The benefits of component technologies are well known: they enable encapsulation, modular construction of applications and software reuse. The DOE sponsored Common Component Architecture (CCA) [3] project adopts a component-based approach for building large scale scientific applications. On the other hand, the Web services-based Open Grid Service Architecture (OGSA) and Infrastructure (OGSI) [14] come close to defining a component architecture for the Grid. Using an approach where a CCA component is modeled as a set of Grid services, the XCAT3 framework allows for CCA components to be compatible with the OGSI specification. This enables CCA components to be accessible via standard Grid clients, especially the ones that are portal-based. For CCA compatibility, XCAT3 uses interfaces generated by the Babel [5] toolkit, and for OGSI compatibility, it uses the Extreme GSX [12] toolkit. In this paper, we describe our experience in implementing the XCAT3 system, and how it can be used to compose complex distributed applications on the Grid in a modular fashion.