TACL

TACL (the Tandem Advanced Command Language ) is a scripting language that was originally used on tandem computers. Tandem computers were originally manufactured by Tandem Computers, Inc. of Cupertino , California. Tandem's strategy was the emerging concept of "continuous availability", based on redundant hardware and an operating system optimized for failure safety (NonStop Kernel or NSK, formerly called "Guardian"). The aim was to guarantee continuous application availability by ensuring that the system could survive any hardware failure. This is due to the tandem-specific ultra-reliable transaction processing . Tandem was taken over in 1997 by the computer manufacturer Compaq , which in turn eventually merged with Hewlett-Packard .

TACL is still the scripting language on Hewlett-Packard NonStop servers. NonStop servers are key components of the central infrastructure of the largest banks, casinos, retail chains, telephone companies, e-mail systems and stock exchanges worldwide.

Programming paradigm

TACL is an interpreted language. TACL instructions can be saved in a simple text file as MACROs, ROUTINEs, or DEFINEs in order to create scripts. Such scripts are often used to save start-up and hardware configuration sequences.

The TACL language has a large number of built-in tools that allow the user to process the output of various system programs line by line or character by character. This enables users to write TACL programs that monitor system events by filtering system and application event logs.

Example of a TACL routine stored in file FILE1:

? Section HELLO_BERNARD ROUTINE

#OUTPUT Hello BERNARD

Start the routine:

1. From the TACL prompt, enter: LOAD / KEEP 1 / FILE1 (this loads the routine into memory.)

2nd input: HELLO_BERNARD (to run the routine)

3. Output: Hello BERNARD

Or write a file called FILE1 with the following two lines:

? TACL ROUTINE

#OUTPUT Hello BERNARD!

Execution:

> RUN FILE1

Web links

Course material (English): http://www.hp.com/education/courses/u8636s.html