41947706
Secure Communication in Distributed Ada
This document describes an implementation of secure communication for distributed applications in Ada 95. It explains the basics of cryptography and introduces the problem of key exchange. After a brief description of distributed systems in Ada 95, the modular structure of the implementation and the way it handles key distribution is presented.
11330765
Transparent filtering of streams in GLADE
Note: Also available as Technical Report EPFL 97/241 Reference LGL-CONF-1997-009 Record created on 2005-09-20, modified on 2016-08-08
62754021
Transparent replication for fault tolerance in distributed Ada 95
In this paper we present the foundations of RAPIDS ("Replicated Ada Partitions In Distributed Systems"), an implementation of the PCS supporting the transparent replication of partitions in distributed Ada 95 using semi-active replication. The inherently non-deterministic executions of multi-tasked partitions are modeled as piecewise deterministic histories. I discuss the validity and correctness of this model of computation and show how it can be used for efficient semi-active replication. The R APIDS prototype ensures that replicas of a partition all go through the same history and are hence consistent.
1643372
Fault Tolerance by Transparent Replication for Distributed Ada 95
This paper presents the foundations of RAPIDS ("Replicated Ada Partitions In Distributed Systems"), an implementation of the Distributed Systems Annex E incorporating the transparent replication of partitions in distributed Ada 95 applications. RAPIDS is a replication manager for semi-active replication based on a piecewise deterministic computation model. It guarantees replica consistency for arbitrary Ada 95 partitions despite the inherent non-determinism of multitasking, offering k-resilient partitions. The RAPIDS prototype is implemented for the GNAT compiler and evolved from its PCS, Garlic.
196094
Integrating object-oriented programming and protected objects in Ada 95
Integrating concurrent and object-oriented programming has been an active research topic since the late 1980's. There is a now a plethora of methods for achieving this integration. The majority of approaches have taken a sequential object-oriented language and made it concurrent. A few approaches have taken a concurrent language and made it object-oriented. The most important of this latter class is the Ada 95 language, which is an extension to the object-based concurrent programming language Ada 83. Arguably, Ada 95 does not fully integrate its models of concurrency and object-oriented programming. For example, neither tasks nor protected objects are extensible. This article discusses ways in which protected objects can be made more extensible.
31197886
Object-Oriented Programming and Protected Objects in Ada 95
Integrating concurrent and object-oriented programming has been an active research topic since the late 1980s. The majority of approaches have taken a sequential object-oriented language and made it concurrent. A few approaches have taken a concurrent language and made it object-oriented. The most important of this latter class is the Ada 95 language which is an extension to the object-based concurrent programming language Ada 83. Arguably, Ada 95 does not fully integrate its models of concurrency and object-oriented programming. This paper discusses ways in which protected objects can be made more extensible.
45184054
A package for the analytic investigation and exact solution of differential equations
To find exact solutions of differential equations fDEs) one usually performs a variety of tests and ansaetze as e.g. the symmetry ansatz, separation ansatz, ansaetze for first integrals. When carrying through these ideas one h a s to solve overdetermined systems of partial DEs fPDEs). Whereas the formulation of the overdetermined system f o r each ansatz is achieved by different programs we use one program to investigate the overdetermined sys~. This program CRAOKSTAR contains three basic modules for the deooupling of DEs, for the integration of exact DEs and f o r separation. They are explained by examples. With these new a b i l i t i e s i t becomes poss ib le f o r CRACKSTAR to so lve systems of DEs which are sore difficult, i.e. the ansatz to be carried through ma y be less restrictive. An example shows that in this way not only point s y m m e t r i e s b u t a l s o m o r e g e n e r a l d y n a m i c a l s y m m e t r i e s o f o r d i n a r y DEs ( O D E s ) c a n b e d e t e r m i n e d . F o r t h e I n v e s t i g a t i o n o f L l e s ~ t r i e s o f systems of PDEs an interval strategy is applied which reduces the effort f o r GKACKSTM~ c o n s i d e r a b l y . F u r t h e r t w o new c o n c e p t s , a n i n t e g r a l a n s a t z f o r ODEs and a generalized separation ansatz f o r PDEs are described as w e l l a s t h e p r o g r a m s w h i c h g e n e r a t e o v e r d e t e r m i n e d s y s t e m s for e a c h ansatz.
9140187
The integration of systems of linear PDEs using conservation laws of syzygies
A new integration technique is presented for systems of linear partial differential equations (PDEs) for which syzygies can be formulated that obey conservation laws. These syzygies come for free as a by-product of the differential Grobner basis computation. Compared with the more obvious way of integrating a single equation and substituting the result in other equations the new technique integrates more than one equation simultaneously and therefore introduces temporarily fewer new functions of integration that in addition depend on fewer variables. Especially for high order PDE systems in many variables the conventional integration technique may lead to an explosion of the number of functions of integration which is avoided with the new method. A further benefit is that redundant free functions in the solution are either prevented or that their number is at least reduced.
8186069
On solving large systems of polynomial equations appearing In discrete differential geometry
The poster describes methods that combined find all solutions of a very large overdetermined polynomial algebraic system for only up to 22 unknowns but with billions of equations all homogeneous of degree 8 with on average millions of terms each. This problem resulted from the classification of all integrable 3-dimensional scalar discrete quasilinear equations Q3 = 0 on an elementary cubic cell of the lattice Z3.
46113649
Analytical Decoupling, Decision of Compatibility and Partial Integration of Systems of Non-Linear Ordinary and Partial Differential Equations
40351745
Vom Rechenzentrum zum Zentrum für Informations- und Kommunikationstechnik
Belege fur die technische Unterstutzung der menschlichen Informationsverarbeitung finden sich bis weit in die Vergangenheit. Die historischen Entwicklungslinien der drei Teilfunktionen der Informations- und Kommunikationstechnologie (IuK-Technik) — Transport, Verarbeitung und Speicherung — sind lange Zeit getrennt verlaufen. Hiermit ist gemeint, das die technischen Losungen fur die der drei Teilfunktionen unabhangig waren.