APR - Apache Portable Runtime library

A project by the Apache Software Foundation which allows Apache HTTP Server binary to be embedded in other products.

APR is not new, and has been developed over many years.

Newer versions of Tomcat can use APR to serve static content, to make pages load faster for the user.

The other alternative is to connect Tomcat to a web server via a Tomcat Connector, such as the AJP Connector. This method relies on the web server to serve everything, and to communicate with Tomcat to serve dynamic content such as a JSP page.

Either way, static content is served by a binary application.

Advantage of APR approach:

• Tomcat is the main web interface for incoming requests, so URL mappings, default (welcome) pages, and error handlers can be set up in web.xml.
• Single point of failure, as opposed to a Tomcat Connector method, where a problem with the web server -or- Tomcat can cause downtime.

Advantage of Tomcat Connector approach:

• The web server is the main web interface for incoming requests, so ASP, PHP or Cold Fusion can co-exist with Java-based applications on the same website.

More Information

• APR Project