TRANSFER Programming Manual

Addition of Records to Package Header Items
Developing TRANSFER Applications
8–10 40970 Tandem Computers Incorporated
If you have a choice within the requirements of your application, it is better to
structure large packages and items so that they contain many components at the same
level but incorporate fewer levels. Figure 8-3 illustrates two structures that have the
same number of component items. The items are spread more evenly across the
second structure than across the first.
Figure 8-3. Avoiding a Nesting Problem
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Item Item ItemItem
Components List
Package Header
Item
Components List
Package Header
Components List
Package Header
Components List
Package Header
Item
Components List
Package Header
Item ItemItem
Send #1 gets the package ID.
Send #2 gets these items.
Send #3 gets these items.
Send #4 gets these items.
Send #5 gets these items.
Send #6 gets these items.
Item
Components List
Package Header
Components List
Package Header
Item
Package 1 Package 2
Item
Components List
Package Header
In Figure 8-3, retrieving the components of the first structure requires six SEND
operations, including one SEND to get the item ID of the outermost package.
Retrieving the components of the second structure requires three SEND operations. If
the package needs to be transported across nodes, the second structure entails less
recursive processing by asynchronous requesters.
Addition of Records to
Package Header Items
In addition to adding data records to component items, your application can also add
them to package header items. When transmitting short messages, the application can
save storage space and time by adding records directly to the package header rather
than by creating and attaching other items to the header.
Both PS MAIL packages and TAREQ event packages can contain text records in lieu of
components in their package headers.