Idoc metadata

Question

hi
why should we import idoc metadata while using idoc adapter and what do we mean by metadata.even in mapping idoc structure why we assign segment and begin to constant values and disable cntrol record field.
regards
raghu

Answer 1

Hi Raghu,
What is Metadata:
       IDoc (Intermediate Document) metadata comprises structures for the corresponding IDoc types .This metadata is just a description of available structures
and fields.Using an RFC connection, metadata of this type can be either called directly at runtime or loaded to the Integration Server beforehand.Thus it can be loaded in two ways:
1. During the runtime
2. Before the actual message flow.
To find out what metadata has already been loaded, call the transaction Metadata Overview for IDoc Adapter (IDX2).The system displays a screen with the directory of all systems connected with the IDoc adapter (including a description) for which metadata has already been loaded. Choose Port Maintenance in IDoc Adapter () to call the corresponding transaction and to create additional ports.
Why to Import:
    To process an IDocs in the form of an IDOCXML
message, an IDoc’s metadata must be loaded into
the Integration Server so that SAP XI’s IDoc adapter can
change the native IDoc format into the XML representation.
All IDocs are created according to specific rules: This is the general structure (the record types) of every IDoc. Special rules affect the different IDoc types.
Segment:
Segment is like a container which strores all administration information for technical processing, as well as the actual application data.of an IDOC.
Fields :
A segment comprises segment fields as the smallest unit of the Idoc which contains the actual values and information.
control record :
The control record is identical for all IDocs and contains the administration information, for example, sender, recipient and message. Note that the control record also contains the last processing status ( STATUS field).
If you disable the Apply Control Record Values from Payload indicator in the receiver IDoc adapter, the fields are filled from the system information not from the payload as:
1. From XI sender service, configuration in Integration Directory, System Landscape Directory
2. Constant LS
3 . From XI receiver service, configuration in Integration Directory, System Landscape Directory
If you enable the Apply Control Record Values from Payload indicator in the receiver IDoc adapter, the fields are filled from the IDoc-XML payload.
**Pls: Reward points if helpful **
Regards,
Jyoti