Tomcat 7 Finalized

alphadogg writes "The volunteer developers behind Apache Tomcat have released version 7.0.6 of the open-source Java servlet container. 'This is the first stable release of the Tomcat 7 branch,' developer Mark Thomas wrote in an e-mail announcing the release on various Tomcat developer mailing lists. While not a full application server, Tomcat implements the functionality described in the Java Enterprise Edition Web profile specifications. Most notably, it supports version 3.0 of the Servlet API (application programming interface) and version 2.2 of JavaServer Pages, both part of the recently ratified JEE 6. A servlet container manages Java-based applications that can be accessed from a Web browser. One big area of improvement is in configuration management for Web applications. Previous versions required all Web app configuration changes to be entered in a central file called web.xml, a process that led to unwieldy web.xml files as well as security risks."

XML devils & details

[boorack]

I don't mind XML configuration file as long as it contains only things that are important and has little/no plumbing boilerplate. In most Java frameworks (especially in Spring) there are two things mixed into a single set of configuration files: items created once while developing application (for example Spring depencency injection bindings, Hibernate mappings etc. - let's call it plumbing) and factual configuration settings (for example: database URL, user and password for application). Mixing these two things is a major sin as plumbing and configuration have different characteristics.

Plumbing is like code. It is done while as part of application development and is tightly bound to development process - it should be easily testable, easy to refactor (IDEs should handle this - for example if you change name of some class/method, IDE refactoring features should also change it in all plumbing code). If possible - it should not change between development and production environments. That's why I prefer annotations rather than XML for binding everything into final application (eg. Guice over Spring). One notable exception I often is Hibernate and that's only because hibernate-annotations adds tons of additional JAR files and addidional complexity coming out of it doesn't justify convenience of using annotations instead of XML.

Configuration is a tool for administrators, not for developers. It should be as simple as possible and easy to change by hand. And yes, a generally prefer plain .properties files or YAML over XML, however as long as config file is simple enough and has no unnecessary overhead, I won't complain much about it. It is also important to keep major aspects of configuration separate (for example general server config vs. application specific config) and to keep application configuration separated from application itself (.war/.ear file).

So, in short: there are two things: "plumbing configuration" and real configuration. It is important to keep these two things separate and to keep real config as simple as possible.