Ellen Spertus

Squeal: a structured query language for the Web

The Web contains an abundance of useful semi-structured information that can and should be mined. Types of structure include hyperlinks between pages, structure within hypertext pages, and structure within URLs. We have implemented a programming language, Squeal, that facilitates structure-based queries. Specifically, the Squeal user can query the Web as if it were in a standard relational database. We describe Squeal and show the ease of writing structure-based information tools in Squeal.

Evaluation of mechanisms for fine-grained parallel programs in the J-machine and the CM-5

This paper uses an abstract machine approach to compare the mechanisms of two parallel machines: the J-Machine and the CM-5. High-level parallel programs are translated by a single optimizing compiler to a fine-grained abstract parallel machine, TAM. A final compilation step is unique to each machine and optimizes for specifics of the architecture. By determining the cost of the primitives and weighting them by their dynamic frequency in parallel programs, we quantify the effectiveness of the following mechanisms individually and in combination. Efficient processor/network coupling proves valuable. Message dispatch is found to be less valuable without atomic operations that allow the scheduling levels to cooperate. Multiple hardware contexts are of small value when the contexts cooperate and the compiler can partition the register set. Tagged memory provides little gain. Finally, the performance of the overall system is strongly influenced by the performance of the memory system and the frequency of control operations.

Novel approaches to CS 0 with app inventor for android

1. SUMMARY Googles App Inventor for Android (AIA) is a visual programming environment for creating mobile phone applications that is designed to be accessible and appealing to college nonmajors taking introductory courses in computer science. Specifically, AIA provides a development environment similar to StarLogo TNG [7], Scratch [5], and Alice [2] but enabling users to create mobile applications incorporating social networking, location awareness, and Web-based services for Googles Android platform [1].

Retrospective: the J-machine

1 Computer Systems ’ Department of Computer 3 Department of Electrical Laboratory, Stanford Science, University of Illinois, and Computer Engineering, University Urbana-Champaign Georgia Institute of Technology 4 Netscape Communications 5 Equator Technologies 6 Hewlett Packard Consulting Laboratories 7 Department of Computer 8 DEC, Western Research 9 Silicon Graphics Computer Science, Mills College Laboratory Systems

Just-in-time databases and the World-Wide Web

1. ABSTRACT It is not always possible or practical to store very large data sets in a relational database. For example, in a rapidly changing large-scale environment with distributed control, such as the World-Wide Web, a strict relational approach is not feasible. Nevertheless, it is desirable for a user to be able to make SQL queries on the entire data set, because SQL is well known, supported, and understood. We introduce “just-in-time databases”, which allow the user to query the entire data set as though it were in a relational database. The underlying engine brings data into the relational database only when it is required by user queries. We describe how “just-in-time databases” are implemented, using the WorldWide Web as an example. 1.1

Evaluating the locality benefits of active messages

A major challenge in fine-grained computing is achieving locality without excessive scheduling overhead. We built two J-Machine implementations of a fine-grained programming model, the Berkeley Threaded Abstract Machine. One implementation takes an Active Messages approach, maintaining a scheduling hierarchy in software in order to improve data cache performance. Another approach relies on the J-Machines message queues and fast task switch, lowering the control costs at the expense of data locality. Our analysis measures the costs and benefits of each approach, for a variety of programs and cache configurations. The Active Messages implementation is strongest when miss penalties are high and for the finest-grained programs. The hardware-buffered implementation is strongest in direct-mapped caches, where it achieves substantially better instruction cache performance.

The J-Machine: A fine-grain parallel computer

Abstract Most modern computers, whether parallel or sequential, are coarse grained. They are composed of physically large nodes with tens of megabytes of memory. Only a small fraction of the silicon area in the machine is devoted to computation. By increasing the ratio of computation area to memory area, fine-grain computers offer the potential of improving cost/performance by several orders of magnitude. To efficiently operate at such a fine grain, however, a machine must provide mechanisms that permit rapid access to global data and fast interaction between nodes. The MIT J-Machine is a fine-grain concurrent computer that provides low-overhead mechanisms for parallel computing. Prototype J-Machines have been operational since July 1991. The J-Machine communication mechanism permits a node to send a message to any other node in the machine in μ s. On message arrival, a task is created and dispatched in μ s. A translation mechanism supports a global virtual address space. These mechanisms efficiently support most proposed models of concurrent computation and allow parallelism to be exploited at a grain size of 10 operations. The hardware is an ensemble of up to 65,536 nodes each containing a 36-bit processor, 4K 36-bit words of on-chip memory, 256K words of DRAM and a router. The nodes are connected by a high-speed three-dimensional mesh network.

Women in Computing

The history of computer science is composed mainly of male achievements and involvements, even though women have played substantial roles. Although women are a significant part of computing history, the numbers of women in computing still have yet to reach parity with men. This article covers womens experiences and impact in the computing history of the United States and in several other nations and explores some of the reasons for the disparities between the number of men and women in this field. Keywords: women in computing; pipeline shrinkage problem; early computing history; gender equality; support; recruitment; retention

Creating an environment for the success of women students in undergraduate, co-ed computer science programs (abstract)

The PipeLINK program seeks to attract and retain women and girls into careers in computer science. Aimed at girls and women from the high school through the Ph.D. level, the program provides activities to aid participants at each level, nd role models and mentors from the levels above, as well as an introduction to a wide variety of computer science topics. This paper describes PipeLINK activities that were carried out during the academic year 1994-95 and the summer of 1995, including an evaluation of their e ectiveness.