Compact integrated microring resonators are promising candidates for various applications in optical signal processing and communication such as optical filters, wavelength (de)multiplexers, single mode sources, dispersion compensators and wavelength converters. Active GaInAsP/InP material is particularly suited for the fabrication of "lossless" filter devices as well as novel laser components with outstanding performance. Design, technology as well as transmission / emission mode characteristics for typical applications are sketched and summarized.