Advertisement

Research and Advances

A View of the Parallel Computing Landscape

Writing programs that scale with increasing numbers of cores should be as easy as writing programs for sequential computers. Here as a concrete example of a coordinated attack on the problem of parallelism.
Research and Advances

Distinct-Value Synopses For Multiset Operations

The task of estimating the number of distinct values (DVs) in a large dataset arises in a wide variety of settings in computer science and elsewhere. We provide DV estimation techniques for the case in which the dataset of interest is split into partitions. We create for each partition a synopsis that can be used to estimate the number of DVs in the partition. By combining and extending a number of results in the literature, we obtain both suitable synopses and DV estimators. The synopses can be created in parallel, and can be easily combined to yield synopses and DV estimates for "compound" partitions that are created from the base partitions via arbitrary multiset union, intersection, or difference operations. Our synopses can also handle deletions of individual partition elements. We prove that our DV estimators are unbiased, provide error bounds, and show how to select synopsis sizes in order to achieve a desired estimation accuracy. Experiments and theory indicate that our synopses and estimators lead to lower computational costs and more accurate DV estimates than previous approaches.
Research and Advances

Balancing Four Factors in System Development Projects

Introduction The success of system development is most often gauged by three primary indicators: the number of days of deviation from scheduled delivery date, the percentage of deviation from the proposed budget, and meeting the needs of the client users. Tools and techniques to help perform well along these dimensions abound in practice and research. However, the project view of systems development should be broader than any particular development tool or methodology. Any given development philosophy or approach can be inserted into a systems development project to best fit the conditions, product, talent, and goals of the markets and organization. In order to best satisfy the three criteria, system development project managers must focus on the process of task completion and look to apply controls that ensure success, promote learning within the team and organization, and end up with a software product that not only meets the requirements of the client but operates efficiently and is flexible enough to be modified to meet changing needs of the organization. In this fashion, the project view must examine both process and product. Often, tasks required for project completion seem contradictory to organizational goals. Within the process, managerial controls are applied in order to retain alignment of the product to the initial, and changing, requirements of the organization. However, freedom from tight controls promotes learning. The product also has contradictions among desired outcomes. Designers must consider tradeoffs between product efficiency and flexibility, with the trend in processing power leading us ever more toward the flexibility side. Still, we rage between conflicting criteria, with the advocates of a waterfall system development lifecycle (SDLC) usually pushing more for control aspects and efficient operations while agile proponents seek more of a learning process and flexible product. Regardless of the development methodology followed, project managers must strive to deliver the system on time, within budget, and to meet the requirements of the user. Thus, both product and process are crucial in the determination of success. To compound the difficulties, those in control of choosing an appropriate methodology view success criteria from a different perspective than other stakeholders. Understanding how different stakeholders perceive these factors impacting eventual project success can be valuable in adjusting appropriate methodologies. Our study looks at these relationships using well established instruments in a survey of IS development professionals to better clarify the importance of these variables in system project success and any perceived differences among different players in IS development (see the sidebar on "How the Study Was Conducted").
Research and Advances

Do SAP Successes Outperform Themselves and Their Competitors?

It's been over 10 years since corporate America embraced ERP systems, but hard evidence on the financial benefits that ERP systems have provided has been elusive. This debate has spilled into the mainstream media, as America's two largest ERP vendors regularly advertise that their customers have benefited financially by using their products; some of these ads even cite studies that discredit the other's claims of financial superiority. Investments in IT are typically justified by the productivity and profitability improvements that follow their implementation. It seems intuitive that IT will help streamline existing business processes, which should lead to a more efficient and ultimately more profitable company. Organizations of all types and sizes have invested heavily in IT based on this simple rationale, but the associated financial benefits have been difficult to nail down. While managers struggled to value their firms' IT investments, researchers tried to better understand the factors that made it so difficult to value corporate investments in IT. Among the factors that have been suggested, three may be especially useful. They are: • Firm-specific resources and capabilities that meaningfully impact the success of IT implementations; • External forces that exert themselves on the firm; and • The nature of the financial indices used to value IT investments. Much of the early research on the value of IT investments was based on industry-level data that masked the effects of important firm-specific resources and capabilities. When researchers finally examined firm-level data, they realized that differences in, for example, IT expertise and management, the quality of a firm's leadership and other human resources, and the uniqueness of its operations affected the success of IT implementations. Companies with firm-specific advantages generally out-produced their competitors. The success of IT implementations also depends on the unique set of unwieldy external forces that exert themselves on the firm. For example, Melville etal. suggest a host of external forces that may affect the impact of IT implementations on organizational performance, including the degree of competition within an industry, the impact of the firm's trading partners, and country characteristics. Unfortunately, studies of the relationship between IT and organizational performance are plagued by disagreements about the external constructs that should be examined, how these constructs are operationalized, and the nature of their interrelationships. There have also been concerns expressed about the financial indices used to measure the affects of IT implementations on corporate performance. Foremost among these indices are measures of corporate productivity and profitability. Productivity is associated with how efficiently a firm manages its business processes to produce a dollar of sales. For example, employee productivity is often calculated as the dollar level of sales generated per dollar paid to employees (net sales/employee cost). Firms usually have substantial control over their business processes, and this makes them potentially easier to measure and value financially. For example, firms often use proprietary processes to more efficiently manage their inventories in order to generate a higher level of sales. Therefore, measuring how efficiently a firm manages its inventory can be calculated using inventory turnover (net sales/inventory). On the other hand, profitability is an organizational performance measure that can be affected by factors unrelated to the IT investment. These factors include, for example, the number and quality of the firm's competitors and trading partners, intra-firm shifts in spending, and macro-economic changes in interest rates, exchange rates and inflation; many pundits would argue that even the formal recognition as a su
Opinion

Following the Leaders

The articles, sections, and services available on Communications' Web site all vie for visitor attention. According to our latest Web statistics, the following features are the most popular in pageviews since the site's formal launch in April 2009.
News

Managing Data

Dealing with terabytes of data is not the monumental task it once was. The difficult part is presenting enormous amounts of information in ways that are most useful to a wide variety of users.
News

New Ranking Algorithm Separates Digital Wheat from Chaff

The ranking algorithm called SPEAR (SPamming-resistant Expertise Analysis and Ranking), developed by PhD candidates Ching Man Au Yeung of the University of Southampton and Michael G. Noll of Hasso Plattner Institute, uses mutual reinforcement and time stamps to identify expert contributors to social bookmarking sites and their recommended content.
Opinion

The Financial Meltdown and Computing

For many of us, the past year has been one of the most unsettling in our lifetime. In the late 1980s and early 1990s, we watched communism collapse of its own dead weight. In late 2008, we saw capitalism nearly crumble. Lehman Brothers, a major U.S. investment bank, declared bankruptcy last September, sending the world's financial system into a tailspin. Only a massive intervention by central banks saved the system from collapse.
News

Entering a Parallel Universe

The promise of parallel computing has run afoul of the harsh reality of Amdahl's Law, which puts a ceiling on the benefit of converting sequential code to parallel code. The upshot is that parallelism will not necessarily reap rewards.

Shape the Future of Computing

ACM encourages its members to take a direct hand in shaping the future of the association. There are more ways than ever to get involved.

Get Involved

Communications of the ACM (CACM) is now a fully Open Access publication.

By opening CACM to the world, we hope to increase engagement among the broader computer science community and encourage non-members to discover the rich resources ACM has to offer.

Learn More