What, in principle, the protocols can PHP somewhere to connect without writing their extensions? Well, for example HTTP, Memcache (vk.com use it as a transport PHP <-> C daemons), MySQL.
What else?
Objective: to gash the most simple server in C++ / Python using this Protocol to PHP most cheap could throw on this server kilobytes of arbitrary data well, or at least JSON. Why vk.com transport with demons made it on MC and not on the HTTP overhead is probably less HTTP a ton of text headers (how does MC Protocol I don't know). Why not do something different - apparently Mc is quite simple.
What out of the box simple and angry is there more?
Interested in something higher-level HTTP level / MC implemented for compiled code (core php and its packaged extensions), called in a couple of lines of code of the form
$resp = request("1.2.3.4", 5515, "{ 'r' : 'request', 'param' : 42 }");