featureserver

FeatureServer

An open source implementation of the GeoServices specification

Usage

This is meant to be used as a plugin to Express

Example server

const express = require('express')
const app = express() // set up a basic express server
const FeatureServer = require('featureserver')
const cache = require('cache')

// We only need one handler because FeatureServer.route is going to do all the work
const handler = (req, res) => {
  cache.get(/* some geojson */, (err, data) => {
    if (err) res.status(500).json({error: err.message})
    else FeatureServer.route(req, res, data)
  })
}

// Sets up all of the handled routes to support `GET` and `POST`
const routes = ['/FeatureServer', '/FeatureServer/layers', '/FeatureServer/:layer', '/FeatureServer/:layer/:method']

routes.forEach(route => {
  app.route(route)
  .get(handler)
  .post(handler)
})

API

FeatureServer.route

Pass in an incoming request object, an outgoing response object and geojson and this function will route and return a geoservices compliant response

Supports: '/FeatureServer', '/FeatureServer/layers', '/FeatureServer/:layer', '/FeatureServer/:layer/:method'

Note: only query and info are supported methods at this type

FeatureServer.route(req, res, data, options)

Data is a geojson object extended with some additional properties. These properties are optional and can be used to provide more specific metadata or to shortcut the built in filtering mechanism.

e.g.

{
  type: 'FeatureCollection' // Static
  features: Array, // GeoJSON features
  statistics: Object, // pass statistics to an outStatistics request to or else they will be calculated from geojson features passed in
  metadata: {
    name: String, // The name of the layer
    description: String, // The description of the layer
    extent: Array, // valid extent array e.g. [[180,90],[-180,-90]]
    displayField: String, // The display field to be used by a client
    idField: String, // unique identifier field,
    maxRecordCount: Number, // the maximum number of features a provider can return at once
    timeInfo: Object // describes the time extent and capabilities of the layer,
    fields: [
     { // Subkeys are optional
       name: String,
       type: String, // 'Date' || 'Double' || 'Integer' || 'String'
       alias: String, // how should clients display this field name,
     }
    ]
  },
  filtersApplied: {
    geometry: Boolean, // true if a geometric filter has already been applied to the data
    where: Boolean // true if a sql-like where filter has already been applied to the data
  }
  count: Number // pass count if the number of features in a query has been pre-calculated
}

FeatureServer.query

Pass in geojson and a valid geoservices query object e.g. where=OBJECTID>10 and the function will perform the query and return a valid geoservices query object

FeatureServer.query(geojson, options)

FeatureServer.serverInfo

Generate version 10.21 Geoservices server info

const server = {
  description: String // Describes the collection of layers below,
  maxRecordCount: Number // the maximum number of features a provider can return at once,
  hasStaticData: Boolean // whether or not the server contains any data that is not changing
  layers: [{ // A collection of all the layers managed by the server
    type: 'FeatureCollection',
    metadata: {
      name: String, // The name of the layer
      description: String // The description of the layer
      extent: Array // valid extent array e.g. [[180,90],[-180,-90]]
      displayField: String // The display field to be used by a client
      idField: String // unique identifier field,
      maxRecordCount: Number // the maximum number of features a provider can return at once
      timeInfo: Object // describes the time extent and capabilities of the layer
    }
    features: [// If all the metadata provided above is provided features are optional.
      {
        type: 'Feature',
        geometry: {
          type: 'Point',
          coordinates: [125.6, 10.1]
        },
        properties: {
          name: 'Dinagat Islands'
        }
      }]
    }
  }]
}

FeatureServer.serverInfo(server)

FeatureServer.layerInfo

Generate version 10.21 Geoservices information about a single layer

FeatureServer.layerInfo(geojson, options)

FeatureServer.layers

Generate version 10.21 Geoservices information about one or many layers

Can pass a single geojson object or an array of geojson objects

FeatureServer.layers(geojson, options)