Systems of Systems (SoSs) integrate many critical systems our society relies on. In designing individual systems, stakeholders use bespoke protocols, custom information models, and proprietary components with limited computational resources from various vendors. We present a reference architecture that allows multiple stakeholders to carry out a flexible integration without giving up control to a single entity in the presence of the aforementioned limitations. Our architecture relies on rule engines and graph data model to integrated systems flexibly even when black-box components are used. At the same time, a federation of the rule engines allows each stakeholder to retain control over the rules that reflect their policies. We also rely on a common information model based on ontologies to account for the information model mismatch and reduce the duplication of integration efforts. Moving rule execution to the standalone rule engines allows deployment in resource-constrained and proprietary environments. A uniform application programming interface (API) is used to integrate rule engines across systems as well as components within each system with a respective rule engine. We also present a novel algorithm to determine dependencies across rules deployed in different rule engines within the federation. This allows domain experts to develop rules as usual without having to deal with the distributed aspect of the system. We also present a proof of the sufficient condition to ensure all necessary notifications will be sent to ensure correct rule activation across different rule engines. Compared to other systems involving distributed rules, the proposed architecture is well-suited for the integration of transactional workloads commonly found in enterprises. The qualitative evaluation based on the Architecture Tradeoff Analysis Method (ATAM), applied to a telecommunications use case, shows that the architecture possesses the “interoperability”, “modifiability”, and the “functional completeness” quality attributes with a trade-off around rule expressiveness. The quantitative evaluation demonstrates speedup over the single-node setup in most scenarios except in case of highly optimized rules and a poor network performance simultaneously ($t_r<10ms$, $t_n=100ms$).

系统的系统 (SoS) 集成了我们社会所依赖的许多关键系统。在设计单个系统时，利益相关者使用来自不同供应商的定制协议、定制信息模型和具有有限计算资源的专有组件。我们提出了一个参考架构，允许多个利益相关者进行灵活的集成，而不会在存在上述限制的情况下放弃对单个实体的控制。我们的架构依靠规则引擎和图数据模型来灵活地集成系统，即使使用黑盒组件也是如此。同时，规则引擎的联合允许每个利益相关者保留对反映其政策的规则的控制。我们还依靠基于本体的通用信息模型来解决信息模型不匹配的问题并减少集成工作的重复。将规则执行转移到独立规则引擎允许在资源受限和专有环境中进行部署。统一的应用程序编程接口（API）用于跨系统集成规则引擎以及每个系统内的组件与各自的规则引擎。我们还提出了一种新颖的算法来确定联邦内不同规则引擎中部署的规则之间的依赖关系。这使得领域专家可以照常开发规则，而无需处理系统的分布式方面。我们还提供充分条件的证明，以确保发送所有必要的通知，以确保跨不同规则引擎正确激活规则。与涉及分布式规则的其他系统相比，所提出的架构非常适合企业中常见的事务工作负载的集成。基于架构权衡分析方法（ATAM）的定性评估应用于电信用例，表明该架构具有“互操作性”、“可修改性”和“功能完整性”质量属性，并围绕规则进行权衡表现力。定量评估表明，在大多数情况下，除了高度优化的规则和网络性能较差的情况外，单节点设置的速度都提高了（$t_r<10米s$,$t_n=100米s$）。