AS ABAP: This is based on ABAP- based application. Advanced Business Application Programming language is specially developed for highly scalable applications.
AS JAVA: This is based on JAVA i.e. J2EE-application. J2EE is JAVA 2 Platform Enterprise Edition i.e. a range of software component that is built on JAVA language.
AS ABAP+JAVA: This is known as dual stack system having both ABAP and JAVA platforms on one system. For example Solman system contains both ABAP and JAVA system.
In NetWeaver AS ABAP tables, programs and application data is stored in the ABAP schema of the database while Java data is stored in the Java schema. Here, the ABAP runtime environment can access the ABAP schema of the database, and the Java runtime environment can access the Java schema. In the ABAP+Java system, the different runtime environments communicate directly via the SAP Java Connector (JCo).
Architecture of AS ABAP
Central instance has message server and enqueue work process which makes it different from dialog instances. The services provided by a work process decides the role of an instance for example if an instance is providing dialog login to the system and updating the table too then at the same time an instance is a dialog server and update server too.
|AS ABAP Architecture|
SM50: The tcode is overview of work processes of an instance.
SM51: We get the information of all the instances of a system.
Dispatcher: Dispatcher is present in different instances and through message server it communicates to different work processes.
Message Server is responsible for load distribution of the users to different instances. It communicates with different dispatchers to provide logon load balancing at the time of logon i.e. message server distributes the load amongst different instances.
SM04: We can get the information of users who are currently logged in the system their types i.e. either they are dialog user or RFC user.
ICM: It receives the request when the SAP system is communicating through HTTP protocol. SMICM gives the status of ICM, if it’s not active then we have to check and resolve the issue.
Gateway: If an SAP system wants to communicate to other SAP and Non SAP system through Remote Function Call (RFC) it is done through Gateway reader. Using SMGW we can monitor all the gateway connections which are active.
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