  We investigate the Josephson effect in S$_{\rm F}$XS$_{\rm F}$ junctions,
where S$_{\rm F}$ is a superconducting material with a ferromagnetic exchange
field, and X a weak link. The critical current $I_c$ increases with the
(antiparallel) exchange fields if the distribution of transmission eigenvalues
of the X-layer has its maximum weight at small values. This exchange field
enhancement of the supercurrent does not exist if X is a diffusive normal
metal. At low temperatures, there is a correspondence between the critical
current in an S$_{\rm F}$IS$_{\rm F}$ junction with collinear orientations of
the two exchange fields, and the AC supercurrent amplitude in an SIS tunnel
junction. The difference of the exchange fields $h_1-h_2$ in an S$_{\rm
F}$IS$_{\rm F}$ junction corresponds to the potential difference $V_1-V_2$ in
an SIS junction; i.e., the singularity in $I_c$ [in an S$_{\rm F}$IS$_{\rm F}$
junction] at $|h_1-h_2|=\Delta_1+\Delta_2$ is the analogue of the Riedel peak.
We also discuss the AC Josephson effect in S$_{\rm F}$IS$_{\rm F}$ junctions.
