Net-Centric Design and Analysis of Information Systems

This thesis presents a unique methodology merging state of the art Internet and distributed database technology to support distributed simulations with programming language and platform independence. Standardized models of Command, Control, Communications, Computers, and Intelligence (C4I) systems using Integrated Definition (IDEF) models and executable simulation objects are placed in database repositories which can be accessed and implemented over a distributed simulation network using the Common Object Request Broker Architecture (CORBA). The CORBA distributed simulation network accesses heterogeneous distributed databases, performs distributed processes, and supports portability and reuse of simulation objects and interoperability across operating systems and programming languages

Software To Secure Distributed Propulsion Simulations

Distributed-object computing systems are presented with many security threats, including network eavesdropping, message tampering, and communications middleware masquerading. NASA Glenn Research Center, and its industry partners, has taken an active role in mitigating the security threats associated with developing and operating their proprietary aerospace propulsion simulations. In particular, they are developing a collaborative Common Object Request Broker Architecture (CORBA) Security (CORBASec) test bed to secure their distributed aerospace propulsion simulations. Glenn has been working with its aerospace propulsion industry partners to deploy the Numerical Propulsion System Simulation (NPSS) object-based technology. NPSS is a program focused on reducing the cost and time in developing aerospace propulsion engine

Overload Protection for CORBA Systems with Time Constraints

Scalable and reliable distributed object-oriented computing (DOC) middleware systems is an important technology in, for example, telecommunications service logic and distributed web servers. The Common Object Request Broker Architecture (CORBA), developed by the Object Management Group (OMG) is a speci cation of a common platform for DOC systems. CORBA acts as middleware, by inserting itself between the Operating System (OS) layer and the Application layer on a host. CORBA provides support for transparent interaction of objects situated on different nodes. The original CORBA specications had no support for timing constraints in applications and very little support in the terms of performance optimizations. Present extension to CORBA include support for real-time applications and a number of performance enhancements such as load balancing. However, no work so far address the issue of overload in a CORBA system. This paper presents a discussion of overload issues in distributed CORBA systems with time-constrained tasks. First a performance model of a CORBA system is introduced. Second, overload in distributed CORBA systems is discussed. Third, a number of classic overload protection mechanisms are applied to the performance model and investigated using simulation. The simulations show that even by using very simple protection mechanism, a good throughput can be achieved

The Role of Operating Systems in Object-Oriented Distributed Multimedia Platforms

Considerable progress has been madein# the development of technologies tosupport# distributed multimedia computing, but applicationplatforms# are needed to make such technology accessible# to application programmers. This papersets# out requirements for such platforms and discusses the role of operating systems in object-oriented# platform support. We describe an initial approach to providing such a platform which attempted to factor out all realtime aspects of multimedia support ontoa# hardware based multimedia network interface unit. This solution has been partially successful but lacks the flexibility and level of integration subsequentlydemanded# by application programmers. Our response has been to redesign the multimedia network interface unit, placing more emphasis on the provision ofdynamic# services which require real-time operating system support. The new design described in this paper exploits and extends features of a distributed object-oriented micro-kernel to provide the n..

Migration of an operating system to an object-oriented paradigm

Operating System design has moved from monolithic systems such as UNIX, where all system services are implemented in a single kernel, to microkernel designs where the majority of system services are conducted in user space. A recent trend in operating system design has been to use architectural models based upon the object-oriented paradigms. This approach promotes the modelling of system resources and resource management as an organized collection of objects in such a way that the mechanisms, policites, algorithms, and data representations of the operating system are suitably encapsulated by the objects. Much of the research in this area to date has concentrated on the uses and benefits of object-oriented operating systems m the distributed systems arena. Similarly, almost all of these systems have been designed from the ground-up. I beheve that the progression towards object-oriented operating systems is likely to involve current operating systems incorporating and assimilating object-oriented features into their existing designs in a gradual manner, rather than an overnight switch to a new technology. In this light, the purpose of my thesis is to take an existing operating system and to propose a design which would migrate the original operating systems' facilities and features to an object-oriented paradigm. This thesis also evaluates the advantages and disadvantages of such a design over the existing one. Finally, future enhancements and directions are proposed based on the new operating system design

A Flexible Object Oriented Spacecraft Operating System (FOS)

Satellite Operating Software has traditionally been highly specialized custom software which operates one satellite according to deterministic rules. Software changes are usually accomplished with a complete reload from the ground, and performing patches require explicit knowledge of memory maps, variable locations, etc. and can often result in long term satellite down times. As computer, sensor and communication technology increases, more and more of the computing, routing and decision functions of small satellite systems are occurring onboard, and a need exists for adaptable flexible software. The object oriented approach to satellite operating systems provides a malleable system, resilient to failure, distributable across multiple satellites and easily adaptable to other applications. The Operating System acts as a switch for the distribution and execution of messages whether a command, code or data. Even operating system functions can only be executed by sending a message internally. These technique’s provide for a safe system and simplified software maintenance. Since software code is broken into objects, the particular application can be distributed amongst one or more processors, satellites, ground stations or remote terminals. This allows for multi-processor based communication load balancing algorithms, dynamic fail-over capability and compute bound resource sharing. Since no explicit hardware knowledge is required by the flight application code, most objects can be reused for other satellite applications. Such systems can be implemented on small satellites using current processor technology

A software approach for readout and data acquisition in CMS

Traditional systems dominated by performance constraints tend to neglect other qualities such as maintainability and configurability. Object-Orientation allows one to encapsulate the technology differences in communication sub-systems and to provide a uniform view of data transport layer to the systems engineer. We applied this paradigm to the design and implementation of intelligent data servers in the Compact Muon Solenoid (CMS) data acquisition system at CERN to easily exploiting the physical communication resources of the available equipment. CMS is a high-energy physics experiment under study that incorporates a highly distributed data acquisition system. This paper outlines the architecture of one part, the so called Readout Unit, and shows how we can exploit the object advantage for systems with specific data rate requirements. A C++ streams communication layer with zero copying functionality has been established for UDP, TCP, DLPI and specific Myrinet and VME bus communication on the VxWorks real-time operating system. This software provides performance close to the hardware channel and hides communication details from the application programmers. (28 refs)

Interoperability for smart home environment using web services.

Recent advances in computing and communication technologies paved the growth for applications and devices in smart home environment. A typical smart home is highly characterized by heterogeneity elements that need to perform joint execution of tasks in an efficient manner. Although there are huge growth of services, applications and devices in smart home environment, the interoperability elements still seems ambiguous. Being a distributed architecture, smart home environment needs certain degree of interoperability to manage sub-systems comprising of different platforms. Generally, these sub-systems are developed in isolation and consist of different operating system and tier of services. There is need for a cross-platform interoperability that could make the sub-systems 'talk' each other and operate in an interoperable fashion within smart home environment. Web Services seems to be the emerging technology that could lead the way in providing greater interoperability. In this paper we describe the potential of Web Services technology using Simple Object Access Protocol (SOAP) in addressing the interoperability requirements for smart home environment. The SOAP protocol provides data exchange mechanism as well as optimized performance for interoperation among sub-systems residing in smart home environment. The proposed system performance is evaluated to demonstrate a complete, bi-directional real-time management of sub-systems in smart home environment

A comparative study of structured and un-structured remote data access in distributed computing systems

Recently, the use of distributed computing systems has been growing rapidly due to the result of cheap and advanced microelectronic technology. In addition to the decrease in hardware costs, the tremendous development in machine to machine communication interfaces, especially in local area networking, also favours the use of distributed systems. Distributed systems often require remote access to data stored at different sites. Generally, two models of access to remote data storage exist: the un structured and structured models. In the former, data is simply stored as row of bytes, whereas in the latter, data is stored along with the associated access codes. The objective of this thesis is to compare these two models and hence determines the tradeoffs of each model. First of all, an extended review of the field of distributed data access is provided which addressing key issues such as the basic design principles of distributed computing systems, the notions of abstract data types, data inheritance, data type system and data persistence. Secondly, a distributed system is implemented using the persistent programming language PS-algol and the high level language C in conjunction with the remote procedure call facilities available in Unix(^1) 4.2 BSD operating system. This distributed system makes extensive use of Unix's software tools and hence it is called DCSUNIX for Distributed Computing System on UNIX. Thirdly, two specific applications which employ the implemented system will be given so that a comparison can be made between the two remote data access models mentioned above. Finally, the implemented system is compared with the criteria established earlier in the thesis. keywords: abstract data types, class, database management, data persistence, information hiding, inheritance, object oriented programming, programming languages, remote procedure calls, transparency, and type checking

Next generation software environments : principles, problems, and research directions

The past decade has seen a burgeoning of research and development in software environments. Conferences have been devoted to the topic of practical environments, journal papers produced, and commercial systems sold. Given all the activity, one might expect a great deal of consensus on issues, approaches, and techniques. This is not the case, however. Indeed, the term "environment" is still used in a variety of conflicting ways. Nevertheless substantial progress has been made and we are at least nearing consensus on many critical issues.The purpose of this paper is to characterize environments, describe several important principles that have emerged in the last decade or so, note current open problems, and describe some approaches to these problems, with particular emphasis on the activities of one large-scale research program, the Arcadia project. Consideration is also given to two related topics: empirical evaluation and technology transition. That is, how can environments and their constituents be evaluated, and how can new developments be moved effectively into the production sector