Data Flow Aspects Research Articles

Test generation based on control and data dependencies within system specifications in SDL

In Specification and Description Language (SDL), a distributed system is viewed as a collection of communicating processes and its behavior is specified in terms of definitions of these processes. In particular, the desired control and data dependencies that must be established by a potential implementation of the system are expressed in SDL in terms of Extended Finite State Machine representations of communicating processes. To test the control and data flow aspects of the system, such dependencies in a system specification must be identified and utilized for the construction of tests. Based on a model which exposes the control and data dependencies within a specification of a distributed system given in SDL, this paper investigates the generation of tests for the data flow aspects of a system implementation, through the application of data flow oriented test selection criteria which have been originally proposed for testing programs written in procedural languages.

Clairvoyant: a synthesis system for production-based specification

This paper describes a new high-level synthesis system based on the hierarchical production based specification (PBS). Advantages of this form of specification are that the designer does not describe the control flow in terms of explicit states or control variables, and that the designer does not describe a particular form of implementation. The production-based specification also separates the specification of the control aspects and data-flow aspects of the design. The control is implicitly described via the production hierarchy, while the data-flow is described as action computations. This approach is a hardware analog of popular software engineering techniques. The Clairvoyant system automatically constructs a controlling machine from the PBS and this process is not impacted by the possibly exponentially larger deterministic state space of the designs. The encodings generated by the constructions compare favorably to encodings derived using graph-based state encoding techniques in terms of logic complexity and logic depth. These construction techniques utilize recent advances in BDD techniques. >

Partial orderings of event sets and their application to prototyping concurrent, timed systems

RAPIDE is a concurrent, object-oriented language specifically designed for prototyping large concurrent systems. One of the principle design goals has been to adopt a computation model in which the synchronization, concurrency, data flow, and timing aspects of a prototype are explicitly represented and easily accessible both to the prototype itself and to the prototyper. This article describes the partially ordered event set (poset) computation model and the features of RAPIDE for using posets in reactive prototypes and for automatically checking posets. An example prototyping scenario illustrates uses of the poset computation model, with and without timing.

Verification of protocol conformance test cases using reachability analysis

A methodology is presented to verify manually written test cases against the formal specification of a protocol. Initially, a protocol and a test case are modeled as nondeterministic finite state machines and test case verification is viewed as a reachability analysis problem. An existing reachability analysis algorithm, based on the well-known perturbation technique, is modified to take nondeterminism in protocols and special test case features (timeouts and OTHERWISE events) into account. Correctness aspects of the reachability algorithm are proved. The notion of a synchronization error manifesting in a test case due to the nondeterministic nature of a protocol specification is studied. To verify data flow aspects of test cases, we extend our technique by modeling the test case and protocol specification as extended finite state machines. A test case from a proprietary test suite for the transport protocol Class 2 is taken as an example and is shown to contain several design errors.

Legal aspects of transborder data flow

The technology of international information flows is widely understood, easily applied and generally well coordinated internationally. By contrast, legal responses to it have lacked full understanding, been fitfully applied and fragmentary in nature. The aim of this article is not to provide answers to all legal aspects of Transborder Data Flows (or TBDF) but rather to provide guidance on the types of questions to be asked in the first place. In doing so, the areas likely to give rise to practical problems, especially to users operating an international data network or intending to establish one, will be highlighted.

Aspects of data flow for an Edison-type observatory

Aspects of data flow for an Edison-type observatory

A test sequence selection method for protocol testing

A method for automated selection of test sequences from a protocol specification given in Estelle for the purpose of testing both control and data flow aspects of a protocol implementation is discussed. First, a flowgraph modeling the flow of both control and data expressed in the given specification is constructed. In the flowgraph, definitions and uses of each context variable, as well as each input and output interaction parameter employed in the specification, are identified. Based on this information, associations between each output and those inputs that influence the output are established. Test sequences are selected to cover each such association at least once. The resulting test sequences are shown to provide the capability of checking whether a protocol implementation under test establishes the desired flow of both control and data expressed in the protocol specification. The proposed method is illustrated by using the class 0 transport protocol as an example. >

The synchronous data flow programming language LUSTRE

The authors describe LUSTRE, a data flow synchronous language designed for programming reactive systems-such as automatic control and monitoring systems-as well as for describing hardware. The data flow aspect of LUSTRE makes it very close to usual description tools in these domains (block-diagrams, networks of operators, dynamical sample-systems, etc.), and its synchronous interpretation makes it well suited for handling time in programs. Moreover, this synchronous interpretation allows it to be compiled into an efficient sequential program. The LUSTRE formalism is very similar to temporal logics. This allows the language to be used for both writing programs and expressing program properties, which results in an original program verification methodology.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Integrated data aquisition, transmission and processing systems in two pig breeding schemes in the Federal Republic of Germany

Selection in breeding programs requires complete information on all activities in the population. Since selection decisions are largely based on the results of statistical calculations carried out by computers, information has to be available in computer compatible form. Two operating systems are described. The first deals with the aspects of data flow and analysis in the Federal Hybrid Crossbreeding Scheme for pigs and has been in commercial operation since 1980. The second is based on routine manipulations of data from the pig breeding herdbook societies, comprising all of the station tests and 40 per cent of field tests of boars in Germany. Data collection is carried out under program control using microcomputers. Data are transmitted via the public telephone network, employing a LSV 2 protocol to ensure safe data transmission. Data base management systems are used for data storage and retrieval. Much emphasis has been put on system flexibility to speed up program development and to ease future changes in data and program structure.

The Distributed Data Flow Aspect of Industrial Computer Systems

Today’s computer systems are in general based on the von Neumann type architecture. However, there also exist alternative architectures, for example dataflow systems and (quasi-) continuous systems.This paper presents a new type of computer architecture which is based on broadcast principle and on source addressing. This system can be viewed as a combination and generalisation of dataflow and continuous systems. It has some inherent advantages over the classical architecture, but there are also some difficulties in efficient implementation. A concept has been established which allows to implement broadcast systems efficiently and hence to utilize their advantages.There already exist distributed process control systems based on the broadcast and source addressed architecture. Ongoing research work in the field of fundamental concepts and their efficient implementation will broaden the scope of these systems and make them applicable in a wide range of process control and other applications.

Reliability analysis of fault tolerant pipeline ring networks

In this paper the application of software implemented voting (ring structures) to pipeline networks is presented. The TMR characterization of the ring is extended to various topologies such as trees, cascade and locally voted pipelines. Both the aspects of reliability and data flow are analyzed in detail.

Legal aspects of data flows between public agencies in France

The French public administration keeps a massive amount of information on file, for an ever increasing number of tasks. Moreover, data processing increases the possibility of exchanges of information held by different authorities, although in practice such exchanges are still infrequent, owing to a certain distance they prefer to maintain to each other. The trend confirmed by recent legislation is towards a restriction of personal data flows within the administration and towards third parties. This principle is implemented by the institutional control established over record-keeping, each record serving a specific purpose and being kept separate from the users of other records in the public sector. On the other hand, non-personal data is to circulare more freely within the public sector. The tradition of secrecy in which the public administration was veiled is replaced by a new policy of free access and sharing of information.