How Are Portal Objects Linked?
When managing content in the portal, you can create new objects by duplicating existing objects. Two methods are available for creating object copies:
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Create a delta link instance of a source object
You normally use this method to create object dependencies because you want the properties of the copied (target) object to change when those properties in the source object are modified.
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Create a standard copy of an object
You normally use this method to create a sibling instance of the object that is not directly related to the source object. The new object can be modified to the needs of its new context or role.
This topic describes the relationships created when copying objects using the delta link and the copy methods.
Delta Links
A delta link is a relationship between two objects in the Portal Content Directory that is established when one object (the target object) is based on another object (the source object). The delta link operates on hierarchies and property values of objects. The source object passes its property values to target objects that are derived from the source object. Changes made to the source object are copied to the target object and are visible there. Changes made to the target object have no effect on the source object. For more information, see How Are Object Properties Inherited?
The main advantage of copying with delta links is that objects can be reused or changed without changing the original or source object. You can make changes to delta link objects (target objects) - such as deleting or adding entries in role hierarchies or changing property values for iViews and pages - without having to change the source object.
Using delta links, you can protect your own objects and the content objects shipped by SAP and other vendors against modifications. See also Delta Links and SAP Content Objects .
Using delta links, you can create chained objects , where an object can be both the source and the target object, depending on its position in the chain. The following diagram shows an iView (iView 1) that is created in the Portal Catalog with a delta link and then added to Page X as a delta link. Page X is then added to Workset Y as a delta link and Workset Y is added to Role Z as a delta link. iView 1 is the target object that is derived from the source object iView Template in the Portal Catalog. iView 1 is also the source object for iView 1 , which is contained in Page X as a delta link.
Nearly all objects in the Portal Content Directory (PCD) are linked to other objects with a delta link, meaning that they always reference other objects. Only the objects at the top location of an object inheritance chain are not delta links. In this case the objects are master objects , from which other objects are derived. They themselves have no source object that they reference.
You can display the position of an object within the object chain. For more information, see Tracing Delta Link Dependencies .
Copies
A content object can be a copy of another object. In contrast to the delta link, the copied object is an independent object that is no longer dependent on or linked to the object from which it was copied. A copied object (the new object instance) and the object from which it was copied have a sibling relationship and not a parent-child relationship, as is the case for the delta link.
When you create a portal role by copying an existing role and then pasting it as a copy in a different location, any user or group assignments that were made in the original role are copied together with the role. Use the Identity Management tool to add or remove users and groups from the role.
The following diagram illustrates the difference between a copy and a delta link relationship.
There is a delta link relationship between Object 2 and Object 3 , whereby Object 3 references Object 2 . Object 2 is thus the source object of Object 3 . The two objects have a parent-child relationship. Object 4 is a copy of Object 2 and therefore no longer references Object 2 . Object 2 and Object 4 have a sibling relationship and are linked to Object 1 with a delta link. Object 1 is the common source object of Object 2 and Object 4 .
A copied object is always a delta link. A copy does not reference the object from which it was copied. The source object is therefore the object that is one level higher in the object chain, and not the object on which it is based.