15059814
Caching queues in memory buffers
Motivated by the need for maintaining multiple, large queues of data in modern high-performance systems, we study the problem of caching queues in memory under the following simple, but widely applicable, model. At each clock-tick, any number of data items may enter the various queues, while data-items are consumed from the heads of the queues. Since the number of unconsumed items may exceed memory buffer size, some items in the queues need to be spilled to secondary storage and later moved back into memory for consumption. We provide online queue-caching algorithms under a number of interesting cost models.
2682242
Two Can Keep A Secret: A Distributed Architecture for Secure Database Services
Recent trends towards database outsourcing, as well as concerns and laws governing data privacy, have led to great interest in enabling secure database services. Previous approaches to enabling such a service have been based on data encryption, causing a large overhead in query processing. We propose a new, distributed architecture that allows an organization to outsource its data management to {\em two} untrusted servers while preserving data privacy. We show how the presence of two servers enables efficient partitioning of data so that the contents at any one server are guaranteed not to breach data privacy. We show how to optimize and execute queries in this architecture, and discuss new challenges that emerge in designing the database schema.
45241819
Minimum Networks in Uniform Orientation Metrics
In this paper we use the variational method to systematically study properties of minimum networks connecting any given set of points (called terminals) in a $\lambda$-plane, in which all lines are in $\lambda$ uniform orientations $i\pi /\lambda\ (0\le i<\lambda )$. We prove a number of angle conditions for Steiner minimum $\lambda$-trees, which are similar to the ones in the Euclidean case. In particular, we show that there exists a Steiner minimum $\lambda$-tree whose minimum angles at Steiner points are $\lfloor 2\lambda /3\rfloor\pi /\lambda$ and whose maximum angles are $\lceil 2\lambda /3\rceil\pi /\lambda$. We also investigate the assignment of nonstraight edges and unequal angles in Steiner minimum $\lambda$-trees, and we prove that there exists a Steiner minimum $\lambda$-tree in which every full component has at most one nonstraight edge. From these properties we are able to devise a number of finite methods for constructing Steiner minimum $\lambda$-trees. One of these methods is based on using algorithms for finding graphical Steiner minimum trees, and the other uses a generalization of the method of Melzak for Euclidean Steiner trees.
20719755
On The Next Move in Programming
1329133
Model driven development: the case for domain oriented programming
In this paper, we offer an alternative vision for domain driven development (3D). Our approach is model driven and emphasizes the use of generic and specific domain oriented programming (DOP) languages. DOP uses strong specific languages, which directly incorporate domain abstractions, to allow knowledgeable end users to succinctly express their needs in the form of an application computation. Most domain driven development (3D) approaches and techniques are targeted at professional software engineers and computer scientists. We argue that DOP offers a promising alternative. Specifically we are focused on empowering application developers who have extensive domain knowledge as well as sound foundations in their professions, but may not be formally trained in computer science.We provide a brief survey of DOP experiences, which show that many of the best practices such as patterns, refactoring, and pair programming are naturally and ideally practiced in a Model Driven Development (MDD) setting. We compare and contrast our DOP with other popular approaches, most of which are deeply rooted in the OO community.Finally we highlight challenges and opportunities in the design and implementation of such languages.
3170175
Using Objects To Design and Build Radar ESM Systems
This paper describes the application of object-oriented programming to the design of a multiprocessor ESM testbed. The ESM testbed uses an object-oriented development environment which integrates Smalltalk and C language tools with the Harmony real-time operating system in a shared memory multiprocessor. All development for an application is done using personal computers which are themselves processors in the real-time testbed. We first discuss two aspects of the ESM testbed: a framework for investigating ESM signal processing algorithms based on an object-oriented emitter database and blackboard objects which implement probabilistic reasoning; and an object-oriented ESM simulation environment which illustrates the use of object-oriented techniques for the development of complex real-time systems. In the second part of the paper we describe our software engineering approach and tools. Throughout the paper, the role played by object-oriented programming in the design of hybrid multiprocessors is highlighted.
22841183
Graham's problem on shortest networks for points on a circle
Suppose a configurationX consists ofn points lying on a circle of radiusr. If at most one of the edges joining neighboring points has length strictly greater thanr, then the Steiner treeS consists of all these edges with a longest edge removed. In order to showS is, in fact, just the minimal spanning treeT, a variational approach is used to show the Steiner ratio for this configuration is at least one and equals one only ifS andT coincide. The variational approach greatly reduces the number of possible Steiner trees that need to be considered.