OSI/TS Configuration and Management Manual

NonStop Kernel File-System Interface
OSI/TS Configuration and Management Manual—424831-001
7-22
WRITEREAD Procedure
The subdevice through which connection-establishment requests are issued must
contain the correct address of the device with which you want to exchange data.
You can assign a set of remote addresses to a subdevice by using SCF, or your
application can alter the remote DTE or TSELs associated with your subdevice
by issuing, respectively, a SETPARAM 1 call or a SETPARAM 15 call.
The following subsections explain the WRITEREAD and CONTROL 17
procedures.
WRITEREAD Procedure
To request a transport connection using WRITEREAD, your application issues a
call with the following syntax:
The first two octets of the buffer contain a 16-bit message control word (MCW).
The MCW contains information that OSI/TS uses to identify the call as a
request for connection. To indicate a connection-establishment request, insert the
following values in the MCW:
Your application can include up to 32 octets of data following the MCW.
OSI/TS puts this data in the user-data field of the CR-TPDU. read-count
must be a minimum of two octets, since two octets of space is needed for the
received buffer's MCW. Figure 7-6
illustrates the contents of the WRITEREAD
buffer.
The OSI/TS subsystem responds to WRITEREAD by preparing and sending a
CR-TPDU. OSI/TS chooses connection-establishment parameters for the CR-
TPDU according to the subdevice attributes.
CALL WRITEREAD (filenum, buffer, write-count, read-
count,
count-read [, tag ]
)
Bit in
MCW Value Meaning
0 1 Connection-establishment phase.
1 1 OSI/TS is initiator
2-15 0 Reserved.
Figure 7-6. WRITEREAD buffer: Connection Establishment
706CDT .CDD
Octet 1
Octet 0
Octet 2
Through Octet n
110
0
0
MCW
Data