Gregory Simco

Resource utilization prediction: a proposal for information technology research

Research into predicting long-term resource needs has been faced with a very difficult problem of extending the accuracy period beyond the immediate future. Business forecasting has overcome this limitation by successfully incorporating the concept of human interaction as the basis of prediction patterns at the hourly, daily, weekly, monthly, and yearly time frames. Computer resource utilization is also impacted by human interaction therefore influencing research into predictability of resource usage based on human access patterns. Emulated human web server access data was captured in a feasibility study that used time series analysis to predict future resource usage. For prediction beyond several minutes, results indicate that the majority of projected resource usage was within an 80% confidence level thus supporting the foundation of future resource prediction work in this area.

Using aspects for testing nonfunctional requirements in object-oriented systems

Software testing is one of the most time consuming activities in the software development cycle. Current research suggests that aspect-oriented programming (AOP) can enhance testing and has the potential to be more effective than macros or test interfaces. There are two major weaknesses when using aspects which are the inability of aspect code to be woven at all execution points and the lack of direct support for interweaving aspects with other aspects. In this paper we address the two major weaknesses and provide a means to overcome them. In addition, current research has focused only on using aspects to test functional requirements (FRs) and paid little attention to nonfunctional requirements (NFRs). In this paper we perform a feasibility study of using aspects to test NFRs which is based on two categorizations of NFRs. The first categorization splits NFRs into four types namely functionally restrictive, additive restrictive, policy restrictive, and architecturally restrictive and the second categorization splits the NFRs into two types: operational and nonoperational. These categorizations would serve as an initial point for developing frameworks or methodologies for testing NFRs with aspects.

Choke-based switching algorithm in stochastic P2P networks to reduce file download duration

Content Delivery Networks download performance is dependent on byte-based or time-based switching algorithms. To overcome an extended relationship with a poor performing server, a client based choking algorithm was developed that enables clients to preemptively depart poor performing servers to decrease download duration. The choking algorithm employees a client based choke threshold that enables individual clients to determine when a servers performance degrades to an unacceptable level. Two separate experiments were run through a peer-to-peer simulator: single-client and multi-client scenarios. Temporal fluctuations were incorporated as well as a stochastic AR-1 random process to closely mimic expected server loads. In both instances, the choking algorithm reduces download duration.

Internet 2 Access Grid

Abstract Collaboration among universities, businesses, and the US government is essential to the success of the Internet 2 Initiative. However, face-to-face meetings are not always possible. The Access Grid provides the Internet 2 with the resources to enable remote collaboration among the research community. This effort extends the Alliance Computational Grid, a distributed high-speed computing environment that supports seamless resource integration and access (mcRae, 1997). The Access Grid effort has advanced audio and video applications and has increased Internet 2 collaboration.

Performance evaluation and the Internet 2 performance initiative

Performance is a key factor in the development and execution of modern computer systems and networks. In order to understand the performance of a computer system, the elements of the system must be defined as well as the evaluation strategy. The Internet 2 end-to-end performance initiative is focused on performance measurement, analysis, and improvements that lead to a standard set of network capabilities and limitations. By using current Internet 2 project groups, the end-to-end performance initiative is a collaborative effort that will maximize current infrastructure performance and provide guidelines for future systems. The focal points of this initiative are: network applications, end computer and operating systems, and the supporting network. As a result of this performance initiative, a performance evaluation and review framework will provide direction for current and future network development.

Refining and reasoning about nonfunctional requirements

Nonfunctional requirements (NFR) must be addressed early in the software development cycle to avoid the cost of revisiting those requirements or re-factoring at the later stages of the development cycle. Methods and frameworks that identify and incorporate NFR at each stage of development cycle reduce this cost. The methodology used in this work for refining and reasoning about NFR is based on the NFR framework. This work identifies four NFR types and provides the methodology for developing domain specific NFR by using techniques for converting the requirements into design artifacts per NFR type. The contribution is four NFR types: Functionally Restrictive, Additive Restrictive, Policy Restrictive, and Architecture Restrictive and the software engineering process that provides specific refinements that result in unique architectural and design artifacts. By applying the same functional requirement focus to the different NFR domains it enhances the development process and promotes software quality attributes such as composability, maintainability, evolvability, and traceability.

The Internet 2 Middleware Initiative.

Middleware exists between distributed applications and the operating system, networks, and hardware. This layer of software hides the details of the distributed system while providing common services. The Internet 2 Middleware Initiative is focused on a set of research and development objectives in the area of core middleware services. Through the use of working groups, the Internet 2 community supports various middleware projects that develop and use core middleware services.

Quantifying the cluster speedup behavior in the realm of internode communication

Networked clusters of computers are commonly used to either process multiple sequential jobs concurrently, or to execute complex scientific and commercial parallel applications that are based on a message passing paradigm. In some areas, these clusters represent a cost-effective alternative to the more expensive supercomputers that are in use today. However, workstation clusters normally lack the high-powered interconnect fabric, as well as the more optimized protocol system architecture that is an integral part of commercial supercomputer systems. This study quantifies the speedup of parallel applications in a cluster environment in an analytical model that takes parallel processing, internode communication, and I/O latency into consideration. The model illustrates the (relative) impact that CPU and I/O parallelism has on the speedup behavior based on the 3 different inter-node communication scenarios: broadcast, nearest-neighbor, and request-response. This work revealed that it is important to consider the performance impact that the application has with regard to features such as remote memory access, completion notification, and address translation issues.

Extending the Internet 2 domain

Partnerships involving universities, businesses, and the US government form the backbone of the Internet 2 community. These members have experienced the innovative spirit and outcomes of advanced networking and applications. The K-20 Initiative extends the Internet 2 to the educational sectors outside the Internet 2 community. This effort provides the vehicle for distributing Internet 2 developments to nonmember environments while gaining the perspective of this environment. The target groups are K-12, community colleges, universities, libraries, and museums. This effort has pushed advanced networking and applications to new heights and has increased educational collaboration.

Internet 2 Commons: A Collaborative Environment

Partnerships among the educational community provide the substance and catalyst for future generations of teachers and students. The Internet 2 Commons provides a collaboration framework for the advancement of research and education. This effort incorporates technological advancements in support of research and pedagogical activities. Available to Internet 2 members are advanced networking and application services, which include collaborative data services and videoconferencing.