Multi-tenancy in PaaS: Server PaaS vs. Resource PaaS
Whether SaaS, IaaS or PaaS, one of the central concepts of all layers of cloud computing is multi-tenancy.
In most SaaS offerings, the multi-tenancy is manifold - the servers, the application code, the database and even the individual tables or pages within the database might be shared among different customers and users of the system. In IaaS, multi-tenancy is implemented via virtualization technology: a hypervisor allocates and manages a number of complete virtual machines on a particular physical computing resource.
There are two primary approaches to multi-tenancy in PaaS: Server PaaS simply relies upon the IaaS multi-tenancy. Resource PaaS looks more like SaaS multi-tenancy.
Server PaaS is essentially an automated deployment and management system. Examples of Server PaaS include RightScale, Standing Cloud and EngineYard.
Resource PaaS provides an abstract "container" for an application that allows it to share computing resources in a granular way with other such applications. It eliminates the concept of "servers" in favor of functional resources." Examples of Resource PaaS include Force.com, Google AppEngine, and Heroku.
This presentation will take an in-depth look at the benefits, disadvantages and tradeoffs between Server PaaS vs. Resource PaaS, and how to evaluate each for current and future needs in your environment. If control, flexibility, security, and portability are important, then Server PaaS has many advantages. If ease of deployment and management and/or rapid and efficient scaling are crucial, Resource PaaS may be a better fit.