The current efforts on programming grid applications often rely on service-oriented approaches like Grid Services. This paper presents HOC-SA - a Service Architecture for Higher-Order Components, which provides the programmer with reusable and composable patterns of parallelism and is interoperable with the latest Globus Toolkit implementations. We describe our implementation of HOC-SA using OGSA-DAI, a framework for integrating grids with distributed databases. We present a simple example application and report first measurements on our grid testbed.