There are several strategies/philosophies of IS development (structured, data-oriented, object-oriented, service-oriented, and agile programming). Their application was to a high degree implied by technological conditions. The strategies have been determining the information systems architecture and the tools and methods of requirement specification. Due the success of new strategies the older ones are improperly considered to be obsolete. There are discussed the conditions under which the application of a particular strategy is not only feasible but optimal and when and how different strategies are to be combined. All the strategies except the service-oriented one are suited to the development of application more or less from scratch. The application has a programmed number of threads. The current largest information systems like the systems supporting e-government or global enterprises must have service-oriented architecture of a specific form -- software confederations. Confederation-oriented strategy is different from the other strategies but it can (should) be combined with them. The main differences are in the use of legacy systems and software standards.