NonStop Systems Introduction

The Application Server Environment
NonStop Systems Introduction—527825-001
3-11
Server Handling
Client applications communicate with server programs, which carry out requests they
receive from clients. These servers comprise the middle tiers of the client/server
architecture. The following discussion takes a closer look at these servers.
Server Handling
The server programs perform the business logic and database access functions
required by ZLE applications and services. Components in the application server
environment play a key role in communicating between clients and servers. The
particular components that perform this function depend on the application server
being used. For the Pathway, NonStop Tuxedo, and NonStop CORBA environments,
the HP NonStop TS/MP product fulfills this role. For the WebLogic Server/J2EE
environment, WebLogic Server components provide the link between clients and
servers.
We now examine some of the server-handling tasks performed by the application
server in a multi-tiered, multiple processor environment.
Process Management and Link Management
Process management is handled by components of the application server
environment. These components start additional copies of server processes as needed
to handle an increasing workload, automatically restart failed server processes, and
delete server processes when they are no longer needed. This strategy helps to
maintain consistent and rapid throughput as the workload varies.
Link management is also handled by the application server environment. The
application server sets up communication paths between client and server processes
and distributes client requests to server processes to optimize system throughput and
response time.
Process management and link management are performed automatically and require
no changes to application code. Figure 3-7 on page 3-12 shows three servers used in
a simple application. The figure shows how requests from multiple clients are routed to
multiple servers in an application.