Quality of Service Attributes for Software as a Service

Software as a Service (SaaS) has been developing for over ten years and, is reaching a mature level, where quality and its monitoring and management become significant. Although, SaaS is derived from the ASP model, SaaS background and architecture is different and therefore also SaaS quality management is based on different concepts. This paper is focused on the difference between traditional IT outsourcing and SaaS and proposes a set of quality attributes appropriate for the management of the SaaS quality. 1. Problem Area Service Level Agreement (SLA), a contract between service provider and service customer (Sandholm, T. 2005), is well researched in the IT outsourcing (ITO) context as a way to define the quality of delivered IT service. Now in the era of Software as a Service (SaaS), SLA is also used for the same purpose, but the context has changed - SaaS has different background in comparison to ITO from the business and technological perspective while the SLA structure, content and form should reflect such fact. There is a lack of research literature covering SLA topic in SaaS environment and this is the motivation for this paper. Firstly, we will summarize important literature and discuss the key differences between SaaS and ITO from the several perspectives to distinguish both terms. Then we will focus on the concept of Quality of Service (QoS), important for the structure and content of SLA. The final part of this paper will be dedicated to quality attributes of SaaS service with the objective to formalize the fundamental set of important SaaS quality attributes to be used while creating SLA for SaaS service.