servletcontainer

A servlet container, also known as a web container, is a component of Java EE/Jakarta EE implementations that provides a runtime environment for web components such as servlets and JSPs. It implements the Servlet API and handles HTTP requests by invoking the appropriate servlet, applying the container’s lifecycle and security rules.

Key responsibilities include managing the lifecycle of servlets (init, service, destroy), handling multi-threaded request processing, performing URL routing from patterns to servlet instances, applying filters, and firing lifecycle listeners. The container also provides session management, security, and access to container-managed resources via JNDI, as well as context-scoped data through the web application context.

The container loads and isolates web applications packaged as WAR files or exploded directories, deploying one or more contexts within a single instance. It supports both annotation-based configuration and deployment descriptors (such as web.xml), and it can perform request dispatching, include, and forward operations through request dispatchers.

Containers can be embedded in applications or run standalone. They may be used as lightweight servers (embedded Jetty or Tomcat) or as part of a full Java EE server. Examples of servlet containers include Apache Tomcat, Jetty, and Undertow; in contrast, full application servers such as GlassFish, WebLogic, and WebSphere include servlet containers along with additional enterprise services.

Servlet containers are aligned with the Servlet API versions; newer implementations may target Jakarta Servlet packages as the platform migrated to the Jakarta EE namespace.