Distribution Using Message Types
When message types are used to transfer data asynchronously in ALE:
Outbound Processing
An application function module creates a master IDoc in outbound processing, the so-called master IDoc.
The following steps are carried out in the ALE layer:
The formatted IDoc is passed to the communication layer and from here sent to the system that was called (server) via a transactional remote function call (RFC) or via file interfaces (for example, EDI).
If an error occurs in the ALE layer, the IDoc containing the error is saved and a workflow task is created. The ALE administrator can use this workflow to correct the error.
For information on programming see the
Implementing Outbound Processing.The individual steps are explained below.
Receiver Determination
Like a normal letter, an IDoc has a sender and a receiver. If the application does not explicitly specified the receiver, the ALE layer uses the distribution model to help determine the receivers of the message.
The ALE layer can find out from the model whether any distributed systems should receive the message and, if so, then how many. The result may be that one, several or no receivers at all are found.
For each of the distributed systems identified as receiver systems, the data specified by the filter objects in the distribution model is selected from the master IDoc. This data is then entered into an IDoc, and the appropriate system is specified as the receiver.
Segment Filtering
Individual segments can be removed from the IDoc before it is dispatched. If you want to remove IDoc segments, in Customizing for ALE choose:
Modelling and Implementing ALE Business Processes
Master Data Distribution
Scope of Data for Distribution
Filter IDoc Segments
The appropriate setting depends on the sending and receiving logical R/3 System.
Field Conversion
You can define field conversions for specific receivers in ALE Customizing:
Modelling and Implementing ALE Business Processes
Converting Data Between Sender and Receiver
Standard rules can be specified for field conversions. One set of rules is created for each IDoc segment and rules are defined for each segment field. These are important for converting data fields to exchange information between R/2 and R/3 Systems. For example, the field plant can be converted from a two character field to a four character field.
Standard Executive Information System (EIS) tools are used to convert fields.
IDoc Version Change
SAP guarantees that ALE works correctly between different releases of the R/3 System. By changing the IDoc format you can convert message types from different R/3 releases.
SAP uses the following rules to convert existing message types:
ALE Customizing records the version of each message type used in each receiver. The communication IDoc is created in the correct version in outbound processing.
Dispatch Control
Time and quantity are the factors that control the dispatch of IDocs in the dispatch control.
Scheduling the dispatch time:
IDocs can either be sent immediately or in the background. This setting is made in the partner profile.
If the IDoc is sent in the background, a job has to be scheduled. You can choose how often background jobs are scheduled.
Controlling the amount of data sent:
IDocs can be dispatched in packets. The packet size is assigned in ALE Customizing in accordance with the partner profile.
Modeling and Implementing ALE Business Processes
®
Partner Profiles and Time of Processing
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Maintain Partner Profiles
This setting only affects IDocs that are processed in the background.
Inbound Processing
The following processes are carried out on inbound IDocs in the ALE layer:
For information on programming see the
Implementing Inbound Processing.The individual steps are explained below.
Segment Filtering
You can filter IDoc segments in inbound processing.
In inbound processing this function is principally the same as in outbound processing.
Field Conversion
You can define field conversions for specific receivers in ALE Customizing:
Modelling and Implementing ALE Business Processes
Converting Data Between Sender and Receiver
Standard rules can be specified for field conversions. One set of rules is created for each IDoc segment and rules are defined for each segment field. These are important for converting data fields to exchange information between R/2 and R/3 Systems. For example, the field plant can be converted from a two character field to a four character field.
Standard Executive Information System (EIS) tools are used to convert fields.
For reduced message types field values are not overwritten in the receiving R/3 System, if the corresponding IDoc field contains the character "/".
Transfer control
Once the IDocs have been written to the database, they can be posted by the application.
IDocs can be passed to the application either immediately on arrival or at a later time in background processing.
Inbound IDocs can be posted in three ways:
The inbound IDocs are posted directly. An error workflow is started, if an error occurs.
Workflows for ALE are not provided.
A single step performs the IDoc posting.
The standard inbound processing setting is for ALE to call a function module directly. For information about the options in SAP Business Workflow see the
Inbound Processing Using SAP Workflow.You can specify the people to be notified for handling IDoc processing errors in SAP Business Workflow. Different people can be responsible for each message type.