Hi Lakshman Balanagu,
Check my reply below for your questions:
I want to take an example here. Let say you have a data object created in DOE with one root node and one child node. Each of them have 5 fields. Let me also give some names for better understanding here.
Data object name : TEST
Fields at header node : A B C D E
Fields at child node : F G H I J
1. What is the use of creating projections?
You might have created the data object based on the backend BAPI wrappers which are written by somebody. Now based on your business requirement, you want to develop a mobile application. Based on the given requirements you feel that only 4 fields out of each node are required for your application at any point of time. If we use plain data objects, then you get all fields. So in order to avoid that we create projections.
Point to remember here : ESDMA is to define list of all data objects which you need for your application from different SWCV's. Projection is to restrict certain fields from the created ESDMA.
2. What is the difference between Design time projection, and run time projection (could please tell with a real time example)?
Design Time Projection: As I explained in point 1, you need only first 4 fields of each node. So if you create a design time projection with fields ABCD at root node and FGHI at child node, then only those fields will be availalbe on device application. Meaning, when you use the ESDMA to create application, the tables on the device application are created only with those 4 fields at each node. All your messages will contain a max of only 4 fields.
In one shot if I have to say, design time projection actually defines the meta model of your device application.
Runtime Projection : By default when you create ESDMA, a default design time projection and run time projection is created with all the fields. The idea is, during design phase of your application you really never know what all fields might be needed on device application. So you create design time projection with all max fields in our case we selected 4 in each node. Now during runtime, if we feel only 3 fields in each node are required to run the device application/to suffice business needs then you can create the runtime projection with only 3 fields ABC and FGH at respective nodes.
3. What is the need of creating run time header?
This is again one more level filter on top of run time projections. Lets say you have a different requirement where in you want to send only very few fields of run time projection. And these fields change based on certain requirements. So you create all different possible combinations of runtime headers on top of runtime projection and activate any one of them to be active at any point of time. So whenever business requirement changes, instead of creating a new runtime header you just have to activate one of the existing ones.
4. I have search on help.sap.com for ESDMA related stuff but I did not find anything, I donu2019t know, why sap doesnu2019t update the nw mobile 7.1 developers guide?
You can also refer : http://help.sap.com/saphelp_nw73/helpdata/en/5c/12967fe4c44857bce4ef93afa09bf7/content.htm
5. I have found 5 documents from http://wiki.sdn.sap.com/wiki/display/mobile/SAPNWMobile+KnowledgePedia
But in each document they explain with different example?
Best Regards,
Siva.
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