
The principle architecture of a SAP Process Integration landscape is described in the SAP NetWeaver Master Guide and in the SAP NetWeaver Technical Infrastructure Guide on SAP Service Marketplace at service.sap.com/instguidesnw .
This section covers the technical system landscape of the SAP PI dual usage type installation option.
For a high-level view of the technical system landscape, see SAP PISAP PI Dual-Stack Installation .
The figure below illustrates an SAP PI dual usage type landscape:

An SAP PI dual usage type landscape contains the following groups of components:
Messaging components responsible for message processing and protocol handling. These components include the Integration Server with the central Integration Engine and the central Advanced Adapter Engine (AAE), optional non-central Advanced Adapter Engines, and optional Adapter Engines (Java SE).
The Adapter Engine (Java SE) is only supported for compatibility reasons. It hosts only a subset of the adapter functions and does not support standard security features such as security logs or integrated user management. You should only use this Adapter Engine if it is a precondition in your environment.
Tools for design, configuration, administration, and monitoring purposes (Enterprise Services Builder (ES Builder), Integration Builder, Exchange Profile, System Landscape Directory, Search and Classification Engine TREX) that require user interaction and are not directly involved in messaging.
Back-end systems and business partner systems that act as the sender or receiver of messages.
By default, Internet Communication Manager (ICM) ports are deactivated in business systems to prevent unwanted system access. When you want to enable communication based on the proxy or web services runtime, you need to activate the corresponding ICM ports in the business systems.
More information on the Internet Communication Manager: Internet Communication Manager (ICM) - SAP NetWeaver
Concerning security, the following components have to be considered in more detail:
Integration Server
The Integration Server acts as a hub for a set of senders and receivers of messages. Technically, an Integration Server consists of three engines:
Integration Engine
This engine processes messages according to the configuration defined with the Integration Builder.
Central Advanced Adapter Engine
This engine connects senders and receivers that do not speak the XI message protocol by handing over messages to the Integration Engine and the other way round. Additional non-central Advanced Adapter Engines can be installed on an SAP NetWeaver Application Server for Java (AS Java) without Integration Engines.
Through integrated configuration, communication between sender and receiver system is brokered only by the Advanced Adapter Engine.
Business Process Engine
This engine is part of the Integration Server, but it is not relevant for security and therefore not depicted in the figure above.
Non-central Advanced Adapter Engines
Technically, there are two different types of non-central engines:
Advanced Adapter Engine
This type of Advanced Adapter Engine runs on AS Java. There may be any number of non-central Advanced Adapter Engines, each associated with exactly one Integration Server with which the Advanced Adapter Engine communicates using the XI protocol.
Adapter Engine (Java SE)
This type of Adapter Engine was already available with XI 2.0. It merely requires a Java Virtual Machine to run.
Enterprise Services Builder
Provides tools for designing an SAP PI landscape.
Enterprise Services Repository and Registry
Contains interfaces and mappings available across several landscapes. The Enterprise Services Repository runs on AS Java.
The Services Registry is part of the AS Java.
Integration Builder
Provides tools for configuring an SAP PI landscape.
Integration Directory
Contains metadata for a given landscape, such as routing relations, communication channels, and security settings. The Integration Directory runs on AS Java.
TREX (optional, not shown in the figure below)
Standalone engine required for payload-based message search in PI.
More information about TREX security: TREX Security Guide .
Exchange Profile
Contains the most basic technical configuration data of a PI landscape.
System Landscape Directory
Describes the components that make up the given landscape.
Sender and receiver business systems
Depending on the message protocol, there are several types of systems:
SAP business systems residing on SAP Web Application Server 6.40 or higher.
These communicate with the Integration Server by using proxies (ABAP or Java).
SAP business systems residing on SAP Web Application Server 6.20.
These incorporate XI 2.0 proxies that enable them to send and receive XML messages in the XI 2.0 message format. The Integration Server maps between XI 2.0 and XI 3.0 message formats.
XI 3.0 is the XI message format valid for all SAP NetWeaver versions.
SAP business systems residing on SAP Web AS 6.10 or lower
These do not contain proxies, thus have to communicate with the Integration Server by using RFC and IDoc adapters.
Non-SAP business systems
Any systems that exchange XML messages or other protocols by using the Integration Server. They are connected by using adapters.