Flat files in Data transfer

Question

Iam able to do tutorials for Direct input and batch input method.I tried doing BAPI and IDOCs too.The point where Iam getting strucked is with flat file.
For example If i want to transfer Purcharse order or vendor master information,I need to put valid data in text file.Lets say for material master, the valide material type is 'XYZ',if i put '123' in flat file,it throws the error that 123 is not valid material type(during the session processing).So I need to put only valid data in the flat text file.How to go about this?
Hope you understood my question.
Another question is that does ALE deals with creating segments.In my understanding
LSMW is a tool which helps in data transfer with following ways
i)Direct input method
ii)Batch input method - recording
iii)BAPI - using built in business objects
iv)Idcos - using inbout idoc processing where we create ports.
BDC is another tool like LWMW,where the ways are call transaction and session.
Is what I understood correct?Any changes?

Answer 1

Hi Gopi
For the First Question:
We should always havea valid data in the input file for successful processing. otherwise by very nature of the program the LSMW throw an error saying that the data is invalid and I believe that this is the functionality that is required.
I am not sure abt ALE part
BDC is not a tool in SAP but its a programming done which is similar to the recording method in LSMW. instead of Autmatic generation of the code we write a custome code to upload the data using the recording done either by call transaction or session method. in short its not a tool but one kid of programming logi to upload the data.
Santosh