Summary With the single‐instance multitenancy (SIMT) model for composite Software‐as‐a‐Service (SaaS) applications, a single composite application instance can host multiple tenants, yielding the benefits of better service and resource utilization and reduced operational cost for the SaaS provider. An SIMT application needs to share services and their aggregation (the application) among its tenants while supporting variations in the functional and performance requirements of the tenants. The SaaS provider requires a middleware environment that can deploy, enact, and manage a designed SIMT application, to achieve the varied requirements of the different tenants in a controlled manner. This paper presents the SDSN@RT (software‐defined service networks at runtime) middleware environment that can meet the aforementioned requirements. SDSN@RT represents an SIMT composite cloud application as a multitenant service network, where the same service network simultaneously hosts a set of virtual service networks, one for each tenant. A service network connects a set of services and coordinates the interactions between them. A virtual service network realizes the requirements for a specific tenant and can be deployed, configured, and logically isolated in the service network at runtime. SDSN@RT also supports the monitoring and runtime changes of the deployed multitenant service networks. We show the feasibility of SDSN@RT with a prototype implementation and demonstrate its capabilities to host SIMT applications and support their changes with a case study. The performance study of the prototype implementation shows that the runtime capabilities of our middleware incur little overhead.

A composite cloud application can achieve economies of scale by sharing partner services between tenants at runtime, following the Single-Instance Multi-Tenancy (SIMT) model. However, supporting runtime sharing with tenant-specific functional and performance variations in an SIMT application is challenging. We address this challenge by proposing the Software-Defined Service Networking (SDSN) approach. SDSN realizes an SIMT composite cloud application with a managed service network and a set of managed virtual service networks (VSNs) that share the service network. The service network is formed by connecting a set of partner services according to their capabilities and interoperability. To achieve the functional and performance requirements of a particular tenant, a VSN composes a subset of the services under a specific configuration design over the service network, and regulates the interactions between the services concerned according to a specific regulation design. We describe how a service network and its VSNs are designed and enacted to achieve the SIMT objectives. We show the feasibility of SDSN, demonstrate the utilization benefits it achieves, and quantify the runtime overhead it incurs.

In Software-as-a-Service (SaaS) delivery model a vendor maintains a single application instance, which is used by multiple tenants. However, due to changing business requirements tenants expect customizations. Providing such customizations is trivial to retain tenants but a challenge to the vendor due to multi-tenancy. In this paper we present an approach to define such customizable business processes in multi-tenant SaaS applications without unnecessary and hard to maintain duplication of process definitions and deployments.

Service oriented architecture plays a prominent role in creating and utilizing business services in enterprise computing environments. The service composers produce value by aggregating lower-level re-usable services, scattered across the internet to create application level services. Web service middleware facilitates in defining service compositions in a comprehensive manner. However, in order to ensure the business viability amidst unpredictably changing business requirements, such compositions may need to adapt during the runtime. Such changes might vary from a minor regulation to a major re-structuring of the IT service composition. However, the complexity of the composition shouldn't increase and the runtime interruptions to the service delivery need to be kept to a minimum. In this paper we introduce ROAD4WS, which is a middleware extension to the popular Apache Axis2 web service engine. The extension brings together the modular adaptive architecture of the Role Oriented Adaptive Design (ROAD) with the web services deployment and consumption capabilities of the Apache Axis2 engine, in order to facilitate deploying adaptive service compositions.