Use websockets to exchange data

Use websockets to send binary messages to the server. The server logs
the time taken by the client, as well as the time calculated with the
received messages sent by the client.

Cargo.lock

@@ -88,9 +88,11 @@ checksum = "c9e3356844c4d6a6d6467b8da2cffb4a2820be256f50a3a386c9d152bab31043"
 dependencies = [
  "async-trait",
  "axum-core",
+ "base64",
  "bitflags",
  "bytes",
  "futures-util",
+ "headers",
  "http",
  "http-body",
  "hyper",
@@ -103,8 +105,10 @@ dependencies = [
  "serde",
  "serde_json",
  "serde_urlencoded",
+ "sha-1",
  "sync_wrapper",
  "tokio",
+ "tokio-tungstenite",
  "tower",
  "tower-http",
  "tower-layer",
@@ -133,12 +137,30 @@ version = "0.13.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "904dfeac50f3cdaba28fc6f57fdcddb75f49ed61346676a78c4ffe55877802fd"
 
+[[package]]
+name = "bincode"
+version = "1.3.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b1f45e9417d87227c7a56d22e471c6206462cba514c7590c09aff4cf6d1ddcad"
+dependencies = [
+ "serde",
+]
+
 [[package]]
 name = "bitflags"
 version = "1.3.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "bef38d45163c2f1dde094a7dfd33ccf595c92905c8f8f4fdc18d06fb1037718a"
 
+[[package]]
+name = "block-buffer"
+version = "0.10.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "69cce20737498f97b993470a6e536b8523f0af7892a4f928cceb1ac5e52ebe7e"
+dependencies = [
+ "generic-array",
+]
+
 [[package]]
 name = "boolinator"
 version = "2.4.0"
@@ -172,6 +194,12 @@ version = "3.11.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "c1ad822118d20d2c234f427000d5acc36eabe1e29a348c89b63dd60b13f28e5d"
 
+[[package]]
+name = "byteorder"
+version = "1.4.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "14c189c53d098945499cdfa7ecc63567cf3886b3332b312a5b4585d8d3a6a610"
+
 [[package]]
 name = "bytes"
 version = "1.2.1"
@@ -227,12 +255,19 @@ dependencies = [
 name = "client"
 version = "0.1.0"
 dependencies = [
+ "bincode",
  "console_error_panic_hook",
+ "futures",
+ "gloo-net",
  "gloo-timers",
  "instant",
  "log",
+ "serde",
+ "tokio",
+ "wasm-bindgen-futures",
  "wasm-logger",
  "yew",
+ "yew-router",
 ]
 
 [[package]]
@@ -245,6 +280,15 @@ dependencies = [
  "wasm-bindgen",
 ]
 
+[[package]]
+name = "cpufeatures"
+version = "0.2.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "28d997bd5e24a5928dd43e46dc529867e207907fe0b239c3477d924f7f2ca320"
+dependencies = [
+ "libc",
+]
+
 [[package]]
 name = "crc32fast"
 version = "1.3.2"
@@ -254,6 +298,26 @@ dependencies = [
  "cfg-if",
 ]
 
+[[package]]
+name = "crypto-common"
+version = "0.1.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1bfb12502f3fc46cca1bb51ac28df9d618d813cdc3d2f25b9fe775a34af26bb3"
+dependencies = [
+ "generic-array",
+ "typenum",
+]
+
+[[package]]
+name = "digest"
+version = "0.10.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "adfbc57365a37acbd2ebf2b64d7e69bb766e2fea813521ed536f5d0520dcf86c"
+dependencies = [
+ "block-buffer",
+ "crypto-common",
+]
+
 [[package]]
 name = "flate2"
 version = "1.0.24"
@@ -279,6 +343,21 @@ dependencies = [
  "percent-encoding",
 ]
 
+[[package]]
+name = "futures"
+version = "0.3.24"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7f21eda599937fba36daeb58a22e8f5cee2d14c4a17b5b7739c7c8e5e3b8230c"
+dependencies = [
+ "futures-channel",
+ "futures-core",
+ "futures-executor",
+ "futures-io",
+ "futures-sink",
+ "futures-task",
+ "futures-util",
+]
+
 [[package]]
 name = "futures-channel"
 version = "0.3.24"
@@ -286,6 +365,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "30bdd20c28fadd505d0fd6712cdfcb0d4b5648baf45faef7f852afb2399bb050"
 dependencies = [
  "futures-core",
+ "futures-sink",
 ]
 
 [[package]]
@@ -294,6 +374,34 @@ version = "0.3.24"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "4e5aa3de05362c3fb88de6531e6296e85cde7739cccad4b9dfeeb7f6ebce56bf"
 
+[[package]]
+name = "futures-executor"
+version = "0.3.24"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9ff63c23854bee61b6e9cd331d523909f238fc7636290b96826e9cfa5faa00ab"
+dependencies = [
+ "futures-core",
+ "futures-task",
+ "futures-util",
+]
+
+[[package]]
+name = "futures-io"
+version = "0.3.24"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "bbf4d2a7a308fd4578637c0b17c7e1c7ba127b8f6ba00b29f717e9655d85eb68"
+
+[[package]]
+name = "futures-macro"
+version = "0.3.24"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "42cd15d1c7456c04dbdf7e88bcd69760d74f3a798d6444e16974b505b0e62f17"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
 [[package]]
 name = "futures-sink"
 version = "0.3.24"
@@ -312,13 +420,28 @@ version = "0.3.24"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "44fb6cb1be61cc1d2e43b262516aafcf63b241cffdb1d3fa115f91d9c7b09c90"
 dependencies = [
+ "futures-channel",
  "futures-core",
+ "futures-io",
+ "futures-macro",
+ "futures-sink",
  "futures-task",
+ "memchr",
  "pin-project-lite",
  "pin-utils",
  "slab",
 ]
 
+[[package]]
+name = "generic-array"
+version = "0.14.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "bff49e947297f3312447abdca79f45f4738097cc82b06e72054d2223f601f1b9"
+dependencies = [
+ "typenum",
+ "version_check",
+]
+
 [[package]]
 name = "getrandom"
 version = "0.2.7"
@@ -385,12 +508,33 @@ version = "0.2.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "a8d5564e570a38b43d78bdc063374a0c3098c4f0d64005b12f9bbe87e869b6d7"
 dependencies = [
+ "futures-channel",
  "gloo-events",
  "js-sys",
  "wasm-bindgen",
  "web-sys",
 ]
 
+[[package]]
+name = "gloo-net"
+version = "0.2.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ec897194fb9ac576c708f63d35604bc58f2a262b8cec0fabfed26f3991255f21"
+dependencies = [
+ "futures-channel",
+ "futures-core",
+ "futures-sink",
+ "gloo-utils",
+ "js-sys",
+ "pin-project",
+ "serde",
+ "serde_json",
+ "thiserror",
+ "wasm-bindgen",
+ "wasm-bindgen-futures",
+ "web-sys",
+]
+
 [[package]]
 name = "gloo-render"
 version = "0.1.1"
@@ -422,6 +566,8 @@ version = "0.2.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "5fb7d06c1c8cc2a29bee7ec961009a0b2caa0793ee4900c2ffb348734ba1c8f9"
 dependencies = [
+ "futures-channel",
+ "futures-core",
  "js-sys",
  "wasm-bindgen",
 ]
@@ -445,6 +591,31 @@ version = "0.12.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "8a9ee70c43aaf417c914396645a0fa852624801b24ebb7ae78fe8272889ac888"
 
+[[package]]
+name = "headers"
+version = "0.3.8"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f3e372db8e5c0d213e0cd0b9be18be2aca3d44cf2fe30a9d46a65581cd454584"
+dependencies = [
+ "base64",
+ "bitflags",
+ "bytes",
+ "headers-core",
+ "http",
+ "httpdate",
+ "mime",
+ "sha1",
+]
+
+[[package]]
+name = "headers-core"
+version = "0.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e7f66481bfee273957b1f20485a4ff3362987f85b2c236580d81b4eb7a326429"
+dependencies = [
+ "http",
+]
+
 [[package]]
 name = "heck"
 version = "0.4.0"
@@ -523,6 +694,16 @@ dependencies = [
  "want",
 ]
 
+[[package]]
+name = "idna"
+version = "0.3.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e14ddfc70884202db2244c223200c204c2bda1bc6e0998d11b5e024d657209e6"
+dependencies = [
+ "unicode-bidi",
+ "unicode-normalization",
+]
+
 [[package]]
 name = "indexmap"
 version = "1.9.1"
@@ -597,7 +778,10 @@ version = "0.1.0"
 dependencies = [
  "anyhow",
  "axum",
+ "bincode",
  "clap",
+ "client",
+ "headers",
  "log",
  "tokio",
  "tower",
@@ -762,6 +946,12 @@ version = "0.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "8b870d8c151b6f2fb93e84a13146138f05d02ed11c7e7c54f8826aaaf7c9f184"
 
+[[package]]
+name = "ppv-lite86"
+version = "0.2.16"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "eb9f9e6e233e5c4a35559a617bf40a4ec447db2e84c20b55a6f83167b7e57872"
+
 [[package]]
 name = "proc-macro-error"
 version = "1.0.4"
@@ -804,6 +994,36 @@ dependencies = [
  "proc-macro2",
 ]
 
+[[package]]
+name = "rand"
+version = "0.8.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "34af8d1a0e25924bc5b7c43c079c942339d8f0a8b57c39049bef581b46327404"
+dependencies = [
+ "libc",
+ "rand_chacha",
+ "rand_core",
+]
+
+[[package]]
+name = "rand_chacha"
+version = "0.3.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e6c10a63a0fa32252be49d21e7709d4d4baf8d231c2dbce1eaa8141b9b127d88"
+dependencies = [
+ "ppv-lite86",
+ "rand_core",
+]
+
+[[package]]
+name = "rand_core"
+version = "0.6.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ec0be4795e2f6a28069bec0b5ff3e2ac9bafc99e6a9a7dc3547996c5c816922c"
+dependencies = [
+ "getrandom",
+]
+
 [[package]]
 name = "redox_syscall"
 version = "0.2.16"
@@ -813,6 +1033,12 @@ dependencies = [
  "bitflags",
 ]
 
+[[package]]
+name = "route-recognizer"
+version = "0.3.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "afab94fb28594581f62d981211a9a4d53cc8130bbcbbb89a0440d9b8e81a7746"
+
 [[package]]
 name = "ryu"
 version = "1.0.11"
@@ -840,6 +1066,18 @@ dependencies = [
  "serde_derive",
 ]
 
+[[package]]
+name = "serde-wasm-bindgen"
+version = "0.3.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "618365e8e586c22123d692b72a7d791d5ee697817b65a218cdf12a98870af0f7"
+dependencies = [
+ "fnv",
+ "js-sys",
+ "serde",
+ "wasm-bindgen",
+]
+
 [[package]]
 name = "serde_derive"
 version = "1.0.144"
@@ -874,6 +1112,28 @@ dependencies = [
  "serde",
 ]
 
+[[package]]
+name = "sha-1"
+version = "0.10.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "028f48d513f9678cda28f6e4064755b3fbb2af6acd672f2c209b62323f7aea0f"
+dependencies = [
+ "cfg-if",
+ "cpufeatures",
+ "digest",
+]
+
+[[package]]
+name = "sha1"
+version = "0.10.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f04293dc80c3993519f2d7f6f511707ee7094fe0c6d3406feb330cdb3540eba3"
+dependencies = [
+ "cfg-if",
+ "cpufeatures",
+ "digest",
+]
+
 [[package]]
 name = "sharded-slab"
 version = "0.1.4"
@@ -984,6 +1244,21 @@ dependencies = [
  "once_cell",
 ]
 
+[[package]]
+name = "tinyvec"
+version = "1.6.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "87cc5ceb3875bb20c2890005a4e226a4651264a5c75edb2421b52861a0a0cb50"
+dependencies = [
+ "tinyvec_macros",
+]
+
+[[package]]
+name = "tinyvec_macros"
+version = "0.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "cda74da7e1a664f795bb1f8a87ec406fb89a02522cf6e50620d016add6dbbf5c"
+
 [[package]]
 name = "tokio"
 version = "1.21.1"
@@ -1016,6 +1291,18 @@ dependencies = [
  "syn",
 ]
 
+[[package]]
+name = "tokio-tungstenite"
+version = "0.17.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f714dd15bead90401d77e04243611caec13726c2408afd5b31901dfcdcb3b181"
+dependencies = [
+ "futures-util",
+ "log",
+ "tokio",
+ "tungstenite",
+]
+
 [[package]]
 name = "tokio-util"
 version = "0.7.4"
@@ -1140,6 +1427,31 @@ version = "0.2.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "59547bce71d9c38b83d9c0e92b6066c4253371f15005def0c30d9657f50c7642"
 
+[[package]]
+name = "tungstenite"
+version = "0.17.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e27992fd6a8c29ee7eef28fc78349aa244134e10ad447ce3b9f0ac0ed0fa4ce0"
+dependencies = [
+ "base64",
+ "byteorder",
+ "bytes",
+ "http",
+ "httparse",
+ "log",
+ "rand",
+ "sha-1",
+ "thiserror",
+ "url",
+ "utf-8",
+]
+
+[[package]]
+name = "typenum"
+version = "1.15.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "dcf81ac59edc17cc8697ff311e8f5ef2d99fcbd9817b34cec66f90b6c3dfd987"
+
 [[package]]
 name = "unicase"
 version = "2.6.0"
@@ -1149,12 +1461,44 @@ dependencies = [
  "version_check",
 ]
 
+[[package]]
+name = "unicode-bidi"
+version = "0.3.8"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "099b7128301d285f79ddd55b9a83d5e6b9e97c92e0ea0daebee7263e932de992"
+
 [[package]]
 name = "unicode-ident"
 version = "1.0.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "dcc811dc4066ac62f84f11307873c4850cb653bfa9b1719cee2bd2204a4bc5dd"
 
+[[package]]
+name = "unicode-normalization"
+version = "0.1.22"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5c5713f0fc4b5db668a2ac63cdb7bb4469d8c9fed047b1d0292cc7b0ce2ba921"
+dependencies = [
+ "tinyvec",
+]
+
+[[package]]
+name = "url"
+version = "2.3.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0d68c799ae75762b8c3fe375feb6600ef5602c883c5d21eb51c09f22b83c4643"
+dependencies = [
+ "form_urlencoded",
+ "idna",
+ "percent-encoding",
+]
+
+[[package]]
+name = "utf-8"
+version = "0.7.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "09cc8ee72d2a9becf2f2febe0205bbed8fc6615b7cb429ad062dc7b7ddd036a9"
+
 [[package]]
 name = "uuid"
 version = "1.1.2"
@@ -1199,6 +1543,8 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "eaf9f5aceeec8be17c128b2e93e031fb8a4d469bb9c4ae2d7dc1888b26887268"
 dependencies = [
  "cfg-if",
+ "serde",
+ "serde_json",
  "wasm-bindgen-macro",
 ]
 
@@ -1385,3 +1731,34 @@ dependencies = [
  "quote",
  "syn",
 ]
+
+[[package]]
+name = "yew-router"
+version = "0.16.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "155804f6f3aa309f596d5c3fa14486a94e7756f1edd7634569949e401d5099f2"
+dependencies = [
+ "gloo",
+ "gloo-utils",
+ "js-sys",
+ "route-recognizer",
+ "serde",
+ "serde-wasm-bindgen",
+ "serde_urlencoded",
+ "thiserror",
+ "wasm-bindgen",
+ "web-sys",
+ "yew",
+ "yew-router-macro",
+]
+
+[[package]]
+name = "yew-router-macro"
+version = "0.16.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "39049d193b52eaad4ffc80916bf08806d142c90b5edcebd527644de438a7e19a"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+]

client/Cargo.toml

@@ -14,5 +14,12 @@ yew = "0.19"
 console_error_panic_hook = "0.1"
 log = "0.4"
 wasm-logger = "0.2"
+futures = "0.3"
 gloo-timers = "0.2"
+gloo-net = "0.2"
 instant = { version = "0.1", features = [ "wasm-bindgen" ] }
+wasm-bindgen-futures = "0.4"
+bincode = "1"
+yew-router = "0.16"
+serde = { version = "1", features = ["derive"] }
+tokio = { version = "1", default-features = false, features = ["sync"] }

client/src/lib.rs

@@ -0,0 +1,9 @@
+use serde::{Deserialize, Serialize};
+use std::time::Duration;
+
+#[derive(Debug, Deserialize, Serialize)]
+pub enum Message {
+    Start,
+    Stop,
+    Duration(Duration),
+}

client/src/main.rs

@@ -1,6 +1,58 @@
+use futures::{
+    stream::{SplitSink, SplitStream},
+    SinkExt, StreamExt,
+};
+use gloo_net::websocket::{futures::WebSocket, Message};
 use gloo_timers::callback::Interval;
 use instant::Instant;
+use log::debug;
+use std::sync::Arc;
+use tokio::sync::Mutex;
+use wasm_bindgen_futures::spawn_local;
 use yew::prelude::*;
+use yew_router::prelude::*;
+
+#[derive(Clone, Debug, Eq, PartialEq, Routable)]
+pub enum Route {
+    #[at("/")]
+    LockWatch,
+    #[not_found]
+    #[at("/404")]
+    NotFound,
+}
+
+struct WebSocketHandle {
+    writer: Arc<Mutex<SplitSink<WebSocket, Message>>>,
+    _reader: Arc<Mutex<SplitStream<WebSocket>>>,
+}
+
+impl WebSocketHandle {
+    fn connect(url: &str) -> Self {
+        debug!("connecting to websocket `{}`", url);
+        let ws = WebSocket::open(url)
+            .unwrap_or_else(|_| panic!("could not connect to websocket `{}`", url));
+        let (writer, reader) = ws.split();
+
+        Self {
+            writer: Arc::new(Mutex::new(writer)),
+            _reader: Arc::new(Mutex::new(reader)),
+        }
+    }
+
+    fn send(&self, msg: client::Message) {
+        let writer = self.writer.clone();
+        spawn_local(async move {
+            writer
+                .lock()
+                .await
+                .send(Message::Bytes(
+                    bincode::serialize(&msg).expect("could not serialize websocket message"),
+                ))
+                .await
+                .expect("could not send websocket message");
+        });
+    }
+}
 
 enum Msg {
     Start,
@@ -9,6 +61,7 @@ enum Msg {
 }
 
 struct LockWatch {
+    websocket: WebSocketHandle,
     duration: Option<Instant>,
     duration_handle: Option<Interval>,
 }
@@ -38,6 +91,7 @@ impl Component for LockWatch {
 
     fn create(_ctx: &Context<Self>) -> Self {
         Self {
+            websocket: WebSocketHandle::connect("ws://localhost:3000/api/ws"),
             duration: None,
             duration_handle: None,
         }
@@ -47,6 +101,8 @@ impl Component for LockWatch {
         match msg {
             Msg::Start => {
                 self.duration = Some(Instant::now());
+                self.websocket.send(client::Message::Start);
+
                 self.duration_handle = {
                     let link = ctx.link().clone();
                     Some(Interval::new(1, move || {
@@ -54,7 +110,12 @@ impl Component for LockWatch {
                     }))
                 };
             }
-            Msg::Stop => self.duration_handle = None,
+            Msg::Stop => {
+                self.duration_handle = None;
+                self.websocket.send(client::Message::Stop);
+                let duration = self.duration.expect("could not get duration").elapsed();
+                self.websocket.send(client::Message::Duration(duration));
+            }
             Msg::UpdateDuration => {}
         }
 

lockwatch/Cargo.toml

@@ -12,9 +12,12 @@ categories = ["web-programming::http-server"]
 [dependencies]
 anyhow = "1"
 log = "0.4"
-axum = "0.5"
+axum = { version = "0.5", features = ["ws", "headers"] }
 tokio = { version = "1.0", features = ["full"] }
 tracing-subscriber = "0.3"
 tower = "0.4"
 tower-http = { version = "0.3", features = ["full"] }
 clap = { version = "3", features = ["derive"] }
+headers = "0.3"
+bincode = "1"
+client = { path = "../client" }

lockwatch/src/main.rs

@@ -1,16 +1,22 @@
 use anyhow::Result;
 use axum::{
+    extract::{
+        ws::{Message, WebSocket},
+        WebSocketUpgrade,
+    },
     http::StatusCode,
     response::IntoResponse,
-    routing::get_service,
+    routing::{get, get_service},
-    Router,
+    Router, TypedHeader,
 };
 use clap::{ArgAction, Parser};
-use log::{error, info};
+use headers::UserAgent;
+use log::{debug, error, info, trace, warn};
 use std::{
     env, io,
     net::{IpAddr, SocketAddr},
     path::PathBuf,
+    time::Instant,
 };
 use tower::ServiceBuilder;
 use tower_http::{
@@ -35,6 +41,64 @@ struct Cli {
     verbosity: u8,
 }
 
+async fn handle_websocket(mut socket: WebSocket) {
+    let mut start: Option<Instant> = None;
+
+    loop {
+        if let Some(msg) = socket.recv().await {
+            if let Ok(msg) = msg {
+                match msg {
+                    Message::Binary(b) => {
+                        if let Ok(message) = bincode::deserialize::<client::Message>(&b) {
+                            trace!("received message on websocket: {:?}", message);
+
+                            match message {
+                                client::Message::Start => start = Some(Instant::now()),
+                                client::Message::Stop => {
+                                    if let Some(start) = start {
+                                        info!("server measured {:?}", start.elapsed());
+                                    } else {
+                                        error!("received stop message without running clock");
+                                    }
+                                }
+                                client::Message::Duration(d) => info!("client measured {:?}", d),
+                            }
+                        } else {
+                            error!("received invalid message: {:?}", b);
+                        }
+                    }
+                    Message::Ping(p) => {
+                        debug!("websocket ping: {:?}", p);
+                    }
+                    Message::Pong(p) => {
+                        debug!("websocket pong: {:?}", p);
+                    }
+                    Message::Close(m) => {
+                        info!("client disconnected: {:?}", m);
+                        return;
+                    }
+                    Message::Text(_) => warn!("websocket text messages are not implemented"),
+                }
+            } else {
+                info!("client disconnected");
+                return;
+            }
+        }
+    }
+}
+
+#[allow(clippy::unused_async)]
+async fn websocket_handler(
+    ws: WebSocketUpgrade,
+    user_agent: Option<TypedHeader<UserAgent>>,
+) -> impl IntoResponse {
+    if let Some(TypedHeader(user_agent)) = user_agent {
+        info!("`{}` connected", user_agent.as_str());
+    }
+
+    ws.on_upgrade(handle_websocket)
+}
+
 #[allow(clippy::unused_async)]
 async fn file_error(err: io::Error) -> impl IntoResponse {
     error!("could not read from file: {}", err);
@@ -52,6 +116,7 @@ async fn main() -> Result<()> {
     tracing_subscriber::fmt::init();
 
     let app = Router::new()
+        .route("/api/ws", get(websocket_handler))
         .nest(
             "/client",
             get_service(ServeDir::new(&cli.static_dir)).handle_error(file_error),