TY CONF TI THE CONCEPT OF PHASED MODERNIZATION OF LEGACY-CLASS PDM SYSTEM USING THE EXAMPLE OF LOTSIA PDM PLUS IN JSC GSP ENGINEERING KW Legacy systems modernization KW PDM KW API gateway KW interface reengineering KW security KW information systems KW Gasproektinzhiniring JO MODELING INFORMATION SYSTEMS AND TECHNOLOGIES – 2026 AU Synorov, S.O. PY 2026 PB FSBE Institution of Higher Education Voronezh State University of Forestry and Technologies named after G.F. Morozov