Windows NT Research Articles

Securing the Operating System: Does lesser-known mean less at risk? Is the OS an example of security though obscurity?

It is no secret that Microsoft Windows NT is the hacker’s favourite Operating System (OS). According to defacement-tracking site Attrition.org, ( www.Attrition.org) Windows NT received 54.41% of all recorded OS attacks between August 1999 and April 2001. In stark contrast, some of the lesser-known Operating Systems made up for as little as 0.1% of all OS attacks. However, despite the huge difference in the quantity of attacks, companies that employ the lesser-known systems may be at greater risk…

Automatic predicate abstraction of C programs

Model checking has been widely successful in validating and debugging designs in the hardware and protocol domains. However, state-space explosion limits the applicability of model checking tools, so model checkers typically operate on abstractions of systems. Recently, there has been significant interest in applying model checking to software. For infinite-state systems like software, abstraction is even more critical. Techniques for abstracting software are a prerequisite to making software model checking a reality. We present the first algorithm to automatically construct a predicate abstraction of programs written in an industrial programming language such as C, and its implementation in a tool — C2BP. The C2BP tool is part of the SLAM toolkit, which uses a combination of predicate abstraction, model checking, symbolic reasoning, and iterative refinement to statically check temporal safety properties of programs. Predicate abstraction of software has many applications, including detecting program errors, synthesizing program invariants, and improving the precision of program analyses through predicate sensitivity. We discuss our experience applying the C2BP predicate abstraction tool to a variety of problems, ranging from checking that list-manipulating code preserves heap invariants to finding errors in Windows NT device drivers.

Rapid response manufacturing through a rapidly reconfigurable robotic workcell

This article describes the development of a component-based technology robot workcell that can be rapidly configured to perform a specific manufacturing task. The workcell is conceived with standard and inter-operable components including actuator modules, rigid link connectors and tools that can be assembled into robots with arbitrary geometry and degrees of freedom. The reconfigurable “plug-and-play” robot kinematic and dynamic modeling algorithms are developed. These algorithms are the basis for the control and simulation of reconfigurable robots. The concept of robot configuration optimization is introduced for the effective use of the rapidly reconfigurable robots. Control and communications of the workcell components are facilitated by a workcell-wide TCP/IP network and device-level CAN-bus networks. An object-oriented simulation and visualization software for the reconfigurable robot is developed based on Windows NT. Prototypes of the robot workcells configured to perform the light-machining task and the positioning task are constructed and demonstrated.

Three-Dimensional Kernel Development for Injection Mould Design

Today, many software plug-ins have been developed on high-level 3D modelling platforms to facilitate processes such as FEM analysis, CAM, injection mould design, simulation and visualisation. Such an arrangement is advantageous in many ways. However, it is not without shortcomings. Ideally, these plug-ins could also be developed using low-level 3D kernels for higher flexibility and better portability. This paper examines the various issues and methodologies related to the development of such 3D-based applications. The emphasis is placed on the software aspect. First, a methodology for the development of 3D-based applications is proposed. The idea is then implemented by developing an injection mould design application using a low-level 3D kernel called Parasolid. Based on design concepts used in an established mould design application, IMOLD, the development of a mould base design module is illustrated. An object-oriented programming language has been chosen for the development of the software on a Windows NT platform.

Transparent checkpointing and rollback recovery mechanism for Windows NT applications

Clusters of industry-standard computers running Windows NT are emerging as a competitive alternative for large-scale parallel computing. However, clusters have increased susceptibility to failure especially when they contain many nodes. Therefore it is necessary to implement high availability on Windows NT. This paper introduces the Checkpoint and Rollback Recovery (CRR) mechanism on Windows NT and presents WinNTCkpt, a Checkpointing and recovery tool implemented by us. WinNTCkpt can be used to transparently checkpoint and recover applications running on Windows NT. To use this tool, user is only required to provide the application's executable code instead of source code. WinNTCkpt also provides a set of CRR APIs for users to construct applications with high availability. Owing to API interception and thread injection mechanisms, WinNTCkpt endows some existing applications with CRR functions. WinNTCkpt has been proved valid for Windows NT 4.0 and Windows 2000 applications.

CONUGA: Constrained User-Group Assignment

In role-based access control (RBAC), permissions are associated with roles and users are made members of appropriate roles, thereby acquiring the roles’ permissions. The principal motivation behind RBAC is to simplify administration. In this paper, we investigate one aspect of RBAC administration concerning assignment of users to roles. We introduce a constrained user-role assignment model, called CONUGA (CONstrained User-Group Assignment) and describe its implementation in the Windows NT system. Rather than set user and file rights individually for each and every user, the administrator can give rights to various groups, then place users within those groups in Windows NT. Each user within a group inherits the rights associated with that group. We demonstrate how to extend the Windows NT group mechanism supporting our model that is useful in managing group-based access control.

Using NDIS intermediate drivers for extending the protocol stack. A case study

Internet protocols continuously evolve through the development of new protocols and new extensions being added to the existing protocols, as a result of the increasing demands on information transfer. Consequently, operating systems need to embed periodically the new low-level protocols and protocol extensions. Since this is not always possible, especially when proprietary operating systems are involved, the means for extending the protocol stack with kernel extensions implementing support for the new added services should be provided by the operating systems' owners. This is exactly what the authors aim to demonstrate within this paper with the IP mobility support (Mobile IP), a newly defined service, and Windows NT version 4, a proprietary operating system that does not natively implement this service. The paper addresses the architecture trade-off of a suitable protocol stack, platform configuration, and resource reusing. The case is made for an intermediate driver approach, and the paper addresses packet flow control and packet management based on reusing the Tcpip.sys provided services. The parameters affecting the architecture and processing related performance of the extended protocol stack are identified and performance data are provided. All the assertions below are based on the prototype developed by the authors.

Safepaq-II, a new tool for the production of activation data libraries

Activation data and inventory codes are a major input to much of the safety related work carried out on fusion devices. The inventory code recommended for European activation calculations is fispact-99; this requires a large amount of nuclear data, which is available in the European Activation File ( EAF-99). The production of an EAF library uses new sources of data, both evaluated and calculated, differential measurements and integral data. In order to store, evaluate, and use all the various data sources an efficient software tool is required. Earlier versions of EAF have been produced using the tools sympal and safepaq, which enabled a large degree of automation as compared with the original construction ‘by hand’. However, these relied on the direct manipulation of the ENDF formatted text files using fortran-77. This is not an efficient approach, as editing of the text files is inconvenient and liable to errors. It was decided to use relational databases to store the data, with data extraction carried out by standard queries written in sql. Other objectives were the provision of a user-friendly graphical interface to allow data to be viewed and manipulated and a high level of QA by logging all data changes. These objectives have been realised by the safepaq-II application; this uses the ideas of the previous tools, but has been designed from scratch using new methods. Visual Basic is used to build the application running under Windows NT 4, which is linked to a series of access databases.

Computer Measurement of Oral Movement in Swallowing

This article describes a computer program that automatically detects and tracks small metal markers affixed to a subject's tongue and teeth in fluoroscopic image sequences of swallowing. The program, written in Microsoft Visual C++ using Windows NT 4.0 and the SAVANT imaging toolkit, involves marker detection and marker tracking. Marker detection is done by template matching. A generic marker template was designed by extracting the grayvalues of pixels within an imaged marker. Template matching with a weighted center-of-mass calculation determined marker location with subpixel accuracy. Marker tracking employed a nearest-neighbor algorithm since (a) the movement of each marker was less than the distance between any two markers and (b) marker trajectories did not overlap. Effects of head motion were attenuated by computing tongue trajectories with respect to a constant frame of reference given by reference markers on the maxillary teeth. Motions were converted from pixels/frame to millimeters/second using a calibration ring secured to the subject's neck. Results for several image sequences showed that our program performs very well in terms of marker detection and trajectory determination. Comparison of automatic and manual tracking of the same image sequences indicated a high degree of correspondence. Automatic tracking of oral movement by computer is a useful tool in kinematic studies of swallowing.

MICO, An Open Source CORBA Implementation

Arno Puder and Kay Romer Third Edition, MKF, San Francisco, CA, 2000, 195 pp. ISBN 1-55860-666-1, $39.95 I would like to recommend this book to all people wanting to start learning about CORBA and interested in implementing this standard to build distributed systems. It, in a short and easy way presents ORB and the ways it can be implemented. Object Request Broker is the central piece of the CORBA architecture, serving as a carrier for invocations from the client (querying object) to other object implementations. MICO ( Mico Is COrba ) is one of the ORBs fully complying with the CORBA standard, and it was initially created as a didactic tool. It is an Open Source project presented in public for the first time in April 1997. MICO sources are at present freely offered under the GNU General Public License, and are used successfully in both academic and commercial applications (for more information about software you may want to look at: http://www.mico.org/ ). The book is offered with a CD that contains precompiled binaries as well as the complete sources for MICO, version 2.3.2 compliant to CORBA version 2.3. The software is offered for Solaris 2.6, AIX 4.2, Linux 2.2.x, Unix 4.x, HP-UX 10.20, Windows NT and 95 platforms. The book is partly an installation guide, tutorial, as well as a user and reference manual. Additionally, it includes lots of general information about CORBA with a more detailed ORB description. The first part of the book is very short and contains a simple preamble to the standard of CORBA and introduces readers to the MICO project. The second chapter explains the procedure of installation of MICO on the user's operating system (with the use of the CD which accompanies this book). In addition, it contains many tips concerning a compilation of source code, unquestionably useful for all persons who would come to the challenge of making some modifications in the original codes. The third section consists of a full guide through MICO, enriched with some characteristics from the CORBA acquaintance, implemented in the context of distributed computer systems. This part is enhanced with the practical example, showing how to use MICO to modify one-address-space application to a distributed application, running on different remote hosts. The fourth chapter embraces an implementation overview; it is generally a description of different tools, being offered with the MICO software. The practical example, as mentioned in the third section, is presented here once again, this time in much more complicated scenarios, in order to present more advanced CORBA activation modes. The fifth part of the book explains an implementation of IDL (Interface Definition Language) to C++ mapping. Interface Definition Language is a notation used by the OMG group in the CORBA standard to describe object interfaces. Description presented in this book includes rules about how to map an IDL specification to C++, and also mentions some design matters specific to MICO solution. The sixth chapter, titled Interoperability , demonstrates how to implement MICO's cooperation with other ORB implementations. The examples used here by the authors are very popular commercial tools: Orbix (a CORBA compliant ORB for C++ and Java, made by IONA Technologies: http://www.iona.com/ ) and VisiBroker (a support for CORBA with C++ and Java language bindings, implemented by Borland Software Corporation: http://www.borland.com/us/products/visibroker/ ). The seventh chapter describes a naming service, which was implemented as a fully CORBA-compliant module, and presents additionally how to practically employ it in the users' own applications. The penultimate chapters of the book include description of the Interface Repository Browser, and the ninth and final chapter contains GNU License usage rules, which close the presentation of the MICO software included inside this book. This book is obviously not a complete CORBA manual, and it looks like the authors did not want to achieve the goal in producing it as such. However, the book presents an exceptional value for its price, including many practical solutions supported by nice theoretical explanations. I personally believe it could be very helpful in initial studies of Distributed Systems as well as it could be successfully used in preliminary lecture for people interested in CORBA standard. Rafal Angryk Tulane University New Orleans, Louisiana

Adaptive Fast Path Architecture

Adaptive Fast Path Architecture (AFPA) is a software architecture that dramatically improves the efficiency, and therefore the capacity, of Web and other network servers. The architecture includes a RAM-based cache that serves static content and a reverse proxy that can distribute requests for dynamic content to multiple servers. These two mechanisms are combined using a flexible layer-7 (content-based) routing facility. The architecture defines interfaces that allow these generic mechanisms to be exploited to accelerate a variety of application protocols, including HTTP. Efficiency is derived from maximizing the number of requests that are handled entirely within the kernel, using a deferred-interrupt context instead of threads wherever possible. AFPA has been implemented on several server platforms including Microsoft Windows NT® and Windows® 2000, OS/390®, AIX®, and most recently Linux. By conservative estimates, AFPA more than doubles cap acity for serving static content compared to conventional server architectures, and has allowed IBM to establish a leadership position in Web server performance. A prototype implementation of AFPA on Linux delivers more than 10000 SPECweb96 operations per second on a single processor.

Experience with building a commodity Intel-based ccNUMA system

Commercial cache-coherent nonuniform memory access (ccNUMA) systems often require extensive investments in hardware design and operating system support. A different approach to building these systems is to use Standard High Volume (SHV) hardware and stock software components as building blocks and assemble them with minimal investments in hardware and software. This design approach trades the performance advantages of specialized hardware design for simplicity and implementation speed, and relies on application-level tuning for scalability and performance. We present our experience with this approach in this paper. We built a 16-way ccNUMA Intel system consisting of four commodity four-processor Fujitsu® Teamserver™ SMPs connected by a Synfinity™ cache-coherent switch. The system features a total of sixteen 350-MHz Intel® Xeon™ processors and 4 GB of physical memory, and runs the standard commercial Microsoft Windows NT® operating system. The system can be partitioned statically or dynamically, and uses an innovative, combined hardware/software approach to support application-level performance tuning. On the hardware side, a programmable performance-monitor card measures the frequency of remote-memory accesses, which constitute the predominant source of performance overhead. The monitor does not cause any performance overhead and can be deployed in production mode, providing the possibility for dynamic performance tuning if the application workload changes over time. On the software side, the Resource Set abstraction allows application-level threads to improve performance and scalability by specifying their execution and memory affinity across the ccNUMA system. Results from a performance-evaluation study confirm the success of the combined hardware/software approach for performance tuning in computation-intensive workloads. The results also show that the poor local-memory bandwidth in commodity Intel-based systems, rather than the latency of remote-memory access, is often the main contributor to poor scalability and performance. The contributions of this work can be summarized as follows: • The Resource Set abstraction allows control over resource allocation in a portable manner across ccNUMA architectures; we describe how it was implemented without modifying the operating system. • An innovative hardware design for a programmable performance-monitor card is designed specifically for a ccNUMA environment and allows dynamic, adaptive performance optimizations. • A performance study shows that performance and scalability are often limited by the local-memory bandwidth rather than by the effects of remote-memory access in an Intel-based architecture.

CMEIAS: A Computer-Aided System for the Image Analysis of Bacterial Morphotypes in Microbial Communities.

A major challenge in microbial ecology is to develop reliable and facile methods of computer-assisted microscopy that can analyze digital images of complex microbial communities at single cell resolution, and compute useful quantitative characteristics of their organization and structure without cultivation. Here we describe a computer-aided interactive system to analyze the high degree of morphological diversity in growing microbial communities revealed by phase-contrast microscopy. The system, called "CMEIAS" (Center for Microbial Ecology Image Analysis System) consists of several custom plug-ins for UTHSCSA ImageTool, a free downloadable image analysis program operating on a personal computer in a Windows NT environment. CMEIAS uses various measurement features and two object classifiers to extract size and shape measurements of segmented, digital images of microorganisms and classify them into their appropriate morphotype. The first object classifier uses a single measurement feature to analyze relatively simple communities containing only a few morphotypes (e.g., regular rods, cocci, filaments). A second new hierarchical tree classifier uses an optimized subset of multiple measurement features to analyze significantly more complex communities containing greater morphological diversity than ever before possible. This CMEIAS shape classifier automatically categorizes each cell into one of 11 predominant bacterial morphotypes, including cocci, spirals, curved rods, U-shaped rods, regular straight rods, unbranched filaments, ellipsoids, clubs, rods with extended prostheca, rudimentary branched rods, and branched filaments. The training and testing images for development and evaluation of the CMEIAS classifier were obtained from 1,937 phase-contrast grayscale digital images of various diverse communities. The CMEIAS shape classifier had an accuracy of 96.0% on a training set of 1,471 cells and 97.0% on a test set of 4,270 cells representing all 11 bacterial morphotype classes, indicating that accurate classification of rich morphological diversity in microbial communities is now possible. An interactive edit feature was added to address the main sources of error in automatic shape classification, enabling the operator to inspect the assigned morphotype of each bacterium based on visual recognition of its distinctive pseudocolor, reassign it to another morphotype class if necessary, and add up to five other morphotypes to the classification scheme. The shape classifier reports on the number and types of different morphotypes present and the abundance among each of them, thus providing the data needed to compute the morphological diversity within the microbial community. An example of how CMEIAS can augment the analysis of microbial community structure is illustrated by studies of morphological diversity as an indicator of dynamic ecological succession following a nutrient shift-up perturbation in two continuously fed, anaerobic bioreactors with morphologically distinct start communities. Various steps to minimize the limitations of computer-assisted microscopy to classify bacterial morphotypes using CMEIAS are described. In summary, CMEIAS is an accurate, robust, flexible semiautomatic computing tool that can significantly enhance the ability to quantitate bacterial morphotype diversity and should serve as a useful adjunct to the analysis of microbial community structure. This first version of CMEIAS will be released as free, downloadable plug-ins so it can provide wide application in studies of microbial ecology.

Integrated optimization of energy supply systems in horticulture using genetic algorithms

Although simulation models are most suitable to examine real world systems, they would not be used enough for optimization programs. Genetic algorithms are now offering a good way to integrate simulation models in optimization tools. The search for optimized energy supply systems in horticulture serves as an example for this assumption: The design tools HORTSI and HORTOS were developed to support the efforts for a resource and environmentally friendly energy supply in horticulture. The simulation tool HORTSI integrates the simulation of selected energy supply systems whereby total costs, primary energy demands and carbon dioxide emissions are calculated. HORTSI covers the heat and power demand that is calculated by the tool HORTEX (T. Rath, 1992. Dissertation, Universität Hannover). The optimization tool HORTOS is based on HORTSI: the aim is to cover the heat, power and carbon dioxide demands with optimized supply systems. The designer can optimize the energy supply system for a given horticultural enterprise by hand or can automatically generate optimal solutions with the available optimization tool, where a genetic algorithm achieves and offers several optimal solutions. The tool optimizes the system as a whole, thereby taking into account interrelations between the supply components. All the tools are embedded in an integrated planning system called HORTEV, which runs under Windows 95 or Windows NT 4.0.

A Distributive and Collaborative Concurrent Product Design System through the WWW/Internet

Concurrent engineering involves the integration of people, tools, information, and processes into a responsive and efficient system. This paper addresses, a key requirement in distributed concurrent engineering, namely, the ability for geographically dispersed and disparate parties, having heterogeneous computing platforms, to exchange design and manufacturing data. The development of an effective and efficient collaborative product design support environment based on the WWW/Internet is presented. A new method that reduces the transmission time through the use of macro files is proposed to realise the real-time communication, together with a monitoring methodology for synchronising group operations, and maintaining consistency of shared CAD models in a cooperative design review (co-modifying) process. Based on the proposed methods, a software interface has been developed to extend the traditional single location CAD software system to a multi-location application for coordinated product design through the Internet. This software interface was coded in Java. The architecture is a connection-oriented client/server structure using TCP/IP protocol. Unigraphics on a UNIX Workstation and MicroStation on Windows NT have been successfully integrated. The findings of this paper allow product designers to exchange and share product data, communicate with team members, modify geometry data on particular aspects of the design, and maintain operations consistency in all the distributed cooperative sites on a wide variety of platforms.

Using an isolated network laboratory to teach advanced networks and security

This paper discusses the use of an isolated network laboratory to teach computer security using persistent cooperative groups and an active learning approach. Computer security and computer security education are areas of increasing importance as computer systems become more interconnected. When offered, undergraduate and graduate computer security courses are routinely taught using a traditional lecture format. If the course includes a class project, the class project is limited in scope and constitutes a relatively small portion of the student's grade. This paper examines a different approach in which the class project is the dominant factor in the student's grade. The students work in persistent cooperative teams as either a black or gold team. Black teams attempt to break into other black team computers or attack the gold team. The gold team operates Windows NT, LINUX, and Solaris-based servers and attempts to defend their servers and role-play system administrators. The entire exercise takes place in an isolated lab so as to separate student class activities from the rest of the departmental intranet. Four years of experience running the class with this format suggests that the use of persistent cooperative groups and active learning are effective approaches for teaching network security and are preferred over a lecture-based course.

Decentralized user group assignment in Windows NT

The notion of groups in Windows NT is much like that in other operating systems. Rather than set user and file rights individually for each and every user, the administrator can give rights to various groups, then place users within those groups. Each user within a group inherits the rights associated with that group. In this paper, we describe an experiment to extend the Windows NT group mechanism in two significant ways that are useful in managing group-based access control in large-scale systems. The goal of our experiment is to demonstrate how group hierarchies (where groups include other groups) and decentralized user-group assignment (where administrators are selectively delegated authority to assign certain users to certain groups) can be implemented by means of Microsoft remote procedure call (RPC) programs. In both respects the experimental goal is to implement previously published models (RBAC96 for group hierarchies and URA97 for decentralized user-group assignment). Our results indicate that Windows NT has adequate flexibility to accommodate sophisticated access control models to some extent.

Maximizing the net present value of a project with linear time-dependent cash flows

The paper studies the unconstrained project-scheduling problem with discounted cash flows where the cash flow functions are assumed to be linear-dependent on the completion times of the corresponding activities. Each activity of this unconstrained project-scheduling problem has a known deterministic cash flow function that is linear and non-increasing in time. Progress payments and cash outflows occur at the completion times of activities. The objective is to schedule the activities in order to maximize the net present value (npv) subject to the precedence constraints and a fixed deadline. Despite the growing amount of research concerning the financial aspects in project scheduling, little research has been done on the problem with time-dependent cash flow functions. Nevertheless, this problem gives an incentive to solve more realistic versions of project-scheduling problems with financial objectives. We introduce an extension of an exact recursive algorithm that has been used in solving the max-npv problem with time-independent cash flow functions and which is embedded in an enumeration procedure. The recursive search algorithm schedules the activities as soon as possible and searches for sets of activities to shift towards the deadline in order to increase the npv. The enumeration procedure enumerates all sets of activities for which such a shift has not been made but could, eventually, have been advantageous. The procedure has been coded in Visual C++ v.4.0 under Windows NT and has been validated on a randomly generated problem set.

Spatially modulated illumination microscopy: online visualization of intensity distribution and prediction of nanometer precision of axial distance measurements by computer simulations.

During the last years, measurements considerably beyond the conventional "Abbe-Limit" of optical resolution in far field light microscopy were realized by several light microscopical approaches. Point spread function (PSF) engineering, spectral precision distance microscopy (SPDM), and related methods were used to demonstrate the feasibility of such measurements. SPDM allows the measurement of position and multiple distances between point-like fluorescent objects of different spectral signatures far below the optical resolution criterion as defined by the full width at half maximum of the PSF. Here, we report a software method to obtain online visualization of light distribution in the lateral and axial direction of any object detected in a spatially modulated illumination (SMI) microscope. This strongly facilitates routine application of SMI microscopy. The software was developed using Microsoft Visual C++ running on Windows NT. Furthermore, some aspects of the theoretical limits of the SPDM method were studied by virtual microscopy. For the case of SMI microscopy the precision of axial distance measurements was studied, taking into account photon statistics and image analysis procedures. The results indicate that even under low fluorescence intensity conditions typical for biological structure research, precise distance measurements in the nanometer range can be determined, and that axial distances in the order of 40 nm are detectable with such precision.

Sharing attractions on the Net with VPark

We present a networked virtual environment (NVE) system and an attraction building system based on Windows NT that enables users to introduce their own scenario-based applications into a shared virtual environment. Our goal was to develop and integrate several modules into a system capable of animating realistic virtual humans in a real-time performance. This includes modeling and representing virtual humans with high realism and simulating human face and body movements in real time. Realism becomes quite important in NVEs, where the communication among participants is crucial for their sense of presence.