TRANSFER Programming Manual

Error Reporting
Developing TRANSFER Applications
8–14 40970 Tandem Computers Incorporated
Error Reporting Plan the methods for reporting errors to users. Your application can find out about
errors in several different ways.
Problem reports can arrive as packages in the INBOX folder. A package might
state that another package expired before it was acknowledged or that it could not
be delivered on time to a specific recipient.
Errors in a request, but not specific to a UOW, are reported by the TRANSFER
delivery system in the reply header. These errors usually indicate programming
errors in the SCREEN COBOL program that makes the request. Examples of such
errors are an incorrect session ID or 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 the TRANSFER delivery system. Examples of such errors are ITEM-
NOT-FOUND, for a UOW that refers to an item, or INVALID-FOLDER-NAME,
for a UOW that names a folder. The user may have entered an invalid name,
which the requester passed to the server as a parameter in a UOW.
In some cases, an error might be cause to abort and restart a transaction. If a
transaction is creating an item and adding records and the request fails because a
processor fails, you cannot tell how many records were added successfully to the
item; in this case, you should abort and restart the transaction.
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 user, revising a set of values used to calculate
timeframes and priorities, or automatically sending a package again.
Coding and Testing
the Software
Before coding your programs, read the associated language and PATHWAY manuals.
Consider carefully the conventions for ensuring fault-tolerant operation and for using
TMF to guarantee database consistency. 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).