Dracena: A Real-Time IoT Service Platform Based on Flexible Composition of Data Streams. - Hisatoshi Yamaoka; Kota Itakura; Eiichi Takahashi; Gaku Nakagawa; Julius Michaelis; Yasuhiko Kanemasa; Miwa Ueki; Tatsuro Matsumoto; Riichiro Take; Sayuri Tanie; Daigo Inoue (SII, 2019)