Open System Services Management and Operations Guide (G06.29+, H06.07+)

Introducing Open System Services
Open System Services Management and Operations Guide—527191-005
1-19
Interprocess Communication Facilities
For example, given the situation pictured in Figure 1-6 on page 1-18, suppose
Process 2 sends a message to Process 4. The following occurs:
1. The message is forwarded by $ZTA01 (the transport-agent process on
processor 1 of Node A, where Process 2 is running) to $ZTC0 (the transport-
provider process that supports the IP address used by Process 2).
2. The message is sent over the network and is received on Node B by $ZTC0
(the transport-provider process that supports the IP address used by Process
4).
3. The message is forwarded to $ZTA01 (the transport-agent process on
processor 1 of Node B, where Process 4 is running).
4. The message is delivered to Process 4 when that process is ready to accept
the message.
•
For NonStop Parallel Library TCP/IP, Internet domain socket application processes
exchange data through their embedded library code; however, other processes not
managed as part of the OSS environment must be running. The NonStop Parallel
Library TCP/IP component TCPMON, which runs as a process with the name
$ZPTMn (where n is its processor number), must be running in a processor that
runs an OSS sockets application program. See the TCP/IP (Parallel Library)
Configuration and Management Manual for more information on data flow between
sockets applications.
•
For NonStop TCP/IPv6, Internet domain socket application processes exchange
data through their embedded library code; however, other processes not managed
as part of the OSS environment must be running. The NonStop TCP/IPv6
component TCP6MON, which runs as a process with the name $ZPTMn (where n
is its processor number), must be running in a processor that runs an OSS sockets
application program. See the TCP/IPv6 Configuration and Management Manual for
more information on data flow between sockets applications.
AF_UNIX Sockets:
•
AF_UNIX sockets allow an application program to use an OSS socket as if it were
a named disk file or a named pipe.
•
For AF_UNIX sockets, the OSS sockets local server, $ZPLS, is the transport
provider process and $ZTAnn is the transport agent process. AF_UNIX sockets
initially require an OSS name server to provide addressing information.
•
Figure 1-7 on page 1-20 shows these processes. In this case, the OSS name
server ($ZPNS) for the root fileset provides the addressing information used by the
OSS sockets local server for an AF_UNIX socket when that socket is created by
Process 3 in a directory that is part of the root fileset.
In the figure, Processes 3 and 4 use AF_UNIX sockets to communicate, as do
Processes 3 and 7. When Process 3 sends a message to Process 4, the message
is forwarded to $ZTA01, then to $ZPLS, then to $ZTA01, and then to Process 4.