Optimising development and deployment of ... - ResearchGate

4
• Level 3 corresponds to levels 2 and 3 in Microsoft’s model. Scalability, multitenancy,
and customisability through configuration are considered prerequisites,
similarly to Microsoft’s level 3. However, the Forrester model adds an additional
characteristic: the fact that platforms/vendors at this level of maturity offer single
well-defined SaaS applications (e.g. a CRM solution).
• Level 4 is for platforms where applications can be extended by additional business
logic through custom extensions (beyond configuration) and by third-party
packaged SaaS solutions, thus making it possible to build SaaS applications for
entire business domains.
• Finally, level 5 refers to platforms that satisfy all criteria for level 4, and moreover,
are pre-populated with numerous business applications or business services which
can be dynamically composed to create tenant-specific or even user-specific SaaS
business applications.
Considering the state of practice in the contemporary PaaS technology and market
space [7, 8, 9] relative to the above maturity criteria, it can be noted that most of
today’s PaaS providers are lacking with regard to support for one or more of the
following platform capabilities, which are central to a mature PaaS offering:
1. Support for sharing of an application’s codebase or runtime instances by multiple
tenants in order to minimise operational costs for the provider (multi-tenancy)
2. Support for modifying/tailoring applications already deployed on the platform
(through metadata-driven configurability and/or code-driven customisability)
3. Support for reusing applications that were developed by third parties as building
blocks for creating completely new applications (ecosystem-centric extensibility)
4. Support for creating applications without restrictions to a particular business
domain such as CRM only (multi-domain applicability)
Lacking with respect to the first platform capability, i.e. enabling a multi-tenant
infrastructure, severely limits the platform provider’s potential to achieve economies
of scale, and inevitably becomes a roadblock for growth in a cloud computing
context. Lacking with respect to the other three platform capabilities limits the
platform provider’s potential with regard to the emergence of a technology and
business ecosystem around the platform.
3 Summary of challenges in the design of the CAST platform
The CAST project is working towards the direction of a fully-fledged PaaS model. It
is investigating techniques, methods and tools for the realisation of a software
platform that overcomes the abovementioned deficiencies in the current state of
practice, and enables efficient and effective development, deployment and
provisioning of on-demand enterprise software applications.
To achieve this goal, the design of the CAST platform needs to address two
distinct (but complementary) sets of challenges, which shape the platform’s model of
operation and its technical architecture: