Queue Manager Manual

Application Development Steps
Developing Queue Manager Applications
46517 Tandem Computers Incorporated 3–5
SCREEN COBOL program that makes the request. An example of such an error is
an incorrect request length (more or fewer UOWs than the request indicated).
Errors encountered while processing specific UOWs are reported in the response
UOWs by Queue Manager. An example of such an error is W-QUEUE-EMPTY,
returned by DEQ when there are no entries on the Queue file for a specified queue
name. An operator could have entered an invalid name, which the requester
passed to the server as a parameter in a UOW.
Errors can be reported by the GUARDIAN 90 operating system, input/output
processes, and other software in response to file system requests if the application
includes its own servers. PATHWAY reports a variety of errors to SCREEN
COBOL programs.
Certain errors are reported to the system administrator as console messages or
entries to a log file.
Error-handling strategies vary with the type of error and with the application. For
example, an agent might react to reports of expiration or delivery problems by
reporting those conditions to the operator, revising a set of values used to calculate
timeframes and priorities, or automatically posting a package again under certain
conditions.
Step 8: Coding and Testing
the Software
Before coding your programs, read the associated language and PATHWAY manuals.
Guidelines for coding SCREEN COBOL programs operating in a PATHWAY
environment appear in the PATHWAY SCREEN COBOL Reference Manual and the
PATHWAY Application Programmer's Guide. Guidelines for coding programs in
COBOL, FORTRAN, or TAL (which do not run under PATHWAY) appear in the
manuals covering those languages.
Consider carefully the conventions for ensuring fault-tolerant operation and for using
TMF to guarantee database consistency. Various support notes and Tandem Softdoc
information might be useful to you.
For programs written in TAL, FORTRAN, Pascal, or C, values entered in fields with
data types equivalent to the COBOL/SCREEN COBOL type PIC(4) COMP are limited
to the range 0 through 9999. This limitation applies even if it is not explicitly stated in
the TAL, FORTRAN, Pascal, or C definition for fields of that particular type. Although
a PIC(4) COMP field would be assigned type INT in a TAL program, entry of a value
less than 0 or greater than 9999 in that field would still result in an error (such as E-
INVALID-REC-TYPE).
Fields with the PIC X characteristic, such as the ITEM-ID or SESSION-ID fields, are not
displayable as output to terminal sessions.
Test your application module-by-module. If your application is based upon the
requester/server model, you can test your servers alone before evaluating their
interaction with SCREEN COBOL requesters. Later, you can evaluate your requesters
with debugged servers.