Analysis and optimisation of event-condition-action rules on XML

XML is a now a dominant standard for storing and exchanging information With its increasing use in areas such as data warehousing and e commerce there is a rapidly growing need for rule based technology to support reactive functionality on XML repositories Event condition action ECA rules automatically perform actions in response to events and are a natural facility to support such functionality In this paper we study ECA rules in the context of XML data We de ne a simple language for specifying ECA rules on XML repositories The language is illustrated by means of some examples and its syntax and semantics are then speci ed more formally We then investigate methods for analysing and optimising these ECA rules a task which has added complexity in this XML setting compared with conventional active databases