HP 3000 Manuals HP 3000 Manuals
Creating Remote Processes
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
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| |
| |
| dsnum := POPEN ( location,progname [, itag][, entryname] |
| [, param][, flags][,stacksize][, dlsize][, maxdata][ ,bufsize])|
| |
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* 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 NS3000/V starting with UB-delta-1 MIT
and on NS3000/XL with Release 1.1.)
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* 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 |
| | |
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* 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
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| |
| |
| ifun := GET [([ itag][ il][,ionumber]|
| |
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* 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
acknowledgement 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
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| |
| |
| ACCEPT [([ itag][, target][, tcount])]|
| |
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* 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.