The article discusses the reliability of distributed systems and the role of process groups and group programming tools in constructing reliable distributed software. It reviews 10 years of research on ISIS, a system designed to support the development of reliable distributed software. The thesis underlying ISIS is that reliable distributed software can be simplified by using process groups and group programming tools. The article describes the approach taken, surveys the system, and discusses experiences with real applications, particularly in brokerage and trading systems. The article highlights the importance of reliable communication and fault-tolerant behavior in distributed systems, especially in applications where high reliability is crucial, such as trading strategies that rely on accurate pricing and market-volatility data. It emphasizes the need for a system that can serve multiple communities, including the firm, brokers, and system administrators, each with their own requirements for reliability, speed, customization, and uniformity. The article also addresses the challenges of group communication patterns and programming in contemporary distributed computing environments, which often lack support for these features. It proposes a virtual synchrony execution model to integrate group programming mechanisms into a single environment, providing a powerful guarantee that simplifies distributed application design. The model allows for asynchronous interactions, which can significantly improve performance in high-throughput applications. Finally, the article discusses the technical issues and solutions related to group addressing, message delivery ordering, state transfer, and fault tolerance, emphasizing the importance of reliable communication and fault-tolerant behavior in distributed systems.The article discusses the reliability of distributed systems and the role of process groups and group programming tools in constructing reliable distributed software. It reviews 10 years of research on ISIS, a system designed to support the development of reliable distributed software. The thesis underlying ISIS is that reliable distributed software can be simplified by using process groups and group programming tools. The article describes the approach taken, surveys the system, and discusses experiences with real applications, particularly in brokerage and trading systems. The article highlights the importance of reliable communication and fault-tolerant behavior in distributed systems, especially in applications where high reliability is crucial, such as trading strategies that rely on accurate pricing and market-volatility data. It emphasizes the need for a system that can serve multiple communities, including the firm, brokers, and system administrators, each with their own requirements for reliability, speed, customization, and uniformity. The article also addresses the challenges of group communication patterns and programming in contemporary distributed computing environments, which often lack support for these features. It proposes a virtual synchrony execution model to integrate group programming mechanisms into a single environment, providing a powerful guarantee that simplifies distributed application design. The model allows for asynchronous interactions, which can significantly improve performance in high-throughput applications. Finally, the article discusses the technical issues and solutions related to group addressing, message delivery ordering, state transfer, and fault tolerance, emphasizing the importance of reliable communication and fault-tolerant behavior in distributed systems.