Building layered active services

The NodeOS and execution environment (EE) layers of the active network architectural framework are designed to offer a general purpose programming environment to active applications (AAs). However, the architecture suffers from the lack of higher-level APIs and services that would simplify AA code and could be shared by multiple AAs. We propose a modified architecture that introduces an Application Environment (AE) layer above the EE layer to fill the gap. The AE layer offers higher-level services to simplified User-define Processing Modules (UPMs). Together they replace the conventional AA and offer a higher-level API to code to. This paper discusses the issues that arise when breaking the existing AA layer into two layers, and presents our experiences implementing a concast service using the new architecture. We also present performance numbers for our concast service (running on the ASP EE) that show the additional overhead incurred is acceptable.