SAP Data Ports ( WE21 ) in idoc

IDoc data can be sent and received through a multitude of different media. In order to decouple the definition of the media characteristics from the application using it, the media is accessed via ports.

A port is a logical name for an input/output device. A program talks to a port which
is presented to it with a common standard interface. The port takes care of the
translation between the standard interface format and the device dependent format.

Communication media is defined via a port definition.

Instead of defining the communication path directly in the partner profile, a port
number is assigned. The port number then designates the actual medium. This
allows you to define the characteristics of a port individually and use that port in
multiple profiles. Changes in the port will then reflect automatically to all profiles without touching them.

Typical ports for data exchange :

• Disk file with a fixed name
• Disk file with dynamic names
• Disk file with trigger of a batch routine
• Standard RFC connection via TCP/IP
• A network channel
• TCP/IP FTP destination (The Internet)
• Call to a individual program e.g. EDI converter

Every application should send or receive its data via the logical ports only. This
allows you to easily change the hardware and software used to make the physical
I/O connection without interfering with the program itself.

The transactions used to define the ports are

• WE21 to create the port and assign a logical name, and
• SM59 to define the physical characteristics of the I/O device used.

The difference between the port types is mainly the length of some fields. E.g. does
port type 3 allow segment names up to 30 characters in length, while port type 3 is
constrained to a maximum segment name of 8 characters.