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Jackson Structured Programming (JSP) – Read Ahead and PeopleCode —

Jackson Structured Programming – now that brings back memories of my COBOL training at British Telecom in the late 1980’s.

What prompted this short post was a dreadful piece of hand-crafted PeopleCode to load a CSV file using a file layout. The usual “Operand of . is null” occurred unless the input file contained a “blank line” at the end.

The underlying reason for this was a failure to apply one of the fundamental techniques in JSP – the single read-ahead rule:

Single Read-ahead rule: Place the initial read immediately after opening the file, prior to any code that uses the data; place subsequent reads in the code that processes the data, immediately after the data has been processed.

In fact, this approach is exactly what you get when you drag a file layout into a PeopleCode step in Application Engine – sample code that uses the JSP single read-ahead rule.


Categorised as: App Engine | Hints and Tips | Peoplecode | Peoplesoft | PeopleTools | Performance | Tuning



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