a step -by -step approach January 19, 2008 by Riyaz
This article will help you understand the basics of ALE and IDocs via a simple do-
it-yourself example. We will create a custom IDoc in one SAP system and then post it-yourself example. We will create a custom IDoc in one SAP system and then post
some business data through it to another SAP system. Business data will be picked
up from custom data dictionary tables.
ALE Application Link Enabling is a mechanism by which SAP systems
communicate with each other and with non-SAP EDI subsystems. Thus it helps
integration of distributed systems. It supports fail-safe delivery which implies that
sender system does not have to worry about message not reaching the source due
to unavoidable situations. ALE can be used for migration and maintenance of
master data as well as for exchanging transactional data.
The messages that are exchanged are in the form of IDocs or Intermediate
Documents. IDocs act like a container or envelope for the application data. An
IDOC is created as a result of execution of an Outbound ALE. In an Inbound ALE
an IDOC serves as an input to create application document. In the SAP system
IDocs are stored in the database tables. They can be used for SAP to SAP and SAP
to non-SAP process communication as long as the participating processes can
understand the syntax and semantics of the data. Complete documentation on
IDOC is obtained by using transaction WE60.
Every IDoc has exactly one control record along with a number of data records and Every IDoc has exactly one control record along with a number of data records and
status records. Control record has the details of sender/receiver and other control
information. Data records contain the actual business data to be exchanged while
the status records are attached to IDoc throughout the process as the IDoc moves
from one step to other.
Now, let us understand the ALE Configuration by means of an example scenario
below:
The Scenario
Data from custom tables (created in
customer namespace) is to be formatted customer namespace) is to be formatted
into an IDoc and sent from one SAP
R/3 system to another using ALE
service. We need to have two instances
of SAP R/3 systems or we can simulate this on two clients of the same SAP R/3
system.
Create three tables as shown below.
Creating Custom IDoc type and Message type
All the objects created should be present on both source as well as target system(s). All the objects created should be present on both source as well as target system(s).
1. Create segments Transaction WE31
Create a segment ZRZSEG1
Add all fields of table ZCUSTOMERS to it
Save the segment and go back
Release it using the menu path Edit -> Set Release
Similarly create two more segments given below
Seg. ZRZSEG2 to hold all fields of table Z SOHEADERS
Seg. ZRZSEG3 to hold all fields of table ZSOITEMS
2. Create Basic IDoc type Transaction WE302. Create Basic IDoc type Transaction WE30
Create a Basic type ZRZORDER
Add the created segments in the hierarchy shown
Maintain attributes for each of the segments
Save the object and go back
Release the object using the menu path Edit -> Set Release
3. Create/Assign Message type Transactions WE81/WE82
Go to WE81 Go to WE81
Create a new Message type ZRZSO_MT
Save the object
Go to WE82 and create new entry
Assign the message type ZRZSO_MT to the basic type ZRZORDER
Also specify the Release Version
Save the object
Thus we have defined the IDoc structure which will hold the data to be transferred.
In the next part of the article we will understand the outbound settings, i.e. the
settings to be done in the source system.