University of Twente Student Theses


A massively scalable architecture for instant messaging & presence

Schippers, Jorrit (2009) A massively scalable architecture for instant messaging & presence.

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Abstract:In this thesis we design a scalable architecture for the instant messaging & presence service offered by Hyves. The current architecture consists of a variable number of application nodes and database slave nodes, which are located pair-wise on machines. Persistent presence information is distributed using two database master nodes. Network and database bottlenecks exist in the slave and master nodes, preventing the architecture to scale to future workloads. We have developed a modelling and analysis approach to measure scalability properties of three new architectures. The first architecture was the result of applying database partitioning to the current architecture. The other two architectures are inspired by the architectures of Facebook chat and of Windows Live Messenger, which have been published by their respective creators. The Facebook-inspired architecture aggregates presence updates to reduce the amount of internal messages, whereas the Windows Live Messenger-inspired architecture uses subscriptions to coordinate presence propagation. We use HIT to model the architectures and analyse the relation between workload and usage of databases and network links. It shows that the first architecture does not scale linearly: doubling the workload requires more than twice the number of machines. The second architecture scales sublinearly for increased workloads, but is in uenced the most by changes in the total number of users or the portion of users online at peak times. The third architecture shows linear scalability, as it has a constant relation between workload and utilisation of resources. We recommend the third, subscription-based alternative as a scalable replacement for the current architecture.
Item Type:Essay (Master)
Faculty:EEMCS: Electrical Engineering, Mathematics and Computer Science
Subject:54 computer science
Programme:Internet Science and Technology MSc (60032)
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