NonStop Systems Introduction

The Application Server Environment
NonStop Systems Introduction— 527825-001
3-14
Server Handling
Using the capabilities of the application server, the administrator can reconfigure
clients and servers without stopping online service to users. (Note that depending on
the application server in use, there may be some restrictions on the reconfigurations
that can be done online).
Effective Use of Multiple Processors
The client/server architecture makes effective use of multiple processors. Figure 3-9 on
page 3-14 shows how a simple application could be distributed across a three-
processor system. In this figure, three clients are attached to processor 1. Server A
also runs in processor 1. Server B runs in processor 2, while Server C runs in
processor 3.
Because any of the servers can run in any processor in the system, all the servers can
service client requests at the same time. This ability of several processors to run
different parts of an application simultaneously in the same system is known as
parallel processing. This feature greatly enhances the performance of applications on
NonStop servers.
The parallel processing capability makes it easy for applications to expand. For
example, suppose additional clients are added to the configuration shown in Figure 3-9
on page 3-14, thus placing a heavy demand on Server A. Using capacity planning
tools, it is then determined that processor 3 is the least busy of the three processors.
The system administrator can then configure another copy of Server A in processor 3.
The two copies of Server A are known as a server class.
Figure 3-10 on page 3-15 shows the reconfigured server environment. Note that the
additional client systems are connected to different processors. Application server
components automatically handle the communications paths required for the additional
clients.
Figure 3-9. Parallel Processing
Processor 1
Processor 3
Processor 2
Database
C
Database
B
Server C
Server B
Server A
Database
A
VST024.vsd
Process and link
management
NonStop server
Client A
Client B
Client C