Introduction to Pathmaker

Overview of Pathway
Introduction to Pathmaker and Pathway
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Benefits of Using Requesters and Servers
Terminal processing and database access are two operations performed by an OLTP
application that have very little in common. Therefore, splitting the online application
into a terminal handler and a database handler is useful because it is a logical way to
modularize an application.
Also remember these points:
Applications written in modular format are easier to write, control, and maintain.
Requester-server applications make system tuning and load-balancing tasks easier
for a multiprocessor Tandem system.
Service Functions
A service is a portion of a Pathmaker server that an application developer creates to
perform a single, specific business transaction such as registering a new car.
(Remember that a transaction is a multistep operation that changes a database from
one consistent state to another consistent state.) Code for a service is written using a
programming language such as COBOL85 or C. Services are contained in servers and
cannot function outside of them.
After a request message is received by a service, the service can perform the following
functions needed to complete all the steps of the transaction:
Input validation
Data manipulation
Calculations
Database access such as to read, write, or delete information from one or more
related tables
When the service completes its work, it formats a reply message that will be sent back
to the requester.
Benefits of Using Services
Splitting a database management program into even smaller units of code, with each
performing a specific business transaction, adds an additional level of modularity to
an application. In fact, this makes services easier to write and maintain because all of
the code that deals with a transaction is contained in one place.
The decision as to which services are packaged together in a particular server affects
the consistency of performance of an application. In general, services should be
grouped together if they access a common table or tables and if they take
approximately the same amount of time to run.
Because services are separate, they can be easily packaged and repackaged numerous
times to achieve the best performance without application developers having to
change source code.