  Context: Because it is viewed simply edge-on, the HH212 protostellar system
is an ideal laboratory for studying the interplay of infall, outflow, and
rotation in the earliest stages of low-mass star formation. Aims: We wish to
exploit the unmatched combination of high angular resolution, high sensitivity,
high-imaging fidelity, and spectral coverage provided by ALMA to shed light on
the complex kinematics of the innermost central regions of HH212. Methods: We
mapped the inner 10" (4500 AU) of the HH212 system at about 0.5 arcsec
resolution in several molecular tracers and in the 850 $\mu$m dust continuum
using the ALMA interferometer in band 7 in the extended configuration of the
Early Science Cycle 0 operations. Results: Within a single ALMA spectral
set-up, we simultaneously identify all the crucial ingredients known to be
involved in the star formation recipe namely: (i) the fast, collimated bipolar
SiO jet driven by the protostar, (ii) the large-scale swept-up CO outflow,
(iii) the flattened rotating and infalling envelope, with bipolar cavities
carved by the outflow (in C$^{17}$O(3--2)), and (iv) a rotating wide-angle flow
that fills the cavities and surrounding the axial jet (in C$^{34}$S(7--6)). In
addition, the compact high-velocity C$^{17}$O emission ($\pm$ 1.9--3.5 km
s$^{-1}$ from systemic) shows a velocity gradient along the equatorial plane
consistent with a rotating disk of about 0.2 arcsec = 90 AU around a $\simeq
0.3 \pm 0.1 M_{\rm \odot}$ source. The rotating disk is possibly Keplerian.
Conclusions: HH212 is the third Class 0 protostar with possible signatures of a
Keplerian disk of radius $\geq 30 AU$. The warped geometry in our CS data
suggests that this large keplerian disk might result from misaligned magnetic
and rotation axes during the collapse phase. The wide-angle CS flow suggests
that disk winds may be present in this source.
