SPI Common Extensions Manual

Extended SPI Concepts

SPI Common Extensions Manual—427508-001

2-13

Requester Identification

Most subsystems receive commands through an intermediate routing process such as

SCP. It is difficult for the subsystem to identify the true originator of the request when it

only communicates directly with the routing process. So every command received must

contain the identity of its originator in requester identification (REQID) tokens. SCP

adds REQID information to each command before forwarding it to a subsystem.

Messages sent to unconverted subsystems contain ZCOM-MAP-REQID, which

conveys the process ID (CRTPID) and process access ID (PAID) of the requester.

Messages sent through an SCP process to converted subsystems contain a set of

REQID tokens conveying process identifiers:

The SCP process forwards these tokens to converted subsystems only. The SCP

process continues to send ZCOM-MAP-REQID to unconverted subsystems.

(Subsystems declare their level of support for data structures by providing an

appropriate value for ZCOM-TKN-GETVSN-LVL in their GETVERSION responses.)

An SCP process does not accept REQID tokens in your command message unless

your PAID is the super ID. So the super ID is required for an application that funnels

command messages and responses to and from an SCP process for other

applications.

If your PAID is not the super ID and you include REQID tokens in your command

message, the SCP process returns ZCOM-ERR-REQID-INV.

For full descriptions of the REQID tokens, see ZCOM Tokens on page 4-3.

REQID Token Value

ZCOM-TKN-REQID-CPU The process CPU of the requester

ZCOM-TKN-REQID-PAID The process access ID of the requester

ZCOM-TKN-REQID-PHANDLE The process handle of the requester

ZCOM-TKN-REQID-PIN The process identification number of the requester

ZCOM-TKN-REQID-PPROGXFILE The program file name of the requester

ZCOM-TKN-REQID-PROC-DESC The process descriptor of the requester

ZCOM-TKN-REQID-PSTRING The process string of the requester