Linked Universe are the universe in which one universe act as a core universe and other
encapsulate the core universe act as Derived universe. The core universe are also called
source universe as they share it’s components like parameters, classes,
objects, or joins with the derived one. The major advantage of this concept is that, when you make changes in the core/source universe it get reflected in the Derived .
Before we go to more details let me depict the link universe concept as follows
In the above diagram Universe A is the core/ Source universe and Universe B is the derived universe.
Advantages of using Linked universe :
- You can share the common objects and classes with different universe, but note that change in the core universe will impact all universe using it.
- Can distribute the build of large universe into small core universe and link them into main universe.
- It allow to implement concept call specialization, by splitting the responsibility between database administrator for core universe and specialized universe for more functional universe.
- Implement minor changes in the universe is easy task, because you have to change the small core universe only once. And the changes made are reflected to all derived universe using it.
How to create Linked universe Step By Step
Here I am using e-fashion connection as connection for both Core and Derived universe.
Step 1. Create Core universe say “ Core Universe “
Step 2. Make schema and define objects and Classes as shown below .
Now save and export the universe to Repository.
Note: Linking of universe is done on repository base universe only.
Step 3. Now we will create a derived universe which will use the core universe created in the previous step.
Imp point to be noted here is
- Derived universe must have the same connection and parameters as defined in the core universe.
- Core universe must be exported first to the repository before derived universe.
In the link tab of the “universe parameter “ window click on Add Link button
It will ask for the core universe in the pop-up window
Select the appropriate universe and say OK.
You can see in the below screen the core universe objects , class and schema is available.
Note : these objects, classes and schema are grayed out , because you can’t change them in the derived universe . To make any changes in this , you have to change the core universe . The changes made in the core universe will be reflected here in the derived universe.
Now you can save and export the Derived universe to the repository .
Cons Of Linked universe.
- You can link only those universe, that have same connection. i.e you cant link universe that have different data sources.
- You can apply only one level of linking. i.e you can not use derived universe as link universe to create another derived universe.
- Context and aliases have to be identified in the Derived universe again to avoid cross join.
- If there is structural change in the Core universe , the changes are not reflected in the Derived universe and hence have to be done manually.
Including Universe Instead of Linking.
To avoid the dependency and impact of change in the core universe . you can include the core universe instead of linking it.
Which means we can copy the structure and objects of the core universe , without having any dependency on it.
It have following advantages.
- It remove dependency from core universe i.e any changes in the core universe doesn’t effect the derived universe.
- It can speed up the Development of the Huge Universe by copying the core universe.
- Can edit the schema defined in the core universe .
Steps to Include universe.
Step 1. Follow the same steps as defined above and then go to link tab in the Universe Parameter window.
Step 2. Select the universe you want to include and press Include…
The linked universe will be copied into the derived one and link will be removed .
Step 3. You can see that schema and objects included from the core universe are now in solid color and hence can be edited .
The include concept can depicted with modified version of the figure 1 in this Document. as follows
The dotted line represent that link is broken when Universe is Included in Derived Universe B.