====== Node.js for plugins  ======

<WRAP center round tip 100%>
== LoxBerry 2.0 ==

This information applies to LoxBerry 2.0 and above.
</WRAP>

LoxBerry ships with Node.js V12. On LoxBerry 2.0 release, Node.js V12.10.0 was installed. With LoxBerry Update, we will update Node.js to newer **minor** releases, but stay on Node.js V12 LTS.

We recommend to not install Node.js on your own, as this may possibly lead to a downgrade to Node.js V10.

==== Node.js servers ====

If you run Node.js servers on a specific port, try to not collide with already used ports from other plugins: [[entwickler:used_ports_of_loxberry_and_plugins|Used ports of LoxBerry and plugins]]

==== npm and yarn ====

Both npm and yarn are available to install libraries and dependencies. yarn is based on npm and has better version dependency management.

<code syntaxhighlighter-pre>
# npm
npm install jayson

# yarn
yarn add jayson
</code>

==== Run Node.js scripts via the installed Apache webserver ====

Admittedly, this is not the concept of Node.js, but it is possible to run Node.js scripts from Apache webrequests.

Therefore, create your script named *.cgi and place it in the webfrontend/html or webfrontend/htmlauth folder.

Start the script with the shebang ''%%#!/usr/bin/node%%''

<code bash>
#!/usr/bin/node
console.log("Content-type: text/html\n");
console.log("<h1>Hello World!</h1>\n");
</code>

You need to care to send the correct headers. Output from ''%%console.log%%'' is sent as response.

The response time is pretty bad (the above example on a Pi2 takes about 0,6 seconds), because every request needs to startup the nodejs engine.

==== Use LoxBerry's JsonRpc to use LoxBerry's library functions ====

This example uses the jayson library (''%%yarn add jayson%%'', or ''%%npm install jayson%%'') to generate a LoxBerry plugin frontend.

<code javascript>
#!/usr/bin/node

'use strict';

console.log("Content-type: text/html\n");

const jayson = require('jayson/promise');
const client = jayson.client.http('http://localhost:80/admin/system/jsonrpc.php');

// Using Promises in batch mode from jayson to get all JsonRpc requests done before writing the user interface

const batch = [
    client.request('LBWeb::get_lbheader', [ "My Plugin", "https://loxwiki.eu", "helptemplate.html" ], undefined, false),
    client.request('LBWeb::get_lbfooter', [], undefined, false),
    client.request('LBWeb::mslist_select_html', [ { LABEL: 'Select your Miniserver', FORMID: 'MSNR', SELECTED: '1' }], undefined, false),
    client.request('getdirs', [ "myplugin" ], undefined, false),
    
    // Some other example JsonRpc calls
    // client.request('LBSystem::get_localip', [], undefined, false),
    // client.request('LBWeb::loglist_url', [ {'PACKAGE': 'squeezelite' } ], undefined, false),
    // client.request('LBWeb::logfile_button_html', [ { PACKAGE:'squeezelite', NAME:'daemon' } ], undefined, false),
    // client.request('LBSystem::get_miniservers', [], undefined, false),
 ];
  
 client.request(batch).then(function(responses) {
    var lbdirs = responses[3].result;
    console.log(responses[0].result);
    console.log("<h1>Demo with Node.js and LoxBerry JsonRpc</h1>");
    console.log("<p>Plugin data directory is ", lbdirs.lbpdatadir, ".</p>");
    console.log(responses[2].result);
    console.log(responses[1].result);
    
 });
</code>

This example code will give you this output in your plugin page.

{{entwickler:advanced_developers:1236861360.png?w=500}}

With JsonRpc, all LoxBerry functions listed in the PHP SDK documentation can be called. The result is returned depending to the datatype (string, or an object). The Promises approach let you query several data in parallel, and runs the ''%%.then%%'' block when all requests have finished. The method ''%%getdirs%%'' (line 16) requests the plugin name and returns all absolute paths of the plugin (web, data, config, log etc.). 

Parameters of the methods have two different approaches:

  * When a list of single parameters are requested, use ''%%[ "paramter1", "parameter2", "parameter3" ] %%''
  * When named parameters are requested, use ''%%[ { PARAM1: 'Value1', PARAM2: 'Value2 } ]%%'' 
  * Methods without parameters request to use ''%%[]%%'' 

As returning datatypes are different for different methods, during development you possibly first dump the response.