CrossRoads vol 16 issue1

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Fall 2009 • Issue 16.1

Fall 2009—Issue 16.1

CROSSROADS STAFF MANAGING EDITOR: Justin Solomon, Stanford University COPY EDITOR: Joe Nyiri, Niagara University ASSOCIATE EDITORS: Malay Bhattacharyya, Indian Statistical Institute Andrew David, University of Minnesota Twin Cities Aris Gkoulalas-Divanis, Vanderbilt University Dan Goldberg, University of Southern California Ryan K. L. Ko, Nanyang Technological University Sumit Narayan, University of Connecticut CONTRIBUTORS: Anna Ritchie, University of Cambridge Tal Rusak, Stanford University INSTITUTIONAL REVIEWERS: Ernest Ackermann, Mary Washington College Peter Chalk, London Metropolitan University Nitesh Chawla, University of Notre Dame José Creissac Campos, University of Minho Ashoke Deb, Memorial University of Newfoundland Steve Engels, University of Toronto João Fernandes, University of Minho Chris Hinde, Loughborough University Michal Krupka, Palacky University Piero Maestrini, ISTI-CNR, Pisa José Carlos Ramalho, University of Minho Suzanne Shontz, Pennsylvania State University Roy Turner, University of Maine Ping-Sing Tsai, University of Texas— Pan American Andy Twigg, University of Cambridge Joost Visser, Software Improvement Group Tingkai Wang, London Metropolitan University Charles Won, California State University, Fresno GRAPHICS EDITOR: Salik Syed, Stanford University ONLINE EDITORS: Gabriel Saldaña, Instituto de Estudios Superiores de Tamaulipas (IEST), Mexico Srinwantu Dey, University of Florida ASSOCIATE COPY EDITORS: David Chiu, Ohio State University Scott DuVall, University of Utah Leslie Sandoval, University of New Mexico SPANISH EDITOR: Pablo Cayuela, Universidad Tecnológica Nacional, Facultad Regional Córdoba, Argentina OFFERING #XRDS0161 ISSN#: 1528-4981 (PRINT) 1528-4982 (ELECTRONIC) Front cover photograph by Josep Rosell

COLUMNS & REVIEWS INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 by Justin Solomon, Managing Editor

CS EDUCATION IN THE U.S.: HEADING IN THE WRONG DIRECTION? . . . 17 by Robert Dewar and Owen Astrachan What are the most effective methods for teaching students the fundamental principles of software engineering?

FEATURES DON’T CHANGE A THING: HOW ADOPTING A SERVICE PROVIDER ATTITUDE CAN BOOST YOUR CAREER by Michael DiBernardo In software development, treating recently graduated new employees as “apprentices only” is a waste of talent. Michael DiBernardo advises CS students, as those future new hires, to adopt a service-provider mentality to leverage their experience, improve the organization, and more quickly establish trust and credibility there.

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DYNAMIC DISPLAYS: TOUCHSCREENS, MEET BUTTONS by Chris Harrison and Scott Hudson What happens when you take an interface that combines the graphical flexibility of touchscreens and add the beneficial tactile properties of physical buttons? Two bright minds at Carnegie Mellon University’s Human-Computer Interaction Institute built a device that is just that.

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SERVER VIRTUALIZATION ARCHITECTURE AND IMPLEMENTATION by Jeff Daniels PhD student Jeff Daniels explores the history of the virtual machine, since its birth in the 1960s, and outlines the key concepts in virtualization technology today.

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GETTING FROM HERE TO THERE: AN INTERVIEW WITH TRONSTER HARTLEY, SENIOR PROGRAMMER AT FIRAXIS GAMES by Crossroads Staff Tronster Hartley, a senior programmer at Firaxis Games, explains why he started his own game company as an educational side project to his day job, and considers how CS education helped shape his career path.

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Introduction: Maxed Out? By Justin Solomon, Managing Editor

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uring the recent ACM SIGGRAPH conference for computer graphics (August 3-7 in New Orleans), Pixar vice president Rob Cook gave a particularly thought-provoking speech on the future of graphics as an area of research. Cook, the most recent winner of the Steven Anson Coons Award for Outstanding Contributions to Computer Graphics, highlighted the evolution of graphics from a fast-moving, speculative area of research to a massive enterprise with millions of dollars pouring in from entertainment, electronics, and other industries.

During this transformation, graphics research progressively became narrower. While older SIGGRAPHs may have been exciting venues to see technology unimaginable just a year earlier, more recent conferences have shown a convergence in the topics of interest to graphics researchers, who are presenting refinements and polishing techniques for existing approaches to graphics problems rather than sharing totally new ideas. As a result, the papers at the conference have become narrower and less interesting to a general audience. In 2009, they focused on topics like rendering insects encased in amber and refining geometric structures already explored in previous papers. Several years ago, on the other hand, we saw the introduction of cloth simulation, a technique that formed the basis for several other innovative animation processes. Although some of Cook’s observations may have been particular to computer graphics, his impressions of the changing profile of graphics research reflect a similar story in other areas of interest to computer scientists. The ubiquity of personal computing has moved the PC from a novelty or even curiosity to a less exciting computational tool. This shift in perspective necessarily changed researchers’ outlooks and enthusiasm for computing as its own scientific endeavor. Such a development brings with it several pertinent questions. On the whole, the history of computer science is miniscule when compared to that of more “established” fields, like physics or biology. If researchers are already afraid that their work will fall into obscurity in decades rather than centuries, is computer science likely to stagnate in the near future? Have all the relevant computer-related discoveries already been made? As the next generation of computer scientists and professionals, we students are the only ones who can determine the future of our industry. I am optimistic that we have but scratched the surface of a rich and challenging field of research and engineering likely to offer up interesting problems for centuries to come. It’s true that the foundations of many subfields of computing have been laid out. Nobody would dare discount the importance of data structures, databases, and depth buffers. With these basics out

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of our way, however, we have the unique and exciting opportunity to use the tools in place to generate developments not just within our own areas of interest, but across computing and other disciplines. Just as Rob Cook advocated expanding our conception of graphics to include “interactive techniques” and other settings not directly related to rendering increasingly complex images, we should look for the next generation of interesting problems not in laying groundwork but in solving real-world problems—theoretical or practical—in the larger scientific, mathematical, and engineering communities. As the student members of the ACM, Crossroads readers already make up a self-identified group of the leaders of future developments in computing. Having observed the breadth and depth of our readers’ work by reading their submissions to Crossroads and other venues, I have no doubt that the future of computing is in good hands. After all, in this issue alone we explore topics as diverse as virtualization, careers in video game development, and entering the workforce as a software engineer. Moreover, our readers’ active participation in ACM chapters nationwide demonstrates their commitment to building the social networks and lines of communication necessary to make the next big discoveries in computer science. As we continue to share the latest accomplishments of your peers in computing as well as news and career advice, we welcome your comments and suggestions via email, at [email protected]. I wish you the best of luck in the 2009-2010 academic year. And please keep Crossroads posted as you continue to impress programmers and non-programmers alike with your talents and creativity solving tough computer problems.

Biography Justin Solomon is an undergraduate at Stanford University double majoring in Computer Science and Mathematics. Along with his work as the managing editor for ACM Crossroads, he participates in computer graphics research in collaboration with the Stanford Department of Computer Science and Pixar Animation Studios, competes in programming contests, and plays cello and piano.

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Don’t Change a Thing How Adopting a Service Provider Attitude Can Boost Your Career By Michael DiBernardo

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s a student of computer science, there’s a significant chance you will end up working in software development after graduation. Despite whether your career path takes you into industry or academia, you’re likely to have some kind of interaction with software development companies or organizations, if only in trying to get the most out of a project or collaboration.

Students and experienced software developers alike often assume that a new graduate starting his or her first job will work within an existing development process, without necessarily contributing to it or changing it. The new hire, it’s assumed, has enough academic training to contribute to the codebase and intellectual framework around the product, but not to the methodology that’s actually used to guide that development. This process can include status-quos for project planning, work estimation, revision control, check-in policies, product architecture, development techniques (such as design by contract, test-driven development, Scrum), testing methodologies, build management, and deployment. But are software developers wasting their recent graduate employees by keeping them out of the process? The idea of the “new graduate as apprentice only” reduces both the new hire’s experience as an employee and the organization’s return on investment of hiring. Many CS graduates of today’s universities have significant experience with companies and organizations that have a track record of engineering excellence. Typically, this experience comes from co-op or internship placements, contributions to opensource projects, community or volunteer projects, and research assistanceships or “honors projects” that are supervised by professors or other highly esteemed mentors. In the course of their internship-level work, new graduates gain experience working with processes that are often more efficient than the ones that are in place at their new employer. Failing to leverage these prior experiences to improve the performance is a major disservice to both the new graduates and the software companies that hire them. On the other hand, there are many things that can go wrong when trying to change processes that are already in place, especially if the person initiating the change is perceived as less experienced. However, by presenting themselves as “service providers,“ CS graduates can overcome much of the resistance that they would otherwise face. Taking on this role can speed up the process of establishing trust and credibility in a new organization.

The New Employee Trap Before I discuss the service-provider approach to encourage change, I want to first consider how a new hire, who is eager to improve the status quo of software development, might approach the problem. Let’s say we have a new graduate named Mark, who has just joined a medium-sized organization called Informila on a team of about Crossroads

50 developers. Within a few weeks of working at Informila, Mark identifies some existing processes that he would like to changed or replaced. Specifically, he finds that using Concurrent Versions System (CVS) as a revision-control system is causing problems that could be obviated by switching to a new system. Mark has already lost some work due to failed commits that submitted partial changes. Having previously implemented a conversion from CVS to Subversion during a co-op term, he believes that he could implement the change in his new organization with very little negative impact. In a sentence, here’s how Mark sees the problem from his perspective: As a new but experienced team member, I want to make things better by changing the way Informila has always done things. In other words, Mark views himself as part of the team already, albeit a bit green. However, the other developers at Informila may not feel quite this way just yet. It takes time to become an integrated member of a team, and Mark just hasn’t been around long enough. Another premise we can draw from Mark’s statement is that he has a genuine desire to make things better, and to do so, he believes he needs to change existing processes. Change always comes at a cost. In this scenario, there are at least two currencies: time and money (which we treat interchangeably) and trust or reputation. The latter currency is much harder to gauge and is often forgotten—but it is a real cost. If Mark has not built up the trust or reputation required within his team to lead change, the other developers will resist it. Back to the scenario: Mark suggests to his teammates that they migrate their current revision control system to Subversion. He is unable to convince them and their development manager that this is a good idea. Even though Mark has written some sample scripts to demonstrate that he can make the conversion without losing the existing revision history, and he has previous experience and thus some credibility, the team worries that this would be a risky change to their process and isn’t worth the potential benefit. Mark decides that he needs to spend more time doing his best to demonstrate his development prowess by writing quality code before he can build the trust needed to make such changes.

The Service-Provider Approach Thwarted from making any inroads, Mark had decided to operate within his narrow job responsibilities for some time while he slowly builds trust with the team. The problem with this approach is that it

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will take much longer than Mark expects to build his reputation. Even if Mark is an exceptionally good programmer, his team is already quite competent, and the decision-makers within the organization are more concerned with the performance of the team as a whole than they are with any individual. Mark may not realize it yet, but it will be difficult for him to differentiate himself technically from his teammates. In the interim, Mark will struggle with the development processes that he strongly feels are inefficient, and as a result, he’ll enjoy his work less. This will in turn affect his own motivation to differentiate himself from his peers. There is a better way. In his article “At Your Service: Creating a Service-Oriented Software Engineering Team within your Organization” (STQE Magazine, May/June 2001), Robert Sabourin describes how reframing a software engineering team as a service provider to other teams in the organization can greatly improve the ease with which that team is able to enact measurably positive change on the organization as a whole. And there’s no reason this idea should be limited to only teams of testers or developers. Sabourin says that when a service provider is first seeking out ways to earn trust from its customers, it’s much simpler to build trust by adding services instead of trying to convince the customer to abandon a service provided by some other organization in exchange for one you will provide. Almost every student of computer science is taught in introductory algorithms courses that a change can be viewed as some combination of an addition and a deletion. We can view the changing of an existing process in the same way. There are costs—time and money and trust—associated with removing or “deleting” the old process, and then similar costs for adding the new service. However, it typically requires much less of an investment of trust to add a service, because doesn’t disrupt an existing structure. If you can manage to add a service that’s useful to the organization and meet a need that was not currently being met before, you will build trust that can then be “spent” to change existing processes. In fact, once you have successfully added a few processes, you may even be asked to change things that you previously petitioned to improve in the first place.

A Matter of Mindset Let’s say Mark decides to take this approach. How does it differ from what he was already doing? There are two steps to adapting a service-provisioning based outlook. The first is to reflect on the services that you are capable of providing, which may or may not already exist in the company. For example, Mark is working in a Windows-centric environment, but he’s also quite accomplished in Linux development. He has done a great deal of web application development using open source technologies. He is willing to spend some extra hours outside work on side projects related to his job, which is a luxury that many of his older coworkers cannot afford due to other responsibilities. Finally, he has a fair amount of experience in operating and integrating bug-tracking and revision-control systems. Mark decides that within his organization, he is capable of adding value by providing services related to 1) Linux development, 2) web application development, and 3) revision control and bug tracking. The second step involves finding opportunities to “sell” these services in situations where people want to add to the existing process. This step is fairly simple because most people who are in pain are not shy about expressing their anguish. There’s one sticking point in the second step for many people, though. Most developers will hesitate to add components process that

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they feel aren’t really needed, no matter how loudly others are clamoring for it. This desire to be efficient in the short term can actually hamper one’s ability to improve the overall efficiency of the process in the long term, since adding services can be a great way to build up the trust needed to make broader changes. As an example, Mark has often heard Andy, the director of test engineering, complaining that he has no good way of visualizing the statistics maintained by their current bug-tracking system. Andy would really like an application that could generate charts to show the trend of how the number of bugs opened, re-opened, resolved, and so forth, has changed over the course of a project, especially when each project approaches its deadline, and different branches are required to be maintained. Mark’s first thought when he hears this request is that some other open-source bug-tracking tools already have this capability, and that this functionality could be acquired “for free” by simply switching over. It’s a procedure that he has implemented before, and he knows it can be done relatively painlessly, save for the fact that the test team and product owners would need to learn how to use the new system (a time and money cost). The other approach—writing a program to solve a problem that has already been solved—is something Mark finds highly distasteful. In many respects, writing new software is wasteful compared to simply switching to the other bug-tracking system. However, Mark reasons that if he were a consultant offering his services to this organization, this perceived need would provide the perfect opportunity to build trust with the client, because it doesn’t involve changing any existing processes at all, and it’s something the client feels is desperately needed. By meeting the perceived need, Mark can start to acquire the trust currency he needs to make things more efficient in the long run, especially since the director of test engineering is such an influential person in the organization.

Perceive and Be Perceived It may seem as if adopting a service-oriented “method” isn’t really much of a change at all. Mark’s intent has not changed. He still wants to make things better within the organization. However, his perspective of what he’s fundamentally doing has shifted subtly, and in a way that will improve how others perceive Mark and his actions. Mark’s new statement of action would be something like: As a provider of Linux development, web application development, and revision control and bug tracking services at Informila, I would like to make things better by adding components or processes to fulfill needs that have been expressed by the organization. The outlook is totally different. Mark has gone from focusing on himself as an individual to identifying himself as a provider of services. While the shift is strictly one of notation, it removes some of the ego from his perceived role, and allows him to occasionally see the opportunity in courses of action that he might otherwise dismiss as silly or ineffectual. In my experience, this seemingly superficial change has a very real effect on the kinds of opportunities that one will pursue, and the ways in which one will react when confronted with adversity in these pursuits. Another shift Mark has made is that he’s focused on adding processes to build trust before trying to introduce changes to existing processes. Lastly, he’s focusing first on needs that have already been recognized by the organization, before trying to address things he has only noticed himself.

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Don’t Change a Thing

Mark ends up working on the bug charting system for Andy, and has a first version ready within a month. Andy uses the system to demonstrate some of the current statistics to management, and everyone remarks on how much easier the data is to interpret now with the new charts. Despite the fact that Mark has just essentially replicated functionality that was available in another system, by adding this component to Informila’s existing workflow, he has made more headway toward garnering trust than he would have been able to accomplish through months and months of focusing solely on fulfilling his declared job duties.

In Perspective I have met many recruiters, managers, and company owners who have commented that people in technical roles are expected to have excellent technical skills as a prerequisite. However, they are differentiated based on their ability to communicate and how they get along well with others. Seeing yourself—and getting others to see you—as a service provider is a highly valued soft skill. And you might just make your work environment a happier place for yourself while you’re at it.

Biography Michael DiBernardo ([email protected]) is a software craftsmen who writes, teaches, and practices the art of software development. He has worked for the government of Canada, the universities of Waterloo and Toronto, Google Inc., and Novell Canada Inc. He holds a B.Math in Computer Science and Bioinformatics from the University of Waterloo, and an M.Sc in Computer Science from the University of British Columbia.

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Dynamic Displays Touchscreens, Meet Buttons By Chris Harrison and Scott Hudson

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hile touchscreens allow extensive programmability and have become ubiquitous in today’s gadgetry, such configurations lack the tactile sensations and feedback that physical buttons provide. As a result, these devices require more attention to use than their button-enabled counterparts. Still, the displays provide the ultimate interface flexibility and thus afford a much larger design space to application developers. But from the user’s point of view, touchscreens require direct visual attention. This makes them dangerous in contexts like driving, and potentially disruptive in casual social situations. Furthermore, even with visual attention, touchscreen interfaces tend to be slower and more error prone than gadgets with keyboards, buttons, knobs, and the like. The tactile sensations produced by physical buttons often make them easier to find and use; thus, they require less attention from the user. Pumping the music in a car while driving, for instance, doesn’t require much more than a quick reach and turn of knob, or a few taps of a button. Nevertheless, most buttons are static, both in appearance and tactile expression, meaning a single button must be used for many different functions.

Our goal is to devise a display technique that occupies the space between these two extremes, offering some graphical flexibility while retaining some of the beneficial tactile properties. To achieve this, we require that graphics be displayed without interference from hands or the tactile control and actuation elements. The screen has to sense user input without preventing tactile deformation or hiding graphics. Finally, the screen has to provide support for tactile expression beyond simple on/off state changes.

What We Built Our design consists of one or more air chambers that are created by layering several specially cut pieces of clear acrylic. On top of this, we drape a thin sheet of translucent latex, held in place with a specifically structured pattern of adhesive. Through pneumatic actuation, we can create dynamic physical features and allow a small set of distinct interface elements to occupy the same physical space at different times. The fabrication is straightforward. We are able to assemble working prototypes with complex features in under an hour using a laser cutter. The displays rely on inexpensive materials: acrylic, glue, and latex. Air chambers can be negatively or positively pressurized with a small and inexpensive pump, allowing for easy actuation. Applying clear acrylic to such a display allows the image to be rear projected. Our design doesn’t suffer occlusion from user input. This novel approach enables us to employ diffused infrared illumination and an infrared camera for multi-touch sensing.

Biographies Chris Harrison ([email protected])is a PhD student in the Human-Computer Interaction Institute at Carnegie Mellon University. His research interests primarily focus on novel input methods and interaction technologies, especially those that leverage existing hardware in new and compelling ways. Over the past four years, he has worked on several projects in the area of social computing and input methods at IBM Research, AT&T Labs, and most recently, Microsoft Research. Scott Hudson ([email protected])is a professor in the HumanComputer Interaction Institute within the School of Computer Science at Carnegie Mellon University, where he directs the HCII PhD program. His research interests have covered a wide range of topics within the area of user interface software and technology, though his work has always revolved around the invention and building of things that lead to a better user experience, often indirectly through tools for the UI developer.

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The acrylic elements are shown in various shades of grey. Areas where adhesive is applied are shown with a textured blue. The thin latex layer is shown in translucent green.

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Server Virtualization Architecture and Implementation By Jeff Daniels

Abstract irtual machine technology, or virtualization, is gaining momentum in the information technology community. While virtual machines are not a new concept, recent advances in hardware and software technology have brought virtualization to the forefront of IT management. Stability, cost savings, and manageability are among the reasons for the recent rise of virtualization. Virtual machine solutions can be classified by hardware, software, and operating system/containers. From its inception on the mainframe to distributed servers on x86, the virtual machine has matured and will play an increasing role in systems management.

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Introduction Virtualization in the enterprise is catching on across the country. Hardware vendors are packaging systems tuned to support virtual machines, and software vendors are developing virtual server management tools for migrations, performance, and high-availability. Customer IT organizations have defined a virtualization strategy and have begun deploying virtualized data centers. The virtual machine concept has been around for years. The recent revolution in virtualization technology, hypervisors, and paravirtualization has allowed servers using the popular x86 architecture to operate efficiently and effectively with virtual machines. Virtual machine technology is an enabler for service-oriented architectures, isolated secure systems, and flexible deployment. This paper describes the virtual machine from its inception in the 1960s to present day virtual machines. Various types of virtualization will be discussed, as well as the associated costs and benefits of using virtual machines. Information from this paper should outline the basics of virtualization and offer key concepts when implementing virtualization technology.

What is a Virtual Machine? A virtual machine (VM) is an abstraction layer or environment between hardware components and the end-user. Virtual machines run operating systems and are sometimes referred to as virtual servers. A host operating system can run many virtual machines and shares system hardware components such as CPUs, controllers, disk, memory, and I/O among virtual servers [8]. A “real machine” is the host operating system and hardware components, sometimes described as “bare metal,” such as memory, CPU, motherboard, and network interface. The real machine is essentially a host system with no virtual machines. The real machine operating system accesses hardware components by making calls through a low-level program called the BIOS (basic input/output system). Virtual machines are built on top of the real machine core components. Goldberg describes virtual machines as “facsimiles” or a “hardware-software duplicate of a real existing machine“ [4, 5]. Abstraction layers called hypervisors or VMMs (virtual machine monitors) make

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calls from the virtual machine to the real machine. Current hypervisors use the real machine hardware components, but allow for different virtual machine operating systems and configurations. For example, a host system might run on SuSE Linux, and guest virtual machines might run Windows 2003 and Solaris 10. Virtual machine monitors and hypervisors are similar to “emulators.” Emulation is a “process whereby one computer is set up to permit the execution of programs written for another computer” [9]. Hypervisors offer a level of efficiency, in that emulators translate every instruction or system call to the CPU, memory, and disk. Hypervisors have specialized management functions that allow multiple VMs to co-exist peacefully while sharing real machine resources. Mallach concludes the differences are largely semantic because both hypervisors and emulators require I/O requests, memory mapping, and logical memory schemes [10].

Virtual Machine History Virtual machines have been in the computing community for more than 40 years. Early in the 1960s, systems engineers and programmers at MIT recognized the need for virtual machines. In her authoritative discourse, “VM and the VM Community: Past, Present, and Future,” Melinda Varian [17] introduces virtual machine technology, starting with the Compatible Time-Sharing System (CTSS). IBM engineers had worked with MIT programmers to develop a time-sharing system to allow project teams to use part of the mainframe computers. Varian goes on to describe the creation, development, and use of virtual machines on the IBM OS/360 Model 67 to the VM/370 and the OS/390 [17]. Varian’s paper covers virtual machine history, emerging virtual machine designs, important milestones and meetings, and influential engineers in the virtual computing community. In 1973, Srodowa and Bates [15] demonstrated how to create virtual machines on IBM OS/360s. In “An Efficient Virtual Machine Implementation,” they describe the use of IBM’s Virtual Machine Monitor, a hypervisor, to build virtual machines and allocate memory, storage, and I/O effectively. Srodowa and Bates touch on virtual machine topics still debated today: performance degradation, capacity, CPU allocation, and storage security.

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Server Virtualization Architecture and Implementation

Goldberg concludes “the majority of today’s computer systems do not and cannot support virtual machines. The few virtual machine systems currently operational, e.g., CP-67, utilize awkward and inadequate techniques because of unsuitable architectures“ [6]. Goldberg proposes the “Hardware Virtualizer,” in which a virtual machine would communicate directly with hardware instead of going through the host software. Nearly 30 years later, industry analysts are excited about the announcement of hardware architectures capable of supporting virtual machines efficiently. AMD and Intel have revealed specifications for Pacifica and Vanderpool chip technologies with special virtualization support features. The 1980s and early 1990s brought distributing computing to data centers. Centralized computing and virtual machine interest was replaced by standalone servers with dedicated functions: email, database, Web, applications. After significant investments in distributed architectures, renewed focus on virtual machines as a complimentary solution for server consolidation projects and data center management initiatives has resurfaced [14]. Recent developments in virtual machines on the Windows x86 platform merit a new chapter in virtual machine history. Virtual machine software from Virtuozzo, Microsoft, Xen, and EMC (VMWare) has spurred creative virtual machine solutions. Grid computing, computing on demand, and utility computing technologies seek to maximize computing power in an efficient, manageable way. The virtual machine was created on the mainframe. It has only recently been introduced on the mid-range, distributed, x86 platform. Technological advancements in hardware and software make virtual machines stable, affordable, and offer tremendous value, given the right implementation.

Figure 1: Software virtual machines.

Figure 2: Hardware virtual machines.

Types of Virtualization Virtual machines are implemented in various forms. Mainframe, open source, paravirtualization, and custom approaches to virtual machines have been designed over the years. Complexity in chip technology and approaches to solving the x86 limitations of virtualization have led to three different variants of virtual machines: 1. software virtual machines (see Figure 1), which manage interactions between the host operating system and guest operating system (e.g., Microsoft Virtual Server 2005); 2. hardware virtual machines (see Figure 2), in which virtualization technology sits directly on host hardware (bare metal) using hypervisors, modified code, or APIs to facilitate faster transactions with hardware devices (e.g., VMWare ESX); and 3. virtual OS/containers (see Figure 3), in which the host operating system is partitioned into containers or zones (e.g., Solaris Zones, BSD Jail). A simple UNIX implementation called chroot allows an alternate directory path for the root file system. This creates a “jail,” or sandbox, for new applications or unknown applications. Isolated processes in chroot are best suited for testing and applications prototyping. They have direct access to physical devices, unlike emulators. Sun Microsystems’ “Solaris Zones” technology is an implementation of chroot, similar to the FreeBSD jail design, with additional feaCrossroads

Figure 3: Virtual OS/containers virtual machines. tures. Zones allow multiple applications to run in isolated partitions on a single operating system [16]. Each zone has its own unique process table and management tools that allow each partition to be patched, rebooted, upgraded, and configured separately. Distinct root privileges and file systems are assigned to each zone. Microsoft Corporation’s Virtual Server 2005 is a new virtual machine manager in the market. After acquiring virtual machine technology from software vendor Connectix in 2003, Microsoft introduced the Virtual Server 2005 product, which runs on a Windows 2003 host and, predictably, supports Windows guest operating systems only. At the time of publishing this paper, Virtual Server is lim-

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ited to running on single-processor hosts and cannot support symmetric multiprocessing (SMP). SMP was introduced on RISC platforms, such as Sun Sparc and DEC Alpha chipsets, before being adopted on the x86 Intel Xeon and AMD Athlon processors. SMP allows multiple, identical chipsets to share one memory bank. Instructions can be shared among the processors or isolated to a dedicated processor on the system. The system can share a workload, and with increased efficiency. A variation of SMP is AMD’s Opteron technology, which allows dual-processor chips. The Opteron uses DDR SDRAM memory dedicated to each processor, as opposed to a single shared memory bank. The multiprocessing nature of numerous virtual machine guest servers on one host makes dual-core Opteron chips an attractive platform. Paravirtualization is a variant of full operating system virtualization. Paravirtualization avoids “drawbacks of full virtualization by presenting a virtual machine abstraction that is similar but not identical to the underlying hardware” [18]. This technique allows a guest operating system to be “ported” through a special API (application programming interface) to run. The Xen paravirtualization research project, at the University of Cambridge, is a virtual machine monitor (hypervisor) that allows commodity operating systems to be consolidated and effectively mobilizes guests across physical devices. Xen currently supports only open source guest systems, though a Windows XP port is being developed. Denali is another paravirtualization implementation, but it requires significant modification to host system binaries and focuses on high-performance virtual machines. EMC’s VMWare technology is the market leader in x86 virtualization technology. VMWare ESX server uses a special hypervisor to “dynamically rewrite portions of the hosted machine code to insert traps wherever VMM intervention might be required” [1]. The VMWare solution is more costly, but it provides a robust management console and full-virtualization support for an array of guest operating systems including Solaris, Linux, Windows, and DOS.

Why Virtualization? A recent Gartner survey revealed that “less than one-quarter of enterprises use virtual machines. However, more than 70 percent say they plan to test them in the near future” [12]. Data center floor space and rack space are prime real estate in computing environments. Cooling and electricity costs have risen in recent years. Infrastructure managers are looking to maximize the investment in existing computing power while keeping server sprawl and overhead costs in check. Virtual servers generate hardware cost savings by allowing devices to be used to their full potential. Most distributed computing environments underutilize server capacity. Estimates for distributed, Windows-based servers indicate average capacity of 8 to 12 percent; UNIX servers use 25 to 30 percent of their capacity on average [3]. Virtual server technology unlocks unused capacity and allows the CPU, memory, disk, and controllers to be maximized for each physical device. Based on performance measurements, testing, estimates, and trial and error, any number of virtual servers can be added to a physical device, thereby increasing server utilization to sustainable levels. Instead of purchasing expensive servers with unused or excess capacity, a new virtual machine could be created for an application. Maintenance costs are avoided on the idle servers, and floor space is

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freed for virtual server hosts. A manageable growth plan can be created to add virtual servers, host servers, and related services. The cost to implement virtual machines has significantly decreased. Recent virtual machine monitors, hypervisors, and paravirtualization tools make it easy to create virtual machine instances, instead of developing virtual machine code. The 1980 paper “A Virtual Operating System” identifies two costs to implement virtual machines: cost to write virtual machine software and implementation costs. The estimated cost of labor to develop the initial virtual machine monitor was eight to ten person-months and an estimated four person-months to port the entire system [7]. With current virtual machine monitors, an engineer can have an Oracle 10g cluster hosted on Red Hat Enterprise Linux running within minutes—basically, the amount of time it takes to download the binaries. While the development and implementation costs of virtual machines are significantly less today than in 1980, “A Virtual Operating System” touches on another benefit of virtual machines: migration costs. Traditional systems are tied to server or desktop hardware. The life expectancy of servers is typically three to five years. When server technology becomes obsolete, the data must be migrated to a new platform, and applications must be reconfigured in the new environment. Worse, if the equipment is leased or acquired under a capacity services agreement, large scale system migrations must occur at the end of the term in order to avoid contract penalties. Virtual machines make those transitions easier. VMWare offers a migration tool called P2V, physical to virtual machine, which helps engineers move from legacy environments to virtual servers. Platespin Ltd. offers a flexible suite of tools to automatically migrate between virtual and physical machines (and back again), dynamically reallocate disk space, network configuration, unique identifiers, and other configuration settings. In contrast to traditional standalone systems, migrating virtual machines from one host platform to another host platform is relatively simple, in terms of configuration, man-hours, and resources required.

Licensing Virtual servers can provide opportunities for software consolidation and reduced licensing costs. A Forrester study concludes Windows licenses and maintenance costs total $5,800 per year. Adapting to new virtual machine technology, many vendors have changed their licensing models to a “cost per instance” model instead of the “cost per processor” model. Saving licensing fees when migrating from physical to virtual servers may not be effective under the cost per instance model. For example, Microsoft recently announced its new licensing model, noting that “per-processor licensed software will be licensed by virtual processor when used in a virtual OS environment and by physical processor when run in physical OS environments” [12]. However, virtual servers offer the ability to consolidate similar systems and software packages on common platforms to recognize license cost savings. Consolidation is a key driver for many organizations implementing virtual machine technology. Nearly 60 percent of IT managers are considering consolidation [11] projects. Consolidation efforts represent an attempt by IT management to capture cost savings by retiring or decommissioning legacy devices and standardizing support processes. Consolidation projects present the opportunity to minimize the number of physical devices as well as software licenses, various packages, and management tools.

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Server Virtualization Architecture and Implementation

Once legacy systems are migrated to a consolidated, virtual environment, standardized images can be built and cloned to ensure integrity. High availability systems and clustered environments can be quickly configured with virtual machines. Strategic initiatives can start with standardized images as a launching pad for new applications builds. When physical hosts need to be retired or phased out, virtual machines can easily be moved to the new platform with little interruption. Products such as Virtual Motion and Xen can move virtual machines on the fly, with little or no user downtime.

change control. This also reduces risk of misconfiguration or non-configuration of features that may occur due to human error when building and rebuilding physical systems. Common platforms serve as an enabler for business objectives and other enterprise architecture components. Initiatives such as ERP implementations and service-oriented architecture applications rely on infrastructure being available, standardized, and usable. Virtual server technologies can be used as a building block in standardization and integration in enterprise architectures.

Virtualization in the IT Strategic Plan

Implementation plans differ at every organization. What is applicable for one industry or business may not work for others. However, there are some common implementation techniques that transcend business lines. VMWare, a leading vendor of virtualization products, uses the VMWare Infrastructure Methodology (VIM): assess, plan, build, manage. The process considers the existing inventory of systems, creates a plan to “virtualize” the systems, install and configure the hosts, and manage the new virtual server infrastructure. Many organizations will follow these steps even if they are outside of the VIM methodology, but the figures, processes, and systems will be different. Organizations tend to start using virtual servers in development systems, instead of production, to prove the new technology. Generally, the lower service levels and less criticality of development systems make an ideal choice to implement and evaluate the impact to the environment before going to production. Teranet, an e-commerce and government systems integrator, offers a modified approach: perform the assessment, build a business case for all servers, perform a proof-of-concept, build a business case for all development and test servers, and, finally, deploy in phases. Using this implementation methodology, Teranet successfully deployed more than 270 virtual servers at a cost savings of over $3 million. The phased approach was also used by Moen, the faucet manufacturer. Moen went through four phases of implementation, each integrating more virtualization technologies in the data center. In Moen’s case, each phase had specific success criteria, such as cost avoidance, performance, cost reduction, and operating efficiencies [2]. The Moen team carefully evaluated success factors, process changes, and implementation goals following each phase. Moen also captured tangible and intangible costs and benefits throughout the implementation. The figures below show some of the types of costs and benefits identified by Moen. Similar to the proof-of-concept approach, a pilot implementation is another way to “kick the wheels,“ so to speak. Pilots offer a quick win in many ways. Virtual server technology is proven during the pilot.

Virtual Server Implementation Virtual servers should be a component in any Information Technology Strategic Plan (ITSP). As organizations plan for technologies, roadmaps are developed in one, three, five, seven, and out years. For example, an ITSP might have biometric readers on a three year plan, while an enterprise resource planning (ERP) upgrade is on a five year outlook. Virtualization technologies will fall in the one to three year planning cycle for most organizations. The goal of IT projects and initiatives is to create business opportunities or generate cost savings. Virtualization is a key component in several planning areas:

• • • • •

expanding business lines, such as shared and dedicated hosting; faster deployment, time to market; increased standardization, leading to lower total cost of ownership; consolidation efforts; and increased utilization of computing capital.

There are various other possibilities where virtual server technologies could create opportunities or cost savings. As business goals are defined and objectives determined by the business, virtualization technologies should be considered as one of the ways IT can help meet those goals. Enterprise architecture is “the organizing logic for business process and IT infrastructure capabilities reflecting the integration and standardization requirements of the firm’s operating model” [13]. Enterprise architecture seeks to align business goals and organizational needs with technology. The idea is to plan, deploy, and manage technologies to meet business objectives. Similar to the IT strategic plan, virtualization technologies have their place in the enterprise architecture model. Ross mentions two important concepts in her definition of enterprise architecture: integration and standardization. Virtual servers offer increasingly flexible methods of systems integration. Hot failovers, highly available systems, real-time relocation of virtual systems, dynamic reallocation of system resources, and even wide-area network disaster recovery (backup) are integrated with virtual servers. The “data-center in a box” concept is a physical device with many integrated virtual servers that performs data center functions such as routing, messaging, and directory services. Virtual servers go a long way towards standardization for infrastructure operations. Servers can be commoditized using the “gold image” model, where a virtual machine with the latest compliant system configuration is used to build new servers, ensuring standardization and Crossroads

Figure 4: Moen tangible and intangible costs during implementation of virtual servers [2].

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4. Goldberg, R. P. 1971. Virtual machines—Semantics and examples. IEEE Computer Society Conference. 141-142. 5. Goldberg, R. P. 1971. Hardware requirements for virtual machine systems. In Proceedings of the Hawaii International Conference on System Sciences. 6. Goldberg, R. P. 1973. Architecture of virtual machines. Honeywell Information Systems, Inc., Billerica, MA.

Figure 5: Moen tangible and intangible benefits during implementation of virtual servers [2]. The pilot team will test-drive the systems and test functionality in an operational or small subset of systems. Pilots can promote virtualization success by sharing early wins with project management. Successful pilots allow users and project teams to gain valuable experience that will come in handy during full-scale production roll-outs.

Summary Virtual machines have enjoyed a special niche within the information technology community over the years. Systems engineers and developers have continued to support virtual machines and push innovation in new ways. Virtual machines are gaining wider acceptance due to new efficiencies, ease of use, and users’ demands for flexibility. Hardware, software, and operating system (container) virtual server technology are among the various virtual machine implementations. There is no “one size fits all” virtual machine solution. Rather, many options are designed around specialized approaches. Hardware advances such as the AMD Opteron dual-core processors are making it possible to build powerful servers to host guest operating systems. Intel’s Vanderpool and AMD’s Pacific next-generation architecture will allow more flexible virtual systems at the hardware level. Data centers and IT management are implementing virtual server technology, often as part of a consolidation strategy. Cost savings in the areas of software license management, systems management, data center, and overhead costs, such as electricity, generators, and floor space are key benefits for consolidated virtual server environments. IT managers trying to contain server sprawl, standardize and control systems, and build strategic platforms see virtual machine technology as an enabler. Virtual storage area networks and grid computing are taking virtual machines to new levels. Advanced technologies such as highperformance computing, grid computing, and service-oriented architectures with dynamic allocation of resources are complimentary solutions to virtual machines. From its inception on the mainframe to distributed servers on x86, the virtual machine has matured and will play an increasing role in systems management.

References 1. Barnham, P., Dragovic, B., Fraser, K. et al. Xen and the art of virtualization. 2003. In Proceedings of the 19th ACM Symposium on Operating System Principles (SOSP’03). 164–177. 2. Buchwald, R. 2005. Many happy returns: Techniques on how to identify VMware return on investment and how to use it to justify VMware expansion. VMWorld. Presentation SLN693 (Oct. 20). 3. Day, B. 2005. Identifying server consolidation cost savings. Forrester Research, Cambridge, MA.

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7. Hall, D. E., Scherrer, D. K., and Sventek, J. S. 1980. A virtual operating system. Comm. ACM 23, 9. 8. Kreuter, D. 2004. Where server virtualization was born. Virtual Strategy Magazine (July 21). 9. Lichstein, H. A. 1969. When should you emulate? Datamatlon 15, ii. 205-210. 10. Mallach, E. G. 1972. Emulation: A survey. Honeywell Comput. J. 6, 4. 287-297. 11. ONStor, Inc. 2005. Top 10 requirements for effective server consolidation. www.onstor.com. 12. Park, A. R. and Gammage, B. 2005. Microsoft updates server licensing to enable virtualization. ID Number G00132810. Gartner Group, Stamford, CT. 13. Ross, J. W. 2007. Enterprise architecture as a strategy. Center for Information Systems Research, MIT Sloan-CISR. 14. Serjeant, A. 2005. Building a case for server consolidation. VMWorld. Presentation (Oct. 20). 15. Srodawa, R. J. and Bates, L. E. 1973. An efficient virtual machine implementation. In Proceedings of ACM SIGARCH-SIGOPS Workshop on Virtual Computer Systems. 16. Tucker, A. and Comay, D. 2004. Solaris zones: Operating system upport for server consolidation. Sun Microsystems, Inc. 17. Varian, M. 1997. VM and the VM community: Past, present, and future. Office of Computing and Information Technology, Princeton University, Princeton, NJ. 18. Whitaker A., Shaw, M., and Gribble, S. D. 2002. Denali: Lightweight virtual machines for distributed and networked applications. Tech. rep. 02-02-01. University of Washington.

Biography Jeff Daniels ([email protected]) is a doctoral candidate in digital communications at the Indiana State University in Terre Haute. He has authored papers and presented numerous international conference presentations on topics including virtualization, security, and systems architecture. He is the recipient of several awards, including the Lockheed Martin Pinnacle Award for Excellence and the Lockheed Martin President’s Award, and holds a Master’s degree from Rensselaer Polytechnic Institute and a BS degree from the University of Central Florida.

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Crossroads

Getting from Here to There: An Interview with Tronster Hartley,: Senior Programmer at Firaxis Games: Tronster Hartley is a senior programmer at Firaxis Games, the video game development company best known for its Civilization series, as well as president of Geek House Games. In this interview with Crossroads, he explains how his career path was influenced by not only his computer science education, but also his willingness to experiment with game-making and interact with new people on his own time. Crossroads: Can you explain what the difference is between your two jobs, Firaxis and Geek House Games? Tronster Hartley: Sure. Firaxis Games is my day job. I work it Monday through Friday, roughly 40 hours a week, but during crunch time [when extreme overtime occurs in order for the company to meet its deadline] a little bit more. Geek House Games is more of a personal passion. On nights and weekends, myself along with other professionals, students, and indies [independent game developers] come together to work on a game that will go into realms that we might not have a chance to explore in our day-to-day activities. Crossroads: Can you talk a little bit about why having something like Geek House Games is important, not just to you personally, but in terms of your career development? TH: Before I even started working full-time in the game industry, I was always fascinated by games. I loved playing them. I would tinker around and make them in college during spring break. After working a computer programming-based job in a few business sectors, I realized my passion for games had not been diminishing. I really missed doing game projects that were structured and organized and I wanted something that would hold me accountable to finishing a game. My hard drive had half a dozen or a dozen projects that were started but never completed. I realized in order to hold myself accountable, it was important to establish a business entity and strive to make some sort of goal with milestones and deadlines that would force me to finish a game. Once every year, I intend to submit a game to the IGF [Independent Games Festival, an annual competition that is well-recognized in the video game development industry for introducing experimental and innovative concepts]. Making games in my spare time, even before working full time for a AAA studio, actually helped get me a leg up when I started interviewing at some of the game studios. One thing I tell students whenever I talk to them about the game industry is that even if they don’t have a job lined up or an internship lined up, the best thing they can do for their careers is to start making games right now. If the best prospect for them is to create a business entity, do that. If they are disciplined enough to make games on their own time and see it through from start to finish, then I recommend doing that—whatever works best for them. Crossroads

Now that I’m full-time in the game industry, I found that I am most valuable if I specialize in a particular area of programming. For me it’s been user interfaces. And while this is my focus, I still have a passion to do a bit more with computer graphics, game design, and pixel shaders. Every now and again, I even get the urge to just to make a well-written system for playing sounds. Since I’ve become very specialized in user interface, I put most of my energy into it during my day job. Occasionally I will get opportunities to do more in art or design; I welcome those opportunities. But when there are no opportunities outside of UI, during my day job, I can always satisfy my other interests in what I do at Geek House Games. Crossroads: I think something a lot of people don’t realize, especially when they are new to the workforce, is that they don’t have to be beholden to the thing that pays their bills 100 percent completely. That really is a difficult thing for many people. TH: Very much so. Before breaking into the game industry—my first full-time job was working on a AAA title at BreakAway Games—I had a job at a start-up that was creating and supporting backup software. Early on in my life I set some financial goals. I wanted to be making six figures by the time I was 30, and I was making well beyond that on contractor rates, but it didn’t make me happy. When the opportunity arose at BreakAway, even though the salary was a third of what I was making, my quality of life was going to increase. At BreakAway, when I was coming out of meetings, we were talking about where we’d be placing Tiberium on a map [in the game Command & Conquer 3: Tiberium Wars] rather than what files had to be restored on someone’s hard drive. Even crunching is different. I welcome crunching at a game company. Crunching happens at every other type of job I’ve been at, but I don’t think there’s been a single case, outside of the game industry, where I can say I’ve had a good experience from doing a crunch. Crossroads: Just to back up, BreakAway Games is a studio that does serious games, or games with objectives other than entertainment, as well as AAA titles, right? TH: Right. BreakAway is diversified. At least when I was there, there was an entertainment section and a serious games section. They have some of the most cutting-edge serious games technology. The people who built that technology were able to transfer their skill sets very well into the AAA space.

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In the past, BreakAway had done a few contracts with EA to put out an expansion to Battle for Middle Earth, an extension, and when I came on board, I was hired to do UI work on Command & Conquer 3: Kane’s Wrath. Crossroads: What is your educational background? I know you went to Ohio Wesleyan University. TH: Yes. Before I talk about my degree, I’m going to take you way far back because it explains how and when I got interested in programming. I’ve always had long-term goals on my mind. From kindergarten, I was going to be a chef, until third grade when I learned how to do AppleSoft Basic, and from third grade on, I realized I wanted to make games. This is way back in the early 1980s, and I realized the only way I was going to make games was to get proficient with a computer, so I knew I would need to go for a CS degree. All through middle school and high school, that was the target. OWU had a very good program. I think there were about seven people per class. The entire school has about 2,000 people on campus, so it was bigger than my high school, but still small enough to get the personal attention that I was looking for. Crossroads: Did you find you were naturally adept at learning computing and programming before you started at Wesleyan? TH: I did, but I was a bit of an ass in high school. I’m a big geek; I think one of the problems with geeks in general, myself included, is that we become very specialized in technology early on and it can breed a bit of arrogance. My arrogance was the biggest issue for me, especially amongst my friends. I would be taking an advanced placement computer science course in Pascal and I would be working with various libraries the teachers were not familiar with. I actually had an ASCii, 3D, rotating cube in a program for a help screen, when all my teacher wanted was a line of text along the lines of “This will count cards and score them for a hand of bridge.” I was thirsting to do more with what I knew, and it did cause a lot of conflicts in high school. But once college started, I was quickly put in my place. A lot of it had to do with the curriculum and programming competitions. There was an ACM programming competition where OWU represented with two teams. It was a fantastic experience as the problems were challenging, showing me how much I still needed to learn. One of our teams placed; my team did not. Crossroads: You were saying you started at Ohio Wesleyan and it had a small class size and you got a lot of personal attention. Talk a little bit more about what you studied there. TH: Because of my AP scores in high school, I started immediately in the Assembly class. It involved a lot of low-level “register” work, which required an existing knowledge of programming. So my class was filled with sophomores and one other student who also jumped ahead via AP scores. Ironically, that student was the one who had hired me for the backup software job. The course was hard, due to so many factors. It had a long time slot, started at 8 a.m., and involved looking at low-level code on a black-and-white LCD that was projected via an overhead projector in a dark room. I have this one memory of Dr. Zaring, our professor, showing a difficult concept via the computer, and then flipping on the lights. The six other people in the class were all asleep, heads on desks,

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except me. I was lucky enough to have had a Mountain Dew in one hand and a Surge in the other, double-fisting caffeine the whole time. It was hard picking up the concepts, in this environment, but the small class size and availability of Dr. Zaring made it possible. In my senior year I had finished a lot of the courses that were required to graduate, and instead, I was taking a lot more interesting courses, such as compilers and a computer graphics study. I was having a lot more fun learning concepts that I knew would be more immediately applicable to the projects I wanted to do when I graduated. I also became the president of the student chapter of the ACM at Ohio Wesleyan. At that time, not many people on campus knew about the ACM. We continued that year to do all the stuff that had been done in the previous years, mostly computer competitions. But additionally, I wanted to do things that would make the ACM more visible. Once a month, we would have an open, campus-wide “computer” movie night. One night we’d show Tron and another night we would show Lawnmower Man or War Games in the student areas. I see the ACM as being about computers and culture and the fact that we cannot live without computers today, and those types of movies helped bridge the gap between those of us who loved computers and those who felt they were a necessary evil. Now this is in the late 1990s, and today our society is even more reliant on them, but at that time, I felt it was key for the rest of the campus to understand how important computers were becoming. Crossroads: So, you used movies as a hook into showing other people how this field could actually be applicable in their everyday entertainment lives, as well as the deep backchannel stuff that goes on. TH: Right. It was one of two hooks that we tried, but it was the only successful one. The other hook was shut down by the administration. That year, for Valentine’s Day we decided to have a match-making service. All the students submitted ballots and then we had a computer algorithm—one of the guys had figured out a matching system— and paired up students on campus. If people wanted to act on it they could, but they didn’t have to. But some of the questions were a little cheeky, like, “How far is too far on the first date?” Even though the language wasn’t crude, the dean pulled me aside and told me he was pulling the plug on our project. There are a lot of misconceptions about what computers can and cannot do, and the people behind them. Just today, I heard on the radio about a local college, which is offering some degree in computer security, and there was a voiceover of this woman who said, “When I nab my first hacker, I’m going to dedicate that to my sister!” I grew up in a hacker culture, and am offended by that commercial. “Hacker” should not be synonymous with “evil person trying to commit crimes.” Having misperceptions of people who use computers, what they do with computers, and being able to assess who is doing good and who is doing bad, what it means to be doing good and what it means to be doing bad—those kinds of things were important to me when I was in college leading the ACM chapter, and continue to be important to me today. Crossroads: I can imagine that that has a lot of crossover with working in the game industry, too, this whole notion of doing good. I would think it might be complicated at a company like BreakAway, where you

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Getting from Here to There

were working on a violent title like Command & Conquer 3, but on the other hand, BreakAway does all this altruistic stuff in its serious games. TH: Right. As games are becoming more realistic, as they’re becoming better at what they’re supposed to represent, the lines are becoming blurred, and I recognize that. I loved playing the original Doom and the original Quake. But I can’t play Doom 3 because I dislike horror movies. After the first level, it freaked me out so much that I had to put it down. Some games, such as what the U.S. Army has put together, are amazing in terms of technology, but at the same time, are a little disturbing in what they are portraying. But I don’t have a hard stance on violent video games; different games for different people. And while I don’t play violent games I think for the most part those types of games are used as a scapegoat, particularly when people act out and blame their actions on a game. I do recognize that games, like movies, have the ability to evoke emotion. But neither games nor movies make a person behave outside their norm. As I understand it, studies have been performed that show while aggressive people may play “aggressive” games, aggressive games do not convert docile people into being more combative. At the most, playing violent games is a cathartic activity. Crossroads: It’s really interesting to consider the fact that if you go in to study computer science or programming, nobody would ever on that basis accuse you of having bad intentions or doing some sort of ill to the world, until it becomes clear that you intend to program video games, or that you know about hacker culture. Those things are so intertwined in one sense, in the popular culture sense, but then in the academic sense, we think of people who study computer science as being very very different, almost harmless or geeky. It’s kind of funny. TH: It is. Crossroads: I wanted to also ask about your involvement with the International Game Developers Association (IGDA). You’re the president of your local chapter, is that right? TH: I could be considered the president, but we call the position chapter chair. It’s the person with the responsibility of coordinating the rest of the board. In 2006, when I was creating Geek House Games, I wanted to get a local IGDA chapter started in Baltimore because although there was one in Washington D.C., that’s a far commute from Baltimore, particularly after a full day’s work. I knew about the IGDA from attending a few Game Developers Conferences, but I had held off because I heard through the local grapevine that there was someone else at BreakAway who was already trying to start a local chapter. And so while I waited for it to start, I began having meetings in my house with some friends. Once a month, everyone would come over and show what games they had, whether they were board games or computer games or computer systems. Once Geek House Games started to get rolling, I realized I should just try to start to create an IGDA chapter because I didn’t know if the grapevine was correct or if that other person had time to follow through. Once I contacted the IGDA headquarters, they put me in contact with Jonathan Hamel, who was the game designer at BreakAway lookCrossroads

ing to start a local chapter. He and I came together with Soren Johnson, who was working at Firaxis at the time, and Paul Stephanouk, who was a lead game designer at Big Huge Games. The four of us talked over coffee about what it would be like for us to create a chapter, and then in 2006 we kicked off the first meeting at The Tree House Lounge. It was only later that I discovered this was a place where Microprose developers use to hang out at in the 1980s. Jonathan was elected chair for the first two years, and I have been elected chair the past two years. Our chapter has been strong, with 50/50 attendance from developers at the local AAA studios, and the other half comprising indies and educational institutions with game-related programs. Crossroads: What are some of those in your area? TH: Studio-wise, we have Firaxis Games, ZeniMax, Day 1 Studios, Digital Steamworks, Big Huge Games, BreakAway Games, and most recently Zynga and Kalypso have set up shops. Crossroads: What are some of the universities or institutes? TH: We have had tremendous support from UMBC [University of Maryland, Baltimore County], UB [University of Baltimore], and MICA [Maryland Institute College of Art]. They’ve been refining their programs for a few years and they’ve had excellent curriculum for getting students ready for game development. Recently Johns Hopkins University has started a game-related program, as well as a few other universities outside of the immediate Baltimore area. Crossroads: What do you think those students get out of attending an IGDA meeting? Can you describe what goes on at the meetings your chapter has? TH: We have a broad spectrum of meetings, but we always try to make the topic accessible to anyone regardless of what discipline they’re in— programming, animation, game design, and so forth. We want to make it interesting enough so that after spending all day working on music or art or code, developers will still want to come out. If it’s interesting to them, it should be interesting to the students as well. We’ve done some postmortems of games. We’ve had Day 1 Studios talk about how they built the engine they use inside of Fracture. We’ve had a few other companies outside Baltimore, such as Fallen Earth, come out to promote their upcoming MMO. Scaleform, who are located in D.C., came up and promoted their GFx 3.0 user interface solution about a month before they premiered it at GDC’09. We occasionally have topics that are not tied directly to a game, but broader topics, such as what makes a game fun, or this month we talked about all the new input devices that are out, from the additions on the Wiimote to Microsoft Natal, and hosted a roundtable discussion on how they’re shaping the industry. Once every year, we hold our biggest meeting with slightly over a hundred attendees, where we have an indie and student showcase of games. In the last two years, BreakAway has been kind enough to host it. We set up game stations all around for students and indie game developers to set up their games. The first year we tried this format, Firaxis hosted it. I hope we can have each Hunt Valley studio host one of these meetings as time rolls on. This year we were lucky to have Sid Meier and Firaxis’s executive producer Barry Caudil, make time to see the games. That was a treat for

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both the students, who got to see these established individuals try out their games, and employees at Firaxis, who got to hear Sid’s thoughts on the new games and their mechanics later at his weekly design meeting.

guage. I’ve found that people who tend to keep learning have the opportunities to move up to the senior-level programmers, the architects, and management.

Crossroads: To tie all these things together—being involved in the ACM during college, joining the IGDA, participating in events where you get to meet people like Sid Meier—it sounds like you’re really talking about networking.

Crossroads: Is that what you do with Geek House Games? You were saying before that it’s a creative outlet, but it seems like it would also be a place where you could self-learn some things that you may not have time to do in a regular full-time job.

TH: The industry is very small. There are thousands of game developers out there, but it seems that everyone is just a few degrees off from knowing someone else inside the industry. I know at least here, it’s a very tight-knit group inside of Hunt Valley, Maryland. Even when studios need to bring new people in, they’ll usually pool from people whom they’ve worked with before, sometimes even from other cities. During some recent layoffs in my local area, I knew of one person who didn’t get hired into a new job because he had a reputation for not being very positive and not being an easy person to work with. In that, networking is key. To be out there, to show that you do have a personality that makes people want to work with you. “Is this someone that I could go to if I needed help?” or if I needed help, I wouldn’t mind sitting in an office with for two or three hours going over lowlevel code. Trying to debug code is bad enough. Imagine having to do it with someone whom you don’t even want to be in the same space with.

TH: Yes, that is spot on. For example, I wanted to learn more about graphics programming and pixel shaders, and the engine that we’re using at Geek House Games right now support Pixel Bender, Adobe’s version of pixel shaders, and while the language is a little different from what Xbox 360 or PCs are using right now, the fundamentals translate from one to the next. Likewise, we have an artist, Toby Franklin, who worked with me at Geek House Games on a game called Collide Reactor, and he had limited experience with Flash, but working on that project, not only was he able to increase his portfolio for his 3D modeling ability, but he also increased how well he knew Flash and created games using a Flashbased pipeline. Toby is someone who has since been picked up by Firaxis since Collide Reactor came out. He’s a good example of someone who benefited directly from networking. When he was interviewing here, I could say, “I worked with this guy on a project, and I can speak to his work ethic, temperament, and ability to work with a good deal of confidence.” And that’s why I love doing Geek House Games. Besides helping me gain skills, it’s also going to lend opportunities to students or others who haven’t gotten a break yet. —Crossroads Staff

Crossroads: What kind of advice do you have for people looking to finish at university and go into the job market in the next year? TH: Never stop learning. The most important thing college should have taught you or is teaching you is how to learn. The concept of learning is more important than knowing a particular skill or lan-

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CS Education in the U.S.: Heading in the Wrong Direction? By Robert Dewar and Owen Astrachan

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ast year, Edmond Schonberg and I published an article in CrossTalk (a U.S. Department of Defense software engineering journal) titled “Computer Science Education: Where Are the Software Engineers of Tomorrow?” in which we criticized the state of computer science education in U.S. universities [9]. The article caused quite a mini-storm of discussion and was picked up by Slashdot and also by Datamation in an article titled “Who Killed the Software Engineer? (Hint: It Happened in College)” [6]. In our CrossTalk article, we expressed the general concern that the computer science curriculum was being “dumbed down” at many universities, partly in an effort to bolster declining enrollments. The enrollment decline at many universities has been dramatic, and still has not shown much sign of recovery. The twin effects of the dot-com crash and the concern of outsourcing of IT jobs seem to have convinced many parents and students that IT is not a field with a future, despite studies that project a shortage of software engineers in the near future [5]. Perhaps the global economic meltdown will slow this cycle a bit, but I tend to agree that we will be facing a real shortage of well-trained software engineers in the future. So obviously the question is what do I mean by a well-trained software engineer? To me, the critical need is the knowledge required to build large complex reliable systems. It is undeniable that our society depends in a critical manner on complex software. This is not only in the familiar areas of safety-critical software like avionics systems, but also in everyday financial systems. For example, consider the report from Moody stating a bug in the Moody computer system caused an incorrect AAA rating to be assigned to $1 billion worth of “constant proportion debt obligations” [4]. Now I do not know exactly what this means but it is surely one of the variety of peculiar economic instruments that have been factors in the current financial crisis: the credit ratings provided by agencies such as Moody are a critical element. I frequently give talks on safety- and security-critical software, and whenever I give such a talk, I peruse the news the week before for stories on computer security failures. Prior to a talk last year, the high-profile stories receiving the most media attention included the break-in to vice presidential candidate Sarah Palin’s email account and the successful hacking of the Large Hadron Collider Web site. Recently, one of my credit card companies reissued a card to me because a third-party database had been hacked (the credit card company would not identify the database). I often encounter CS faculty members who take it for granted that all large computer systems are full of bugs and unreliable, and of course our experience with popular software such as Microsoft Windows reinforces this notion. The very use of the word “virus” is annoyingly misleading because it implies that really such infections are expected and impossible to eliminate, when in fact it is perfectly possible to design reliable operating systems that are immune to casual attacks. Early in This article originally appeared in the “Viewpoints” section of Communications of the ACM 52, 7, pp. 41-45. It is reprinted here with the authors’ permission.

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the history of eBay, its auction software failed for nearly a week, and the company lost billions of dollars in capitalization. At the time I wrote to the founders of eBay that they had a company with a huge value depending on one relatively simple software application, and that there was no excuse for this application being other than entirely reliable. I commented that if their software people were telling them that such failures were inevitable, they should all be fired and replaced; I never received a reply. So just what do we need to teach our students if they are to have the right viewpoint and skills to construct the complex reliable software systems of tomorrow, and to maintain, extend, and fix the systems in use today? In my experience, undergraduate computer science curricula simply do not regard complex software construction as a central skill to be taught. Introductory courses are dumbed down in an effort to make them fun and attractive, and have sacrificed rigor in designing and testing complex algorithms in favor of fiddling around with fun stuff such as fancy graphics. Most of these courses at this stage are using Java as a first language, and all too often Java is the only language that computer science graduates know well. The original CrossTalk article was widely regarded as an anti-Java rant (one follow-up article was titled “Boffins Deride Java”) [8]. It is indeed the case that the use of Java complicates basic education of programmers. It’s not impossible to teach the fundamental principles using Java, but it’s a difficult task. The trouble with Java is twofold. First it hides far too much, and there is far too much magic. Students using fancy visual integrated development environments working with Java end up with no idea of the fundamental structures that underlie what they are doing. Second, the gigantic libraries of Java are a seductive distraction at this level. You can indeed put together impressive fun programs just by stringing together library calls, but this is an exercise with dubious educational value. It has even been argued that it is useless to teach algorithms these days. It’s as though we decided that since no one needs to know anything about how cars work, there is no point in teaching anyone the underlying engineering principles. It is vitally important that students end up knowing a variety of programming languages well and knowledge of Java libraries is not in itself sufficient. Although the article was regarded as being anti-Java that misses the main point, which is that the curriculum lacks fundamental components that are essential in the construction of large systems. The notions of formal specification, requirements engineering, systematic testing, formal proofs of correctness, structural modeling, and so forth are typically barely present in most curricula, and indeed most faculty members are not familiar with these topics, which are not seen as mainstream. For an interesting take on the importance of a practical view, see Jeff Atwood’s column discussing the need to teach deployment and related practical subjects [1]. Another area of concern is that the mathematics requirements for many CS degrees have been reduced to a bare minimum. An interesting data point can be found in the construction of the iFacts system [7], a ground-based air-traffic control system for the U.K. that is being programmed from scratch using SPARK-Ada and formal specification and proof of correctness techniques [2]. It has not been easy to find programmers with the kind of mathematical skills needed to deal with formal reasoning. And yet, such formal reasoning will become an increasingly important part of software construction. As an example,

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consider that of the seven EAL levels of the Common Criteria for security-critical software, the top three require some level of formal reasoning to be employed [3]. It is true that a lot of software development is done under conditions where reliability is not seen as critical, and the software is relatively simple and not considered as safety- or security-critical. However, if this is all we train students for then we won’t have the people we need to build large complex critical systems, and furthermore this kind of simple programming is exactly the kind of job that can be successfully transferred to countries with less expensive labor costs. We are falling into a trap of training our students for outsourceable jobs. The original article in CrossTalk was based on our observations as faculty members and as software company entrepreneurs, rather than on a carefully researched study. When several people asked us for data to back up our claims, we had none to offer. Since then, however, it has been very interesting to read the flood of email we received in response to this article. In hundreds of messages, we did not get anyone saying “what are you talking about? We have no trouble hiring knowledgeable students!” On the contrary, we got hundreds of messages that said “Thank you for pointing out this problem, we find it impossible to hire competent students.” One person related an experience where he had a dump from a customer for a program that had blown up and was sifting through it trying to determine what was causing the problem. A newly hired student asked him what he was doing, and he said that he was disassembling the hex into assembly language to figure out the problem. The student, who had always considered himself superior because of his computer science degree, replied “Oh yes, assembly language, I’ve heard of that,” and was amazed that the senior programmer (whose degree was in music) could in fact figure out the problem this way. Another company noted that it had found it a complete waste of time to even interview graduates from U.S. universities, so they added at the end of the job description the sentence “This work will not involve Web applications or the use of Java,” and that had served to almost completely eliminate U.S. applicants. Here was a case of domestic outsourcing where they were looking for people in the U.S. who had been trained in Europe and elsewhere and were better educated in the fundamentals of software engineering. These are just two examples of many similar responses, so it is clear that we have hit on a problem here that is perceived by many to be a serious one.

Biography Robert Dewar ([email protected]) is a professor emeritus of computer science at the Courant Institute of New York University and is cofounder, president, and CEO of AdaCore.

References 1. Atwood, J. 2008. How should we teach computer science? Coding horror. http://www.codinghorror.com/blog/archives/001035.html. 2. Barnes, J. 2003. High Integrity Software—The SPARK Approach to Safety and Security. Addison-Wesley. 3. Common Criteria. 2006. Common criteria for information technology security evaluation, Version 3.1. http://www. commoncriteriaportal.org.

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CS Education in the U.S.: Heading in the Wrong Direction?

4. Farrell, N. 2008. Boffins deride Java. The Inquirer. http://www. theinquirer.net/gb/inquirer/news/2008/01/08/boffins-deride-java. 5. Maloney, P. and Leon, M. 2007. The state of the national security space workforce. http://www.aero.org/publications/crosslink/ spring2007/01.html. 6. McGuire, J. 2008. Who killed the software engineer? (Hint: It happened in college.) Datamation. http://itmanagement.earthweb. com/career/article.php/3722876. 7. National Air Traffic Services. NATS pioneers biggest ATC advance since radar. http://www.nats.co.uk/article/218/62/nats_pioneers_ biggest_atc_advance_since_radar.html. 8. Oates, J. 2008. Moody’s to fix sub-prime computer error. The Register. http://www.theregister.co.uk/2008/07/03/moodys_ computer_bug. 9. USAF Software Technology Support Center (STSC). 2008. Computer science education: Where are the software engineers of tomorrow? CrossTalk. http://www.stsc.hill.af.mil/CrossTalk/2008/ 01/0801DewarSchonberg.html.

Counterpoint: Owen Astrachan Robert Dewar has graciously shouldered the task of castigating the language commonly used in introductory programming courses. Dewar, like Edsger Dijkstra [13] and others before him, holds the language at least partially responsible for, and decries the state of, computer science curricula; he then attempts to use the programming language as a lever to move curricula in a particular direction. However, the lever of the introductory programming language is neither long enough nor strong enough to move or be responsible for our curricula. Attempts to use it as such can generate discussion, but often more heat than light. The discussion is often embroiled in fear, uncertainty, and doubt (aka FUD) rather than focused on more profound issues. There are definite elements of FUD in the arguments offered by Dewar just as there have been by his predecessors in making similar arguments. Whereas Dijkstra lamented “the college pretending that learning BASIC suffices or at least helps, whereas the teaching of BASIC should be rated as a criminal offense: it mutilates the mind beyond recovery” we see Dewar noting that “It’s not impossible to teach the fundamental principles using Java, but it’s a difficult task.” Dewar and Dijkstra perhaps would like us to return to the glorious days of text editors and punch cards rather than “fancy visual IDEs.” However, the slippery slope of assumption that the new generation just doesn’t get it leads to the Sisyphean task of pushing the pebble of language, be it BASIC or Java, uphill against the landslide of boulders that represents the reality of computer science. This is the case regardless of whether we’re in Dijkstra’s world of 25 years ago, the world of 2009, or the Skynet world of tomorrow—which is probably closer than we think. I don’t mean to suggest that Dewar and Dijkstra are arguing for the same thing. Dewar would like computer science programs to produce well-trained software engineers who can build large complex reliable systems. Dijkstra excoriated software engineering at every opportunity fixing as its charter the phrase “how to program if you cannot.” Both miss part of the bigger picture in the same way that Stephen Andriole missed it in the July 2008 Communications Point/Counterpoint “TechCrossroads

nology Curriculum for the Early 21st Century” [10]. In his Counterpoint, Eric Roberts points out the flaw of “generalizing observations derived from one part of the field to the entire discipline.” Computer science programs must embrace a far wider audience than software engineers building secure systems. Many top programs are housed in schools of Arts and Sciences rather than in Engineering, many have chosen not to be accredited by CSAB/ABET Students may choose computer science as a stepping-stone to law, medicine, philosophy, or teaching rather than as a foundation for becoming a programmer or software engineer. Schools like Georgia Tech are developing innovative programs to address the different needs of diverse audiences: students looking to computer science as the basis for visual studies or biology rather than preparing them for a software-oriented career. There is no one-size-fitsall solution to addressing the skills and knowledge needed to succeed in these areas. Should we expect Craig Venter or Gene Myers to ask computer science programs to include more computational biology because the demand for bioinformaticians exceeds supply? Will we be surprised if Ken Perlin asks for programs to embrace games and graphics more than they do to ensure a steady supply of people interested in animation or computer-generated imagery? We are discussing the requirements and curricula of an undergraduate degree! Our programs can certainly build a superb foundation on which students can continue to gain knowledge and skills as they work and study in different areas, but we should no more expect students to be expert or even journeymen than we expect our premed students to be able to remove an appendix after four years of undergraduate study. As Fred Brooks reminded us more than 20 years ago, there is no silver bullet that will solve the problems endemic to software development nor is there a panacea to cure the ills that may plague computer science curricula and programs [11]. Studying more mathematics will not make software bugs disappear, although both Dijkstra and Dewar seem to think so. Dewar points out the need for “formal specification and proof of correctness techniques” as foundational for software development using Ada. Dijkstra tells us “where to locate computing science on the world map of intellectual disciplines: in the direction of formal mathematics and applied logic,” but pines for Algol rather than Ada. Both miss Brooks’ point about the essential complexity of building software, the essence in the nature of software. In a wonderful treatise that has more than stood the passage of 20 years and in which he presciently anticipated the tenets of Agile software methodologies, Brooks claims that “building software will always be hard,” and that this essence will not yield dramatic improvements to new languages, methodologies, or techniques. Brooks has hopes that the essential aspects and difficulties of software may be improved by growing software rather than building it, by buying software rather than constructing it, and by identifying and developing great designers. He differentiates between essential and accidental aspects of software where accidental is akin to incidental rather than happenstance. Changing programming languages, using MapReduce or multicore chips, and employing a visual IDE in introductory courses address these accidental or incidental parts of software development, but these don’t mitigate the essential problems in developing software nor in educating our students. As Brooks notes, addressing these accidental aspects is important—high-level languages offer dramatic improvements over assembly-language programming both for software design and for introductory programming courses.

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Brooks’ view, which I share, calls for “Hitching our research to someone else’s driving problems, and solving those problems on the owners’ terms, [which] leads us to richer computer science research” [12]. I will return to problem-driven approaches later. It would seem from the juxtaposition of amusing anecdotes regarding flawed software systems that Dewar would like to make the academic community and the larger computer science and software communities aware that a simple change in attitude and programming language in our colleges and curricula will help make the world more secure and safe with respect to the reliable systems on which it depends. Although software runs on computers it produces outputs and effects that transcend computers. It was not a simple bug in Moody’s computer system that caused constant proportion debt obligations to be incorrectly assigned the AAA rating. The model that Moody used was likely incorrectly parameterized. Even if the flaw was related to code, rather than to a model, Moody‘s correction of the model did not lead to a change in the AAA rating as it should have because of larger and more deeply entrenched financial and political concerns. Standard and Poor’s model also assigned the AAA rating to the same constant proportion debt obligations. Both services eventually lowered their ratings, but arguably these actions were insufficient. Blaming the current economic crisis even in part on software errors is more than a stretch. Similarly, Dewar notes that U.S. vice presidential nominee Sarah Palin’s email account was compromised and that a Web site was hacked, implying these are security failures that might be fixed if only we didn’t use Java in our introductory courses. Because Governor Palin used Yahoo mail for what appears to be at least semiofficial business, her password recovery mechanisms were based on publicly available information such as her birthday, and her hacked email was posted on 4chan and Wikileaks: this is a case study in social engineering rather than one in secure systems. Dewar’s claim that Java is part of a “dumbing down” of our curricula has been echoed in other venues, notably by Joel Spolsky [15] and Bjarne Stroustrup [14]. However, Stroustrup notes that it isn’t the language that’s a problem—it is attitude. He says, and I agree that: “Education should prepare people to face new challenges; that’s what makes education different from training. In computing, that means knowing your basic algorithms, data structures, system issues, etc., and the languages needed to apply that knowledge. It also means having the high-level skills to analyze a system and to experiment with alternative solutions to problems. Going beyond the simple library-user level of programming is especially important when we consider the need to build new industries, rather than just improving older ones.” These articles, like Dewar’s, associate Java with a “dumbing down” of curricula. Spolsky specifically mentions the school at which I teach as one of the new JavaSchools. He laments that our students are lucky in that: “The lucky kids of JavaSchools are never going to get weird segfaults trying to implement pointer-based hash tables. They’re never going to go stark, raving mad trying to pack things into bits.” We didn’t become a JavaSchool because we wanted to avoid segfaults, pointers, and bits. We use the same assignments and have the same attitude we did when we used C++. We switched from C++ for well-founded pedagogical reasons: Java is a better teaching language for the approach we were using than C++. Note that I’m not claiming Java is the best language for every program, but we spend much more

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time in our courses dealing with the Brooksian essence of programming, algorithms, and software using Java rather than with the accidental aspects symbolized by the kind of cryptic error messages that result from misusing the STL in C++. Our switch to Java was grounded neither in perceived demands from industry nor in an attempt to attract majors to our program, but in working to ensure that our beginning courses were grounded in the essence of software and algorithms. We must work to ensure we attract motivated and capable students, not because it is incumbent on us as faculty to train the next generation of software engineers, but because it is our responsibility as educators and faculty to encourage passion and to nurture and increase the amazing opportunities that computing is bringing to our world. It is highly likely that some programming languages are better for teaching, others are better for Ajax applications, and the right flavor of Linux makes a difference. But we shortchange our students and ourselves if we live at the level of what brand of brace and bit or drill is best for a carpenter. Instead, we should look for problems that motivate the study of computing, problems that require computation in their solution. Just as we cannot escape the essential complexity and difficulty of developing software we cannot escape the essence of undergraduate education. We each bear the burden of our past experiences in constructing models for education. In my case this is the grounding of computer science as a liberal art, since my education began in that realm. For others, computer science is clearly an engineering discipline and to others still it is a science akin to biology or physics. We don’t need to look for which of these is the correct view; they are all part of our discipline. The sooner we accept differing views as part of the whole, rather than insisting that our personally grounded view is the way to look at the world, the sooner we will make progress in crafting our curricula to meet the demands and dreams of our students.

Biography Owen Astrachan ([email protected]) is professor of the practice of computer science at Duke University and the department’s director of undergraduate studies for teaching and learning.

References 1. Andriole, S. J. and Roberts, E. 2008. Technology curriculum for the early 21st century. Comm. ACM 51, 7. 27-32. 2. Brooks, F. 1987. No silver bullet: Essence and accidents of software engineering. IEEE Computer 20, 4. 10-19. (Reprinted in The Mythical Man-Month: Essays on Software Engineering, Anniversary Edition. Addison-Wesley, 1995.) 3. Brooks, F. 1996. The computer scientist as toolsmith II. Comm. ACM 39, 3. 61-68. 4. Dijkstra, E. 1984 Keynote address at ACM South Central Regional Conference. http://www.cs.utexas.edu/users/EWD/ transcriptions/EWD08xx/EWD898.html. 5. Maguire, J. 2008. Bjarne Stroustrup on educating software developers. Datamation. http://itmanagement.earthweb.com/features/ article.php/3789981/. 6. Spolsky, J. 2005. The perils of JavaSchools. Joel on Software. http:// www.joelonsoftware.com/articles/ThePerilsofJavaSchools.html.

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