Chapter 3. Sakai 2.x Anatomy

Sakai is not only a collaborative learning environment it is also a framework for building tools, such as the Wiki and Chat tools in the core. The Sakai framework is based on industry-standard open source technologies and best practice. Sakai (and its predecessor, Chef) were forged in the fire of the campus-wide deployments and now, with over six years of hammering and hardening, Sakai makes for a robust component of a modern academic enterprise. Various internal hooks allow data integration with external systems, authentication, and single sign-on. Rather than requiring expertise with a single operating system or database, Sakai can run on the databases and operating systems that each institution has the expertise to support.

Sakai is a collection of web applications and components that run on an application server (typically Apache Tomcat). The application needs to read from and write to a database and the file system. For small setups with only hundreds of users, a single server can host all the parts. However, as usage scales and the value of the service increases, greater redundancy and load distribution is required. Large-scale Sakai deployments serve hundreds of thousands of end users using technologies such as dedicated databases, multiple application servers, and load balancers.

Sakai is designed to be a stable, scalable infrastructure that uses standard technologies to achieve its goals. This is evidenced not only by the use of standard and well-understood hardware, such as load balancers and Solaris, Linux, Macintosh, or Windows servers, but also in the range of well-known Java frameworks called within the applications, such as Spring and Hibernate, Servlets, Java Server Faces, and so on.

The multiple pressures of rapid life cycles, fixed release dates, and the need to deliver flawless Sakai applications to vast number of students forces a strong quality assurance cycle. Over the course of its history, Sakai has been tested and the code examined by hundreds of volunteers.This chapter tackles the fundamentals of Sakai, starting with the abstract framework concepts, then the less-abstract definition of core technologies, then the motivations for the use of these technologies, and finally how system integrators have deployed large-scale Sakai installations in practice.