OSI/AS Management Programming Manual

Programmatic Commands

Introduction

1–10 056785 Tandem Computers Incorporated

An SU (subdevice) object is a subdevice created in response to an application request

for OSI services. When a communications application requests establishment of a

connection (called an association for ACSE) by calling APS_ASSOC_CONNECTREQ_

or APS_ASSOC_ATTACH_ , OSI/AS causes SU objects to be created in the NSP, TSP,

and TAPS processes that service the connection. There are two types of SUs: static

and dynamic. A static SU object is temporary, it is added dynamically by the OSI

manager process and lasts only as long as the connection exists. A dynamic SU object

is saved when the connection is finished and can be reused by another connection if

that connection desires the same addresses and configuration used by the first

connection. You specify the SU type with the ZDEL-TIME attribute. The TAPS

process deletes its SU objects automatically when the last opening process closes the

subdevice. A value of 0 indicates a dynamic SU and a value of -1D indicates a static SU.

Information about a previous connection (including error information) is available

until the static SU is deleted or reused, this is useful for problem diagnosis. Static SUs

remain in the OSI/AS subsystem until an APS_SUBDEVICE_DISCARD_ , an SCF

ABORT SU, or an SCF STOP SU is issued for that SU.

Note The ACSE standards use the word association for an ACSE connection, which maps directly onto a

Presentation Layer connection. Because of the need to make general statements about connections that

apply similarly to ACSE and to the layers below it, the Tandem OSI/AS manuals use the word connection

for all layers.

TSP and NSP subdevices (that is, SU objects for OSI/TS, X25AM, and TLAM) are

handled somewhat differently from TAPS (OSI/AS) subdevices. For more

information, refer to the management programming manuals for those underlying

subsystems.

Hierarchy of Object Types

Figure 1-4 shows the hierarchy of the OSI/AS object types. As shown, the hierarchy

for an OSI manager process differs from that for a TAPS process.

To an OSI manager process, the SUBSYS object (which corresponds to the OSI

manager process) is at the highest point of the hierarchy. (The null object type is not

an actual object type, but is used in commands that do not require specification of an

object type.) Subordinate to the SUBSYS or OSI manager PROCESS object are the

PROCESS (TAPS, TSP, and NSP), ENTRY, SERVICE, and PROFILE objects.

To a TAPS process, the TAPS PROCESS object is at the highest point of the hierarchy.

It can have subordinate SU and SERVICE objects.

OSI manager PROCESS objects have no subordinate SU objects. In OSI/AS

commands, TSP and NSP PROCESS objects have no subordinate objects.

The SERVICE object appears in two places in the hierarchy because L5, L6, and ACSE

SERVICE objects can be inquired about either indirectly through the OSI manager