Perl Utilities for Server Creation

Server processes in the Designer's Interface use a standardized input/output language for passing data. This is described in server input/output language.

Perl utilities have been created to aid in adapting existing programs to communicate in this format. A Perl script is written as a wrapper around the existing program, using the Perl command

require server_util.pl;
to enable access to the routines.

The Perl variables take their names from the server specification file. The actual variable string ``name'' is used for parameter names, and ``name(type)'' for input and output variable names. Only parameters and variables in the specification file may be used.

The following procedures are defined:

read_spec(spec_file_name)
Read the named specification file to initialize variables. read_spec must be the first utility routine called, and may be called only once.
read_input()
Read server input from stdin and set input variables and parameters accordingly. read_input is called immediately after read_spec, and may be called only once.
check_parameter(param_name)
Check if a parameter has been set by the call to read_input. This is used because get_parameter will exit if a target parameter has not been set.
get_parameter(param_name)
Return the value of an input parameter (set by read_input). get_parameter will terminate the program if the named parameter has not been set, so check_parameter should be used to test optional parameters.
check_input(input_name)
Check if an input variable has been set by the call to read_input. This is used because get_input will exit if a target input variable has not been set.
get_input(input_name)
Return the value of an input variable (set by read_input). get_input will terminate the program if the named variable has not been set, so check_input should be used to test optional variables.
put_output(output_name, value)
Assign a value to an output variable. Each output variable may be assigned only once. Output variables are not written to stdout until write_output is called.
write_output()
This causes all assigned output variables to be written to stdout. It must be the very last utility routine called and may be called only once.

Example

Here is a sample of a server wrapper (``synth1'') for an executable which reads a filename containing three input variables. It outputs a measure of merit to stdout, and constraint values to a file.

The wrapper manages these resources, and communicates using the server input/output language.

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