Here are few additional
concepts which are broadly applicable to ALE and will help readers
understand SAPís integration services.
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. 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.
(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.