When you execute the inter-process communications using TCP/IP, you need to establish a connection between processes before transmitting data. Port numbers are assigned to both ends of the connection.

The send port is allocated by the OS within the range of port numbers available for automatic allocation by the OS (short-lived ports). The receive port is also allocated by the OS within the range of port numbers available for automatic allocation by the OS (short-lived ports). Note, however, that some OpenTP1 system services enable you to specify any desired receive port number.

OpenTP1 uses the following port numbers:

• Port numbers that are automatically allocated by the operating system
  The operating system determines these numbers and you cannot change them.
  
• Port numbers that are specified individually
  For example, port numbers that are specified by the following operands are applicable.
  
  • name_port and prc_port operands in the system common definition
  • scd_port operand in the schedule service definition
  • rap_listen_port operand in the RAP-processing listener service definition
• Port numbers starting from the value specified in the rpc_port_base operand in the system common definition up to the value specified in the rpc_port_base operand + prc_process_count in the process service definition + 129

The following table shows the system definition operands that enable you to specify a receive port number.

Table 7-2 System definition operands that enable you to specify a receive port number

Definition name	Operand	Permitted range	Default value	Applicable system service
System common definition	name_port	5001 to 65535	10000	Name service
	domain_masters_port	5001 to 65535	Range of ports available for automatic allocation	Domain representative schedule service
	prc_port	5001 to 49999	Range of ports available for automatic allocation	Process service
Schedule service definition	scd_port	5001 to 65535	Range of ports available for automatic allocation	Schedule service
Client service definition	clt_port	5001 to 65535	Range of ports available for automatic allocation	Client extended service
	cltcon_port	5001 to 65535	Range of ports available for automatic allocation	Transactional RPC executing process
RAP-processing listener service definition	rap_listen_port	5001 to 65535	Range of ports available for automatic allocation	RAP-processing listener
RAP-processing client manager service definition	rap_client_manager_port	5001 to 65535	Range of ports available for automatic allocation	RAP-processing client manager

For details about the operands, see the manual OpenTP1 System Definition.