Current Grid-aware applications are developed on existing software infrastructures, such as Globus, by developers who are experts on Grid software implementation. Although many useful applications have been produced this way, this approach may hardly support the additional complexity to Quality of Service (QoS) control in real application. We describe the ASSIST programming environment, the prototype of parallel programming environment currently under development at our group, as a suitable basis to capture all the desired features for QoS control for the Grid. Grid applications, built as compositions of ASSIST components, are supported by an innovative Grid Abstract Machine, which includes essential abstractions of standard middleware services and a hierarchical Application Manager, which may be considered as an early prototype of AutonomicManager.