  The nature of dark matter, dark energy and large-scale gravity pose some of
the most pressing questions in cosmology today. These fundamental questions
require highly precise measurements, and a number of wide-field spectroscopic
survey instruments are being designed to meet this requirement. A key component
in these experiments is the development of a simulation tool to forecast
science performance, define requirement flow-downs, optimize implementation,
demonstrate feasibility, and prepare for exploitation. We present SPOKES
(SPectrOscopic KEn Simulation), an end-to-end simulation facility for
spectroscopic cosmological surveys designed to address this challenge. SPOKES
is based on an integrated infrastructure, modular function organization,
coherent data handling and fast data access. These key features allow
reproducibility of pipeline runs, enable ease of use and provide flexibility to
update functions within the pipeline. The cyclic nature of the pipeline offers
the possibility to make the science output an efficient measure for design
optimization and feasibility testing. We present the architecture, first
science, and computational performance results of the simulation pipeline. The
framework is general, but for the benchmark tests, we use the Dark Energy
Spectrometer (DESpec), one of the early concepts for the upcoming project, the
Dark Energy Spectroscopic Instrument (DESI). We discuss how the SPOKES
framework enables a rigorous process to optimize and exploit spectroscopic
survey experiments in order to derive high-precision cosmological measurements
optimally.
