PHP developers will gain from using Quercus, even if they have no intention of writing Java code. Because Quercus is written for Resin, a Java application server, it gains all the advantages of Java applications including:

• Security: since Quercus and its modules are entirely in Java, C pointer overruns and segmentation violations are no longer possible.
• Scalability: PHP programs can take advantage of distributed sessions in PHP and load balancing.
• Performance: Quercus outperforms a straight mod_php implementation by about 4x (for Mediawiki and Drupal). Quercus roughly matches PHP performance with accelerators like APC.
• Caching: PHP applications using Quercus can immediately take advantage of Resin's proxy caching. They can also use the PHP APC caching API since the APC functions are included with Quercus.
• Connection pooling, transactions, JMS: PHP programs using Quercus automatically take advantage of Resin's connection pooling, and can use the full distributation transactions, and Java capabilities like JMS.
• Java tools: PHP developers can use Java tools like profilers to get in-depth information about the PHP program performance.

• Java developers can use Quercus immediately to deploy PHP applications such as MediaWiki, Drupal, Wordpress, Gallery2 and DocuWiki.
• Since Resin's administration uses PHP to script JMX beans, Resin users can customize the administration views of the JMX management.

Although PHP users and Java users can take advantage of Quercus immediately without modifying their application, the real benefits come from developing mixed Java/PHP applications:

• PHP libraries written in Java are fast, safe, and relatively easy to develop, compared with C libraries. Since Java is the library language, developers won't need to be paranoid about third-party libraries having C-memory problems or segvs.
• PHP applications can take advantage of Java libraries and capabilities like JMS, SOA frameworks, Hibernate, or Spring. (Or EJB if you really wanted.)
• Java application can move presentation code to PHP, leaving behind templating systems, or languages with small libraries, and taking advantage of PHP flexibility and capability.