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With PTOP, the creation of the slave process and the set up of the
communications channel is done by the POPEN call in the master and
the first GET and ACCEPT (or REJECT) calls in the
slave. The POPEN call specifies the remote node's location, the name
of the program on the remote node to be created, and various process-creation
parameters. The dsnum parameter returned by POPEN
identifies the slave process and its communications channel. On the slave side,
the GET and ACCEPT calls complete the set up.
With NetIPC and RPM, the actions of creating the slave process and setting up
the communications channel are split up. RPM handles the process creation,
while NetIPC handles the communications. The calls necessary for these tasks
are more complicated than the POPEN and GET/ACCEPT calls.
The master process creates a call socket and registers it in the local socket
registry. It passes the name of the socket and the local node name to the
slave by using the RPM string feature of RPMCREATE. The master calls
RPMCREATE to create the slave, including any process-creation
parameters. The slave retrieves the master socket and node names from the RPM
strings. It creates its own socket, looks up the master's socket, and
establishes a virtual-circuit connection between the two sockets. The steps
for each side are given below.
Creating Remote Processes: In the Master Program
To convert the PTOP intrinsic listed below, perform the following steps.
Syntax
dsnum := POPEN ( location, progname [,itag] [,entryname]
[,param] [,flags] [,stacksize] [,dlsize]
[,maxdata] [,bufsize] );
- Get the local node name. You can use the NSINFO intrinsic,
provided that you execute a DSLINE or a REMOTE command
prior to the call. This should normally be the case for a PTOP
application. You can use local node name and length item numbers (19
and 18) in NSINFO.
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NOTE: NSINFO is supported on NS 3000/V starting with
UB-delta-1 MIT and on NS 3000/XL with Release 1.1.)
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NSINFO is supported on NS 3000/V starting with UB-delta-1 MIT
and on NS 3000/XL with Release 1.1.)
- Create a TCP call socket for the master program and name the socket,
using the IPCCREATE and IPCNAME intrinsics. You can
use a randomly generated name from IPCNAME.
- Build the opt array for the RPMCREATE call, using the
INITOPT and ADDOPT intrinsics. In the opt array,
include RPM strings (opt code 20000) for the socket name and the local
node name. (These will be used by the slave program to set up the
virtual circuit connection.) If any process-creation options are
included in the POPEN call (entryname,
param, flags, stacksize,
dlsize, or maxdata), include them in the
opt array with the corresponding RPM opt codes:
| Parameter |
Opt Code |
| entry name | 22001 |
| param | 22002 |
| flags | 22003 |
| stacksize | 22004 |
| dlsize | 22005 |
| maxdata | 22006 |
- Call RPMCREATE to create the slave process on the remote node.
Use the progname and location parameters
as they appear in the POPEN call, although you will have to
supply the (byte) lengths of progname and location. You
should set the dependent bit of the flag parameter, so the
slave will terminate if the master does. Save the program descriptor,
returned by RPMCREATE, for a future RPMKILL.
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NOTE: RPMCREATE requires the program to be linked with
Process Handling (PH) capability. PTOP does not require PH capability.
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- Call IPCRECVCN to wait for the connection request from the slave.
Save the returned virtual-circuit descriptor for subsequent
IPCSEND and IPCRECV calls.
- Now that the virtual-circuit connection has been set up, call
IPCSHUTDOWN to delete the master's call socket and
IPCNAMERASE to delete the socket name.
- If a tag is specified, call IPCSEND to send the tag on the
virtual circuit to the slave.
- If the slave could respond to the POPEN with either an
ACCEPT or a REJECT, call IPCRECV to receive a
one-byte accept or reject indication from the slave.
- If a tag is specified, call IPCRECV to receive the tag from the
slave (but see the comment on IPCRECV under "Exchanging
Data").
Creating Remote Processes: In the Slave Program
To convert the PTOP intrinsic listed below, perform the following steps.
Syntax
ifun := GET [ ( [itag] [il] [,ionumber] ) ];
- Call RPMGETSTRING twice to get the master's socket name and
node name.
- Create a TCP call socket by using the IPCCREATE intrinsic.
- Call IPCLOOKUP to look up the master's socket, using the master
socket name and node name passed in the RPM strings. This returns a
destination descriptor to be used in the IPCCONNECT call.
- Set up a virtual-circuit connection between the master and the slave
sockets, using IPCCONNECT. Call IPCRECV to wait for
the connection acknowledgment from the slave. Save the returned
virtual-circuit descriptor for subsequent IPCSEND and
IPCRECV calls.
- After setting up the connection, delete the call socket and destination
descriptor using IPCSHUTDOWN.
- If a tag is specified, call IPCRECV to receive the master's tag
on the virtual circuit (see the comment on IPCRECV under Data
Exchange).
To convert the PTOP intrinsic listed below, perform the following steps.
Syntax
ACCEPT [ ( [itag] [,target] [,tcount] ) ];
- If the slave can call either ACCEPT or REJECT in
response to the POPEN, send a one byte accept or reject
indication on the virtual circuit to the master.
- If a tag is specified, call IPCSEND to send the slave's tag on
the virtual circuit back to the master.
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