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