Publications Home » Monitoring of Distributed Systems
Monitoring is essential for obtaining the required information about the operation of distributed systems in order to make management decisions and control their behaviour. This thesis presents a generic model of monitoring based on the life-cycle of monitoring information which consists of four stages - generation, processing, dissemination and presentation. A generalised monitoring service for distributed systems can be constructed as a configuration of generic components which can perform the functionalities identified in the model. Based on the model a survey of the area is presented and some representative existing approaches are described in detail.
The main contribution of this thesis is the support for a flexible and scalable distributed event monitoring service. In particular, this thesis presents features of a new declarative, interpreted and Generalised Event Monitoring language (GEM), used to program event monitors which can perform common processing activities such as filtering, composition and notification on event reports generated in a distributed system. The novelty of this work can be summarised as follows:
It allows on-the-fly detection of composite events in the presence of variable communication delays and unordered delivery of messages. The notion of real-time has been tightly integrated into the language with built-in facilities to deal with delays in a flexible and user-defined manner. Many temporal constraints which would otherwise have been very difficult to express in a distributed environment can be specified.
The interpreted nature of the language allows dynamic changes to the observed composite events. It is shown that a scalable, dynamic and distributed event processing service can be constructed as a configuration of multiple event monitors which can receive and interpret appropriate GEM scripts. This thesis describes the implementation of the event monitor and presents examples implemented in the prototype version of GEM.
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