Building Executable Research Workflows for SSH Infrastructures: A WSO2-Based Orchestration Methodology within the H2IOSC Marketplace

Research infrastructures in the Social Sciences and Humanities (SSH) offer a growing number of specialized digital services – from image repositories and handwritten text recognition engines to semantic annotation platforms and digital publishing systems. However, researchers who need to combine multiple services into coherent research workflows typically face the burden of manually transferring data between systems, adapting output formats, and managing authentication across platforms. This paper presents a methodology for building executable, orchestrated research workflows within the H2IOSC Marketplace, using WSO2 Micro Integrator as the orchestration engine. The methodology builds on the orchestration framework that CNR-ILIESI and OPERAS-IT have designed and documented since March 2023 as the reference model for cross-infrastructure service integration within H2IOSC. We describe the complete lifecycle of an orchestrated workflow: from service registration and API specification, through pipeline design and implementation using WSO2 artifacts (APIs, sequences, mediators, message stores, and message processors), to packaging, deployment, and publication in the Marketplace. We detail the architectural patterns required for robust cross-infrastructure orchestration, including asynchronous polling for long-running services, payload transformation between heterogeneous APIs, XSLT-based format conversion, and error handling in distributed environments. The methodology is grounded in the orchestration framework conceived by OPERAS-IT within the H2IOSC project, which distinguishes between orchestration (remote, cross-infrastructure service coordination) and composition (local, intra-infrastructure service organization). We provide reusable design patterns and implementation guidelines that can be adopted by other federated research infrastructure projects facing similar integration challenges. The methodology applies to both WSO2 Micro Integrator (for workflow execution) and WSO2 API Manager (for API governance and lifecycle management), covering the complete WSO2 integration stack as deployed within the H2IOSC Marketplace architecture.