Camel-harness NPM

camel-harness

Node.js - Electron - NW.js package for asynchronous handling of Perl scripts

Quick Start

npm install camel-harness

const camelHarness = require("camel-harness");

let perlTest = {};
perlTest.script = "/test/test.pl";

perlTest.stdoutFunction = function (stdout) {
  console.log(stdout);
};

camelHarness.startScript(perlTest);

Core Dependency

child_process

External Dependency

Perl interpreter identified by filename on PATH or full pathname

camel-harness npm package test will fail if no perl binary is available on PATH.

API

All settings of a Perl script executed by camel-harness are stored in a JavaScript object with an arbitrary name and the following object properties:

script
String for Perl script full path or Perl code executed as an one-liner
This object property is mandatory.

perlTest.script = "/full/path/to/test.pl";

The -e interpreter switch must be set when Perl code is executed in one-liner mode.
Perl code must not be surrounded in single quotes and all double quotes must be escaped.

One-liner example:

let oneLiner = {};

oneLiner.interpreterSwitches = [];
oneLiner.interpreterSwitches.push("-e");

oneLiner.script = "use English; print \"Perl $PERL_VERSION\";"

oneLiner.stdoutFunction = function (stdout) {
  console.log(`${stdout}`);
};

camelHarness.startScript(oneLiner);

stdoutFunction
will be executed every time data is available on STDOUT
The only parameter passed to the stdoutFunction is the STDOUT String.
```
perlTest.stdoutFunction = function (stdout) {
  document.getElementById("DOM-element-id").textContent = stdout;
};
```
stderrFunction
will be executed every time data is available on STDERR
The only parameter passed to the stderrFunction is the STDERR String.
```
perlTest.stderrFunction = function (stderr) {
  console.log("Perl script STDERR:\n");
  console.log(stderr);
};
```
errorFunction
will be executed on Perl script error
The only parameter passed to the errorFunction is the error Object.
The errorFunction can generate a message when Perl interpreter is not found:
```
perlTest.errorFunction = function (error) {
  if (error.code === "ENOENT") {
    console.log("Perl interpreter was not found.");
  }
};
```
exitFunction
will be executed when Perl script has ended
The only parameter passed to the exitFunction is the exit code String.
The exitFunction can generate a message when Perl script is not found:
```
perlTest.exitFunction = function (exitCode) {
  if (exitCode === 2) {
    console.log("Perl script was not found.");
  }
};
```
perlInterpreter
String for a Perl interpreter: either filename on PATH or full pathname
If no perlInterpreter is defined, perl binary on PATH is used, if available.
```
perlTest.interpreter = "/full/path/to/perl";
```

interpreterSwitches
Array for Perl interpreter switches

perlTest.interpreterSwitches = [];
perlTest.interpreterSwitches.push("-W");

scriptArguments
Array for Perl script arguments

perlTest.scriptArguments = [];
perlTest.scriptArguments.push("argument-one");
perlTest.scriptArguments.push("argument-two");

options
Object for Perl script options passed to the child_process core module.
Click here for a full list of all available child_process options.

options.cwd
String for a new Perl script current working directory

perlTest.options = {};
perlTest.options.cwd = "/full/path/to/current-working-directory";;

options.env
Object for a new Perl script environment

Script environment with an inherited PATH and a new variable:

perlTest.options = {};
perlTest.options.env = {};
perlTest.options.env.PATH = process.env.PATH;
perlTest.options.env.TEST = "test";

options.detached
Boolean option for starting detached Perl processes like servers
options.detached must be set to true and
options.stdio must be set to "ignore" to
start a detached process without receiving anything from it.
A process detached with the above options can run even after its parent has ended.
Example settings for a Perl server application:
```
let perlServer = {};
perlServer.script = "/path/to/perl-server-application";

perlServer.options = {};
perlServer.options.detached = true;
perlServer.options.stdio = "ignore";

const camelHarness = require("camel-harness");
camelHarness.startScript(perlServer);

perlServer.scriptHandler.unref();
```
inputData
String or Function supplying user data as its return value.
inputData is written on script STDIN.
inputData function with no dependencies:
```
perlTest.inputData = function () {
  let data = document.getElementById("input-box-id").value;
  return data;
}
```

Interactive Scripts

camel-harness can also start and communicate with interactive scripts having their own event loops and capable of repeatedly receiving STDIN input. Use the following code to send data to an interactive script waiting for input on STDIN:

let data = document.getElementById("interactive-script-input").value;
perlTest.scriptHandler.stdin.write(data);

camel-harness demo packages for Electron and NW.js include a Perl script that can be constantly fed with data from an HTML interface. Perl with the AnyEvent CPAN module has to be available on PATH.