An integrated software environment for distributed systems development

New tools simplify many tasks associated with designing, managing, andevaluatingcomputer programsthat runonthousandsofcomputers worldwide. As the number and diversity of Internet users continue to increase, Internet-based services—such as search engines and news websites—require more computing power in remote loca- tions to satisfy user demand. Rather than hosting these services on a single centrally located server, companies are beginning to distribute the computing workload across thousands of servers worldwide. These distributed systems offer a number of advantages, including improved reliability and performance. However, designing and implementing a program that simulta- neously runs on thousands of computers also introduces many new challenges to software developers, such as maintaining con- sistency across machines, evaluating performance, and detecting and recovering from errors. To better understand these challenges, we now consider the tasks required to develop a distributed system. We group these tasks into three distinct phases: design and implementation, large-scale testing and evaluation, and wide-area deployment. The design and implementation phase involves writing code that accomplishes the goals of the target system. Next, the test- ing and evaluation phase looks for potential problems with the initial system design and corrects any bugs that may hinder per- formance. It is important to thoroughly test the code in a variety of settings that represent several different potential usage mod- els of the system. After determining that the code behaves as ex- pected and achieves high performance in the test cases, the final step is to deploy the program across the Internet and evaluate its performance. We have developed a number of tools that sim- plify the tasks involved with each of these phases, as described below. While individually valuable, together these tools form an