Data-dependence analysis can identify causally-unordered events in a pending event set. The execution of these events is independent from all other scheduled events, making them ready for execution. These events can be executed out of order or in parallel. This approach may find and utilize more parallelism than spatial-decomposition parallelization methods, which are limited by the number of subdomains and by synchronization methods. This work provides formal definitions that use data-dependence analysis to find causally-unordered events and uses these definitions to measure parallelism in several discrete-event simulation models. A variant of the event-graph formalism is proposed, which assists with identifying ready events, by more clearly visualizing data dependencies between event types. Data dependencies between two event types may be direct or indirect, where the latter case considers the scheduling of intermediate events. Data dependencies and scheduling dependencies in a discrete-event simulation model are used to define time-interval limits that support the identification of events that are ready for execution. Experimental results from serial simulation testing demonstrate the availability of numerous events that are ready for execution, depending on model characteristics. The mean size of the ready-event set varies from about 1.5 to 110 for the tested models, depending on the model type, the size of the model, and delay distribution parameters. These findings support future work to develop a parallel capability to dynamically identify and execute ready events in a multi-threaded environment.

Experience from a full scale effort to apply formal methods to automated testing in the open systems software arena is described. The formal method applied in this work is based upon the Clemson Automated Testing System (CATS) which includes a formal specification language, a set of guidelines describing how to use the method effectively, and tool support capable of translating formal specifications into executable tests. This method is currently being used to develop a full scale test suite for IEEE's Ada Language Binding to POSIX. Following an overview of CATS, an experience report consisting of results, lessons learned and future directions is presented.

Open systems standards are developed through a consensus building process for the purpose of promoting portability and interoperability of software and hardware. Clearly, the ability to achieve such goals is directly related to the ability to enforce adherence to a standard. Perhaps less obvious is the impact of developing test specifications concurrently with the development of the standards. As the standards development process matures, lessons learned through experience will likely demonstrate that both these roles of testing are crucial to the success of a standard.>

This paper illustrates the power and flexibility of a new approach to creating conformance test suites for open systems software standards such as POSIX. The approach incorporates an automated process for the generation and validation of conformance tests. The automated process has been implemented and comprises key components of the Clemson Automated Testing System (CATS). CATS is a testing facility designed to provide a life-cycle support environment for the development of conformance tests. This paper introduces the CATS facility and presents examples of its use.>

Abstract Information hiding in software design leads to the concept of module closure. The function of modularization in a design is to hide a design decision, facilitating the design of programs which employ that module. This produces a module which may be used elsewhere regardless of its implementation details. Module closure has two components—access closure, wherein the module and user share no data objects, but only the values of formal parameters, and computation closure, wherein the model which the module emulates is as simple as possible, and implementation independent.

Abstract A design medium for software is proposed and illustrated. The medium, which employs rectangular, embedded contours, provides a high level of scale independence. Module specifications, logic design and program elements are easily intermixed in a design. The proposed module formalization includes interface specification, exceptions, logic design and effects in an order which will ultimately be exhibited by the program code as well.