Installation Requirements
Requirements at a glance:
- Java >=1.7
- Servlet container supporting servlet specification >=3.0
- Apache Maven >=3.3
- Familiarity with the Spring Framework
- Internet connectivity
Depending on choice of configuration components, there may be additional requirements such as LDAP directory, database, and caching infrastructure. In most cases, however, requirements should be self evident to deployers who choose components with clear hardware and software dependencies. In any case where additional requirements are not obvious, the discussion of component configuration should mention system, software, hardware, and other requirements.
Servlet Containers
There is no officially supported servlet container for CAS, but Apache Tomcat is the most commonly used. Support for a particular servlet container depends on the expertise of community members, but the following are known to work well and should receive first-class support on the Community Discussion Mailing List:
Apache Maven
CAS uses Maven for building and creating a deployable package for installation into a Java servlet container. Maven is also strongly recommended for configuration management required for the CAS installation process. CAS is fundamentally a complex software product that becomes embedded and tighly integrated into the software environment of an institution. For this reason it tends to require customization well beyond turnkey solutions, and the integration requirements tend to change over time. A source-based installation process like Maven WAR overlay provides a straightforward and flexible solution to complex and dynamic requirements. While it admittedly requires a high up-front cost in learning, it reaps numerous benefits in the long run
Spring Framework
CAS uses the many aspects of the Spring Framework; most notably, Spring MVC and Spring Webflow. Spring provides a complete and extensible framework for the core CAS codebase as well as for deployers; it’s straightforward to customize or extend CAS behavior by hooking CAS and Spring API extension points. General knowledge of Spring is beneficial to understanding the interplay among some framework compoents, but it’s not strictly required. The XML-based configuration used to configure CAS and Spring components, however, is a core concern for installation, customization, and extension. Competence with XML generally and the Spring IOC Container in particular are prerequisites to CAS installation.
Internet Connectivity
Internet connectivity is generally required for the build phase of any Maven-based project, including the recommended Maven WAR overlays used to install CAS. Maven resolves dependencies by searching online repositories containing artifacts (jar files in most cases) that are downloaded and installed locally. While it is possible to override this behavior by alterning Maven configuration settings, it is considered advanced usage and not supported.
A common solution to overcoming lack of Internet connectivity on a CAS server is to build CAS on a dedicated build
host with internet connectivity. The cas.war file produced by the build is subsequently copied to the CAS server
for deployment.