AsyncSLA: Towards a Service Level Agreement for Asynchronous Services

Complex distributed systems increasingly involve physical components as part of cyber-physical systems or Internet of things initiatives. Communication with such subsystems is typically asynchronous. Several initiatives like Web of Things or AsyncAPI have emerged to standardize and facilitate the definition of such asynchronous communications. However, these initiatives do not cover standards to specify the quality of service or define service level agreements (SLAs) for these asynchronous interactions. To address this issue, this paper proposes both a comprehensive quality model for asynchronous services based on the ISO/IEC 25010 standard, and a domain specific language to specify SLAs for asynchronous services based on the WS-Agreement standard. To facilitate its adoption, our proposed solution has been expressed also as an extension for the AsyncAPI specification. Finally, we provide a tool support to define these SLAs by extending an existing toolkit.