OSI/AS Configuration and Management Manual

Management Environment

OSI/AS Configuration and Management Manual—424119-001

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SU (Subdevice) Objects

. OSI/AS SU (subdevice) objects are logical constructs between two processes through

which the processes can communicate with each other (sometimes thought of as a kind

of port). Subdevices created by each process (TAPS, TSP, and NSP) form a kind of

logical channel that is mapped onto a physical communications line and through which

applications can communicate with each other.

There are two methods for allocating subdevices:

•

Dynamic allocation

•

Static allocation

In addition to the discussion in the following paragraphs, performance considerations of

each method are discussed in Section 6, Performance Considerations

; the use of static

subdevices when troubleshooting is discussed in Section 8, Troubleshooting Guide.

Dynamic Subdevices

Dynamic subdevices are created by the appropriate process in response to an application

request for OSI services; they are deleted when the connection is terminated. If a

connect request is sent to a TSP process, the TSP process generates requests to a

corresponding NSP subdevice for that connection.

Ordinarily, TAPS processes delete SU objects automatically when the last opening

process closes the subdevice. TSP and NSP subdevices, that is, SU objects for OSI/TS,

X25AM, and TLAM (with D-series release) or PAM (with G06 and above releases), are

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

see the SCF manuals for those underlying subsystems.

Static Subdevices

Static subdevices are initially created by the appropriate process but are not

automatically deleted when connections are terminated. They are reopened, reused, and

then closed. When no longer needed, TAPS static subdevices can be deleted using the

SCF STOP SU command (or deleted programmatically, using an APS procedure call).

You configure your system for static subdevices using the DELETETIME attribute in

APPL ENTRY objects.