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An IDOC consists of
three record types: the control record, the data record, and the status record
(see Figure 1).
Figure 1
Structure of an IDOC.
• The control
record, or
EDI_DC, is a control structure that contains several fields with information
about the IDOC, such as what IDOC type it is, the message type, sender and
receiver information, and direction (1 for outbound, 2 for inbound). This
information provides control data on the outbound, and processing options on an
inbound IDOC. It also has as its key the Client (MANDT) and the IDOC number (DOCNUM).
The EDI_DC record of an IDOC is stored in table EDIDC. Every IDOC has one
control record.
• The data record,
which conforms to the structure EDI_DD, contains the application data. Every
EDI_DD record has a key portion that is 55 bytes in length (or 63, depending on
the SAP release), which consists of several fields describing the content of the
record. The key of 55/63 bytes is followed by a field SDATA, which is 1000 bytes
in length and of data type Long Character. The SDATA field holds the application
data, and its structure is determined by the key field SEGNAM (Segment Name). An
IDOC consists of one or more data records, and its sequence and structure are
dictated by the sequence and structure of segments in a given IDOC type. The
SDATA portion of the data record is redefined for every occurrence based on the
structure of the segment, with the first 55/63 bytes of the data record
identifying the segment name, sequence, and hierarchy. In an outbound interface,
ALE/EDI function modules populate these segments with application data. In an
inbound interface, the application modules process the data contained in the
segments. Data records are stored on table EDID2 that belongs to the cluster
EDI30C.
In SAP, from a Data
Dictionary perspective, IDOC segments adhere to a naming convention. Each
segment has three components, each marked by a different prefix —E1 for segment
type, E2 for segment definition, and E3 for segment documentation. For example,
the first segment of IDOC type DEBMAS02 is E1KNA1M. Its definition is contained
in structure E2KNA1M, and its documentation is in E3KNA1M. When the IDOC is
externalized, we see the segment name addressed by its E2 prefix. For all
practical purposes, we will use only the E2 prefix when referring to IDOC
segments. Also, most segment names represent Data Dictionary tables.
• The status
record
conforms to the dictionary structure EDI_DS. It contains information on the
state of the IDOC as it passes through the various stages of processing. The
STATUS field has a length of two bytes (data type CHAR), with a range of values:
01–41 for outbound and 50–73 for inbound IDOCs. The status record also includes
date and timestamps for when that particular state was reached. The status
records maintain a history of the IDOC states. An IDOC may have one or more
status records, which are stored in table EDIDS (see Figure 2, page 82). These
records can be accessed or created only by SAP function modules (APIs), and are
not externalized.
Figure 2 the
IDOC database.
IDOC objects consist
of a Basic IDOC type, an Extension type, and an IDOC type.
In an R/3 system,
IDOCs are identified by a unique IDOC number (field DOCNUM), and all three
record types are tied together with this number. The IDOC number is internally
assigned by SAP. It is possible to maintain the number range of IDOCs.
You can display
information about IDOC record types by executing transaction WE61 or using the
following menu path from the main R/3 menu:
Tools ->
Administration -> Administration -> Process Technology -> IDOC -> IDOC Basis (*)
-> Documentation -> IDOC Record Types.
You can reach IDOC Basis (*) by executing transaction WEDI, which is frequently
used in ALE and EDI. You can display information about IDOC types, such as
DEBMAS02 and INVOIC01 by executing transaction WE60 or using the following menu
path from WEDI:
Documentation -> IDOC types.
See
Structure of MATMAS01 IDOC type
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