From: ahemavathy (ahemavathy_at_hotmail.com)
Date: Wed Feb 25 2004 - 12:22:43 PST
This paper discusses the architecture of two systems : tranSend and Hotbot both of which are based on cluster architecture. Cluster architecture provide three primary benefits over single large machines : incremental scalability, high availability and cost/performance and maintenance benefits.
The design follows the BASE semantics : basically available, soft state, Eventual Consistency since most of the internet services don't need consistency. The system has pool of front end HTTP servers, pool of workers implementing the actual business logic, a front end database which stores user profiles, a Manager whose primary role is load balancing across workers and a Monitor all connected by a System Area Network. Some of the roles like the Manager is centralized but are supposed to be fault tolerant because of cached soft states. Further to free the front end servers and workers from interfacing complexity they have introduced manager stubs and worker stubs.
The performance measurements show that the scalability and performance observed with tranSend are good enough for internet applications. Since the architecture is reusable authors could build their new applications over this architecture.
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