Instant yet Simple PHP notification with HTML5 Server-Sent Events
sse.php
<?php
$dbconn = new PDO("pgsql:host=localhost;dbname=mydb", "pduser", "userpass");
$dbconn->exec('LISTEN "channel_name"'); // those doublequotes are very important
header("X-Accel-Buffering: no"); // disable ngnix webServer buffering
header("Content-Type: text/event-stream");
header("Cache-Control: no-cache");
ob_end_flush(); // close PHP output buffering
$inc=0;
while (1) {
$result = "";
// wait for one Notify 10seconds instead of using sleep(10)
$result = $dbconn->pgsqlGetNotify(PDO::FETCH_ASSOC, 10000);
if ( $result ) {
echo "id: $inc\ndata: ".stripslashes(json_encode($result))."\n\n";
$inc++;
}
flush();
}
?>
Tested with HTML+JS sample file from Mozilla web site (ssedemo.php)
pg_get_notify
(PHP 4 >= 4.3.0, PHP 5, PHP 7, PHP 8)
pg_get_notify — 获取 SQL NOTIFY 消息
说明
pg_get_notify() 取得 SQL 命令 NOTIFY
生成的消息。要接收通知，必须发送 SQL 命令 LISTEN。
参数
-
connection -
PgSql\Connection 实例。
-
mode -
An optional parameter that controls how the returned array is indexed.
modeis a constant and can take the following values:PGSQL_ASSOC,PGSQL_NUMandPGSQL_BOTH. UsingPGSQL_NUM, the function will return an array with numerical indices, usingPGSQL_ASSOCit will return only associative indices whilePGSQL_BOTHwill return both numerical and associative indices.
返回值
包含 NOTIFY 消息名称和后端 PID 的 array。如果服务器支持，该数组还包含服务器版本和有效负载。否则，如果没有
NOTIFY 正在等待，则返回 false。
更新日志
| 版本 | 说明 |
|---|---|
| 8.1.0 |
现在 connection 参数接受 PgSql\Connection
实例，之前接受 resource。
|
示例
示例 #1 PostgreSQL NOTIFY 消息
<?php
$conn = pg_pconnect("dbname=publisher");
if (!$conn) {
echo "An error occurred.\n";
exit;
}
// 从其它进程监听 'author_updated' 消息
pg_query($conn, 'LISTEN author_updated;');
$notify = pg_get_notify($conn);
if (!$notify) {
echo "No messages\n";
} else {
print_r($notify);
}
?>
add a note
User Contributed Notes 2 notes
glococo at gmail dot com ¶
7 years ago
david at frankieandshadow dot com ¶
4 years ago
It appears that pg_get_notify does not distinguish between no message waiting and a failure when checking - both seem to return FALSE.
I had to add a pg_check_connection(...) before pg_get_notify to check the connection is still alive (it's quite likely to be a long-standing connection with pg_get_notify as you'll be polling waiting for something to happen). In my case the remote database server had a hiccup, and without pg_check_connection the listeners failed to notice, so never saw later notifications.
