If I use https://pecl.php.net/package/event library on Windows then I got following error out of the box

PHP Warning:  EventBase::__construct(): event_base_new_with_config: no event mechanism available

After small investigation I found that if following line commented then all works as expected
https://github.com/reactphp/event-loop/blob/master/src/ExtEventLoop.php#L47

$config->requireFeatures(EventBaseConfig::FEATURE_FDS);

Examples

Server: https://github.com/inri13666/web-socket-echoserver
Client: https://github.com/inri13666/web-socket-test

Library Info

composer show | grep loop
react/event-loop                     v1.1.0  ReactPHP's core reactor event loop that libraries can use for evented I/O.

Environment

systeminfo | findstr /B /C:"OS Version" /C:"System Type" /C:"System Locale"

php -i | findstr /B /C:"PHP Version" /C:"Architecture" /C:"Compiler" /C:"Configure Command" /C:"Zend Extension Build"

Configure Command: cscript /nologo configure.js "--enable-snapshot-build" "--enable-debug-pack" "--with-pdo-oci=c:\php-snap-build\deps_aux\oracle\x64\instantclient_12_1\sdk,shared" "--with-oci8-12c=c:\php-snap-build\deps_aux\oracle\x64\instantclient_12_1\sdk,shared" "--enable-object-out-dir=../obj/" "--enable-com-dotnet=shared" "--with-mcrypt=static" "--without-analyzer" "--with-pgo"

PHP Extensions

php -m
[PHP Modules]
bcmath
bz2
calendar
com_dotnet
Core
ctype
curl
date
dom
event <====
exif
fileinfo
filter
gd
hash
iconv
intl
json
ldap
libxml
mbstring
mcrypt
memcache
mysqli
mysqlnd
openssl
pcre
PDO
pdo_mysql
pdo_pgsql
pdo_sqlite
pdo_sqlsrv
pgsql
Phar
readline
Reflection
session
SimpleXML
soap
sockets
SPL
sqlsrv
standard
tokenizer
wddx
xdebug
xml
xmlreader
xmlrpc
xmlwriter
xsl
zip
zlib

[Zend Modules]
Xdebug