Project Jar Repository contents

Library, project, and third-party jars can be stored in project-jars and resolved using a Maven WEB-INF/pom.xml. Resin will match the correct versions from project-jars and create classloaders for the web-app's libraries.

Because projects use many library jars such as Hibernate, Wicket, and Apache Commons, Resin provides a repository for the jars, letting you add all your jars in one directory and select the ones you need either in the resin-web.xml or in a Maven-standard WEB-INF/pom.xml file. This repository gives several benefits: simplifying jar management, resolving versions, reusing jar files, and reducing .war deployment sizes.

Resin will create internal classloaders for each of your libraries, and resolve the dependencies of those libraries. So if you use "foo" and "bar" libraries, and both depend on a "log" library, Resin will hook up the classes correstly.

At startup, Resin scans all the jars in ${resin.root}/project-jars directory for pom.xml files and create an internal database of the artifact names and versions. A WEB-INF/pom.xml will select the jars for use in the web-app.

For example, your project might use two main libraries: framework-1.0.1.jar and persistence-2.0.2.jar, and those libraries might depend on parser-1.1.1.jar, log-3.3.3.jar and parser-2.2.2.jar. Using the jars is a two step process:

  1. Add jars to ${resin.root}/project-jars/
  2. Add WEB-INF/pom.xml or WEB-INF/resin-web-pre.xml to declare dependencies

To install, you would add all the jar files into ${resin.root}/project-jars and then add a WEB-INF/pom.xml telling Resin that you need the "framework" artifact with version 1.0.1 and the "persistence" artifact with version 2.2.2.

Your web-app can declare its dependencies in two ways: a Maven-standard WEB-INF/pom.xml jar, or using a <dependency> tag in the resin-web-pre.xml. The following example shows that the pom.xml might look like:

<project xmlns="http://maven.apache.org/POM/4.0.0"> <groupId>com.myfoo</groupId> <artifactId>my-webapp</artifactId> <version>1.0.0</version> <dependencies> <dependency> <groupId>com.foo</groupId> <artifactId>framework</artifactId> <version>1.0.1</version> </dependency> <dependency> <groupId>com.bar</groupId> <artifactId>persistence</artifactId> <version>2.0.2</version> </dependency> </dependencies> </project>

You can also declare your dependencies directly in a WEB-INF/resin-web-pre.xml. The "resin-web-pre" means Resin evaluates the file before the web.xml and resin-web.xml, so the classes will be loaded before any servlets need them.

<web-app xmlns="http://caucho.com/ns/resin"> <class-loader> <dependency org="com.foo" name="framework" version="1.0.1"/> <dependency org="com.bar" name="persistence" version="2.0.2"/> </class-loader> </web-app>