Regarding this, ns_http is now the preferred low-level interface for HTTP client functionalities. A higher level interface, that deprecates all the "old school" procs like ad_httpget and such, you can find in [1] and [2].
These are basically wrappers around the API that make easier to issue the requests, also providing backward compatibility with Aolserver by using curl.
Hope this helps
Antonio
[1] https://openacs.org/api-doc/proc-view?proc=util%3a%3ahttp%3a%3aget&source_p=1
[2] https://openacs.org/api-doc/proc-view?proc=util%3a%3ahttp%3a%3apost&source_p=1
