Introduction to Pathmaker

Overview of Pathway
Introduction to Pathmaker and Pathway
067867 Tandem Computers Incorporated 1–21
Server Class
A server class is a named family of identical server processes, each of which is created
from the same object file on disk. Server classes are created by Pathway at run time.
The purpose of identical server processes is to maximize the performance of an
application by fully utilizing the processing power of a Tandem system. Although
several requesters can use a single server process, if too many requesters try to use a
process concurrently, all the requests will be queued and delayed. To solve this
problem, Pathway can start identical server processes and run them simultaneously to
improve performance and throughput. Then, when the demand has subsided,
Pathway can stop the unneeded processes.
In Figure 1-9, when the Pathway application that uses Server A is started, two Server
A processes are created (and, therefore, two copies of the services it contains are
created). This group of processes is referred to as Server Class A.
Figure 1-9. Server Class
Database
Send
Request
Return
Reply
Server A Process 1 Server A Process 2
Server Class A
009
Service 3
Service 2
Service 1
Service 3
Service 2
Service 1
Requester
If an end user presses a function key that initiates a business transaction (service)
contained in Server A, Pathway selects which copy to use. For example, if Service 1
contains code to read one vehicle row by vehicle ID number, Pathway will select
which Server A process, containing Service 1, will be used for this request. That copy
of Service 1 will find the requested row.