13997680
Distributed real-time system design using CBS-based end-to-end scheduling
Distributed real-time applications share a group of processors connected by some local area network. A rigorous and sound methodology to design real-time systems from independently designed distributed real-time applications is needed. In this paper, we study a distributed real-time system design scheme using CBS-based end-to-end scheduling. The scheduling scheme utilizes CBS to allocate both CPU shares and network bandwidth to a distributed real-time application when it arrives at the system. Our proposed solution uses the same scheduling paradigm for both resources. In this way, we believe the system can have a more consistent scheduling objective and may achieve a tighter schedulability condition.
10903877
WISE-building simple intelligence into Web services
Web services are self contained and self described modular applications that can be published, discovered and employed on the Web. Many standard protocols supporting Web services have been adopted and more are being proposed. We study the issue on providing intelligent Web services. We propose the enhancement of Web service functionalities by deploying software agents on both server side and/or client side. Our goal of designing the WISE Web service architecture is to provide a working middle ground between the current Web service standards and the semantic Web architecture. The WISE software agent architecture for Web services is presented. We discuss the design issues of WISE. We also present the QoS management protocol and algorithm that can be used by WISE servers.
27364789
Efficient on-line schedulability tests for priority driven real-time systems
Many computer systems, such as those for open system environments or multimedia services, need an efficient schedulability test for online admission control of new jobs. Although various polynomial-time schedulability tests have been proposed, they often fail to decide the schedulability of the system precisely when the system is heavily loaded. This paper presents efficient online schedulability tests which are are shown to be more precise and efficient than any existing polynominal-time schedulability tests. Moreover, our proposed tests can be used for the multiframe model, where a task may have different computation times in different periods. We show the performance of the proposed schedulability tests in several simulation experiments.
15828117
Enhancing external consistency in real-time transactions
Real-time computing brings two new requirements to database management. The first is the deadline constraint which requires better scheduling algorithms to meet transaction deadfines. The second requirement is the temporal validity, or external consistency[Lin89], requirement of data: a real-time database must prevent data from being corrupted not only by the executions of concurrent transactions but also by the delay from sharing computing resources and real-time scheduler decisions. In this paper, we study the external consistency requirement in real-time databases. We propose a semantic-based concurrency control scheme that prefers the external consistency to the traditional serializability. Two new concepts are introduced in our work. An update of a physical object value is considered to be compatible to those read operations that need to access the most recent data. Secondly, if a transaction depends strongly on the validity of the value of an object, a new update may cause the transaction to be aborted since continuing the transaction may be harmful to the appfication. A real-Life example is the stock market database. A trading program may be executed for a long time and its read operations should not block any new updates. Moreover, if there is a big sudden change in a particular stock price, it may be better to abort an on-going transaction rather than letting it make some invalid decisions.
14104203
SM: real-time multicast protocols for simultaneous message delivery
Traditionally, a multicast message is sent once by a sender. All receivers will receive the same message but may receive it at different times. This may result in unfair advantage for some receivers. Simultaneous Multicast (SM) applications require that all receivers receive the same message at the same time. SM protocols therefore need to meet a strict deadline to ensure that each receiver will receive a message at the same time, regardless of the network conditions, heterogeneity of the environment and differences between the local clocks in the receivers. Such a real time SM protocol is proposed so that the coordinated deadline can be met by controlling the reserved bandwidth and without the overhead of clock synchronization. A sensing protocol is also proposed to continuously search for better levels of quality and to avoid the overhead of an external feedback protocol. The protocols are bandwidth conscious, enforce fairness and provide scalability.
44711812
An open real-time environment for parallel and distributed systems
Most computer-based systems have hard real-time constraints. Schedulers in complex systems must be designed to manage a set of applications developed and deployed independently. We study an open real-time environment architecture for distributed systems where real-time applications may run concurrently with non-real-time applications. The architecture uses a two-level scheduling scheme. Each application is assigned a sporadic server to schedule the processes in the application. All sporadic servers are then scheduled by a system-wide fixed priority scheduler. Using the proposed open environment architecture, all hard real-time applications are guaranteed to have their reserved CPU utilization in order to meet all their deadlines. The guarantee is independent of the behaviors of all other applications in the same system. We present the schedulability analysis methods on systems with or without shared memory.
20361854
Protein Metal Binding Residue Prediction Based on Neural Networks
Over one-third of protein structures contain metal ions, which are the necessary elements in life systems. Traditionally, structural biologists were used to investigate properties of metalloproteins (proteins which bind with metal ions) by physical means and interpreting the function formation and reaction mechanism of enzyme by their structures and observations from experiments in vitro. Most of proteins have primary structures (amino acid sequence information) only; however, the 3-dimension structures are not always available. In this paper, a direct analysis method is proposed to predict the protein metal-binding amino acid residues from its sequence information only by neural networks with sliding window-based feature extraction and biological feature encoding techniques. In four major bulk elements (Calcium, Potassium, Magnesium, and Sodium), the metal-binding residues are identified by the proposed method with higher than 90% sensitivity and very good accuracy under 5-fold cross validation. With such promising results, it can be extended and used as a powerful methodology for metal-binding characterization from rapidly increasing protein sequences in the future.
9933111
Service-oriented computing
Service-oriented computing using Web services has emerged as a major research topic in recent years. Strong support from major computer companies including IBM, Microsoft, Hewlett-Packard, Oracle, and SAP has accelerated the acceptance and adoption of SOC using Web services. With SOC, enterprises can define and execute transactions across multiple business. Companies can use SOC's plug-and-play interoperability to compose business processes and integrate different information systems on the fly to enable ad hoc cooperation between new partners. Thus, SOC reinvents the way enterprises work together: common tasks in a business process or supply chain can be easily outsourced to external service providers for both performance and cost reasons.
15536346
An Index Structure for Data Mining and Clustering
Abstract. In this paper we present an index structure, called MetricMap, that takes a set of objects and a distance metric and then maps those objects to a k-dimensional space in such a way that the distances among objects are approximately preserved. The index structure is a useful tool for clustering and visualization in data-intensive applications, because it replaces expensive distance calculations by sum-of-square calculations. This can make clustering in large databases with expensive distance metrics practical. We compare the index structure with another data mining index structure, FastMap, recently proposed by Faloutsos and Lin, according to two criteria: relative error and clustering accuracy. For relative error, we show that (i) FastMap gives a lower relative error than MetricMap for Euclidean distances, (ii) MetricMap gives a lower relative error than FastMap for non-Euclidean distances (i.e., general distance metrics), and (iii) combining the two reduces the error yet further. A similar result is obtained when comparing the accuracy of clustering. These results hold for different data sizes. The main qualitative conclusion is that these two index structures capture complementary information about distance metrics and therefore can be used together to great benefit. The net effect is that multi-day computations can be done in minutes.
5900836
The TV-tree: An index structure for high-dimensional data
We propose a file structure to index high-dimensionality data, which are typically points in some feature space. The idea is to use only a few of the features, using additional features only when the additional discriminatory power is absolutely necessary. We present in detail the design of our tree structure and the associated algorithms that handle such “varying length” feature vectors. Finally, we report simulation results, comparing the proposed structure with theR*-tree, which is one of the most successful methods for low-dimensionality spaces.The results illustrate the superiority of our method, which saves up to 80% in disk accesses.
12237012
Discovering the Biomedical Deep Web
The rapid growth of biomedical information in the Deep Web has produced unprecedented challenges for traditional search engines. This paper describes a new Deep web resource discovery system for biomedical information. We designed two hypertext mining applications: a Focused Crawler that selectively seeks out relevant pages using a classifier that evaluates the relevance of the document with respect to biomedical information, and a Query Interface Extractor that extracts information from the page to detect the presence of a Deep Web database. Our anecdotes suggest that combining focused crawling with query interface extraction is very effective for building high-quality collections of Deep Web resources on biomedical topics.