resin 4.0 reference

Guide: Admin

Overview and introduction to Resin from an administration perspective.

Clustering

As traffic increases beyond a single server, Resin's clustering lets you add new machines to handle the load and simultaneously improves uptime and reliability by failing over requests from a downed or maintenance server to a backup transparently.

Database

Resin provides a robust and tested connection pool that is used to obtain connections to databases.

Deployment

Resin provides a wide variety of custom packaging and deployment options.

Dynamic Servers

Resin includes the ability to add servers to clusters dynamically. These dynamic servers are able to use distributed sessions and the distributed object cache. The triad also updates these servers with applications that are deployed via the remote deployment server. The Resin load balancer is also able to dispatch requests to them as with any static server.

Jar Repository

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.

Java Injection

Resin's configuration uses a powerful, general dependency injection system (CanDI) to configure servlets, Resin resources, databases, application components, third-party libraries and drivers. By understanding a few rules matching the XML to the configured resources, an administrator can have full control over the application server behavior.

Because of the importance of verifying and debugging configuration, Resin's configuration is stateless, meaning that the XML files fully describe the configuration of the system. Resin avoids hidden state by avoiding deployment tools and internal, hidden database configuration.

Load Balancing

As traffic increases beyond a single server, Resin's load-balancing lets you add new machines to handle the load and simultaneously improves uptime and reliability by failing over requests from a downed or maintenance server to a backup transparently.

Performance

/resin-admin

The /resin-admin web-app provides an administration overview of a Resin server. Resin-Pro users can obtain information across the entire cluster, profile a running Resin instance, and obtain thread dumps and heap dumps.

All Resin users should familiarize themselves with the thread dump, profile, and heap capabilities.

Rewrite

When you need to rewrite an external URL to a more convenient internal format, like rewriting to *.php files, you can use Resin's rewrite capabilities. Because Resin's rewrite is patterned after Apache's mod_rewrite, you can translate older mod_rewrite rules to Resin's rewrite tags.

Scheduling

Resin's <resin:ScheduledTask> capability lets you schedule events using a flexible cron-style trigger. The task can be any Runnable bean, a method specified by EL, or a URL.

Security

Troubleshooting

A list of symptoms and their possible resolution.

Virtual Hosting

A Resin server can serve many virtual hosts, each with its own servlets and documents. The configuration is flexible, allowing dynamic host deployment in a hosts directory or using explicit <host> tags for additional control and security, and compatibility with existing Apache sites, enabling easy upgrades and evaluation for PHP servers to Quercus.

Watchdog

For reliability and security, Resin servers are started and monitored by a separate Resin watchdog process. The watchdog continually checks the health of the Resin server and restarts the Resin instance if is becomes unresponsive.

In most cases, the watchdog reads the resin.xml and configures itself automatically, so no extra configuration is required. Certain specialized configurations like ISPs can configure the watchdog to isolate JVMs for protection and security.

WebApp

A web application is a self-contained subtree of the web site. It uses Servlets, Filters, JSP, and the functionality provided by Resin and any other java code to provide a response to a client that makes an HTTP request.