Abstract
Ada95 is an object-oriented concurrent programming language. PDEFA is a distributed Ada95 system. In PDEFA, task and protected objects in Ada95 are turned into independent and service objects, respectively, and run under the control of a daemon program. Independent and service objects in PDEFA are called parallel objects. An independent object performs independent operations, synchronizing with other independent objects by calling their synchronization interface calls. A service object provides service to other parallel objects via its static and dynamic interface calls. The daemon manages all parallel objects and regulates their creation and termination. PDEFA is an Ada95 system and differs from those earlier systems based on Ada83.