SPI Programming Manual (G06.24+, H06.03+, J06.03+)

SPI Programming Manual—427506-006
8-1
8 SPI Programming in TACL
This section provides language-specific information for the programmer who is using
the TACL to write an SPI requester or server:
Definition Names in TACL
Symbolic names in this section are in the TACL form, using circumflex (^) symbols
rather than hyphens. For example, the DDL token code ZSPI-TKN-RETCODE is
expressed as ZSPI^TKN^RETCODE in TACL.
Limitations of TACL for SPI Programming
TACL is an interpreted language, so TACL macros and routines are quick to code and
test but usually run more slowly than compiled TAL, COBOL, or C programs. For these
reasons, TACL is most useful in prototype applications and in applications for which
performance is not an issue. In addition, you should be aware of several other
restrictions when deciding whether to implement your application in TACL.
TACL does not let routines run as process pairs. If you require a process to run as a
process pair, you must code it in TAL, COBOL, or C.
TACL does not support the programmatic interfaces other than SPI to subsystems
such as the spooler, Measure, Sort/FastSort, and Enform. If your application is in
TACL and it must communicate with one of these subsystems, it must use the
conversational text interface to the subsystem. For instance, it must communicate with
the spooler through the text interface to SPOOLCOM or Peruse.
TACL has an absolute maximum I/O buffer size of 4096 bytes, and STRUCTs are also
limited to 4096 bytes. In addition, TACL requesters using the #REQUESTER feature
cannot do nowait I/O for buffers larger than 239 bytes.
If you are writing a subsystem, TACL does not support the EMS high-level procedures
for preparing event messages (EMSINIT, EMSADDSUBJECT, EMSADDTOKENS, and
EMSADDBUFFER). Therefore, if your subsystem reports events, you must code the
module that prepares the event messages in TAL, C, or COBOL.
Topic Page
Definition Names in TACL
8-1
Limitations of TACL for SPI Programming 8-1
TACL Definition Files 8-2
Declarations and Data Representations in TACL 8-2
Syntax of the TACL Built-Ins 8-8
Interprocess Communication 8-30
Example: Printing or Displaying the Status Structure of the
Subsystem Control Point (SCP)
8-30