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.