Envoy Application Programming Manual
Table Of Contents
- What’s New in This Manual
- About This Manual
- 1 Application Programming With Envoy
- 7 ADM-2 Multipoint Supervisor Protocol
- 8 TINET Multipoint Supervisor Protocol
- 9 Burroughs Point-To-Point Protocol
- 10 Asynchronous Line Supervisor Protocol
- A ASCII Character Set
- B ASCII to EBCDIC Code Conversion
- C File-System Procedures
- D Statistics Messages
- E S-Series Changes to Envoy
- NonStop™ Himalaya S-Series Server Architecture
- G-Series Migration Considerations
- CBSENSEON and CFSENSEON Modifiers
- LEOTRESYN and NOLEOTRESYN Modifiers
- Treatment of Characters After the Termination Character
- Number of SYN Characters
- DTR Drop
- Reporting of Parity Error
- Half-Duplex Support for Asynchronous Lines
- Controller Replacement
- SYSGEN and COUP
- Unit Numbers
- FDX Line Changes
- No Support for Auto-Call Unit
- Glossary
- Index
File-System Procedures
Envoy Application Programming Manual—427159-001
C-24
READ[X]
If the OPEN call is issued by a backup process and any of the following is true, the
OPEN call is rejected with a condition code of CCL (file-system error 12):
•
The specified file is not currently open by the primary process.
•
The parameters specified do not match those supplied when the file was opened by
the primary process.
•
The primary process is not running.
Condition Codes
Examples
CALL OPEN (line^name,fnum);
line^name is an integer array containing the device name (such as $TRIB7) of the
line. This call opens the specified line for read-write access, exclusive access, and wait
I/O. A unique file number generated by Guardian 90 is deposited in the one-word integer
variable fnum. All subsequent I/O calls directed to the specified line refer to it by this
file number.
CALL OPEN (line^name,fnum,%20,,pri^fnum,proc^id);
line^name is an integer array containing the device name (such as $LINE1) of the
line. %20 is the same flags parameter that the primary process used to open the line,
pri^fnum is an integer variable containing the file number returned by Guardian 90
when the primary process opened the line, and proc^id is an integer variable
containing the process id of the corresponding primary process (such as 008,028). A
unique file number generated by Guardian 90 is deposited in the one-word integer array
fnum. In the backup process, all subsequent I/O calls directed to the specified line refer
to it by fnum.
READ[X]
A call to the READ[X] procedure passes one incoming message plus a two-byte
message control word(MCW) to the specified application buffer. After opening a
communications line your application should always have at least one outstanding
READ[X] call to make certain that if something unexpected comes down the line you
can receive it.
< (CCL) Indicates that the OPEN was successful but an exceptional
condition was detected (call FILEINFO).
= (CCE) Indicates that the OPEN procedure was executed successfully.