BULGARELLI, ANDREAANDREABULGARELLI2021-02-232021-02-2320190922-6435http://hdl.handle.net/20.500.12386/30559In this paper is described the approach used to develop the software system of the AGILE γ-ray Observatory, from the definition phase to construction, verification and calibration activities of the satellite, until operations for scientific observations. Flexible software architectures, effective software management workflow, new algorithms (from payload simulators to reconstruction algorithms, from detection algorithms for Real-Time Analysis systems to the follow-up of science alerts in the multi-wavelenght and multi-messenger context) and team management approach are described. The approach followed by the AGILE Team in more than twenty years of work is a key element of the success of the AGILE Observatory, and the foundation for the involvement in new high-energy telescopes and observatories. Our legacy is not only in experience and tools but also in lesson learned, that are described in this work.STAMPAenArticle10.1007/s10686-019-09644-w2-s2.0-85075588316000511714300008https://link.springer.com/article/10.1007%2Fs10686-019-09644-w2019ExA....48..199BFIS/05 - ASTRONOMIA E ASTROFISICAERC sectors::Physical Sciences and Engineering::PE9 Universe sciences: astro-physics/chemistry/biology; solar systems; stellar, galactic and extragalactic astronomy, planetary systems, cosmology, space science, instrumentation::PE9_10 High energy and particle astronomy – X-rays, cosmic rays, gamma rays, neutrinos