Introduction to Pathmaker

Overview of Pathway
Introduction to Pathmaker and Pathway
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Context-Free Services
As stated earlier, the ultimate destination of a Request IPC message is a service within
a server. Several copies of a server process and, therefore, several copies of the
services it contains can run concurrently. Each time a service is needed, any one of the
available copies of the server that contains that service may be used (usually the least
busy one).
If an end user is using a requester to send a series of requests that are related (such as
listing, one by one, each person whose last name begins with the letter B), there is no
guarantee that the same copy of the List Service will be used for each related request.
As a result, the requester must keep track of the most recent name beginning with the
letter B displayed (BRADY, for example) and send that information with the next
request. Having the name of the most recently displayed person will allow whichever
copy of the service receives the next request to resume the list of persons correctly.
Services that do not save information about previous requests as a reference for
subsequent requests are called context-free. All of the service code that application
developers create must be written this way.
A service must not be required to maintain any request-dependent information
between requests. (Request-dependent information can include file positioning,
record counters, and so forth.)