Abstract. In this paper we define the basic concepts for a general language for evolution and reactivity in the Semantic Web. We do this by exposing an UML model that specifies an ontology for the language. The proposed language is based on Event-Condition-Action rules, where different languages for events (including languages for composite events), for conditions (queries) and actions (including complex actions) may be composed, this way catering for language heterogeneity (besides heterogeneity on the data-model) that we think is essential for dealing with evolution and reactivity in the Semantic Web.