11908873
Using high speed networks to enable distributed parallel image server systems
We describe the design and implementation of a distributed parallel storage system that uses high-speed ATM networks as a key element of the architecture. Other elements include a collection of network-based disk block servers, and an associated name server that provides some file system functionality. The implementation is based on user level software that runs on UNIX workstations. Both the architecture and the implementation are intended to provide for easy and economical scalability. This approach has yielded a data source that scales economically to very high speed. Target applications include online storage for both very large images and video sequences. This paper describes the architecture, and explores the performance issues of the current implementation.<<ETX>>
1514436
Dynamic monitoring of high-performance distributed applications
Developers and users of high-performance distributed systems often observe performance problems such as unexpectedly low throughput or high latency. Determining the source of the performance problems requires detailed end-to-end instrumentation of all components, including the applications, operating systems, hosts, and networks. However, one must be very careful to design the instrumentation to have extremely low overhead, and not affect the system being monitored. In this paper we present a very light-weight instrumentation system that can be dynamically activated to unobtrusively collect and aggregate detailed end-to-end monitoring information from distributed applications. We also show how emerging "web services" can be used to facilitate remote interaction with this system.
10444660
A Monitoring Sensor Management System for Grid Environments
Large distributed systems such as Computational Grids require a large amount of monitoring data be collected for a variety of tasks such as fault detection, performance analysis, performance tuning, performance prediction, and scheduling. Ensuring that all necessary monitoring is turned on and that data is being collected can be a very tedious and error-prone task. We have developed an agent-based system to automate the execution of monitoring sensors and the collection of event data.
9722973
Monitoring Data Archives for Grid Environments
Developers and users of high-performance distributed systems often observe performance problems such as unexpectedly low throughput or high latency. To determine the source of these performance problems, detailed end-to-end monitoring data from applications, networks, operating systems, and hardware must be correlated across time and space. Researchers need to be able to view and compare this very detailed monitoring data from a variety of angles. To address this problem, we propose a relational monitoring data archive that is designed to efficiently handle high-volume streams of monitoring data. In this paper we present an instrumentation and monitoring event archive service that can be used to collect and aggregate detailed end-to-end monitoring information from distributed applications. This archive service is designed to be scalable and fault tolerant. We also show how the archive is based on the "Grid Monitoring Architecture" defined by the Global Grid Forum.
1058760
Enabling network-aware applications
Many high-performance distributed applications use only a small fraction of their available bandwidth. A common cause of this problem is not a flaw in the application design, but rather improperly tuned network settings. Proper tuning techniques, such as setting the correct TCP buffers and using parallel streams, are well-known in the networking community, but outside this community they are infrequently applied. In this paper, we describe a service that makes the task of network tuning trivial for application developers and users. Widespread use of this service should virtually eliminate a common stumbling block for high-performance distributed applications.
1519617
Distributed parallel data storage systems: a scalable approach to high speed image servers
We have designed, built, and analyzed a distributed parallel storage system that will supply image streams fast enough to permit multi-user, “real-time”, video-like applications in a wide-area ATM network-based Internet environment. We have based the implementation on user-level code in order to secure portability; we have characterized the performance bottlenecks arising from operating system and hardware issues, and based on this have optimized our design to make the best use of the available performance. Although at this time we have only operated with a few classes of data, the approach appears to be capable of providing a scalable, high-performance, and economical mechanism to provide a data storage system for several classes of data (including mixed multimedia streams), and for applications (clients) that operate in a high-speed network environment.
207320410
On fast supervised learning for normal mixture models with missing information
It is an important research issue to deal with mixture models when missing values occur in the data. In this paper, computational strategies using auxiliary indicator matrices are introduced for efficiently handling mixtures of multivariate normal distributions when the data are missing at random and have an arbitrary missing data pattern, meaning that missing data can occur anywhere. We develop a novel EM algorithm that can dramatically save computation time and be exploited in many applications, such as density estimation, supervised clustering and prediction of missing values. In the aspect of multiple imputations for missing data, we also offer a data augmentation scheme using the Gibbs sampler. Our proposed methodologies are illustrated through some real data sets with varying proportions of missing values.
17811625
A Graph-Based Approach for Modeling and Indexing Video Data
In this work, we propose new graph-based data model and indexing to organize and manage video data. To consider spatial and temporal characteristics of video, we introduce a new graph-based data model called spatio-temporal region graph (STRG). Unlike existing graph-based data structures which provide only spatial features, the proposed STRG further provides temporal features, which represent temporal relationships among spatial objects. The STRG is decomposed into its subgraphs object graphs (OGs) and background graphs (BGs). In addition, a new distance measure, called extended graph edit distance (EGED), is introduced in metric space for matching and indexing. Based on clustering and EGED, we propose a new indexing method STRG-index, which is faster and more accurate. We compare the STRG-Index with the M-tree, which is a popular tree-based indexing method for multimedia data. The STRG-index outperforms the M-tree in terms of cost and speed
14450756
How to Design Optimistic Operations for Peer-to-Peer Replication
As collaboration over the Internet becomes an everyday affair, it is increasingly important to provide high quality of interactivity. Distributed applications can replicate collaborative objects at every site for the purpose of achieving high interactivity. Replication, however, has a fatal weakness that it is difficult to maintain consistency among replicas. This paper introduces operation commutativity as a key principle in designing operations in order to manage distributed replicas consistent. In addition, we suggest effective schemes that make operations commutative using the relations of objects and operations. Finally, we apply our approaches to some simple replicated abstract data types, and achieve their consistency without serialization and locking.
2177844
Design, performance analysis, and implementation of a super-scalar video-on-demand system
Despite the availability of video-on-demand (VoD) services in a number of cities around the world, large-scale deployment of VoD services in a metropolitan area is still economically impractical. This study presents a novel super-scalar architecture for building very large-scale and efficient VoD systems. The proposed architecture combines the use of static multicast, dynamic multicast, and intelligent client-side caching to vastly reduce server and network resource requirement. Moreover, in sharp contrast to conventional VoD systems where the system cost increases at least linearly with the system scale, the proposed architecture becomes more efficient as the system scales up and can ultimately be scaled up to serve any number of users while still keeping the startup latency short. This paper presents this new architecture, proposes methods to support interactive playback controls without the need for additional server or client resources, and derives an approximate performance model to relate the startup latency with other system parameters. The performance model is validated using simulation and the architecture is evaluated under various system settings. Lastly, a system implementation is presented and benchmarking results obtained to further verify the architecture, the performance model, and the simulation results.
7917654
Using kinetic typography to convey emotion in text-based interpersonal communication
Text-based interpersonal communication tools such as instant messenger are widely used today. These tools often feature emoticons that people use to express emotion to some degree. However, emoticons still lack the ability to communicate the details of an emotional response, such as the speaker's tone of voice or intensity of emotion. In this paper, we hypothesize that kinetic typography - text that moves or changes over time - can address some of this problem by enhancing emotional qualities of text communication using its dynamic and expressive properties.This paper presents a study showing that a small sample of designers can create kinetic effects that end-users could employ to consistently convey emotion. In the study, three designers prepared 24 kinetic examples expressing four different emotions. We found that the examples were rated quite consistently by 66 participants. These findings provide a preliminary indication that designers can create predefined kinetic effects which can be applied to a variety of textual messages, and that these effects will reliably convey a particular emotional intent. The findings from this study inform design guidelines for designing an instant messaging client that uses kinetic typography presentation.