WebL - A Programming Language for the Web

In this paper we introduce a programming language for Web document processing called WebL. WebL is a high level, object-oriented scripting language that incorporates two novel features: service combinators and a markup algebra. Service combinators are language constructs that provide reliable access to web services by mimicking a web surfer's behavior when a failure occurs while retrieving a page. The markup algebra extracts structured and unstructured values from pages for computation, and is based on algebraic operations on sets of markup elements. WebL is used to quickly build and experiment with custom web crawlers, meta-search engines, page transducers, shopping robots, etc.