1 files changed, 77 insertions, 0 deletions
diff --git a/v_windows/v/vlib/vweb/sse/sse.v b/v_windows/v/vlib/vweb/sse/sse.v
new file mode 100644
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+++ b/v_windows/v/vlib/vweb/sse/sse.v
@@ -0,0 +1,77 @@
+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.
+
+[heap]
+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: unsafe { 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_string('HTTP/1.1 200')
+	start_sb.write_string('\r\nConnection: keep-alive')
+	start_sb.write_string('\r\nCache-Control: no-cache')
+	start_sb.write_string('\r\nContent-Type: text/event-stream')
+	for k, v in sse.headers {
+		start_sb.write_string('\r\n$k: $v')
+	}
+	start_sb.write_string('\r\n')
+	sse.conn.write(start_sb) 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_string('id: $message.id\n')
+	}
+	if message.event != '' {
+		sb.write_string('event: $message.event\n')
+	}
+	if message.data != '' {
+		sb.write_string('data: $message.data\n')
+	}
+	if message.retry != 0 {
+		sb.write_string('retry: $message.retry\n')
+	}
+	sb.write_string('\n')
+	sse.conn.write(sb) ?
+}