Network Communication

To connect to a database on a remote computer, applications (via interfaces) and database tools use the SAP MaxDB X server (communication server) that is running on the remote database computer.

There is one X server acting as a global listener for each database computer, and one X server for each SAP MaxDB installation. This means that on each database computer, there are at least one global listener and one X server.

Note that for older clients, the global listener acts as X server.

To connect to a remote database, you have the following options:

You specify the database name, the port number for the database and the database computer.
You are then directly connected to the X server of the installation to which the database belongs, and this X server connects you to the database.
You only specify the database name and the database computer. Internally, the system executes the following steps:
1. The global listener receives the connection request and sends back the port number of the database.
2. You are then directly connected to the X server of the installation to which the database belongs, and this X server connects you to the database.

Ports and Network Protocols for Connecting to Remote Databases

This graphic is explained in the accompanying text.

Ports and Network Protocols for Connecting to Remote Databases

Ports and Protocols of the SAP MaxDB X Servers
Scope	Default Port	Function of the X Server	Protocol	Protocol Identifier
All installations on the database computer	7210	Global listener	TCP/IP	`remote://`
	7269	Global listener with SAP networtk protocol NI (for connections via SAPRouter, only available in SAP systems)	NI (based on TCP/IP)	`sapni://`
	7270	Global listener with SAP networtk protocol NI and SAP encryption library (for connections via SAPRouter, only available in SAP systems)	SSL/TLS NISSL (based on TCP/IP)	`remotes://` `sapnis://`
First installation `<installation_1>` on the database computer	7200	X server for `<installation_1>`	TCP/IP	`remote://`
Second installation `<installation_2>` on the database computer	7203	X server for `<installation_2>`	TCP/IP	`remote://`
Separate Database Studio installation	7299	X server for the separate Database Studio installation, only used by the system to access the local user management database `.UMDB`	TCP/IP	`remote://`

The ports are stored in the services file:

Microsoft Windows: C:\WINDOWS\system32\drivers\etc\services
Unix and Linux: /etc/services

Connecting via SAPRouter

Connections to the database via SAPRouter are always established via the global listener. These connections use the NI or the NISSL protocol with designated ports.

Connecting to Local Databases

Connections to databases on the local computer use shared memory and do not need an X server.

If you want to force the database system to establish the connection via an X server, specify localhost as the database computer when logging on to the database.

Note that the JDBC interface needs the X server even if it is installed on the same computer as the database. Because Database Studio uses the JDBC interface to connect to databases, Database Studio also needs an X server for local communication with databases.

Encryption

To encrypt the data transfer between the client and the global listener/X servers, SAP customers can use SSL/TLS.

For more information about encryption, see the Installation Guide for your SAP system on the SAP MaxDB database.

Example

The HOTELDB and SHOPDB databases are both located on the ROME computer. They both belong to the same installation, and therefore use the same installation-specific X server when clients connect to them from other computers.

A user uses Database Studio on the ROME computer to access the HOTELDB database on the same computer. Because Database Studio uses the JDBC interface, which needs the X server even for local communication, the connection is established via the X server of the Database Studio installation.
A second user, on the GENUA computer, uses Database Manager CLI to access the HOTELDB and the SHOPDB databases by means of the installation-specific X server on the ROME computer.
A third, local, user uses SQLCLI on the ROME computer to directly access the HOTELDB database without using an X server.

This graphic is explained in the accompanying text.

Communication Between Clients and Database in the Network (Example)