1 Introduction

HTTP (Hypertext Transfer Protocol) is the W3C standard protocol for transferring information between a web-client (e.g., a browser) and a web-server. The protocol is a simple envelope protocol where standard name/value pairs in the header are used to split the stream into messages and communicate about the connection-status. Many languages have client and server libraries to deal with the HTTP protocol, making this protocol an excellent candidate for building client-server applications. In particular, HTTP is a natural fit for networked systems built according to the principles of “Representational State Transfer” (REST).

In this document we describe a modular infrastructure to access web-servers from SWI-Prolog and turn Prolog into a web-server.

Acknowledgements

This work has been carried out under the following projects: GARP, MIA (dead link), IBROW (dead link), KITS (dead link) and MultiMediaN (dead link).

The following people have pioneered parts of this library and contributed with bug reports and suggestions for improvements: Anjo Anjewierden, Bert Bredeweg, Wouter Jansweijer, Bob Wielinga, Jacco van Ossenbruggen, Michiel Hildebrandt, Matt Lilley and Keri Harris.

Path wildcards (see http_handler/3) have been modelled after the “arouter” add-on pack by Raivo Laanemets. Request rewriting has been added after discussion with Raivo Laanemets and Anne Ogborn on the SWI-Prolog mailinglist.