4 Clustering Web Applications with Terracotta Web Sessions

4.0.1 Architecture of a Terracotta Cluster

The following diagram shows the architecture of a typical Terracotta-enabled web application.

The load balancer parcels out HTTP requests from the Internet to each application server. To maximize the locality of reference of the clustered HTTP session data, the load balancer uses HTTP session affinity so all requests corresponding to the same HTTP session are routed to the same application server. However, with a Terracotta-enabled web application, any application server can process any request.

The application servers run both your web application and the Terracotta client software, and are called "clients" in a Terracotta cluster. As many application servers may be deployed as needed to handle your site load.

For more information on sizing and deployment concerns, see the Deployment Guide and the Operations Guide .

A Terracotta cluster can be deployed with one or more Terracotta servers, which act as the data store for HTTP session data and coordinate access by the application servers to that session data. For more information on setting up a Terracotta cluster, see Configuring Terracotta For High Availability and Terracotta Server Arrays.