Architecture Manual 
This documentation provides an overview of the server for Java. It describes the setup of a Java cluster and the components involved.
Also, it describes the system architecture of the J2EE Engine.
Integration
You can operate the J2EE Engine solely for J2EE applications or together with the SAP Web AS ABAP.
The integrated scenario is described in the documentation section SAP Web Application Server with ABAP and Java.
This architecture overview provides an introduction to and background information for administration and development of J2EE applications with the SAP Web AS.
Features
The Architecture Manual is divided into the following sections:
SAP J2EE Engine System Architecture
SAP NetWeaver Java Development Infrastructure
Java Persistence (You can also find this documentation in the Development Manual)
SAP Web Application Server with ABAP and Java.