Guest editors' introduction : Special issue on trust, security, and privacy in parallel and distributed systems

In modern computing paradigms, most computing systems, e.g., cluster computing, grid computing, cloud computing, the Internet, telecommunication networks, Cyber- Physical Systems (CPS), and Machine-to-Machine communication networks (M2M), are parallel and distributed systems. While providing improved expandability, manageability, efficiency, and reliability, parallel and distributed systems increase their security weaknesses to an unprecedented scale. As the system devices are widely connected, their vulnerabilities are shared by the entire system. Because tasks are allocated to, and information is exchanged among the system devices that may belong to different users, trust, security, and privacy issues have yet to be resolved. This special issue of the IEEE Transactions on Parallel and Distributed Systems (TPDS) highlights recent advances in trust, security, and privacy for emerging parallel and distributed systems. This special issue was initiated by Dr. Xu Li, Dr. Patrick McDaniel, Dr. Radha Poovendran, and Dr. Guojun Wang. Due to a large number of submissions, Dr. Zhenfu Cao, Dr. Keqiu Li, and Dr. Yang Xiang were later invited to the editorial team. Dr. Xu Li was responsible for coordinating the paper review process. In response to the call for papers, we received 150 effective submissions, out of which 24 are included in this special issue after rigorous review and careful revision, presenting an acceptance ratio of 16 percent. The accepted papers are divided into three groups, covering issues related to trust, security, and privacy, respectively.

Study of ensemble strategies in discovering linear casual models

Determining the causal structure of a domain is frequently a key task in the area of Data Mining and Knowledge Discovery. This paper introduces ensemble learning into linear causal model discovery, then examines several algorithms based on different ensemble strategies including Bagging, Adaboost and GASEN. Experimental results show that (1) Ensemble discovery algorithm can achieve an improved result compared with individual causal discovery algorithm in terms of accuracy; (2) Among all examined ensemble discovery algorithms, BWV algorithm which uses a simple Bagging strategy works excellently compared to other more sophisticated ensemble strategies; (3) Ensemble method can also improve the stability of parameter estimation. In addition, Ensemble discovery algorithm is amenable to parallel and distributed processing, which is important for data mining in large data sets.

Technologies and considerations for developing internet and multiplayer computer games: a tutorial (extended abstract)

Games are universal and probably as old as humankind. Today the development of computer technology, especially the development of fast networks and the Internet, brings games a faster growth than ever before. Game design and development is now a fast-growing entertainment field, with a lot to offer professionally and creatively. In fact, from IT professional’s point of view, creating computer games provides us with all the usual technical challenges associated with software development, such as requirement analysis, architectural design, rapid prototyping, HCI, parallel and distributed processing, code reuse, programming, performance evaluation, testing and maintenance. It also provides challenges on other exciting aspects, such as storyboarding, screenplays, illustration, animation, sound effects, music, and social impact. By developing a computer game from start to finish, one would be able to acquire multi-disciplinary knowledge to become an IT professional for the modern era.

Toward an operating system that supports parallel processing on nondedicated clusters

Present operating systems are not built to support parallel computing on clusters - they do not provide services to manage parallelism, i.e., to manage parallel processes and cluster resources. They do not provide support for both programming paradigms, Message Passing (MP) or Distributed Shared Memory (DSM). Due to poor operating systems, users must deal with computers of a cluster rather than to see this cluster as a single powerful computer. There is a need for cluster operating systems. We claim that it is possible to develop a cluster operating system that is able to efficiently manage parallelism, support MP and DSM and offer transparency. To substantiate this claim the first version of a cluster operating system managing parallelism and offering transparency, called GENESIS, has been developed.

A cluster operating system supporting parallel computing

The single factor limiting the harnessing of the enormous computing power of clusters for parallel computing is the lack of appropriate software. Present cluster operating systems are not built to support parallel computing – they do not provide services to manage parallelism. The cluster operating environments that are used to assist the execution of parallel applications do not provide support for both Message Passing (MP) or Distributed Shared Memory (DSM) paradigms. They are only offered as separate components implemented at the user level as library and independent servers. Due to poor operating systems users must deal with computers of a cluster rather than to see this cluster as a single powerful computer. A Single System Image of the cluster is not offered to users. There is a need for an operating system for clusters. We claim and demonstrate that it is possible to develop a cluster operating system that is
able to efficiently manage parallelism, support Message Passing and DSM and offer the Single System Image. In order to substantiate the claim the first version of a cluster operating system, called GENESIS, that manages parallelism and offers the Single System Image has been developed.

A comparative study at the logical level of centralised and distributed recovery in clusters

Cluster systems are becoming more prevalent in today’s computer society and users are beginning to request that these systems be reliable. Currently, most clusters have been designed to provide high performance at the cost of providing little to no reliability. To combat this, this report looks at how a recovery facility, based on either a centralised or distributed approach could be implemented into a cluster that is supported by a check pointing facility. This recovery facility can then recover failed user processes by using checkpoints of the processes that have been taken during failure free execution.

GENESIS: an efficient, transparent and easy to use cluster operating system

Present operating systems are not built to support parallel computing––they do not provide services to manage parallelism, i.e., to globally manage parallel processes and computational resources. The cluster operating environments that are used to assist the execution of parallel applications do not provide support for both programming paradigms, message passing (MP) or distributed shared memory (DSM)––they are mainly offered as separate components implemented at the user level as library and independent server processes. Due to poor operating systems users must deal with clusters as a set of independent computers rather than to see this cluster as a single powerful computer. A single system image (SSI) of the cluster is not offered to users. There is a need for an operating system for clusters. We claim and demonstrate in this paper that it is possible to develop a cluster operating system that is able to efficiently manage parallelism; use cluster resources efficiently; support MP in the form of standard MP and PVM, and DSM; offer SSI; and make it easy to use. We show that to achieve these aims this operating system should inherit many features of a distributed operating system and provide new services which address the needs of parallel processes, cluster's resources, and application developers. In order to substantiate the claim the first version of a cluster operating system managing parallelism and offering SSI, called GENESIS, has been developed.

Distributed network systems : from concepts to implementations

"This textbook covers both theoretical and practical aspects of distributed computing. It describes the client-server model for developing distributed network systems, the communication paradigms used in a distributed network system, and the principles of reliability and security in the design of distributed network systems." "This book is suitable for self-study or for use in classes. Most parts of the book have been used by the authors in their teaching of various topics including distributed systems, computer networks, and distributed database systems. This book can also serve as an invaluable guide for computing professionals in their work for the design and implementation of distributed network systems."

Multiple strategy process migration

The future of computing lies with distributed systems, i.e. a network of workstations controlled by a modern distributed operating system. By supporting load balancing and parallel execution, the overall performance of a distributed system can be improved dramatically. Process migration, the act of moving a running process from a highly loaded machine to a lightly loaded machine, could be used to support load balancing, parallel execution, reliability etc. This thesis identifies the problems past process migration facilities have had and determines the possible differing strategies that can be used to resolve these problems. The result of this analysis has led to a new design philosophy. This philosophy requires the design of a process migration facility and the design of an operating system to be conducted in parallel. Modern distributed operating systems follow the microkernel and client/server paradigms. Applying these design paradigms, in conjunction with the requirements of both process migration and a distributed operating system, results in a system where each resource is controlled by a separate server process. However, a process is a complex resource composed of simple resources such as data structures, an address space and communication state. For this reason, a process migration facility does not directly migrate the resources of a process. Instead, it requests the appropriate servers to transfer the resources. This novel solution yields a modular, high performance facility that is easy to create, debug and maintain. Furthermore, the design easily incorporates providing multiple migration strategies. In order to verify the validity of this design, a process migration facility was developed and tested within RHODOS (ResearcH Oriented Distributed Operating System). RHODOS is a modern microkernel and client/server based distributed operating system. In RHODOS, a process is composed of at least three separate resources: process state - maintained by a process manager, address space - maintained by a memory manager and communication state - maintained by an InterProcess Communication Manager (IPCM). The RHODOS multiple strategy migration manager utilises the services of the process, memory and IPC Managers to migrate the resources of a process. Performance testing of this facility indicates that this design is as fast or better than existing systems which use faster hardware. Furthermore, by studying the results of the performance test ing, the conditions under which a particular strategy should be employed have been identified. This thesis also addresses heterogeneous process migration. The current trend is to have islands of homogeneous workstations amid a sea of heterogeneity. From this situation and the current literature on the topic, heterogeneous process migration can be seen as too inefficient for general use. Instead, only homogeneous workstations should be used for process migration. This implies a need to locate homogeneous workstations. Entities called traders, which store and disseminate knowledge about the resources of several workstations, should be used to provide resource discovery. Resource discovery will enable the detection of homogeneous workstations to which processes can be migrated.

Building the second generation of parallel/distributed virtual reality systems

We present the RhoVeR (Rhodes Virtual Reality) system and classify it as a second generation parallel/distributed virtual reality (DVR) system. We discuss the components of the system and thereby demonstrate its support for virtual reality application development, its configurable, parallel and distributed nature, and its synthesis of first generation DVR techniques.

Investigation of the intersection of constraints model of motion perception

The direction and speed of motion of a one-dimensional (1-D) stimulus, such as a grating, presented within a circular aperture is ambiguous. This ambiguity, referred to as the Aperture Problem (Fennema & Thompson, 1979) results from (i) the inability to detect motion parallel to grating orientation, and (ii) the occlusion of border information, such as the ‘ends’ of the grating, by the surface forming the aperture, Adelson and Movshon's (1982) intcrsection-of-constraints (IOC) model of motion perception describes a two-stage method of disambiguating the motion of 1-D moving stimuli (e.g., gratings) to produce unambiguous motion of two-dimensional (2-D) objects (e.g., plaid patterns) made up of several 1-D components. Specifically, in the IOC model ambiguous 1-D motions extracted by Stage 1 component-selective mechanisms are integrated by Stage 2 pattern-selective mechanisms to produce unambiguous 2-D motion signals. ‘Integration’ in the context of the IOC model involves determining the single motion vector (i.e., combination of direction and speed) which is consistent with the I-D components of a 2-D object. Since the IOC model assumes that 2-D objects undergo pure translation (i.e., without distortion, rotation, etc.), the motion vector consistent with all 1-D components describes the motion of the 2-D object itself. Adelson and Movshon (1982) propose that neural implementation of the computation underlying the IOC model is reflected in the perception of coherent 2-D plaid motion reported when two separately-moving ‘component’ gratings are superimposed. Using these plaid patterns the present thesis assesses the IOC model in terms of its ability to account for the perception of 2-D motion in a variety of circumstances. In the first series of experiments it is argued that the unambiguous motion perceived for a single grating presented within a rectangular aperture (i.e., the Barberpole illusion; Wallach, 1976) reflects application of the IOC computation to the moving 1-D grating and the stationary boundary of the aperture. While contrary to the assumption which underlies the IOC model (viz., that integration occurs between moving 1-D stimuli), evidence consistent with the involvement of the IOC computation in mediating the Barberpole illusion (in which there is only one moving stimulus) is obtained by measuring plaid coherence as a function of aperture shape. It is found that rectangular apertures which bias perceived component motions in directions consistent with plaid direction facilitate plaid coherence, while rectangular apertures which bias perceived component motions in directions inconsistent with plaid direction disrupt plaid coherence. In the second series of experiments, perceived directions of motion of type I symmetrical, type I asymmetrical, and type II plaids are measured with the aim of investigating the deviations in plaid directions reported by Ferrera and Wilson (1990) and Yo and Wilson (1992). Perceived directions of both asymmetrical and type II plaids are shown to deviate away from lOC-predicted directions and towards mean component direction. Furthermore, the magnitude of these deviations is being proportional to the difference between lOC-predicted plaid direction and mean component direction. On the basis of these directional deviations, modification to the IOC model is proposed. In the modified IOC model it is argued that plaid perception involves (i) the activity of Stage 2 pattern-selective mechanisms (and the Stage 1 component-selective mechanisms which input into these pattern-selective mechanisms) involved in implementing the IOC computation, and (ii) component-selective mechanisms which influence plaid perception directly, and ‘extraneously’ to the IOC computation. In the third series of experiments the validity of this modified IOC model, as well as the validity of alternative one-stage models of plaid perception are assessed in relation to perceived directions of plaid-induced MAEs as a function of both plaid direction and mean component direction. It is found that plaid-induced MAEs are shifted away from directions opposite to lOC-predicted plaid direction towards the direction opposite to mean component direction. This pattern of results is taken to be consistent with the modified IOC model which predicts the activity, and adaptation both of mechanisms signalling plaid direction (via implementation of the IOC computation), and ‘extraneous-type’ component-selective mechanisms signalling component directions. Alternative one-stage models which predict the adaptation of only mechanisms signalling plaid direction (the feature-tracking model), or the adaptation only of mechanisms signalling component directions (the distribution-of-activity model), cannot account for the directions of plaid-induced MAEs reported. The ability of the modified IOC model to account for the perceived directions of (i) gratings in rectangular apertures, (ii) various types of plaid in circular apertures, and (iii) directions of plaid-induced MAEs, is interpreted as supporting the proposition that human motion perception is based on a parallel and distributed process involving Stage 2 pattern-selective mechanisms (and the Stage 1 component-selective mechanisms which input into these mechanisms) taken to implement the IOC computation, and component-selective mechanisms taken to provide an 'extraneous' direct contribution to motion perception.

Building reliable distributed systems

[No Abstract]