Two-tiered Calendar Server Architecture

Calendar Server supports scalability by distributing a configuration over multiple front-end and back-end servers. On each server, Calendar Server services can also be distributed across multiple CPUs.

In a two-tiered architecture, sometimes referred to as network front-end/database back-end configuration (shown in the following figure), users log in to a front-end server and connect to a back-end server using the Database Wire Protocol (DWP) service (csdwpd process). The calendar database is connected only to the back-end servers. Though not shown in this figure, the front-end hosts need access to the LDAP directory.

Figure 16–2 Two-tiered Calendar Server Architecture

Calendar Server processes run on both the front-end and back-end servers as follows:

• Users are directed by load balancers to a front-end server, where they log in. Each front-end server requires these services:

  • Administration Service (csadmind process)

  • HTTP Service (cshttpd process)

  • GSE database (csstored)

• Each back-end server is connected to a calendar database, so each back-end server requires these services:

  • Administration Service (csadmind process)

  • Backup Service (csstored)

  • Event Notification Service (enpd and csnotifyd processes)

  • Database Wire Protocol (DWP) Service (csdwpd process) to provide networking capability to the front-end servers for the calendar database

In this configuration, users do not log in to the back-end servers, so the HTTP service (cshttpd process) is not required.

For a description of Calendar Server services, see the Sun Java System Calendar Server 6.3 Administration Guide.

A scalable Calendar Server configuration requires a directory server to authenticate users and to store user preferences.