highcharts-export-server

Highcharts Node.js Export Server

NOTE: This is currently in beta

The export server can be ran as both a CLI converter, and as a HTTP server.

Install

npm install highcharts-export-server -g

OR:

git clone https://github.com/highcharts/node-export-server
npm install
npm link

Running

highcharts-export-server <arguments>

Command Line Arguments

• --infile: Specify the input file.
• --instr: Specify the input as a string.
• --options: Alias for --instr
• --outfile: Specify the output filename.
• --type: The type of the exported file. Valid options are jpg png pdf svg.
• --scale: The scale of the chart.
• --width: Scale the chart to fit the width supplied - overrides --scale.
• --constr: The constructor to use. Either Chart or StockChart.
• --callback: File containing JavaScript to call in the constructor of Highcharts.
• --resources: Stringified JSON.
• --host: The hostname to run a server on.
• --port: The port to listen for incoming requests on.
• --tmpdir: The path to temporary output files.
• --sslPath: The path to the SSL key/certificate. Indirectly enables SSL support.
• --enableServer <1|0>: Enable the server (done also when supplying --host)
• --logDest <path>: Set path for log files, and enable file logging
• --logLevel <0..4>: Set the log level. 0 = off, 1 = errors, 2 = warn, 3 = notice, 4 = verbose
• --batch "input.json=output.png;input2.json=output2.png;..": Batch convert

- and -- can be used interchangeably when using the CLI.

Setup: Injecting the Highcharts dependency

In order to use the export server, Highcharts.js needs to be injected into the export template.

This is largely an automatic process. When running npm install you will be prompted to accept the license terms of Highcharts.js. Answering yes will pull the latest source from the Highcharts CDN and put them where they need to be.

However, if you need to do this manually you can run node build.js.

HTTP Server

The server accepts the following arguments:

• infile: A string containing JSON or SVG for the chart
• options: Aliast for infile
• svg: A string containing SVG to render
• type: The format: png, jpeg, pdf, svg. Mimetypes can also be used.
• scale: The scale factor
• width: The chart width (overrides scale)
• callback: Javascript to execute in the highcharts constructor.
• resources: Additional resources.
• constr: The constructor to use. Either Chart or Stock.
• b64: Bool, set to true to get base64 back instead of binary.
• async: Get a download link instead of the file data
• noDownload: Bool, set to true to not send attachment headers on the response.
• asyncRendering: Wait for the included scripts to call highexp.done() before rendering the chart.

Note that the b64 option overrides the async option.

It responds to application/json, multipart/form-data, and URL encoded requests.

CORS is enabled for the server.

It's recommended to run the server using forever.

SSL

To enable ssl support, drop your server.key and server.crt in the ssl folder, or add --sslPath <path to key/crt> when running the server.

Server Test

Run the below in a terminal after running highcharts-export-server --enableServer.

# Generate a chart and save it to mychart.png    
curl -H "Content-Type: application/json" -X POST -d '{"infile":{"title": {"text": "Steep Chart"}, "xAxis": {"categories": ["Jan", "Feb", "Mar"]}, "series": [{"data": [29.9, 71.5, 106.4]}]}}' 127.0.0.1:7801 -o mychart.png

Using as a Node.js Module

The export server can also be used as a node module to simplify integrations:

//Include the exporter module
const exporter = require('highcharts-export-server');

//Export settings 
var exportSettings = {
    type: 'png',
    options: {
        title: {
            text: 'My Chart'
        },
        xAxis: {
            categories: ["Jan", "Feb", "Mar", "Apr", "Mar", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"]
        },
        series: [
            {
                type: 'line',
                data: [1, 3, 2, 4]
            },
            {
                type: 'line',
                data: [5, 3, 4, 2]
            }
        ]
    }
};

//Set up a pool of PhantomJS workers
exporter.initPool();

//Perform an export
/*
    Export settings corresponds to the available CLI arguments described
    above.
*/
exporter.export(exportSettings, function (err, res) {
    ...
    //Kill the pool when we're done with it
    exporter.killPool();
});

Node.js API Reference

highcharts-export-server module

Functions

• log(level, ...): log something. Level is a number from 1-4. Args are joined by whitespace to form the message.
• logLevel(level): set the current log level: 0: disabled, 1: errors, 2: warnings, 3: notices, 4: verbose
• enableFileLogging(path, name): enable logging to file. path is the path to log to, name is the filename to log to
• export(exportOptions, fn): do an export. exportOptions uses the same attribute names as the CLI switch names. fn is called when the export is completed, with an object as the second argument containing the the filename attribute.
• startServer(port, sslPort, sslPath): start an http server on the given port. sslPath is the path to the server key/certificate (must be named server.key/server.crt)
• server - the server instance
  • enableRateLimiting(options) - enable rate limiting on the POST path
    • max - the maximum amount of requests before rate limiting kicks in
    • window - the time window in minutes for rate limiting. Example: setting window to 1 and max to 30 will allow a maximum of 30 requests within one minute.
    • delay - the amount to delay each successive request before hitting the max
    • trustProxy - set this to true if behind a load balancer
  • app() - returns the express app
  • express() - return the express module instance
  • useFilter(when, fn) - attach a filter to the POST route. Returning false in the callback will terminate the request.
    • when - either beforeRequest or afterRequest
    • fn - the function to call
      • req - the request object
      • res - the result object
      • data - the request data
      • id - the request ID
      • uniqueid - the unique id for the request (used for temporary file names)
• initPool(config): init the phantom pool - must be done prior to exporting. config is an object as such:
  • maxWorkers (default 25) - max count of worker processes
  • initialWorkers (default 5) - initial worker process count
  • workLimit (default 50) - how many task can be performed by a worker process before it's automatically restarted
• killPool(): kill the phantom processes

Using Ajax in Injected Resources

If you need to perform Ajax requests inside one of the resource scripts, set asyncRendering to true, and call highexp.done() in the Ajax return to process the chart.

Example:

{
  asyncRendering: true,
  resources: {
    files: 'myAjaxScript.js'    
  }
}

myAjaxScript.js:

jQuery.ajax({
  url: 'example.com',
  success: function (data) {
    ...
    highexp.done();
  },
  error: function () {
    highexp.done();
  }
});

If the Ajax call doesn't call highexp.done() within 60 seconds, the rendering will time out.

Performance Notice

In cases of batch exports, it's faster to use the HTTP server than the CLI. This is due to the overhead of starting PhantomJS for each job when using the CLI.

As a concrete example, running the CLI with testcharts/basic.json as the input and converting to PNG averages about 449ms. Posting the same configuration to the HTTP server averages less than 100ms.

So it's better to write a bash script that starts the server and then performs a set of POSTS to it through e.g. curl if not wanting to host the export server as a service.

Alternatively, you can use the --batch switch if the output format is the same for each of the input files to process:

highcharts-export-server --batch "infile1.json=outfile1.png;infile2.json=outfile2.png;.."

Other switches can be combined with this switch.

License

MIT.