Prova is a language for rule-based Java scripting to support information integration and agent programming on the web. Prova integrates Java with derivation and reaction rules supporting message exchange with various comminication frameworks. Prova supports transparent access to databases, retrieval of URLs, access to web services, and querying of XML documents. We briefly illustrate Prova and show how to implement a distributed bioinformatics application, which includes access to an ontology stored in a database and to XML data for protein structures. Finally, we compare Prova to other event-condition-action rule systems.