Reduced Message Types

Concept of  Change Pointers: 
If you want to distribute master data changes with the SMD tool (Shared Master Data), changes to the master data objects are flagged for distribution by change pointers .
The SMD tool is connected to the change document interface. If the master data changes are to be distributed, the application writes a change document. The contents of this are passed to the SMD tool. The tool writes change pointers, reads the application data and creates the master IDoc.
The master IDoc is then passed to the ALE layer, which sends it to all interested systems.Generally, whenever changes are done the corresponding data is been maintained in CDHDR and CDPOS tables.

Reduced Message Types  :

When a reduced IDoc is created from a maximal IDoc, a new message type is created and assigned to this IDoc.  The reference to the message type of the maximal IDoc stays the same for e.g the new message type for material is MATSMD and the reference message type is MATMAS.
The new reduced message type  is automatically assigned to the change documents.This  technique of filtering at the IDoc level enables to send a subset of data that is relevant for a receiving system.

Creation of reduced Message type:

 BD53  is used to create the reduced message types.Change pointers for  reduced message types can be activated by clicking on the activate change pointers tab.Activation of change pointers can be checked in BD50.





Click on the create button and mention the Reduced message type name and the actual message type name :


Select the required segments from the list given by placing the cursor on respective segment and clicking the select tab.



The mandatory segments cannot be reduced.The Fields present in the Idoc with reduced message type can be viewed in  BD52 by mentioning the message type name.
In BD59 there are many predefined filtering objects available for message types,here we can mention the field name and segment name which we need to drop .The filtering objects we maintained in BD59 for a message type will be in the Distribution model.

Creation of Distribution Model :  

 Before creation of Distribution model the partner profiles and Ports need to be maintained .The distribution model is created in BD64.Click on the create model view tab to create a new model view and give the mandatory details.

Click on The Add Message type tab to add the Message type and mention the receiver and sender system :


 
The fields Present in the BD59 for that reduced message type will appear on the screen on which you can apply the filter : 

Creation of Idoc :  

The Idocs for the change pointers can be created by the executing the program RBDMIDOC.Give the message type in the popup the idoc will be  generated for that particular  message type.
RBDMIDOC report creates IDocs for the specified message type from the change pointers, sends them to the recipient systems, and flags the change pointers for this message type as processed.
The recipient systems are determined by the distribution model for this message type and also provides the information about the number of master,communication idocs created.

Deletion of change pointers : 

To Delete Change pointers use transaction BD22 and the standard program  RBDCPCLR.


Source: https://wiki.scn.sap.com/wiki/display/ABAP/Reduced+Message+Types