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examples: add examples/vweb/server_sent_events; implement vweb.sse

pull/8536/head
Delyan Angelov 2021-02-03 15:40:06 +02:00
parent a73c20916d
commit f4b757e47d
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7 changed files with 186 additions and 1 deletions
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19
examples/vweb/server_sent_events/assets/site.css 100644
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@ -0,0 +1,19 @@
body {
font-family: Arial, Helvetica, sans-serif;
color: #eee;
background-color: #333;
background-image: url("v-logo.svg");
background-repeat: no-repeat;
background-size: 10em;
margin: 0;
padding-left: 11em;
}
h1 {
color: #6699CC;
}
img.logo {
float: left;
width: 10em;
}

1
examples/vweb/server_sent_events/assets/v-logo.svg 100644
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<?xml version="1.0" encoding="UTF-8" standalone="no"?><!-- Generator: Gravit.io --><svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" style="isolation:isolate" viewBox="0 0 500 500" width="500px" height="500px"><defs><clipPath id="_clipPath_8TWIgR1z3pxinjWBiigzcEIrVJKv9Gq4"><rect width="500" height="500"/></clipPath></defs><g clip-path="url(#_clipPath_8TWIgR1z3pxinjWBiigzcEIrVJKv9Gq4)"><path d=" M 318.422 453.543 L 463.705 49.541 C 466.168 42.689 462.285 37.693 455.037 38.392 L 340.786 49.398 C 333.539 50.097 325.71 56.246 323.316 63.121 L 188.843 449.216 C 186.447 456.091 190.414 461.673 197.695 461.673 L 308.901 461.673 C 312.541 461.673 316.497 458.893 317.729 455.466 L 318.422 453.543 Z " fill="rgb(83,107,138)"/><defs><filter id="Hmac7mZraFWHw0G84Yxj4QuzeTFp0E7Y" x="-200%" y="-200%" width="400%" height="400%" filterUnits="objectBoundingBox" color-interpolation-filters="sRGB"><feGaussianBlur xmlns="http://www.w3.org/2000/svg" in="SourceGraphic" stdDeviation="6.440413594258542"/><feOffset xmlns="http://www.w3.org/2000/svg" dx="0" dy="0" result="pf_100_offsetBlur"/><feFlood xmlns="http://www.w3.org/2000/svg" flood-color="#000000" flood-opacity="0.65"/><feComposite xmlns="http://www.w3.org/2000/svg" in2="pf_100_offsetBlur" operator="in" result="pf_100_dropShadow"/><feBlend xmlns="http://www.w3.org/2000/svg" in="SourceGraphic" in2="pf_100_dropShadow" mode="normal"/></filter></defs><g filter="url(#Hmac7mZraFWHw0G84Yxj4QuzeTFp0E7Y)"><path d=" M 301.848 455.466 L 241.359 280.725 L 250 275.324 L 311.57 453.543 L 301.848 455.466 Z " fill="rgb(235,235,235)"/></g><path d=" M 44.963 38.392 L 159.214 49.398 C 166.461 50.097 174.298 56.243 176.704 63.115 L 314.022 455.448 C 315.224 458.885 313.245 461.673 309.604 461.673 L 197.695 461.673 C 190.414 461.673 182.502 456.111 180.038 449.259 L 36.295 49.541 C 33.832 42.689 37.715 37.693 44.963 38.392 Z " fill="rgb(93,135,191)"/></g></svg>
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examples/vweb/server_sent_events/favicon.ico 100644
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38
examples/vweb/server_sent_events/index.html 100644
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<html>
<header>
<title>@title</title>
<meta charset="utf-8"/>
@css 'assets/site.css'
</header>
<body>
<h1>@title</h1>
<button>Close the connection</button>
<ul></ul>
<script>
"use strict";
var button = document.querySelector('button');
var eventList = document.querySelector('ul');
const evtSource = new EventSource('/sse');
evtSource.onerror = function() { console.log("EventSource failed."); };
console.log(evtSource.withCredentials);
console.log(evtSource.readyState);
console.log(evtSource.url);
evtSource.onopen = function() {
console.log("Connection to server opened.");
};
evtSource.onmessage = function(e) {
var newElement = document.createElement("li");
newElement.textContent = "message: " + e.data;
eventList.appendChild(newElement);
};
evtSource.addEventListener("ping", function(e) {
console.log(e)
var newElement = document.createElement("li");
var obj = JSON.parse(e.data);
newElement.innerHTML = "ping at " + obj.time + ' server data: ' + e.data;
eventList.appendChild(newElement);
}, false);
button.onclick = function() { console.log('Connection closed'); evtSource.close(); };
</script>
</body>
</html>

38
examples/vweb/server_sent_events/server.v 100644
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module main
import rand
import time
import vweb
import vweb.sse
struct App {
vweb.Context
}
fn main() {
vweb.run<App>(8081)
}
pub fn (mut app App) init_once() {
app.serve_static('/favicon.ico', 'favicon.ico', 'img/x-icon')
app.handle_static('.')
}
pub fn (mut app App) index() vweb.Result {
title := 'SSE Example'
return $vweb.html()
}
fn (mut app App) sse() vweb.Result {
mut session := sse.new_connection(app.conn)
// NB: you can setup session.write_timeout and session.headers here
session.start() or { return app.server_error(501) }
session.send_message(data: 'ok') or { return app.server_error(501) }
for {
data := '{"time": "$time.now().str()", "random_id": "$rand.ulid()"}'
session.send_message(event: 'ping', data: data) or { return app.server_error(501) }
println('> sent event: $data')
time.sleep_ms(1000)
}
return app.server_error(501)
}

77
vlib/vweb/sse/sse.v 100644
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module sse
import net
import time
import strings
// This module implements the server side of `Server Sent Events`.
// See https://developer.mozilla.org/en-US/docs/Web/API/Server-sent_events/Using_server-sent_events#event_stream_format
// as well as https://html.spec.whatwg.org/multipage/server-sent-events.html#server-sent-events
// for detailed description of the protocol, and a simple web browser client example.
//
// > Event stream format
// > The event stream is a simple stream of text data which must be encoded using UTF-8.
// > Messages in the event stream are separated by a pair of newline characters.
// > A colon as the first character of a line is in essence a comment, and is ignored.
// > Note: The comment line can be used to prevent connections from timing out;
// > a server can send a comment periodically to keep the connection alive.
// >
// > Each message consists of one or more lines of text listing the fields for that message.
// > Each field is represented by the field name, followed by a colon, followed by the text
// > data for that field's value.
[ref_only]
pub struct SSEConnection {
pub mut:
headers map[string]string
conn &net.TcpConn
write_timeout time.Duration = 600 * time.second
}
pub struct SSEMessage {
id string
event string
data string
retry int
}
pub fn new_connection(conn &net.TcpConn) SSEConnection {
return SSEConnection{
conn: conn
}
}
// sse_start is used to send the start of a Server Side Event response.
pub fn (mut sse SSEConnection) start() ? {
sse.conn.set_write_timeout(sse.write_timeout)
mut start_sb := strings.new_builder(512)
start_sb.write('HTTP/1.1 200')
start_sb.write('\r\nConnection: keep-alive')
start_sb.write('\r\nCache-Control: no-cache')
start_sb.write('\r\nContent-Type: text/event-stream')
for k, v in sse.headers {
start_sb.write('\r\n$k: $v')
}
start_sb.write('\r\n')
sse.conn.write(start_sb.buf) or { return error('could not start sse response') }
}
// send_message sends a single message to the http client that listens for SSE.
// It does not close the connection, so you can use it many times in a loop.
pub fn (mut sse SSEConnection) send_message(message SSEMessage) ? {
mut sb := strings.new_builder(512)
if message.id != '' {
sb.write('id: $message.id\n')
}
if message.event != '' {
sb.write('event: $message.event\n')
}
if message.data != '' {
sb.write('data: $message.data\n')
}
if message.retry != 0 {
sb.write('retry: $message.retry\n')
}
sb.write('\n')
sse.conn.write(sb.buf) ?
}

12
vlib/vweb/vweb.v
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@ -158,6 +158,17 @@ pub fn (mut ctx Context) ok(s string) Result {
return Result{} return Result{}
} }
pub fn (mut ctx Context) server_error(ecode int) Result {
$if debug {
eprintln('> ctx.server_error ecode: $ecode')
}
if ctx.done {
return Result{}
}
send_string(mut ctx.conn, vweb.http_500) or { }
return Result{}
}
pub fn (mut ctx Context) redirect(url string) Result { pub fn (mut ctx Context) redirect(url string) Result {
if ctx.done { if ctx.done {
return Result{} return Result{}
@ -592,6 +603,7 @@ fn handle_conn<T>(mut conn net.TcpConn, mut app T) {
// call action method // call action method
if method.args.len == vars.len { if method.args.len == vars.len {
app.$method(vars) app.$method(vars)
return
} else { } else {
eprintln('warning: uneven parameters count ($method.args.len) in `$method.name`, compared to the vweb route `$method.attrs` ($vars.len)') eprintln('warning: uneven parameters count ($method.args.len) in `$method.name`, compared to the vweb route `$method.attrs` ($vars.len)')
} }