This paper presents a modification of GLADE – the current GNAT implementation of the Ada 95 Distributed Systems Annex (DSA)
– to support the development of distributed applications with hard real-time requirements. This modified implementation, that
we call RT-GLADE (Real-Time GLADE), is specially suitable for embedded applications composed of a small number of heterogeneous
processors and communication networks, because it ensures pre-dictable timing behaviour. A real-time model of the implementation
allows the application developer to determine and optimize the overall timing behaviour by applying the corresponding schedulability
analysis and priority assignment tech-niques. This realtime version of GLADE continues to conform to the DSA, so the entire
real-time application can be built within the Ada 95 context. To imple-ment RT-GLADE, we provide a priority-based communication
network over standard Ethernet that is used to ensure predictable transmission times.
Keywords Real-Time - Embedded Systems - Distributed Systems - Ada 95 - Modelling - Schedulability
This work has been funded in part by the Comisión Interministerial de Ciencia y Tecnologí
a (CICYT) of the Spanish Government under grant number TIC2002-04123-C03-02 (TRECOM), and by the IST Programme of the European
Commission under project IST-2001-34820 (FIRST).