Patterns for Managing Tenants in a Multi-tenant Application

Abstract: A Software-as-a-Service offering provides ready to use solutions for its tenants. Tenants having different quality requirements are deployed on separate dedicated instances. The concerns related to generating variable quality responses using single instance are not explicitly handled in current design approaches. A lack of standardized tactics and design guidelines also make it difficult for an architect to embed these multi-tenant design decisions at the early stage. In this work, we highlight a few domain-independent architectural concerns that can be used to manage multiple heterogeneous tenants on a shared application instance. We derive some quality requirements that are significant in the multi-tenant scenario, related tactics, measurements and analyze the impact on other software product quality attributes.

Abstract: Numerous systems have been designed which use virtualization to subdivide the ample resources of a modern computer. Some require specialized hardware, or cannot support commodity operating systems. Some target 100% binary compatibility at the expense of performance. Others sacrifice security or functionality for speed. Few offer resource isolation or performance guarantees; most provide only best-effort provisioning, risking denial of service.This paper presents Xen, an x86 virtual machine monitor which allows multiple commodity operating systems to share conventional hardware in a safe and resource managed fashion, but without sacrificing either performance or functionality. This is achieved by providing an idealized virtual machine abstraction to which operating systems such as Linux, BSD and Windows XP, can be ported with minimal effort.Our design is targeted at hosting up to 100 virtual machine instances simultaneously on a modern server. The virtualization approach taken by Xen is extremely efficient: we allow operating systems such as Linux and Windows XP to be hosted simultaneously for a negligible performance overhead --- at most a few percent compared with the unvirtualized case. We considerably outperform competing commercial and freely available solutions in a range of microbenchmarks and system-wide tests.

Abstract: Checkpointing of parallel applications can be used as the core technology to provide process migration. Both checkpointing and migration, are an important issue for parallel applications on networks of workstations. The CoCheck environment which we present in this paper introduces a new approach to provide checkpointing and migration for parallel applications. CoCheck sits on top of the message passing library and achieves consistency at a level above the message passing system. It uses an existing single process checkpointer which is available for a wide range of systems. Hence, CoCheck can be easily adapted to both, different message passing systems and new machines.

Abstract: Multi-tenancy is a relatively new software architecture principle in the realm of the Software as a Service (SaaS) business model. It allows to make full use of the economy of scale, as multiple customers - "tenants" - share the same application and database instance. All the while, the tenants enjoy a highly configurable application, making it appear that the application is deployed on a dedicated server. The major benefits of multi-tenancy are increased utilization of hardware resources and improved ease of maintenance, in particular on the deployment side. These benefits should result in lower overall application costs, making the technology attractive for service providers targeting small and medium enterprises (SME). However, as this paper advocates, a wrong architectural choice might entail that multi-tenancy becomes a maintenance nightmare.

Abstract: Attempting to determine how quickly archival information becomes outdated.