  We study analytically the dynamics of cavity QED nodes in a practical quantum
network. Given a single 3-level $\Lambda$-type atom or quantum dot coupled to a
micro-cavity, we derive several necessary and sufficient criteria for the
coherent trapping and generation of a single photon pulse with a given waveform
to be realizable. We prove that these processes can be performed with practical
hardware -- such as cavity QED systems which are operating deep in the weak
coupling regime -- given a set of restrictions on the single-photon pulse
envelope. We systematically study the effects of spontaneous emission and
spurious cavity decay on the transfer efficiency, including the case where more
than one excited state participates in the dynamics. This work should open the
way to very efficient optimizations of the operation of quantum networks.
