gtpc1m4lTransmission Control Protocol/Internet Protocol

Internet Daemon

The behavior of the Internet daemon is controlled by the Internet daemon configuration file (IDCF). Use the ZINET commands to update the IDCF and control the Internet daemon process. See TPF Operations for more information about the ZINET commands.

Internet Daemon Configuration File

The IDCF contains data needed to start and control an Internet server application. The IDCF is subsystem unique and processor shared. It is stored in #IDCF1 fixed file records using 128 records.

There is an entry in the IDCF for every Internet server application that can be started by the Internet daemon. The entries are uniquely identified by the name of the Internet server application and processor ID (CPU ID). Duplicate entries (the same name and processor ID) are not allowed.

Adding an Internet Server Application

Use the ZINET ADD command to add an Internet server application to the IDCF. Some of the parameters for this command are discussed in Internet Server Application.

After adding an Internet server application, enter the ZINET START command so that the Internet daemon starts an Internet daemon listener to listen on the specified port for your Internet server application. If you specified that listening is automatic for your Internet server application, you do not have to enter the ZINET START command for the Internet server application.

For every Internet server application that you add to the IDCF, ensure that the program specified by the PGM parameter in the ZINET ADD command is loaded.

For the WAIT, NOWAIT, and AOR process models, if you want to run the same Internet server application on multiple subsystems, you must do one of the following:

TCP/IP allows only one socket to be bound to a specific port number for an IP address. If you define an Internet server application with IP=ANY and you want to activate the application on multiple subsystems concurrently, you must define the Internet server application with a different port number in each subsystem.

See TPF Operations for more information about the ZINET ADD and ZINET START commands and for restrictions on their use.

Updating the IDCF

Use the ZINET ALTER and ZINET DELETE commands to modify data pertaining to an Internet server application already in the IDCF. After the modifications are done, stop the Internet daemon (ZINET STOP command) and then restart the Internet daemon (ZINET START command) for the changes to take effect.

See TPF Operations for more information about the ZINET ALTER, ZINET DELETE, ZINET START, and ZINET STOP commands and for restrictions on their use.

Internet Daemon Control

When the Internet daemon is started, a long-running process called the Internet daemon monitor is created. The primary functions of the Internet daemon monitor are to:

The Internet daemon listeners monitor Internet server applications, and create and monitor sockets for Internet server applications based on the process model defined for the Internet server application. For each Internet server application defined with the WAIT, NOWAIT, or AOR process model, the Internet daemon listener creates and monitors one or more sockets. For each Internet server application defined with the WAIT, NOWAIT, or DAEMON process model, the Internet daemon listener monitors the Internet server application. For each Internet server application defined with the NOLISTEN or RPC process model, the Internet daemon only starts the Internet server application; the Internet daemon listener does not create or monitor sockets, nor does it monitor the server application.

If an Internet server application is defined with multiple IP addresses in the IDCF, there is an Internet daemon listener process for each IP address. For an Internet server application defined with IP-ANY in the IDCF, there is only one Internet daemon listener process.

All the threshold and error controls defined in the IDCF for an Internet server application, such as the maximum number of Internet server application instances and the maximum number of times an Internet server application can end because of an error (MAXPROC and SERVERRORS parameters, respectively, in the ZINET ADD and ZINET ALTER commands), are tracked by the individual Internet daemon listener processes. For example, if you define an Internet server application to use two IP addresses, MAXPROC-1, SERVERRORS-3, and SERVETIME-10, then:

See TPF Operations for more information about the ZINET ADD and ZINET ALTER commands.

Figure 26 shows the relationship of the Internet daemon monitor and Internet daemon listeners.

Figure 26. Relationship of the Internet Daemon Monitor and Internet Daemon Listeners. SERVER and IP are parameters in the ZINET ADD and ZINET ALTER commands.


Starting the Internet Daemon

The Internet daemon is started in each subsystem by the cycle-up scheduler when it cycles to CRAS state or above. However, if the Internet daemon is stopped, it can be restarted by the ZINET START command. See TPF Operations for more information about the ZINET START command.

Stopping the Internet Daemon

Whenever a subsystem is cycled below CRAS state, the Internet daemon is stopped. However, if the Internet daemon must be stopped, use the ZINET STOP command. See TPF Operations for more information about the ZINET STOP command.