  Most of current Software-as-a-Service (SaaS) applications are developed as
customizable service-oriented applications that serve a large number of tenants
(users) by one application instance. The current rapid evolution of SaaS
applications increases the demand to study the commonality and variability in
software product lines that produce customizable SaaS applications. During
runtime, Customizability is required to achieve different tenants'
requirements. During the development process, defining and realizing commonalty
and variability in SaaS applications' families is required to develop reusable,
flexible, and customizable SaaS applications at lower costs, in shorter time,
and with higher quality. In this paper, Orthogonal Variability Model (OVM) is
used to model variability in a separated model, which is used to generate
simple and understandable customization model. Additionally, Service oriented
architecture Modeling Language (SoaML) is extended to define and realize
commonalty and variability during the development of SaaS applications.
