It was common that software vendors sell licenses to their clients to use software products, such as Enterprise Resource Planning, which are deployed as a monolithic entity on clients’ premises. Moreover, many clients, especially big organizations, often require software products to be customized for their specific needs before deployment on premises. However, as software vendors are migrating their monolithic software products to Cloud-native Software-as-a-Service (SaaS), they face two big challenges that this paper aims at addressing: (1) How to migrate their exclusive monoliths to multi-tenant Cloud-native SaaS; and (2) How to enable tenant-specific customizations for multi-tenant Cloud-native SaaS. This paper suggests an approach for migrating monoliths to microservice-based Cloud-native SaaS, providing customers with a flexible customization opportunity, while taking advantage of the economies of scale that the Cloud and multi-tenancy provide. We develop two proofs-of-concept to demonstrate our approach on migrating a reference application of Microsoft called SportStore to a customizable SaaS as well as customizing another Microsoft’s microservices reference application called eShopOnContainers. We have shown not only the migration to microservices but also how to introduce the necessary infrastructure to support the new services and enable tenant-specific customization. Our customization-driven migration approach can guide a monolith to become SaaS having (synchronous and asynchronous) customization power for multi-tenant SaaS. Furthermore, our event-based customization approach can reduce the number of API calls to the main product while enabling different tenant-specific customization services for real-world scenarios.

It was common that software vendors sell licenses to their clients to use software products, such as Enterprise Resource Planning, which are deployed as a monolithic entity on clients’ premises. Moreover, many clients, especially big organizations, often require software products to be customized for their specific needs before deployment on premises. While software vendors are trying to migrate their monolithic software products to Cloud-native Software-as-a-Service (SaaS), they face two big challenges that this paper aims at addressing: 1) How to migrate their exclusive monoliths to multi-tenant Cloud-native SaaS; and 2) How to enable tenant-specific customization for multi-tenant Cloud-native SaaS. This paper suggests an approach for migrating monoliths to microservice-based Cloud-native SaaS, providing customers with a flexible customization opportunity, while taking advantage of the economies of scale that the Cloud and multi-tenancy provide. Our approach shows not only the migration to microservices but also how to introduce the necessary infrastructure to support the new services and enable tenant-specific customization. We illustrate the application of our approach on migrating a reference application of Microsoft called SportStore.