/server/Cargo.toml
@@ -23,3 +23,4 @@ text_unit = { version = "0.1.2", features = ["serde"] }
 libsyntax2 = { path = "../libsyntax2" }
 libeditor = { path = "../libeditor" }
 libanalysis = { path = "../libanalysis" }
+gen_lsp_server = { path = "../gen_lsp_server" }
diff --git a/crates/server/src/dispatch.rs b/crates/server/src/dispatch.rs
deleted file mode 100644
index 8065349448..0000000000
--- a/crates/server/src/dispatch.rs
+++ /dev/null
@@ -1,151 +0,0 @@
-use std::marker::PhantomData;
-
-use serde::{
-    ser::Serialize,
-    de::DeserializeOwned,
-};
-use serde_json;
-use drop_bomb::DropBomb;
-
-use ::{
-    Result,
-    req::{ClientRequest, Notification},
-    io::{RawResponse, RawRequest, RawNotification},
-};
-
-pub struct Responder<R: ClientRequest> {
-    id: u64,
-    bomb: DropBomb,
-    ph: PhantomData<fn(R)>,
-}
-
-impl<R: ClientRequest> Responder<R> {
-    pub fn into_response(mut self, result: Result<R::Result>) -> Result<RawResponse> {
-        self.bomb.defuse();
-        let res = match result {
-            Ok(result) => {
-                RawResponse {
-                    id: self.id,
-                    result: serde_json::to_value(result)?,
-                    error: serde_json::Value::Null,
-                }
-            }
-            Err(e) => {
-                error_response(
-                    self.id,
-                    ErrorCode::InternalError,
-                    format!("internal error: {}", e),
-                )?
-            }
-        };
-        Ok(res)
-    }
-}
-
-fn parse_request_as<R: ClientRequest>(raw: RawRequest)
-                                      -> Result<::std::result::Result<(R::Params, Responder<R>), RawRequest>>
-{
-    if raw.method != R::METHOD {
-        return Ok(Err(raw));
-    }
-
-    let params: R::Params = serde_json::from_value(raw.params)?;
-    let responder = Responder {
-        id: raw.id,
-        bomb: DropBomb::new("dropped request"),
-        ph: PhantomData,
-    };
-    Ok(Ok((params, responder)))
-}
-
-pub fn handle_request<R, F>(req: RawRequest, f: F) -> Result<::std::result::Result<u64, RawRequest>>
-    where
-        R: ClientRequest,
-        F: FnOnce(R::Params, Responder<R>) -> Result<()>
-{
-    let id = req.id;
-    match parse_request_as::<R>(req)? {
-        Ok((params, responder)) => {
-            let () = f(params, responder)?;
-            Ok(Ok(id))
-        },
-        Err(r) => Ok(Err(r)),
-    }
-}
-
-fn parse_notification_as<N>(raw: RawNotification) -> Result<::std::result::Result<N::Params, RawNotification>>
-    where
-        N: Notification,
-        N::Params: DeserializeOwned,
-{
-    if raw.method != N::METHOD {
-        return Ok(Err(raw));
-    }
-    let params: N::Params = serde_json::from_value(raw.params)?;
-    Ok(Ok(params))
-}
-
-pub fn handle_notification<N, F>(not: &mut Option<RawNotification>, f: F) -> Result<()>
-    where
-        N: Notification,
-        N::Params: DeserializeOwned,
-        F: FnOnce(N::Params) -> Result<()>
-{
-    match not.take() {
-        None => Ok(()),
-        Some(n) => match parse_notification_as::<N>(n)? {
-            Ok(params) => f(params),
-            Err(n) => {
-                *not = Some(n);
-                Ok(())
-            }
-        }
-    }
-}
-
-pub fn send_notification<N>(params: N::Params) -> RawNotification
-    where
-        N: Notification,
-        N::Params: Serialize
-{
-    RawNotification {
-        method: N::METHOD.to_string(),
-        params: serde_json::to_value(params)
-            .unwrap(),
-    }
-}
-
-pub fn unknown_method(id: u64) -> Result<RawResponse> {
-    error_response(id, ErrorCode::MethodNotFound, "unknown method")
-}
-
-fn error_response(id: u64, code: ErrorCode, message: impl Into<String>) -> Result<RawResponse> {
-    #[derive(Serialize)]
-    struct Error {
-        code: i32,
-        message: String,
-    }
-    let resp = RawResponse {
-        id,
-        result: serde_json::Value::Null,
-        error: serde_json::to_value(Error {
-            code: code as i32,
-            message: message.into(),
-        })?,
-    };
-    Ok(resp)
-}
-
-#[allow(unused)]
-enum ErrorCode {
-    ParseError = -32700,
-    InvalidRequest = -32600,
-    MethodNotFound = -32601,
-    InvalidParams = -32602,
-    InternalError = -32603,
-    ServerErrorStart = -32099,
-    ServerErrorEnd = -32000,
-    ServerNotInitialized = -32002,
-    UnknownErrorCode = -32001,
-    RequestCancelled = -32800,
-}
diff --git a/crates/server/src/io.rs b/crates/server/src/io.rs
deleted file mode 100644
index f247327abf..0000000000
--- a/crates/server/src/io.rs
+++ /dev/null
@@ -1,207 +0,0 @@
-use std::{
-    thread,
-    io::{
-        stdout, stdin,
-        BufRead, Write,
-    },
-};
-use serde_json::{Value, from_str, to_string};
-use crossbeam_channel::{Receiver, Sender, bounded};
-
-use Result;
-
-
-#[derive(Debug, Serialize, Deserialize)]
-#[serde(untagged)]
-pub enum RawMsg {
-    Request(RawRequest),
-    Notification(RawNotification),
-    Response(RawResponse),
-}
-
-#[derive(Debug, Serialize, Deserialize)]
-pub struct RawRequest {
-    pub id: u64,
-    pub method: String,
-    pub params: Value,
-}
-
-#[derive(Debug, Serialize, Deserialize)]
-pub struct RawNotification {
-    pub method: String,
-    pub params: Value,
-}
-
-#[derive(Debug, Serialize, Deserialize)]
-pub struct RawResponse {
-    // JSON RPC allows this to be null if it was impossible
-    // to decode the request's id. Ignore this special case
-    // and just die horribly.
-    pub id: u64,
-    #[serde(default)]
-    pub result: Value,
-    #[serde(default)]
-    pub error: Value,
-}
-
-struct MsgReceiver {
-    chan: Receiver<RawMsg>,
-    thread: Option<thread::JoinHandle<Result<()>>>,
-}
-
-impl MsgReceiver {
-    fn recv(&mut self) -> Result<RawMsg> {
-        match self.chan.recv() {
-            Some(msg) => Ok(msg),
-            None => {
-                self.cleanup()?;
-                unreachable!()
-            }
-        }
-    }
-
-    fn cleanup(&mut self) -> Result<()> {
-        self.thread
-            .take()
-            .ok_or_else(|| format_err!("MsgReceiver thread panicked"))?
-            .join()
-            .map_err(|_| format_err!("MsgReceiver thread panicked"))??;
-        bail!("client disconnected")
-    }
-
-    fn stop(self) -> Result<()> {
-        // Can't really self.thread.join() here, b/c it might be
-        // blocking on read
-        Ok(())
-    }
-}
-
-struct MsgSender {
-    chan: Sender<RawMsg>,
-    thread: thread::JoinHandle<Result<()>>,
-}
-
-impl MsgSender {
-    fn send(&mut self, msg: RawMsg) {
-        self.chan.send(msg)
-    }
-
-    fn stop(self) -> Result<()> {
-        drop(self.chan);
-        self.thread.join()
-            .map_err(|_| format_err!("MsgSender thread panicked"))??;
-        Ok(())
-    }
-}
-
-pub struct Io {
-    receiver: MsgReceiver,
-    sender: MsgSender,
-}
-
-impl Io {
-    pub fn from_stdio() -> Io {
-        let sender = {
-            let (tx, rx) = bounded(16);
-            MsgSender {
-                chan: tx,
-                thread: thread::spawn(move || {
-                    let stdout = stdout();
-                    let mut stdout = stdout.lock();
-                    for msg in rx {
-                        #[derive(Serialize)]
-                        struct JsonRpc {
-                            jsonrpc: &'static str,
-                            #[serde(flatten)]
-                            msg: RawMsg,
-                        }
-                        let text = to_string(&JsonRpc {
-                            jsonrpc: "2.0",
-                            msg,
-                        })?;
-                        write_msg_text(&mut stdout, &text)?;
-                    }
-                    Ok(())
-                }),
-            }
-        };
-        let receiver = {
-            let (tx, rx) = bounded(16);
-            MsgReceiver {
-                chan: rx,
-                thread: Some(thread::spawn(move || {
-                    let stdin = stdin();
-                    let mut stdin = stdin.lock();
-                    while let Some(text) = read_msg_text(&mut stdin)? {
-                        let msg: RawMsg = from_str(&text)?;
-                        tx.send(msg);
-                    }
-                    Ok(())
-                })),
-            }
-        };
-        Io { receiver, sender }
-    }
-
-    pub fn send(&mut self, msg: RawMsg) {
-        self.sender.send(msg)
-    }
-
-    pub fn recv(&mut self) -> Result<RawMsg> {
-        self.receiver.recv()
-    }
-
-    pub fn receiver(&mut self) -> &mut Receiver<RawMsg> {
-        &mut self.receiver.chan
-    }
-
-    pub fn cleanup_receiver(&mut self) -> Result<()> {
-        self.receiver.cleanup()
-    }
-
-    pub fn stop(self) -> Result<()> {
-        self.receiver.stop()?;
-        self.sender.stop()?;
-        Ok(())
-    }
-}
-
-
-fn read_msg_text(inp: &mut impl BufRead) -> Result<Option<String>> {
-    let mut size = None;
-    let mut buf = String::new();
-    loop {
-        buf.clear();
-        if inp.read_line(&mut buf)? == 0 {
-            return Ok(None);
-        }
-        if !buf.ends_with("\r\n") {
-            bail!("malformed header: {:?}", buf);
-        }
-        let buf = &buf[..buf.len() - 2];
-        if buf.is_empty() {
-            break;
-        }
-        let mut parts = buf.splitn(2, ": ");
-        let header_name = parts.next().unwrap();
-        let header_value = parts.next().ok_or_else(|| format_err!("malformed header: {:?}", buf))?;
-        if header_name == "Content-Length" {
-            size = Some(header_value.parse::<usize>()?);
-        }
-    }
-    let size = size.ok_or_else(|| format_err!("no Content-Length"))?;
-    let mut buf = buf.into_bytes();
-    buf.resize(size, 0);
-    inp.read_exact(&mut buf)?;
-    let buf = String::from_utf8(buf)?;
-    debug!("< {}", buf);
-    Ok(Some(buf))
-}
-
-fn write_msg_text(out: &mut impl Write, msg: &str) -> Result<()> {
-    debug!("> {}", msg);
-    write!(out, "Content-Length: {}\r\n\r\n", msg.len())?;
-    out.write_all(msg.as_bytes())?;
-    out.flush()?;
-    Ok(())
-}
diff --git a/crates/server/src/main.rs b/crates/server/src/main.rs
index eeb343b809..3e3bd44a13 100644
--- a/crates/server/src/main.rs
+++ b/crates/server/src/main.rs
@@ -17,26 +17,20 @@ extern crate walkdir;
 extern crate libeditor;
 extern crate libanalysis;
 extern crate libsyntax2;
+extern crate gen_lsp_server;
 extern crate im;
 extern crate relative_path;
 
-mod io;
 mod caps;
 mod req;
-mod dispatch;
 mod conv;
 mod main_loop;
 mod vfs;
 mod path_map;
 mod server_world;
 
-use threadpool::ThreadPool;
-use crossbeam_channel::bounded;
 use flexi_logger::{Logger, Duplicate};
-
-use ::{
-    io::{Io, RawMsg, RawResponse, RawNotification},
-};
+use gen_lsp_server::{run_server, stdio_transport};
 
 pub type Result<T> = ::std::result::Result<T, ::failure::Error>;
 
@@ -60,96 +54,10 @@ fn main() -> Result<()> {
 }
 
 fn main_inner() -> Result<()> {
-    let mut io = Io::from_stdio();
-    let res = initialize(&mut io);
+    let (receiver, sender, threads) = stdio_transport();
+    run_server(caps::server_capabilities(), main_loop::main_loop, receiver, sender)?;
     info!("shutting down IO...");
-    let io_res = io.stop();
+    threads.join()?;
     info!("... IO is down");
-    match (res, io_res) {
-        (Ok(()), Ok(())) => Ok(()),
-        (res, Ok(())) => res,
-        (Ok(()), io_res) => io_res,
-        (res, Err(io_err)) => {
-            error!("shutdown error: {:?}", io_err);
-            res
-        }
-    }
-}
-
-fn initialize(io: &mut Io) -> Result<()> {
-    match io.recv()? {
-        RawMsg::Notification(n) =>
-            bail!("expected initialize request, got {:?}", n),
-        RawMsg::Response(res) =>
-            bail!("expected initialize request, got {:?}", res),
-
-        RawMsg::Request(req) => {
-            let req = dispatch::handle_request::<req::Initialize, _>(req, |_params, resp| {
-                let res = req::InitializeResult { capabilities: caps::server_capabilities() };
-                let resp = resp.into_response(Ok(res))?;
-                io.send(RawMsg::Response(resp));
-                Ok(())
-            })?;
-            if let Err(req) = req {
-                bail!("expected initialize request, got {:?}", req)
-            }
-            match io.recv()? {
-                RawMsg::Notification(n) => {
-                    if n.method != "initialized" {
-                        bail!("expected initialized notification");
-                    }
-                }
-                _ => bail!("expected initialized notification"),
-            }
-        }
-    }
-    initialized(io)
-}
-
-enum Task {
-    Respond(RawResponse),
-    Notify(RawNotification),
-    Die(::failure::Error),
-}
-
-fn initialized(io: &mut Io) -> Result<()> {
-    {
-        let mut pool = ThreadPool::new(4);
-        let (task_sender, task_receiver) = bounded::<Task>(16);
-        let (fs_events_receiver, watcher) = vfs::watch(vec![
-            ::std::env::current_dir()?,
-        ]);
-        info!("lifecycle: handshake finished, server ready to serve requests");
-        let res = main_loop::main_loop(
-            io,
-            &mut pool,
-            task_sender,
-            task_receiver.clone(),
-            fs_events_receiver,
-        );
-
-        info!("waiting for background jobs to finish...");
-        task_receiver.for_each(drop);
-        pool.join();
-        info!("...background jobs have finished");
-
-        info!("waiting for file watcher to finish...");
-        watcher.stop()?;
-        info!("...file watcher has finished");
-
-        res
-    }?;
-
-    match io.recv()? {
-        RawMsg::Notification(n) => {
-            if n.method == "exit" {
-                info!("lifecycle: shutdown complete");
-                return Ok(());
-            }
-            bail!("unexpected notification during shutdown: {:?}", n)
-        }
-        m => {
-            bail!("unexpected message during shutdown: {:?}", m)
-        }
-    }
+    Ok(())
 }
diff --git a/crates/server/src/main_loop/mod.rs b/crates/server/src/main_loop/mod.rs
index db7d5ae34a..34d0778053 100644
--- a/crates/server/src/main_loop/mod.rs
+++ b/crates/server/src/main_loop/mod.rs
@@ -6,59 +6,97 @@ use std::{
 };
 
 use threadpool::ThreadPool;
-use crossbeam_channel::{Sender, Receiver};
+use serde::{Serialize, de::DeserializeOwned};
+use crossbeam_channel::{bounded, Sender, Receiver};
 use languageserver_types::{NumberOrString};
 use libanalysis::{FileId, JobHandle, JobToken};
+use gen_lsp_server::{RawRequest, RawNotification, RawMessage, RawResponse, ErrorCode};
 
 use {
-    req, dispatch,
-    Task, Result,
-    io::{Io, RawMsg, RawRequest, RawNotification},
-    vfs::FileEvent,
+    req,
+    Result,
+    vfs::{self, FileEvent},
     server_world::{ServerWorldState, ServerWorld},
     main_loop::subscriptions::{Subscriptions},
 };
 
+enum Task {
+    Respond(RawResponse),
+    Notify(RawNotification),
+}
+
 pub(super) fn main_loop(
-    io: &mut Io,
-    pool: &mut ThreadPool,
-    task_sender: Sender<Task>,
-    task_receiver: Receiver<Task>,
-    fs_events_receiver: Receiver<Vec<FileEvent>>,
+    receriver: &mut Receiver<RawMessage>,
+    sender: &mut Sender<RawMessage>,
 ) -> Result<()> {
+    let pool = ThreadPool::new(4);
+    let (task_sender, task_receiver) = bounded::<Task>(16);
+    let (fs_events_receiver, watcher) = vfs::watch(vec![
+        ::std::env::current_dir()?,
+    ]);
+
     info!("server initialized, serving requests");
     let mut state = ServerWorldState::new();
 
-    let mut pending_requests: HashMap<u64, JobHandle> = HashMap::new();
-    let mut fs_events_receiver = Some(&fs_events_receiver);
+    let mut pending_requests = HashMap::new();
     let mut subs = Subscriptions::new();
+    main_loop_inner(
+        &pool,
+        receriver,
+        sender,
+        task_receiver.clone(),
+        task_sender,
+        fs_events_receiver,
+        &mut state,
+        &mut pending_requests,
+        &mut subs,
+    )?;
+
+    info!("waiting for background jobs to finish...");
+    task_receiver.for_each(drop);
+    pool.join();
+    info!("...background jobs have finished");
+
+    info!("waiting for file watcher to finish...");
+    watcher.stop()?;
+    info!("...file watcher has finished");
+    Ok(())
+}
+
+fn main_loop_inner(
+    pool: &ThreadPool,
+    msg_receiver: &mut Receiver<RawMessage>,
+    msg_sender: &mut Sender<RawMessage>,
+    task_receiver: Receiver<Task>,
+    task_sender: Sender<Task>,
+    fs_receiver: Receiver<Vec<FileEvent>>,
+    state: &mut ServerWorldState,
+    pending_requests: &mut HashMap<u64, JobHandle>,
+    subs: &mut Subscriptions,
+) -> Result<u64> {
+    let mut fs_receiver = Some(fs_receiver);
     loop {
         enum Event {
-            Msg(RawMsg),
+            Msg(RawMessage),
             Task(Task),
             Fs(Vec<FileEvent>),
-            ReceiverDead,
             FsWatcherDead,
         }
         let event = select! {
-            recv(io.receiver(), msg) => match msg {
+            recv(msg_receiver, msg) => match msg {
                 Some(msg) => Event::Msg(msg),
-                None => Event::ReceiverDead,
+                None => bail!("client exited without shutdown"),
             },
             recv(task_receiver, task) => Event::Task(task.unwrap()),
-            recv(fs_events_receiver, events) => match events {
+            recv(fs_receiver, events) => match events {
                 Some(events) => Event::Fs(events),
                 None => Event::FsWatcherDead,
             }
         };
         let mut state_changed = false;
         match event {
-            Event::ReceiverDead => {
-                io.cleanup_receiver()?;
-                unreachable!();
-            }
             Event::FsWatcherDead => {
-                fs_events_receiver = None;
+                fs_receiver = None;
             }
             Event::Task(task) => {
                 match task {
@@ -66,12 +104,10 @@ pub(super) fn main_loop(
                         if let Some(handle) = pending_requests.remove(&response.id) {
                             assert!(handle.has_completed());
                         }
-                        io.send(RawMsg::Response(response))
+                        msg_sender.send(RawMessage::Response(response))
                     }
                     Task::Notify(n) =>
-                        io.send(RawMsg::Notification(n)),
-                    Task::Die(error) =>
-                        return Err(error),
+                        msg_sender.send(RawMessage::Notification(n)),
                 }
                 continue;
             }
@@ -82,16 +118,29 @@ pub(super) fn main_loop(
             }
             Event::Msg(msg) => {
                 match msg {
-                    RawMsg::Request(req) => {
-                        if !on_request(io, &mut state, &mut pending_requests, pool, &task_sender, req)? {
-                            return Ok(());
+                    RawMessage::Request(req) => {
+                        let req = match req.cast::<req::Shutdown>() {
+                            Ok((id, _params)) => return Ok(id),
+                            Err(req) => req,
+                        };
+                        match on_request(state, pending_requests, pool, &task_sender, req)? {
+                            None => (),
+                            Some(req) => {
+                                error!("unknown request: {:?}", req);
+                                let resp = RawResponse::err(
+                                    req.id,
+                                    ErrorCode::MethodNotFound as i32,
+                                    "unknown request".to_string(),
+                                );
+                                msg_sender.send(RawMessage::Response(resp))
+                            }
                         }
                     }
-                    RawMsg::Notification(not) => {
-                        on_notification(io, &mut state, &mut pending_requests, &mut subs, not)?;
+                    RawMessage::Notification(not) => {
+                        on_notification(msg_sender, state, pending_requests, subs, not)?;
                         state_changed = true;
                     }
-                    RawMsg::Response(resp) => {
+                    RawMessage::Response(resp) => {
                         error!("unexpected response: {:?}", resp)
                     }
                 }
@@ -110,13 +159,12 @@ pub(super) fn main_loop(
 }
 
 fn on_request(
-    io: &mut Io,
     world: &mut ServerWorldState,
     pending_requests: &mut HashMap<u64, JobHandle>,
     pool: &ThreadPool,
     sender: &Sender<Task>,
     req: RawRequest,
-) -> Result<bool> {
+) -> Result<Option<RawRequest>> {
     let mut pool_dispatcher = PoolDispatcher {
         req: Some(req),
         res: None,
@@ -141,81 +189,73 @@ fn on_request(
         Ok((id, handle)) => {
             let inserted = pending_requests.insert(id, handle).is_none();
             assert!(inserted, "duplicate request: {}", id);
+            Ok(None)
         },
-        Err(req) => {
-            let req = dispatch::handle_request::<req::Shutdown, _>(req, |(), resp| {
-                let resp = resp.into_response(Ok(()))?;
-                io.send(RawMsg::Response(resp));
-                Ok(())
-            })?;
-            match req {
-                Ok(_id) => {
-                    info!("lifecycle: initiating shutdown");
-                    return Ok(false);
-                }
-                Err(req) => {
-                    error!("unknown method: {:?}", req);
-                    io.send(RawMsg::Response(dispatch::unknown_method(req.id)?));
-                }
-            }
-        }
+        Err(req) => Ok(Some(req)),
     }
-    Ok(true)
 }
 
 fn on_notification(
-    io: &mut Io,
+    msg_sender: &mut Sender<RawMessage>,
     state: &mut ServerWorldState,
     pending_requests: &mut HashMap<u64, JobHandle>,
     subs: &mut Subscriptions,
     not: RawNotification,
 ) -> Result<()> {
-    let mut not = Some(not);
-    dispatch::handle_notification::<req::Cancel, _>(&mut not, |params| {
-        let id = match params.id {
-            NumberOrString::Number(id) => id,
-            NumberOrString::String(id) => {
-                panic!("string id's not supported: {:?}", id);
+    let not = match not.cast::<req::Cancel>() {
+        Ok(params) => {
+            let id = match params.id {
+                NumberOrString::Number(id) => id,
+                NumberOrString::String(id) => {
+                    panic!("string id's not supported: {:?}", id);
+                }
+            };
+            if let Some(handle) = pending_requests.remove(&id) {
+                handle.cancel();
             }
-        };
-        if let Some(handle) = pending_requests.remove(&id) {
-            handle.cancel();
+            return Ok(())
         }
-        Ok(())
-    })?;
-    dispatch::handle_notification::<req::DidOpenTextDocument, _>(&mut not, |params| {
-        let uri = params.text_document.uri;
-        let path = uri.to_file_path()
-            .map_err(|()| format_err!("invalid uri: {}", uri))?;
-        let file_id = state.add_mem_file(path, params.text_document.text);
-        subs.add_sub(file_id);
-        Ok(())
-    })?;
-    dispatch::handle_notification::<req::DidChangeTextDocument, _>(&mut not, |mut params| {
-        let uri = params.text_document.uri;
-        let path = uri.to_file_path()
-            .map_err(|()| format_err!("invalid uri: {}", uri))?;
-        let text = params.content_changes.pop()
-            .ok_or_else(|| format_err!("empty changes"))?
-            .text;
-        state.change_mem_file(path.as_path(), text)?;
-        Ok(())
-    })?;
-    dispatch::handle_notification::<req::DidCloseTextDocument, _>(&mut not, |params| {
-        let uri = params.text_document.uri;
-        let path = uri.to_file_path()
-            .map_err(|()| format_err!("invalid uri: {}", uri))?;
-        let file_id = state.remove_mem_file(path.as_path())?;
-        subs.remove_sub(file_id);
-        let not = req::PublishDiagnosticsParams { uri, diagnostics: Vec::new() };
-        let not = dispatch::send_notification::<req::PublishDiagnostics>(not);
-        io.send(RawMsg::Notification(not));
-        Ok(())
-    })?;
-
-    if let Some(not) = not {
-        error!("unhandled notification: {:?}", not);
-    }
+        Err(not) => not,
+    };
+    let not = match not.cast::<req::DidOpenTextDocument>() {
+        Ok(params) => {
+            let uri = params.text_document.uri;
+            let path = uri.to_file_path()
+                .map_err(|()| format_err!("invalid uri: {}", uri))?;
+            let file_id = state.add_mem_file(path, params.text_document.text);
+            subs.add_sub(file_id);
+            return Ok(())
+        }
+        Err(not) => not,
+    };
+    let not = match not.cast::<req::DidChangeTextDocument>() {
+        Ok(mut params) => {
+            let uri = params.text_document.uri;
+            let path = uri.to_file_path()
+                .map_err(|()| format_err!("invalid uri: {}", uri))?;
+            let text = params.content_changes.pop()
+                .ok_or_else(|| format_err!("empty changes"))?
+                .text;
+            state.change_mem_file(path.as_path(), text)?;
+            return Ok(())
+        }
+        Err(not) => not,
+    };
+    let not = match not.cast::<req::DidCloseTextDocument>() {
+        Ok(params) => {
+            let uri = params.text_document.uri;
+            let path = uri.to_file_path()
+                .map_err(|()| format_err!("invalid uri: {}", uri))?;
+            let file_id = state.remove_mem_file(path.as_path())?;
+            subs.remove_sub(file_id);
+            let params = req::PublishDiagnosticsParams { uri, diagnostics: Vec::new() };
+            let not = RawNotification::new::<req::PublishDiagnostics>(params);
+            msg_sender.send(RawMessage::Notification(not));
+            return Ok(())
+        }
+        Err(not) => not,
+    };
+    error!("unhandled notification: {:?}", not);
     Ok(())
 }
 
@@ -228,10 +268,14 @@ struct PoolDispatcher<'a> {
 }
 
 impl<'a> PoolDispatcher<'a> {
-    fn on<'b, R: req::ClientRequest>(
+    fn on<'b, R>(
         &'b mut self,
         f: fn(ServerWorld, R::Params, JobToken) -> Result<R::Result>
-    ) -> Result<&'b mut Self> {
+    ) -> Result<&'b mut Self>
+    where R: req::Request,
+          R::Params: DeserializeOwned + Send + 'static,
+          R::Result: Serialize + 'static,
+    {
         let req = match self.req.take() {
             None => return Ok(self),
             Some(req) => req,
@@ -239,23 +283,24 @@ impl<'a> PoolDispatcher<'a> {
         let world = self.world;
         let sender = self.sender;
         let pool = self.pool;
-        let (handle, token) = JobHandle::new();
-        let req = dispatch::handle_request::<R, _>(req, |params, resp| {
-            let world = world.snapshot();
-            let sender = sender.clone();
-            pool.execute(move || {
-                let res = f(world, params, token);
-                let task = match resp.into_response(res) {
-                    Ok(resp) => Task::Respond(resp),
-                    Err(e) => Task::Die(e),
-                };
-                sender.send(task);
-            });
-            Ok(())
-        })?;
-        match req {
-            Ok(id) => self.res = Some((id, handle)),
-            Err(req) => self.req = Some(req),
+        match req.cast::<R>() {
+            Ok((id, params)) => {
+                let (handle, token) = JobHandle::new();
+                let world = world.snapshot();
+                let sender = sender.clone();
+                pool.execute(move || {
+                    let resp = match f(world, params, token) {
+                        Ok(resp) => RawResponse::ok(id, resp),
+                        Err(e) => RawResponse::err(id, ErrorCode::InternalError as i32, e.to_string()),
+                    };
+                    let task = Task::Respond(resp);
+                    sender.send(task);
+                });
+                self.res = Some((id, handle));
+            }
+            Err(req) => {
+                self.req = Some(req)
+            }
         }
         Ok(self)
     }
@@ -282,7 +327,7 @@ fn update_file_notifications_on_threadpool(
                     error!("failed to compute diagnostics: {:?}", e)
                 }
                 Ok(params) => {
-                    let not = dispatch::send_notification::<req::PublishDiagnostics>(params);
+                    let not = RawNotification::new::<req::PublishDiagnostics>(params);
                     sender.send(Task::Notify(not));
                 }
             }
@@ -291,7 +336,7 @@ fn update_file_notifications_on_threadpool(
                     error!("failed to compute decorations: {:?}", e)
                 }
                 Ok(params) => {
-                    let not = dispatch::send_notification::<req::PublishDecorations>(params);
+                    let not = RawNotification::new::<req::PublishDecorations>(params);
                     sender.send(Task::Notify(not))
                 }
             }