When to Use Apache vs. Apache+Tomcat?

Question

Since simply using Apache can be enough to run many Web applications, when and why do people also use Tomcat in addition to Apache?

Answer 1

Apache Tomcat is a webserver and Java servlet container in one, while Apache HTTPD is just a plain webserver (often with only PHP support). They use Apache Tomcat when they want be able to run Java/JSP/Servlet. It can be added to an existing Apache HTTPD / PHP setup. Or the other way round, they bring Apache HTTPD in front of Apache Tomcat to be able to have a "This site is in maintenance" page when Tomcat is been shutdown for some upgrade/maintenance.

For communication between Apache HTTPD and Apache Tomcat, the Tomcat Connector is usually been used. It's also known as mod_jk.

Answer 2

Maybe too late to answer.

"Apache" is the name of a foundation that write open-source software. Apache HTTPD is a web server written in portable C (when people say "Apache", they usually mean Apache HTTPD.) It mostly serves static content by itself, but there are many add-on modules (some of which come with Apache itself) that let it modify the content and also serve dynamic content written in Perl, PHP, Python, Ruby, or other languages.

Tomcat is primarily a servlet/JSP container. It's written in Java. It can serve static content, too, but its main purpose is to host servlets and JSPs. Although it's possible to get Tomcat to run Perl scripts and the like, you wouldn't use Tomcat unless most of your content was Java.

It's actually possible to use both Apache and Tomcat together, so that Apache serves the static content, and Tomcat the Servlets and JSPs. Depending on various factors, this may or may not be a good idea.