To integrate the work among different teams and sites working in such a large project, there must be some kind of synchronization to facilitate the communication and cooperation between them. A concurrent engineering infrastructure that encompasses multiple sites and subsystems, called Pallo Alto Collaborative Testbed (PACT), was proposed in [8]. The issues discussed in that work were:
An execution environment for heterogeneous systems called ``InterBase'' was proposed in [4]. It integrates preexisting systems over a distributed, autonomous, and heterogeneous environment via a tool-based interface. In this environment each system is associated with a Remote System Interface (RSI) that enables the transition from the local heterogeneity of each system to a uniform system-level interface.
Object orientation and its applications to integrate heterogeneous, autonomous, and distributed systems are discussed in [42]. The argument in this work is that object-oriented distributed computing is a natural step forward from the client-server systems of today. A least-common-denominator approach to object-orientation as a key strategy for flexibly coordinating and integrating networked information processing resources is also discussed. An automated, flexible and intelligent manufacturing based on object-oriented design and analysis techniques is discussed in [39], and a system for design, process planning and inspection is presented.
Several important themes in concurrent software engineering are examined in [12]. Some of these themes are:
A management system for the generation and control of documentation flow throughout a whole manufacturing process is presented in [13]. The method of quality assurance is used to develop this system that covers cooperative work between different departments for documentation manipulation.
A computer-based architecture program called the Distributed and Integrated Environment for Computer-Aided Engineering (Dice), which addresses the coordination and communication problems in engineering, was developed at the MIT Intelligent Engineering Systems Laboratory [50]. The Dice project addresses several research issues such as, frameworks, representation, organization, design methods, visualization techniques, interfaces, and communication protocols.
Some important topics in software engineering, such as the lifetime of a software system, analysis and design, module interfaces and implementation, and system testing and verification, can be found in [28]. Also, a report about integrated tools for product, and process design can be found in [54].
In the environment we are proposing, several subsystems are communicating through a central interface layer (CI), and each subsystem has a subsystem interface (SSI) responsible for data transformation between the subsystem and the CI. The flexibility of this design arises from the following points:
More about this design is discussed in Section 7.