Jenkins as an open source continuous integration tool for Java

Jenkins, previously known as Hudson, is an open-source continuous integration software tool written in the Java programming language for testing and reporting on isolated changes in a larger code base in real time. The software enables developers to find and solve defects in a code base rapidly and to automate testing of their builds. Jenkins is a fork of a project called Hudson, which is trademarked by Oracle and is currently being developed parallel to Jenkins. The development community and its governing body hosts open meetings about the software.

Jenkins provides continuous integration services for software development, primarily in the Java programming language. It is a server-based system running in a servlet container such as Apache Tomcat. It supports SCM tools including CVS, Subversion, Git, Mercurial, Perforce and Clearcase, and can execute Apache Ant and Apache Maven based projects as well as arbitrary shell scripts and Windows batch commands. Released under the MIT License, Jenkins is free software.

What is Jenkins?

Jenkins is an award-winning application that monitors executions of repeated jobs, such as building a software project or jobs run by cron. Among those things, current Jenkins focuses on the following two jobs:

•     Building/testing software projects continuously, just like CruiseControl or DamageControl. In a nutshell, Jenkins provides an easy-to-use so-called continuous integration system, making it easier for developers to integrate changes to the project, and making it easier for users to obtain a fresh build. The automated, continuous build increases the productivity.
•     Monitoring executions of externally-run jobs, such as cron jobs and procmail jobs, even those that are run on a remote machine. For example, with cron, all you receive is regular e-mails that capture the output, and it is up to you to look at them diligently and notice when it broke. Jenkins keeps those outputs and makes it easy for you to notice when something is wrong.

Features

Jenkins offers the following features:

1. Easy installation: Just java -jar jenkins.war, or deploy it in a servlet container. No additional install, no database.
2. Easy configuration: Jenkins can be configured entirely from its friendly web GUI with extensive on-the-fly error checks and inline help. There's no need to tweak XML manually anymore, although if you'd like to do so, you can do that, too.
3. Change set support: Jenkins can generate a list of changes made into the build from Subversion/CVS. This is also done in a fairly efficient fashion, to reduce the load on the repository.
4. Permanent links: Jenkins gives you clean readable URLs for most of its pages, including some permalinks like "latest build"/"latest successful build", so that they can be easily linked from elsewhere.
5. RSS/E-mail/IM Integration: Monitor build results by RSS or e-mail to get real-time notifications on failures.
6. After-the-fact tagging: Builds can be tagged long after builds are completed
7. JUnit/TestNG test reporting: JUnit test reports can be tabulated, summarized, and displayed with history information, such as when it started breaking, etc. History trend is plotted into a graph.
8. Distributed builds: Jenkins can distribute build/test loads to multiple computers. This lets you get the most out of those idle workstations sitting beneath developers' desks.
9. File fingerprinting: Jenkins can keep track of which build produced which jars, and which build is using which version of jars, and so on. This works even for jars that are produced outside Jenkins, and is ideal for projects to track dependency.
10. Plugin Support: Jenkins can be extended via 3rd party plugins. You can write plugins to make Jenkins support tools/processes that your team uses.

 sample screenshot of jenkins

source: jenkins-ci.org