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 X Server 

The X Server is the communication server of the database system. It listens at service port sql6/TCP for connection requests from database applications and database tools.

If a database application or a database tool wants to communicate with a database instance on a remote computer, then the connection is made through the X Server that is running on this remote computer.

The X Server is a cross-instance server: even if more than one database instance is running on a computer, only one X Server runs.

On UNIX operating systems, the X Server is also used to allow communication with the DBM Server within a computer.

SQL connections on UNIX systems and all connections within computers on Microsoft Windows use Shared Memory. If you still want to force the use of the X Server, specify the option –n localhost when connecting to the database instance.

Prerequisites for Communication

The following prerequisites must be fulfilled to allow communication through the X Server:

·        On Microsoft Windows operating systems, the X Server is registered as the system service XServer. This service must be active. An additional thread within the X Server process is created with every successful connection through the X Server.

·        On UNIX operating systems, the X Server must be running in the background as the process vserver. An additional child process is started for every successful connection through the X Server.

Starting and Stopping the X Server

x_server [<option>] start|stop

You can specify the following options when you call the X Server:

Option

Explanation

-Y

Suppresses the communication through the NI server, which is only relevant for SAP Support

-F

Suppresses the determination of DNS entries, which speeds up connections

-S <service|port>

Specifies an alternative service port at which the X Server can listen

See also:

·        Architecture of the Database Manager

·        Architecture of the Loader

 

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