Quercus (software)

Resin is a web server and Java application server from Caucho Technology. In addition to Resin (GPL), Resin Pro is available for enterprise and production environments. Resin supports the Java EE standard as well as a mod_php/PHP like engine called Quercus.

Resin Pro includes optimizations such as built-in caching and features such as clustering support, advanced administration, and the health system that includes HTTP session replication, Java Monitoring, distributed cache replication, and JMS queue replication. While Caucho describes these as "features and enhancements commonly needed in a production environment", Resin Open Source is used without these features.

Although a Java-based server, key pieces of Resin's core networking are written in highly optimized C. Caucho states Java is the layer that allows Resin to be "full featured" while C provides the speed. Resin, which was released in 1999, predates Apache Tomcat, and is one of the oldest application servers and web servers.

Scalability

Development

Production Ready

App Server'

Web Server

Resin's market share is small in the grand scheme of Java Application Servers, but some high traffic sites use it, such as Toronto Stock Exchange, SalesForce.com, Condé Nast (parent company of Wired, Vogue, GQ), CNET. NetCraft's February 2012 Survey stated Resin grew to 4,700,000 sites; Resin was the only Java-based web server mentioned.

Quercus is a Java-based implementation of the PHP language that is included with Resin. According to a slideshow presented by Emil Ong (from Caucho), to a San Francisco Java Meetup Group in April 2008 pertaining to Resin 3.1, an essential difference in the operation of Quercus between the Resin Open Source and the Resin Professional editions is that in Resin Professional the PHP is compiled to Java bytecode whereas in the open source version PHP is executed by an interpreter.

Caucho states that Quercus is faster than standard PHP although this is only true for the JIT-compiled version in Resin Professional. Quercus ships with Resin.