Listings are special filter object types, which are used to specify a selection criterion for distributing master data. Listings are based on the SAP Classification system. Lists are allocated to an LS using transaction SALE (from the ALE customizing guide) or Distribution Scenarios > Master Data Distribution > Distribution via Listings
Note: Listings are applicable only to Material, Customer, and Vendor master data.
Ports are a logical representation of the communication channels in SAP. R/3 defines four types of ports viz........
Ports are a logical representation of the communication channels in SAP. R/3 defines four types of ports viz. tRFC (transactional Remote Function Calls), File, R/2, and Internet. ALE can use all port types to distribute Idocs.
Process Codes are used in both ALE and EDI framework to identify the function module or API (Application Programming Interface) to be invoked for subsequent processing. Inbound as well as outbound interfaces use process code but for different purposes. Outbound process codes are stored in table TEDE1, while inbound process codes are stored in TEDE2.
Message control is a mechanism by which documents are output based on a selection criteria and requirements. This concept is applicable not only to EDI and ALE, but also to other output mediums (for example: print, fax). Message control determines the type of document, its timing, number, and the medium. NAST table stores output records.
The conditions (selection criteria and requirements) for creating an output message are stored in condition tables. Search mechanisms are used through access sequences, output processes, and requirements to determine whether an application document qualifies for output.
ALE provides powerful capabilities to capture changes occurring to master data using Change pointers. These R/3 objects mark changes to SAP master data. ALE configuration facilitates the relation between Change Document objects and change pointers. This feature can be used to keep two or more systems synchronized with respect to master data.
In conclusion, ALE is a simple add-on application that relies heavily on the customizable distribution scenario. Every time a data object (described in an ALE scenario) changes, an IDoc is triggered. Application Link and Enabling (ALE) is one of the most common and effective technologies available for distributed SAP systems.
