AWS and authors have introduced agentic overlays as a solution for enterprises looking to integrate existing REST-based services into the emerging agent-to-agent (A2A) framework. These overlays allow traditional REST APIs to participate in A2A communication without duplicating code or running parallel infrastructures. This approach helps reduce agent sprawl and operational complexity, enabling enterprises to adopt AI more effectively. The solution is designed to let existing services act as agents without altering their core business logic, making the transition smoother and more cost-effective.
Agentic overlays function as thin wrapper layers that transform REST-based services into agents capable of engaging in A2A interactions. They convert agentic messages into REST payloads and vice versa, while also exposing REST APIs as tools compatible with the Model Context Protocol (MCP). This allows enterprises to add A2A capabilities to legacy systems without the need for major overhauls. The approach also supports a single deployment pipeline, which simplifies the process of adding new routes and scaling to handle increased traffic.
The challenge lies in the difference between REST APIs and A2A communication paradigms. REST is designed for deterministic, client-server integration, while A2A focuses on reasoning-driven coordination and agent collaboration. This difference makes it difficult for enterprises to integrate existing services into standardized agentic communication without significant changes. Agentic overlays aim to bridge this gap by reusing existing services as agents, thus avoiding the need to maintain separate stacks or duplicate code.
Source: awsml
