Special Edition Using SAP R/3, Third Edition
Special Edition Using SAP R/3, Third Edition
Special Edition Using SAP R/3, Third Edition
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<strong>Special</strong> <strong>Edition</strong> <strong>Using</strong> <strong>SAP</strong> R/3, <strong>Third</strong> <strong>Edition</strong> - CH 3 - Exploring R/3 Architecture Page 9 of 26<br />
Presentation by Windows 3.1, UNIX, Windows NT, OS/2, Windows 95<br />
Application by Windows NT, UNIX, Open VMS, MPE/iX<br />
Database by Windows NT, UNIX, Open VMS, MPE/iX, AS/400/DB2<br />
Client/Server Communications<br />
The architecture of R/3 allows various protocols for communication between the elements of the<br />
configuration. TCP/IP and Open Systems Interconnect (OSI) are examples.<br />
The standard network protocol for open systems has become TCP/IP. It is supported by all operating<br />
systems relevant to R/3 systems.<br />
Transfer Protocols<br />
In accord with the <strong>SAP</strong> philosophy of choosing the most appropriate method for the task, different<br />
protocols have been adopted for each type of communication between the components of a<br />
multitiered client/server system:<br />
TCP/IP is used for handling communications within the client/server configurations of the R/3<br />
system.<br />
The IBM network protocol LU6.2 is used for communication between the R/3 system and the<br />
mainframe host.<br />
Whatever transfer protocol is used, the interchange at the user interface is under the Systems,<br />
Applications, Products (<strong>SAP</strong>) presentation protocol.<br />
Data is transferred between an application and a database server using SQL, the fourthgeneration<br />
language for manipulating data defined by American National Standards Institute<br />
(ANSI).<br />
Data Transfer by WAN and LAN Linkage<br />
The <strong>SAP</strong> presentation protocol is optimized for linking presentation servers directly to the R/3 system<br />
and via wide-area networks (WANs). When a large volume of data has to be transferred, a local area<br />
network (LAN) is needed--for example, between database servers and applications.<br />
Program-to-Program Communications<br />
Basic services for program-to-program communications at the ABAP/4 programming level are<br />
implemented by using functions from the Common Programming Interface-Communication (CPI-C)<br />
standard. The start set of CPI-C has been integrated into the ABAP/4 language.<br />
When one program has to communicate with another program, an internal gateway is used to convert<br />
the CPI-C commands to the protocol used for external transfer, such as TCP/IP or LU6.2, according<br />
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