[This is preliminary documentation and subject to change.]
There are three top-level actions in the installer: INSTALL, ADVERTISE, and ADMIN. When one of these top-level actions is executed, the installer accesses the corresponding sequence tables. Sequence tables in the installer list actions in a logical order to perform an overall task. There are six sequence tables in the installer:
All three sequence tables have the following columns.
| Column | Description |
|---|---|
| Action | The primary key for the table; the action name must be unique. |
| Condition | A Boolean expression used to determine whether to perform the action. |
| Sequence | A relative sequence number used to determine the order in which to execute actions. |
When a top-level action is invoked actions in the sequence table are done in the sequence order. If the condition evaluates to True, the action is executed. Sequence tables are the only place in a package where flow is specified, and the flow is always linear. No branching or looping is allowed. Conditions can be thought of as jumps so the linear flow may not execute every action. This simplicity makes following the sequence of events during an installation trivial.