OSI/AS SCF Reference Manual

Table Of Contents
OSI/AS Trace Facility
OSI/AS SCF Reference Manual424121-001
3-4
How Trace Records Cross the OSI Layers
The TAPS process consists of a set of OSI service layer code modules (ACSE,
presentation, and session, and ASN.1), along with support procedures to handle I/O,
shared service layer functions and routing between service layers.
Each layer and some of the support procedures have their own trace capability. If every
possible trace record were captured, you would see trace records of messages received
by TAPS or a service layer, trace records taken during the processing of those messages
and trace records as those messages left TAPS or a service layer. You would also see
interspersed trace records generated by the support procedures.
How Trace Records Cross the OSI Layers
The interface that a service layer module presents to the service layer above is known as
the user side of the service layer. Trace records that capture information crossing the
upper boundary of a module are labeled USER trace records. Trace records that capture
information crossing the lower boundary of a service layer are labeled PROV (for
provider) trace records. Trace records generated within a service layer are labeled State
Machine, Error Report, or Discard Resources.
Figure 3-2. TAPS Process Structure
020CDT .CDD
Session
ACSE
ASN.1
Presentation
TAPS
Support
Procedures