Introduction to Data Management

Developing Applications With PATHWAY
15873 Tandem Computers Incorporated 6-3
Standardized Applications
With PATHWAY, you can standardize your applications by sharing program
modules. Different screen programs can use the same server. As an example,
applications that need to check a credit file can all use the same credit-check server.
Applications can also call the same screen programs. For example, all applications
that require the end user to logon can use the same logon requester. With this kind of
standardization, you can eliminate much duplicated effort.
New Applications Based on Old Ones
Often, you can save time by forming new PATHWAY applications from the
components of existing ones. For example, you can create a new application by
adding new requesters or servers to modules that already exist, or by copying existing
modules from several applications into a separate new application.
Requester Framework Supplied by PATHWAY
Although you must write the screen programs that handle your application’s interface
with the end user, you do not have to provide all the code for managing the end users’
terminals and communicating with server processes. Instead, PATHWAY supplies
this additional code by generating a Terminal Control Process (TCP) during
PATHWAY system configuration. In a running PATHWAY application, all requesters
are actually TCPs that, in turn, run screen programs. PATHWAY supplies the TCP,
and you furnish the screen programs.
A TCP is a multitasking process that:
Supports your application’s interface with the end user by executing your screen
programs. The TCP interprets the SCREEN COBOL statements in the screen
programs and runs the programs on each end user’s terminal. Together, the TCP
and the screen programs manage transaction data at the terminal interface, with
each performing specific tasks.
Manages data for several programs and terminals simultaneously. This feature
allows you to write each screen program as if it dealt with only one terminal at a
time. The TCP, however, can use this program to service as many terminals as you
wish. The TCP automatically takes care of running multiple screen programs
concurrently and interleaves the processing of different transactions from several
terminals.
Validates the data entered by the end user, ensuring that the correct type of data is
passed to the server.
Routes requests for database changes from the screen programs to the server
programs, and returns replies from servers to the correct terminals.