F.A.Q.

Why not just use Quercus?

Quercus is a Java implementation of PHP 5 released under the Open Source GPL license. It allows PHP code to easily interoperate with Java code. It is a mixed interpreted/compiled implementation, meaning that regular PHP code runs in fact in a Java Virtual Machine. Moreover, some extensions have been added to the PHP language (such as the import directive). These allow the usage of Java classes as regular PHP objects.

There are two possible approaches for integrating a PHP application with Quercus:

• leave the PHP code as it is and just drop it into the Quercus web context
• take advantage of the import feature and start using Java classes in existing features or in newly implemented ones

The first approach only provides some potential runtime performance gains. If the application owner is content with his codebase in PHP (the disadvantages of this language are not worth the hassle of migrating), then Quercus is certainly a good choice.

On the other hand, our opinion is that the costs of using the import feature outweigh the benefits. The aspect of the resulting code will be a confusing mixture of PHP and Java, increasing complexity and being a defect risk source. The skills of the development and maintenance team will need to cover both languages. In essence the application will still be a PHP one, but with an increased degree of complexity. By contrast, the pure Java code produced by a migration process will be easier to maintain and further develop (taking advantage of all the tools available for the Java/Java EE platform).