Blackboard Learn is an extensible web application which runs inside an Apache Foundation open source implementation of the Java Servlet and JavaServer Pages container called Apache Tomcat.
The language behind Apache Tomcat is java and common terms used to describe operation are Servlet Container, Servlet Context, Connector and Web Application.
A web application is the combination of servlet's, filters and jsp's that are configured in a web.xml. Together with additional static resources and other objects web applications are packaged as a .war file. A .war file is an archive containing executable code that can run in a servlet container.
A servlet container is an application server that implements the Java Servlet Specification. The servlet specification defines a programming model that allows a developer to write components that process requests.
The servlet context is an object that is created when the web-application is started in a servlet container and destroyed when the web-application is undeployed or stopped. The servlet context object usually contains initialization parameters in the form of a web.xml document.
Connectors provide instructions for the ports a servlet container listens on for incoming requests with incoming requests being directed to configured web application.
Tomcat itself is comprised of three main components: Jasper, Catalina, and Coyote. These components combined allow for the parsing and compilation of JavaServer Pages into java servlet code, the delivery of these servlets, and request processing.
Jasper is Apache Tomcat's JavaServer Pages Engine. Jasper parses JSP files compiling them into Java code as servlets to be handled by Catalina. At runtime, Jasper detects changes to JSP files and recompiles them.
Catalina is Apache Tomcat's servlet container. Catalina implements the specifications for servlet and JavaServer Pages (JSP).
Coyote is Apache Tomcat's HTTP Connector component supporting the HTTP 1.1 protocol. Coyote listens for incoming connections on configured TCP ports on the server and forwards requests to the Tomcat Engine for processing and returning a response to the requesting client.
Learn more about Apache Tomcat on the Apache Tomcat documentation site.
Learn more about Apache Tomcat and Learn in the Performance Optimization Tomcat Help topic.