Integrated server environments are often implemented as 3-tier environments, for example, consisting of (1) Web browsers, (2) Web application servers, and (3) back-end servers. A common physical implementation of such a 3-tier environment is shown in Figure 19-12. The Web browsers run on workstations, the applications servers on UNIX servers, and the back-end server on a mainframe. The examples show VSE/ESA as the traditional mainframe operating system, but it could also be a z/OS system.
Figure 19-12. 3-tier server environment
Linux on the mainframe allows you to implement a logical 3-tier environment on a physical 2-tier. Figure 19-13 shows how the physically distinct application server has been moved to a Linux image on the mainframe.
Figure 19-13. Physical 2-tier implementation for a logical 3-tier server environment
This consolidation can provide the benefits of hosting applications on the mainframe. The benefits possibly include cost savings due to reduced hardware acquisition and maintenance cost, simplified systems administration, and improved availability. For applications running on the mainframe, you can achieve a better operational integration into existing traditional mainframe application environments. For example, you can bring your Web applications closer to your data via virtual communication methods (HiperSockets or Guest LAN). Virtual communication can improve security and performance.