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Persistent Nodes

The system stores instances of a persistent node in the database when a transaction is saved.

From a database viewpoint, a persistent node corresponds to a table in the database, a node attribute to one database column, and a node instance to one database row.

Example

The CUSTOMER_INVOICE business object consists of several persistent nodes. For example, the ROOT node contains attributes describing global invoice data such as the INVOICE_ID. The persistent ITEM node contains, for example, the attributes AMOUNT, QUANTITY, HEIGHT, WIDTH, and DEPTH.

Transient Nodes

The system locates the node instances of a transient node only in the main memory and does not store transient nodes in the database. Determinations help fill the contents of a transient node instance when the consumer accesses the transient node instance or the first time. For more information, see Determinations.

Transient nodes are useful to buffer data. Buffered data can be derived from persistent fields. This avoids the redundant storage of information in the database and the execution of time consuming deriving functions.

Example

The CUSTOMER_INVOICE business object contains, for example, the transient PAYMENT_OPTIONS subnode. Each instance of this node represents one possible payment option. Because the possible payment options for a customer may change, they are not persistent in the CUSTOMER_INVOICE business object but dynamically imported and buffered in the transient node during the selection process.