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Classroom 2000: An Experiment with the Instrumentation of a Living Educational Environment
- IBM Systems Journal
, 2000
"... One potentially useful feature of future computing environments is the ability to capture the live experiences of the occupants and to provide that record to users for later access and review. Over the last 3 years, we have designed and extensively used a particular instrumented environment, the cla ..."
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Cited by 343 (21 self)
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One potentially useful feature of future computing environments is the ability to capture the live experiences of the occupants and to provide that record to users for later access and review. Over the last 3 years, we have designed and extensively used a particular instrumented environment, the classroom, designed to facilitate the easy capture of the traditional lecture experience. We will describe the history of the Classroom 2000 project at Georgia Tech, and provide results of extended evaluations of the impact of automated capture on the teaching and learning experience. In addition to understanding the impact of automated capture in this educational domain, there are many important lessons to take away from this long-term, largescale experiment with a living ubiquitous computing environment. The environment needs to address issues of scale and extensibility, and there needs to be a way to continuously evaluate the effectiveness of the environment and understand and react to the w...
A Hierarchical Characterization of a Live Streaming Media Workload
- IEEE/ACM Transactions on Networking
, 2002
"... We present what we believe to be the first thorough characterization of live streaming media content delivered over the Internet. Our characterization of over five million requests spanning a 28-day period is done at three increasingly granular levels, corresponding to clients, sessions, and transfe ..."
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Cited by 94 (13 self)
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We present what we believe to be the first thorough characterization of live streaming media content delivered over the Internet. Our characterization of over five million requests spanning a 28-day period is done at three increasingly granular levels, corresponding to clients, sessions, and transfers. Our findings support two important conclusions. First, we show that the nature of interactions between users and objects is fundamentally different for live versus stored objects. Access to stored objects is user driven, whereas access to live objects is object driven. This reversal of active/passive roles of users and objects leads to interesting dualities. For instance, our analysis underscores a Zipf-like profile for user interest in a given object, which is to be contrasted to the classic Zipf-like popularity of objects for a given user. Also, our analysis reveals that transfer lengths are highly variable and that this variability is due to the stickiness of clients to a particular live object, as opposed to structural (size) properties of objects. Second, based on observations we make, we conjecture that the particular characteristics of live media access workloads are likely to be highly dependent on the nature of the live content being accessed. In our study, this dependence is clear from the strong temporal correlations we observed in the traces, which we attribute to the synchronizing impact of live content on access characteristics. Based on our analyses, we present a model for live media workload generation that incorporates many of our findings, and which we implement in GISMO [19].
Lessons learned from eclass: assessing automated capture and access in the classroom. http://www.cc.gatech.edu/classes/AY2003/cs7470_spring/papers/eclassevaluation.pdf Clay, Melanie. "Development of training and support programs for distance education ins
- International Review of Research in Open and Distance Learning. (October - 2002) http://www.irrodl.org/content/v3.2/frydenberg.html Gerson و Steven
, 2003
"... This article presents results from a study of an automated capture and access system, eClass, which was designed to capture the materials presented in college lectures for later review by students. In this article, we highlight the lessons learned from our three-year study focusing on the effect of ..."
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Cited by 81 (4 self)
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This article presents results from a study of an automated capture and access system, eClass, which was designed to capture the materials presented in college lectures for later review by students. In this article, we highlight the lessons learned from our three-year study focusing on the effect of capture and access on grades, attendance, and use of the captured notes and media. We then present suggestions for building future systems discussing improvements from our system in the capture, integration, and access of college lectures.
Analysis of Educational Media Server Workloads
, 2001
"... This paper presents an extensive analysis of the client workloads for educational media servers at two major U.S. universities. The goals of the analysis include providing data for generating synthetic workloads, gaining insight into the design of streaming content distribution networks, and quantif ..."
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Cited by 81 (8 self)
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This paper presents an extensive analysis of the client workloads for educational media servers at two major U.S. universities. The goals of the analysis include providing data for generating synthetic workloads, gaining insight into the design of streaming content distribution networks, and quantifying how much server bandwidth can be saved in interactive educational environments by using recently developed multicast streaming methods for stored content.
Characterizing Locality, Evolution, and Life Span of Accesses in Enterprise Media Server Workloads
, 2002
"... The main issue we address in this paper is the workload analysis of today's enterprise media servers. This analysis aims to establish a set of properties specific for enterprise media server workloads and to compare them with well known related observations about web server workloads. We propos ..."
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Cited by 58 (13 self)
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The main issue we address in this paper is the workload analysis of today's enterprise media servers. This analysis aims to establish a set of properties specific for enterprise media server workloads and to compare them with well known related observations about web server workloads. We propose two new metrics to characterize the dynamics and evolution of the accesses, and the rate of change in the site access pattern, and illustrate them with the analysis of two different enterprise media server workloads collected over a significant period of time. Another goal of our workload analysis study is to develop amedia server log analysis tool, called ############, that produces a media server traffic access profile and its system resource usage in a way useful to service providers.
MediSyn: A synthetic streaming media service workload generator
- in Proc. of the 13th International Workshop on Network and Operating System Support for Digital Audio and Video (NOSSDAV 2003
, 2003
"... Currently, Internet hosting centers and content distribution networks leverage statistical multiplexing to meet the performance requirements of a number of competing hosted network services. Developing efficient resource allocation mechanisms for such services requires an understanding of both the s ..."
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Cited by 41 (8 self)
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Currently, Internet hosting centers and content distribution networks leverage statistical multiplexing to meet the performance requirements of a number of competing hosted network services. Developing efficient resource allocation mechanisms for such services requires an understanding of both the short-term and longterm behavior of client access patterns to these competing services. At the same time, streaming media services are becoming increasingly popular, presenting new challenges for designers of shared hosting services. These new challenges result from fundamentally new characteristics of streaming media relative to traditional web objects, principally different client access patterns and significantly larger computational and bandwidth overhead associated with a streaming request. To understand the characteristics of these new workloads we use two long-term traces of streaming media services
Delving into internet streaming media delivery: A quality and resource utilization perspective
- in Internet Measurement Conference Proceedings of the 6th ACM SIGCOMM on Internet measurement
, 2006
"... Modern Internet streaming services have utilized various techniques to improve the quality of streaming media delivery. Despite the characterization of media access patterns and user behaviors in many measurement studies, few studies have focused on the streaming techniques themselves, particularly ..."
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Cited by 41 (6 self)
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Modern Internet streaming services have utilized various techniques to improve the quality of streaming media delivery. Despite the characterization of media access patterns and user behaviors in many measurement studies, few studies have focused on the streaming techniques themselves, particularly on the quality of streaming experiences they offer end users and on the resources of the media systems that they consume. In order to gain insights into current streaming services and thus provide guidance on designing resource-efficient and high quality streaming media systems, we have collected a large streaming media workload from thousands of broadband home users and business users hosted by a major ISP, and analyzed the most commonly used streaming techniques such as automatic protocol switch, Fast Streaming, MBR encoding and rate adaptation. Our measurement and analysis results show that with these techniques, current streaming systems tend to over-utilize CPU and bandwidth resources to provide better services to end users, which may not be a desirable and effective way to improve the quality of streaming media delivery. Motivated by these results, we propose and evaluate a coordination mechanism that effectively takes advantage of both Fast Streaming and rate adaptation to better utilize the server and Internet resources for streaming quality improvement.
Analyzing Client Interactivity in Streaming Media
, 2004
"... This paper provides an extensive analysis of pre-stored streaming media workloads, focusing on the client interactive behavior. We analyze four workloads that fall into three different domains, namely, education, entertainment video and entertainment audio. Our main goals are: (a) to identify qualit ..."
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Cited by 40 (5 self)
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This paper provides an extensive analysis of pre-stored streaming media workloads, focusing on the client interactive behavior. We analyze four workloads that fall into three different domains, namely, education, entertainment video and entertainment audio. Our main goals are: (a) to identify qualitative similarities and differences in the typical client behavior for the three workload classes and (b) to provide data for generating realistic synthetic workloads.
A Generator of Internet Streaming Media Objects and Workloads
- ACM SIGMETRICS Performance Evaluation Review
, 2001
"... This paper presents a tool called Gismo (Generator of Internet Streaming Media Objects and workloads). Gismo enables the specification of a number of streaming media access characteristics, including object popularity, temporal correlation of request, seasonal access patterns, user session durations ..."
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Cited by 34 (1 self)
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This paper presents a tool called Gismo (Generator of Internet Streaming Media Objects and workloads). Gismo enables the specification of a number of streaming media access characteristics, including object popularity, temporal correlation of request, seasonal access patterns, user session durations, user interactivity times, and variable bit-rate (VBR) self-similarity and marginal distributions. The embodiment of these characteristics in Gismo enables the generation of realistic and scalable request streams for use in the benchmarking and comparative evaluation of Internet streaming media delivery techniques. To demonstrate the usefulness of Gismo, we present a case study that shows the importance of various workload characteristics in determining the effectiveness of proxy caching and server patching techniques in reducing bandwidth requirements.
Accelerating Internet Streaming Media Delivery Using Network-Aware Partial Caching
, 2001
"... This paper aims at mitigating such eects by leveraging the availability of client-side caching proxies. We present a novel caching architecture (and associated cache management algorithms) that turn edge caches into accelerators of streaming media delivery. A salient feature of our caching algori ..."
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Cited by 32 (2 self)
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This paper aims at mitigating such eects by leveraging the availability of client-side caching proxies. We present a novel caching architecture (and associated cache management algorithms) that turn edge caches into accelerators of streaming media delivery. A salient feature of our caching algorithms is that they allow ####### caching of streaming media objects and ##### delivery of content from caches and origin servers. The caching algorithms we propose are both ############# and ####### #####; they take into account the popularity of streaming media objects, their bit-rate requirements, and the available bandwidth between clients and servers. Using realistic models of Internet bandwidth (derived from proxy cache logs and measured over real Internet paths), we have conducted extensive simulations to evaluate the performance of various cache management alternatives. Our experiments demonstrate that network-aware caching algorithms can signi cantly reduce service delay and improve overall stream quality. Also, our experiments show that partial caching is particularly eective when bandwidth variability is not very high
