Page 742 - Cloud computing: From paradigm to operation

XaaS 3

7 Maturity levels of SaaS application

In the industry, the maturity of SaaS is classified into four levels which could be shortly named as custom
level, configurable level, multi-tenant level, and scalable level. Each level covers characteristics of the
previous one and provides extended characteristics. The diagram that represents the characteristics of the
different SaaS maturity models is shown in Table 1.

Table 1 – Diagram of SaaS application maturity level

Different maturity levels of the SaaS application have different security requirements to SaaS application
environments, and the requirements will be illustrated from the viewpoint of CSPs and CSNs in clause 8.

7.1 Level 1: Custom SaaS application

Custom SaaS application is similar to the traditional application service provider (ASP) model of software
delivery. Each customer has its own customized solution for SaaS application and runs its individual
application instance on the cloud server. As illustrated in Figure 2, the custom application instance comprises
the whole execution environment including the operating system (OS), the data management system and
the middleware that are specific to each tenant, and the SaaS environment provider has to maintain multiple
instances. This model is difficult to scale in order to satisfy the increasing requirement demands of customers,
and it can be costly to operate.

Figure 2 – Architecture of custom SaaS application

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