Using NS3000/iX Network Services (36920-90008)

134 Chapter 7

Remote Process Management

RPMCONTROL

Description

This intrinsic is used to control a remote process that was created with

an RPMCREATE request. The only RPM control requests deﬁned are

suspend and resume.

Its calling sequence is similar to that of IPCCONTROL. The pd and

reqcode parameters are the only required parameters. To control a

remote process from a process which is not its creator, the location and

loclen must be speciﬁed. RPMCONTROL uses these parameters to

establish a new connection to the remote machine to perform the

request.

The wrtdata and wrtlen parameters must be speciﬁed if the reqcode

speciﬁed requires data to be transferred to the remote node.

Similarly, readdata and readlen should be included if the reqcode speciﬁed

returns data to the caller upon completion of the request. Presently,

there are no request codes that require these parameters.

The ability to specify the suspend and resume request codes (20001,

20002) in an RPMCONTROL request is limited to programs that have

Privileged Mode (PM) capability. Great care should be taken when

using these request codes. If a locally created process is suspended,

(that is, a process that was created with a location and logon matching

that of the caller, or the location and logon were omitted or blank), and

the creator terminates without issuing either an RPMKILL or an

RPMCONTROL with the resume request code, the creator process may

hang. Therefore, these functions should not be used to manipulate

locally created processes unless absolutely necessary.

If the process to be suspended is on a remote node, there is no danger of

hanging the process. However, a process that has been suspended in

this manner cannot be killed or resumed except by explicitly calling

either RPMKILL or RPMCONTROL with the resume request code.

If a process is in a state where the node cannot suspend it, RPMCONTROL

will return an error code in the result parameter indicating this. A

process may not be suspendable because: the process is suspended by a

system process, the process is waiting for critical resources, or the

process is dying.