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The Command Manager processes delta structures in a manner analogous to that
of after-image data. The difference is that, for delta objects, comparative data is
extracted from service data object change summaries.
When the input service data object (SDO) represents an Update operation with a
delta structure, the Command Manager will look up the BOChangeSummary to
find the respective operations on each child SDO. For example, the following
figure shows a delta SDO input with underlined text representing the operation
derived from the change summary.
Command Manager extracts change summaries
Command Manager interpreter logic:
An order attribute establishes the sequence by which the interpreter executes
commands.
The interpreter is given a top level command to execute. Each command has an
order associated with it that is set when the command is created. The order
attribute of each command may be BEFORE_PARENT or AFTER_PARENT. If the order
attribute of a child command is BEFORE_PARENT, that command will execute before
the parent; if the order attribute of a child is AFTER_PARENT, that command will
execute after the parent.
v If an object is marked as created and then as deleted in the ChangeSummary, the
adapter will not take any action.
v If an object is marked as created and then updated in the ChangeSummary, the
adapter will perform a Create.
v If an object is marked as updated and then deleted in the ChangeSummary, the
adapter will perform an Update.
Implementing Command Manager:
You implement commands for each type of operation supported by the adapter, a
command factory to support instances of each operation, and calls to the
Command Manager.
112 WebSphere Adapters: WebSphere Adapter Toolkit User Guide