OSI/AS Programming Manual

Sending and Retrieving User Data
APS Procedures Programming Concepts
2–44 056783 Tandem Computers Incorporated
(user data from FTAM user)
] -- end data element 1
Example 2. Building on the previous example, FTAM begins sending a file. This
requires two different abstract syntaxes: one for the FTAM control PDU, and one for
the document (file) type.
FTAM builds the FTAM control syntax in a user data element with a PCID selected at
connect (A-ASSOCIATE) request time. The control syntax PCID is entered in the
ZPCID field of the user data-element header. FTAM then builds the document data in
a separate user data element of the same P-DATA request. (Note that the document
data must be contained in a separate user data element.) FTAM then passes the entire
request to the Presentation Layer, which builds PDV lists based on the different
PCIDs.
The following set of structures shows the encoding given to the Presentation Layer:
data header [
ZNUM-ELEMENTS = 2
] -- end data header
data element 0 [
ZLEN = ??
ZTYPE = ZAPS-VAL-DATA-TYPE-SAT
ZPCID = 7
(FTAM control FPDU)
] -- end data element 0
data element 1 [
ZLEN = ??
ZTYPE = ZAPS-VAL-DATA-TYPE-SAT
ZPCID = 11
(data from FTAM document type)
] -- end data element 1
Sending User Data The following four procedures send user data as their principal function:
APS_DATA_REQ_
APS_CAPDATA_REQ_
APS_CAPDATA_RSP_
APS_TYPEDDATA_REQ_