Netweaver application server differen

[vds]

Hey guys. I have a question about the netweaver application server.

I dont understand the difference between sap abap dispatcher ( not the web dispatcher) and message server. Message server looks which application server have howmany traffic? But dont execute anything. It has only information about the traffic. And this infos give the message server to the abap dispatcher. The abap dispatcher decide then, on which application server the user can logon and work with this as.

Is this explanation right?

Thx

[raquel_gomez]

Hi,

There's one Message Server per each system.
The SAP Message Server is a part of the ABAP Server central services instance (ASCS instance); where the Enqueue is also running.
As my colleague Mercedes mentioned, it is the communication channel with all the application servers (instances) from the system. The Message Server is also used to perform load distribution, as it has a general overview of the status from all the application servers (instances):
list of available instances, services provided by each instance and load status.
It handles the communication between the instances of the system via the instance dispatchers.

There's one Dispatcher pear each instance of the system.
It initializes the application server, with corresponding ports and shared memory allocation.
It also starts the work processes and the rest of the processes started for each instance.

See Architecture of SAP NetWeaver Application Server ABAP online help:
https://help.sap.com/viewer/ff18034f08af4d7bb33894c2047c3b71/7.5.7/en-US/f9e2350eca7f4a109eb0a7bc631...
to get more details about all Components of SAP NetWeaver Application Server.

Regards,
Raquel

[mercedes_fernandez]

Hello,

the message server performs the following tasks in the SAP system:

- Central communication channel between the individual application servers (instances) of the system

- Load distribution of logons using SAP GUI and RFC with logon groups

- Information point for the Web Dispatcher and the application servers (each application server of the system firsts logs on to the message server)

When an instance is started, the dispatcher process contacts the message server so that it can announce the services it provides (DIA, BTC, SPO, UPD, and so on).
There is one message server per SAP system and a dispatcher process per SAP instance.

Best regards,
Mercedes