HomeOpen Source TechnologiesEnhydra Director

Professional loadbalancing and clustering

Director is a collection of open source web-server plugins to provide loadbalancing, clustering and unified connection methods for different web-servers on different platforms. The Enhydra Director supports several popular Web servers and operating systems, including Apache (on Linux/Unix and Windows), Netscape Enterprise Server (on Linux/UNIX and Windows), and Microsoft Internet Information Server (on Windows). Director also supports several applications servers: Tomcat (v5.xx and v5.5x), Jetty and Enhydra Application server.

Load sharing and balancing are critical features in any serious application framework. The levels of usage commonly experienced by successful Internet applications can easily overwhelm even the fastest single machine. In addition, a number of popular enterprise server machines can realize a performance benefit by distributing application load among several application instances on the same machine.

Enhydra Director has implemented such load balancer as a web server plug-in. The Enhydra Director architecture allows to distribute processing load among one or more instances, both on the same and separate machines. Trough additional modules (Connectors) Enhydra Director also includes 'native' (without Enhydra) load balancing support to several other application servers: Tomcat5.xx (Tomcat prior v5.5x) since release v6.0.1, Tomcat5.5x since release 6.2-1, JOnAS, JBoss and Jetty since Enhydra Director 7 release.

The Enhydra Director supports load balancing managers on several popular Web servers and operating systems, including Apache (on Linux/Unix and Windows), Netscape Enterprise Server (on Linux/UNIX and Windows), and Microsoft Internet Information Server (on Windows). The source code for the Enhydra Director web server interface is designed to be portable.

Enhydra Director understands Session Affinity and can be configured to ensure that a client connects back to the same application server instance (if available) where the session is in memory. Modifing this configuration and the choice of Session Manger allows for various levels of fault tolerant architectures.

An additional benefit of Enhydra Director is that it provides a common method of connecting web servers to application servers. No longer will administrators have to struggle with the difficulty of setting up the Apache connector. Using the high performance interface of the Web server, Enhydra Director provides a direct connection between the front end content and load balancing server, and the backend application workhorses.


The ObjectWeb GForge project

The ObjectWeb GForge project for Enhydra Director contains all the needed links for mailing lists, News, CVS access and Downloads.


Features and Functions

Common connection method on the Application server, independent of which Web server is used

Simple configuration on both the web server and application server

Support for load sharing and balancing among multiple instances on multiple server machines

Fail-over support when an application instance becomes unreachable by the Enhydra Director Web server module

Fail-back support if a server is available again

Use of high performance Web server interfaces such as NSAPI, ISAPI, and the Apache module interface

Session history tracking and resource caching

Dynamically (in run-time) applications servers re-balancing and priority changing

Hot-Standby and Hot-Activation on Failover

Session redistribution on adminitrative intervention or on session timeout




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