  Software as a Service (SaaS) is a new software delivery model in which
pre-built applications are delivered to customers as a service. SaaS providers
aim to attract a large number of tenants (users) with minimal system
modifications to meet economics of scale. To achieve this aim, SaaS
applications have to be customizable to meet requirements of each tenant.
However, due to the rapid growing of the SaaS, SaaS applications could have
thousands of tenants with a huge number of ways to customize applications.
Modularizing such customizations still is a highly complex task. Additionally,
due to the big variation of requirements for tenants, no single customization
model is appropriate for all tenants. In this paper, we propose a
multi-dimensional customization model based on metagraph. The proposed mode
addresses the modelling variability among tenants, describes customizations and
their relationships, and guarantees the correctness of SaaS customizations made
by tenants.
