Confusion Swoole 4.6.6. vs ext-async

[fakharak]

I am using latest Swoole version 4.6.6. but this extension is confusing. My question is

A) "can i make Asynchronous Client / Calls" in Swoole, without "ext-async" ? I mean is there an aleternate mechanism available ? to write Asynchrnous Client / Calls without "ext-async" ?

OR, is the other way round that ...

B) "ext-async" is one and only (mandatory) way in Swoole to write Asynchronous Client / Calls ?

@winslis2 suggests in his comment: swoole version 4.4.4 has coroutines model，ext-async is Outdated

Originally posted by @winslis2 in https://github.com/swoole/ext-async/issues/3#issuecomment-524701044