The design and implementation of remote laboratories present different levels of complexity according to the nature of the equipments operated by the remote laboratory, the requirements imposed on the accessing computers, the network linking the user to the laboratory, and the type of experiments the laboratory supports. This paper addresses the design and implementation of remote laboratories employing web technologies, both at the client and the server side. These types of remote laboratories are called WebLabs, and can be deployed over different networks such as the public internet, campuswide networks, or high-speed private networks. Although most published works on WebLabs focus on their functional and operational aspects, nonfunctional requirements related to security, quality of service, and federated operation of WebLabs have received little attention. This paper addresses how these requirements can be incorporated into WebLab design, and discusses the most appropriate web technologies to fulfill such requirements. (Contains 4 tables and 12 figures.)