D4Science interoperability framework: developer guidance for service integration

The D4Science Interoperability Framework provides the architectural backbone for integrating and operating heterogeneous services within the D4Science ecosystem. D4Science is a distributed digital infrastructure supporting international research communities through the operation of Virtual Research Environments (VREs) that enable collaborative access to data, analytical tools, and computing resources in line with Open Science and FAIR principles. The framework integrates core components such as the VRE Gateway, Virtual Labs, Identity and Access Management (IAM), and the Analytics Engine to deliver secure, scalable, and reproducible workflows. This document offers detailed guidance for service developers, covering containerisation, orchestration with Docker Swarm, authentication with OpenID Connect and OAuth2, and integrated monitoring and auditing tools. By combining federated access, container based deployment, and robust governance mechanisms, this solution enables developers and researchers to create reusable, interoperable, and compliant services that advance collaborative and transparent scientific research.