2093095
Caching with 'Good Enough' Currency, Consistency, and Completeness
SQL extensions that allow queries to explicitly specify data quality requirements in terms of currency and consistency were proposed in an earlier paper. This paper develops a data quality-aware, finer grained cache model and studies cache design in terms of four fundamental properties: presence, consistency, completeness and currency. The model provides an abstract view of the cache to the query processing layer, and opens the door for adaptive cache management. We describe an implementation approach that builds on the MTCache framework for partially materialized views. The optimizer checks most consistency constraints and generates a dynamic plan that includes currency checks and inexpensive checks for dynamic consistency constraints that cannot be validated during optimization. Our solution not only supports transparent caching but also provides fine grained data currency and consistency guarantees.
29819645
Support for relaxed currency and consistency constraints in MTCache
6968558
Relaxed currency and consistency: how to say "good enough" in SQL
Despite the widespread and growing use of asynchronous copies to improve scalability, performance and availability, this practice still lacks a firm semantic foundation. Applications are written with some understanding of which queries can use data that is not entirely current and which copies are "good enough"; however, there are neither explicit requirements nor guarantees. We propose to make this knowledge available to the DBMS through explicit currency and consistency (C&C) constraints in queries and develop techniques so the DBMS can guarantee that the constraints are satisfied. In this paper we describe our model for expressing C&C constraints, define their semantics, and propose SQL syntax. We explain how C&C constraints are enforced in MTCache, our prototype mid-tier database cache, including how constraints and replica update policies are elegantly integrated into the cost-based query optimizer. Consistency constraints are enforced at compile time while currency constraints are enforced at run time by dynamic plans that check the currency of each local replica before use and select sub-plans accordingly. This approach makes optimal use of the cache DBMS while at the same time guaranteeing that applications always get data that is "good enough" for their purpose.
40185955
Improving Multimedia Delivery Performance for Digital Library Applications
Nowadays an educational digital library usually contains instructional materials such as class lectures, seminar presentations, and various training materials. These materials accompany video and audio media. In this case, multimedia streaming and delivery techniques are concerned in the construction of a novel multimedia digital library. In this paper, we focus on multimedia streaming techniques in digital library applications. To achieve scalability and deliver high quality streams, we present the multimedia proxy caching scheme between the server and client path, and a prototype design and implementation of a proxy caching system is proposed. By validate our implementation, the experimental results show that our proxy system can contribute to improve streaming media quality, reduce network transferring latency and decrease streaming service response time.
1856693
Application specific forwarding network and instruction encoding for multi-pipe ASIPs
Small area and code size are two critical design issues in most of embedded system designs. In this paper, we tackle these issues by customizing forwarding networks and instruction encoding schemes for multi-pipe Application Specific Instruction-Set Processors (ASIPs). Forwarding is a popular technique to reduce data hazards in the pipeline to improve performance and is applied in almost all modern processor designs; but it is very area expensive. Instruction encoding schemes have a direct impact on code size; an efficient encoding method can lead to a small instruction width, and hence reducing the code size. We propose application specific techniques to reduce forwarding networks and instruction widths for ASIPs with multiple pipelines. By these design techniques, it is possible to reduce area, code size, and even power consumption (due to reduced area), without costing any performance. Our experiments, on a set of benchmarks using the proposed customization approaches show that, on average, there are 27% savings on area, 30% on leakage power, 16.7% on code size, and at the same time, performance even improves by 4% because of the reduced clock period.
299633
Power reduction in pipelines
The reduction of power consumption for a system level pipeline is addressed in this paper. The pipeline is composed of several stages. Each stage has several behaviours. Different behaviours have differing execution times. The speed of the pipeline is only affected by the behaviours on the critical path of the slowest stages. Other behaviours can be slowed down to decrease the power consumed in the system. We propose a multi-voltage supply scheme, in which differing behaviours are supplied with differing voltages. The formulas for computing the supply voltage of each behaviour and minimal power consumption are derived in this paper. The results of computer experiment show that up to 80% hardware power can be saved with this scheme.
1460421
A New Data-driven Approach for Multimedia Presentation Planning
A number of Multimedia Presentation Systems have been built for technical documentation, traffic management systems, educational software and other applications. However, these systems use handwritten presentation planning operators, which limits their flexibility. In this paper we describe a new data-driven approach for multimedia presentation planning. We present algorithms for acquiring presentation plan operators from Web pages, and for using these operators to generate multimedia presentations. We also show how to use machine learning to adapt multimedia presentation planning to human presentation preferences.
817416
Learning Ontologies to Improve the Quality of Automatic Web Service Matching
Automatically finding suitable Web services given a request is a difficult problem because the interface descriptions of Web services are often terse and cryptic. Dictionary and information retrieval based techniques have proven useful in disambiguating the semantics of service descriptions, but they are limited in their capability to consider the relationships between the words describing the Web services. Current ontology-based approaches typically require a user to explicitly create domain ontologies. This paper presents a novel technique that significantly improves the quality of semantic Web service matching by (1) automatically generating ontologies based on Web service descriptions and (2) using these ontologies to guide the mapping between Web services. Our approach differs from earlier work on service matching by considering the relationship between words rather than treating them as a bag of unrelated words. The experimental results indicate that with our unsupervised approach we can eliminate up to 70% of incorrect matches that are made by dictionary-based approaches.