Reentrancy and Scoping for Multitenant Rule Engines

Multitenant web systems can share one application instance across many clients distributed over multiple devices. These systems need to manage the shared knowledge base reused by the various users and applications they support. Rather than hard-coding all the shared knowledge and ontologies, developers often encode this knowledge in the form of rules to program server-side business logic. In such situations, a modern rule engine can be used to accommodate the knowledge for tenants of a multitenant system. Existing rule engines, however, were not conceptually designed to support or cope with the knowledge of the rules of multiple applications and clients at the same time. They are not fit for multitenant setups since one has to manually hard-code the modularity of the knowledge for the various applications and clients, which quickly becomes complex and fallible. We present Serena, a rule-based framework for supporting multitenant reactive web applications. The distinctive feature of Serena is the notion of reentrancy and scoping in its Rete-based rule engine, which is the key solution in making it multitenant. We validate our work through a simulated case study and a comparison with a similar common-place approach, showing that our flexible approach improves computational efficiency in the engine.