6705104
Embracing agile development of usable software systems
The interdisciplinary nature of system design can lead to communication problems between developers in different fields. This is becoming evident in the emerging field of agile software development which has largely ignored or been unable to address usability. This work presents a development process and toolset that draws on extreme programming--an agile software development process, and scenario-based design--a usability engineering process. This approach will allow developers in both fields to better communicate and work together to efficiently design usable systems.
10486912
VTAssist: a location-based feedback notification system for the disabled
The needs of individuals with limited mobility have not been given as much importance as those of other users of internet-accessible mobile devices. Disabled users have information and service needs that are unique and a timely delivery of these services and information can be invaluable. This has motivated us toward the development of VTAssist, an application that attempts to provide critical location-based information about building accessibility to impaired users. This paper discusses our initial implementation of VTAssist and reports on preliminary evaluation results. Our results indicate that our system can help wheelchair users to better understand and navigate around environments.
12830619
Image is everything: advancing HCI knowledge and interface design using the system image
As the field of human-computer interaction matures, the need for proven, dependable engineering processes for interface development becomes apparent. Our continuing work in developing LINK-UP, an integrated design and reuse environment, suggests that a better understanding of the system image is key to the successful evaluation of design prototypes, and an aide in applying knowledge from the repository. This paper describes our ongoing work to enhance LINK-UP by developing and augmenting the system image to make it the central communication point between different stages of design and between different stakeholders. We report on a study of the new task flow that demonstrated the value of the system image within a broader design context. Overall, our findings indicate that the effective creation and use of knowledge repositories by novice HCI designers hinges on successful application of existing HCI design concepts within a practical integrated design environment.
6216883
Alumni campus tour: capturing the fourth dimension in location based notification systems
When a person visits a place, it is almost always simple to understand the physical environment around them. Often people ignore---or don't have access to---the fourth dimension: time. Our research is an attempt to create a system that adds the aspect of time into location-based notification systems. This allows a person to not only experience their surroundings through five senses and three dimensions, but also to understand the changes the location has undergone over time, by receiving cues. This report describes our experience in designing and implementing such a system and reports on a preliminary evaluation of it.
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>>
2077132
Continuous query processing in data streams using duality of data and queries
Recent data stream systems such as TelegraphCQ have employed the well-known property of duality between data and queries. In these systems, query processing methods are classified into two dual categories -- data-initiative and query-initiative -- depending on whether query processing is initiated by selecting a data element or a query. Although the duality property has been widely recognized, previous data stream systems do not fully take advantages of this property since they use the two dual methods independently: data-initiative methods only for continuous queries and query-initiative methods only for ad-hoc queries. We contend that continuous query processing can be better optimized by adopting an approach that integrates the two dual methods. Our primary contribution is based on the observation that spatial join is a powerful tool for achieving this objective. In this paper, we first present a new viewpoint of transforming the continuous query processing problem to a multi-dimensional spatial join problem. We then present a continuous query processing algorithm based on spatial join, which we name Spatial Join CQ. This algorithm processes continuous queries by finding the pairs of overlapping regions from a set of data elements and a set of queries, both defined as regions in the multi-dimensional space. The algorithm achieves the advantages of the two dual methods simultaneously. Experimental results show that the proposed algorithm outperforms earlier algorithms by up to 36 times for simple selection continuous queries and by up to 7 times for sliding window join queries.
14238943
Secure query processing against encrypted XML data using Query-Aware Decryption
Dissemination of XML data on the internet could breach the privacy of data providers unless access to the disseminated XML data is carefully controlled. Recently, the methods using encryption have been proposed for such access control. However, in these methods, the performance of processing queries has not been addressed. A query processor cannot identify the contents of encrypted XML data unless the data are decrypted. This limitation incurs overhead of decrypting the parts of the XML data that would not contribute to the query result. In this paper, we propose the notion of Query-Aware Decryption for efficient processing of queries against encrypted XML data. Query-Aware Decryption allows us to decrypt only those parts that would contribute to the query result. For this purpose, we disseminate an encrypted XML index along with the encrypted XML data. This index, when decrypted, informs us where the query results are located in the encrypted XML data, thus preventing unnecessary decryption for other parts of the data. Since the size of this index is much smaller than that of the encrypted XML data, the cost of decrypting this index is negligible compared with that for unnecessary decryption of the data itself. The experimental results show that our method improves the performance of query processing by up to six times compared with those of existing methods. Finally, we formally prove that dissemination of the encrypted XML index does not compromise security.
43332794
Hiding Relaxed Memory Consistency with a Compiler
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.