What is application server and role of it?

Question

i need information about application layer in abap.

Answer 1

hi Anil,
Please check these links:
http://help.sap.com/saphelp_nw2004s/helpdata/en/69/c24e034ba111d189750000e8322d00/content.htm
http://www.sapdev.co.uk/file/file_disall.htm
Overview of SAP Application Servers
Use
You can display a list of application servers that have registered themselves with the SAP message server by executing transaction SM51, or by choosing Administration ® System Administration ® Monitor ® System Monitoring ® Servers. From their status you can recognize which application servers are active in this SAP system.
You can also administer the application servers, and manage and display the status of the users and work processes in all application servers belonging to the SAP system.
Components of Application Server
Work Processes
Work processes are components that are able to execute an application (that is, one dialog step each). Each work process is linked to a memory area containing the context of the application being run. The context contains the current data for the application program. This needs to be available in each dialog step.
Dispatcher
The dispatcher is the link between the work processes and the users logged onto the ABAP application server (that is, the SAP GUIs of theseusers). Its task is to receive requests for dialog steps from the SAP GUI and direct them to a free work process. In the same way, it directs screen output resulting from the dialog step back to the appropriate user.
Gateway
This is the interface for the communication protocols of NetWeaver AS ABAP (RFC, CPI/C). It can communicate with other ABAP application servers of the same NW AS, with other SAP Systems, or with external non-SAP systems.
Shared Memory
All of the work processes on an ABAP application server use a common main memory area called shared memory to save contexts or to buffer constant data locally.
Hope this will help.
Regards,
Nitin.