Reliability, scalability and robustness issues in IRI

Over the past two years, we have used the IRI (Interactive Remote Instruction) system to teach several live interactive classes with students in different cities. While this system is a prototype - we are using it to better understand both system performance requirements and what tools can be effective for remote instruction and how to use them - we have used it repeatedly to teach regularly scheduled for-credit university classes. This repeated use has resulted in significant improvements in IRI's functionality, but its evaluative use in real classrooms situations has required that we address significant scalability, reliability, and robustness issues. We discuss features of IRI's software architecture and basic functionality motivated by these scalability and reliability issues.