How does apt invoke dpkg ?

[Qian Hao <yoru.007@gmail.com>]

Hi, everyone
In many documentations, it is said that apt is responsible for
resolving package dependencies while it is the dpkg that actually do
the installation or removing task. But where does apt invoke dpkg ? I
have looked through the apt souce code but haven't found it. Could
anyone point it out for me or give me some hints ?

-- 
Hao Qian
Key Laboratory of Ocean Circulation and Waves (KLOCAW)
Institute of Oceanology, Chinese Academy of Sciences
No.7 Nanhai Road, Qingdao 266071, P.R.China
Phone: +86-18753220258