Managing Serviceguard Extension for SAP on Linux (IA64 Integrity and x86_64), April 2009

About SAP Three-Tier Dual-Stack Client Configurations
A SAP dual stack configuration combines SAP ABAP stack and SAP J2EE (JAVA) stack into one infrastructure.
The following example for a three tier implementation.
Figure 1-4 Dual-Stack Client Configuration
Table 1-2 About the Two and Three Tier Layers
DescriptionLayer
The Presentation Layer consists of two additional components:
• The Internet - represents process request from the Internet using server/port combinations.
• The Web Browser - represents HTTP requests, the Internet component.
Presentation
The SAP Application Layer consists of new J2EE instances and adds the Java Dialog instances JD, the Java
Central Instance JCI, the JAVA SAP Central System SCS (with the Java Standalone Enqueue Server and Message
Server) and the JAVA Enqueue Replication Service ERS.
The Internet Communication Manager (ICM) handles the connection to the Internet. It handles incoming requests
for protocols such as HTTP, HTTPS, SMTP, SOAP and Java Co. The JCI instance runs the Internet Graphic
Service (IGS) to be able to display graphical data in an Web Browser such as a chart. The Software Delivery
Manager SDM is the tool to deliver new software components to the Java Application Server.
The SAP Application Layer also shows how the ABAP CI instance can be further separated into smaller
components with the option of running these components on additional physical machines.
(SAP) Application
Manages all database transactions. There can only be one database instance for each SAP system.Database
In this context, SAP uses new terms to describe such a configuration. In an ABAP environment the instance
running the Enqueue and Message Server is called a ASCS (ABAP Central System). In a JAVA environment,
it is called SCS (SAP Central System). The Enqueue component is called the Standalone Enqueue Server,
since it is independent of an CI instance. A new SAP component is introduced called the Enqueue Replication
Server or Replication instance.
About SAP Client/Server Architecture 19