Intercity.js

An Express-like middleware for serving dynamic geospatial data over WMS, WMTS, WCS and WFS

Built upon gdal-async and fastify

Intercity.js is still unreleased and not ready for use

Intercity.js vs Geoserver

	Geoserver	Intercity.js
Role	Geospatial server	Geospatial middleware
Target audience	System administrators	Developers
Configuration	Traditional GUI	Configuration-as-Code
Best for	High-traffic production deployment	Serving dynamic data for a limited number of users
Focus	Performance	Flexibility
Language	Java	JavaScript (Node.js)

Installation

Intercity.js is a work in progress and it hasn't been published yet.

Current status
WMS	Working demo, not fully standards-compliant
WMTS	Working demo, not fully standards-compliant
Raster reprojection	Usable
Dimensions	Usable, WMS only
WCS	Not started
WFS	Not started

Usage

const intercity = require('intercity');
const gdal = require('gdal-async');

// A layer coming from a tiff
const rain_ds = gdal.open('rain.tiff');
intercity.layer({
    name: 'arome:rain',
    title: 'Rain AROME',
    srs: rain_ds.srs,
    bbox: rain_ds.bands.getEnvelope()
}, async (request, reply) => {
    return reply.send(rain_ds);   // intercity will do the rest (with GDAL's default float -> byte conversion)
});

// A dynamically generated layer filled with a
// client-specified color in a WMS/WMTS dimension
intercity.layer({
    name: 'random:color',
    title: 'random color',
    srs: gdal.SpatialReference.fromEPSG(4326),
    bbox: { minX: -8, minY: 38, maxX: 12, maxY: 53 },
    dimensions: {
        units: 'color',
        unitSymbol: '🎨',
        // values can be dynamic, will be computed at every GetCapabilities
        values: () => ['red', 'green', 'blue'],
        default: 'red'
    }
}, async (request, reply) => {
    // if you return a raster band without geospatial metadata,
    // it is automatically considered to use the main SRS
    // and to cover the declared bounding box
    const ds = await gdal.openAsync('temp', 'w', 'MEM', 128, 128, 3, gdal.GDT_CFloat32);
    const bands = {
        red: await ds.bands.getAsync(1),
        green: await ds.bands.getAsync(2),
        blue: await ds.bands.getAsync(3)
    }
    // intercity will pass a dimensions object with all the parameters
    const color = bands[request.dimensions.color];

    const data = new Uint8Array(128 * 128);
    for (let i = 0; i < data.length; i++)
        data[i] = Math.random() * 255;
    await Promise.all([red.fillAsync(0),
        green.fillAsync(0),
        blue.fillAsync(0)
    ]);
    await color.pixels.writeAsync(0, 0, 128, 128, data);
    return reply.send(ds);   // intercity will do the rest
});

intercity.handle(intercity.wms, 'http://localhost:3000', '/wms');
intercity.handle(intercity.wmts, 'http://localhost:3000', '/wmts');
intercity.use(intercity.png);
intercity.use(intercity.jpeg);
intercity.use(intercity.wkss.GoogleCRS84Quad);

intercity.listen(3000).catch(e => console.error(e));

Project status

intercity is my only major pure-JS project on which I work on paragliding trips during the summer while living off-grid on my 12V Macbook Air.

It may appear stalled, but it is not.