Component-based software composition offers a development approach with reduced time-to-market and cost while achieving enhanced productivity, quality and maintainability. Existent work on the composition paradigm focuses on static composition, which is not sufficient in a distributed environment, in which both constituent components and the assembled distributed system are subject to dynamic adaptation. This paper presents two types of dynamic composition for distributed components: assertive and autonomous over a .NET based Web Services environment. Three case studies are provided to illustrate the use of assertive and autonomous composition.