An open source implementation of the GeoServices specification
This is meant to be used as a plugin to Express
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)
})
FeatureServer allows several defaults to be set at runtime via Express's app.locals
method. Specifically, you will need to set:
app.locals.config = {
featureServer: {
// define default here
}
}
If you are using FeatureServer as part of a Koop instance, the equivalent of Express's app.locals
is koop.server.locals
.
The follow properties can be set at runtime with the noted method:
app.locals.config = {
featureServer: {
currentVersion: 11.01, // defaults to 10.51
fullVersion: '11.0.1', // defaults to '10.5.1'
serviceDescription: 'default service description',
description: 'default layer description'
}
}
- FeatureServer.route
- FeatureServer.query
- FeatureServer.serverInfo
- FeatureServer.layerInfo
- FeatureServer.layers
- FeatureServer.generateRenderer
- FeatureServer.authenticate
- FeatureServer.error.authorize
- FeatureServer.authenticate
- FeatureServer.queryRelatedRecords
Pass in an incoming request object
, an outgoing response object
, a geojson
object, and options
and this function will route and return a geoservices compliant response
- Supports: '/FeatureServer', '/FeatureServer/layers', '/FeatureServer/:layer', '/FeatureServer/:layer/:method'
- Note: only
query
,info
, andgenerateRenderer
are supported methods at this time.
- Note: only
FeatureServer.route(req, res, data, options)
- data is either a geojson object extended with some additional properties or an object with a layers property which an array of extended geojson objects. 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: {
id: number, // The unique layer id. If supplied for one layer, you should supply for all layers to avoid multiple layers having the same id.
name: String, // The name of the layer
description: String, // The description of the layer
copyrightText: String, // The copyright text (layer attribution text)
extent: Array, // valid extent array e.g. [[180,90],[-180,-90]]
displayField: String, // The display field to be used by a client
geometryType: String // REQUIRED if no features are returned with this object Point || MultiPoint || LineString || MultiLineString || Polygon || MultiPolygon
idField: String, // unique identifier field,
maxRecordCount: Number, // the maximum number of features a provider can return at once
limitExceeded: Boolean, // whether or not the server has limited the features returned
timeInfo: Object, // describes the time extent and capabilities of the layer,
transform: Object, // describes a quantization transformation
renderer: Object, // provider can over-ride default symbology of FeatureServer output with a renderer object. See https://developers.arcgis.com/web-map-specification/objects/simpleRenderer, for object specification.
defaultVisibility: boolean, // The default visibility of this layer
minScale: number, // The minScale value for this layer
maxScale: number, // The maxScale value for this layer
fields: [
{ // Subkeys are optional
name: String,
type: String, // 'Date' || 'Double' || 'Integer' || 'String'
alias: String, // how should clients display this field name,
}
]
},
capabilities: {
quantization: Boolean // True if the provider supports quantization
},
filtersApplied: {
all: Boolean // true if all post processing should be skipped
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
offset: Boolean // true if the result offset has already been applied to the data,
limit: Boolean // true if the result count has already been limited,
projection: Boolean // true if the result data has already been projected
}
count: Number // pass count if the number of features in a query has been pre-calculated
}
or
{
layers: [
{
type: 'FeatureCollection'
...
},
{
type: 'FeatureCollection'
...
}
]
- options is an object that dictates method actions. See
FeatureServer.query
andFeatureServer.generateRenderer
for more details.
Pass in geojson
and options
(a valid geoservices query object), and the function will perform the query and return a valid geoservices query object. The in addition to input statistics: {}
, following is an example of all query options
that can be passed into the query route: '/FeatureServer/:layer/query'
e.g.
const options = {
where: `1=1`,
objectIds: '1,2,3',
geometry: {
xmin: -110, ymin: 30, xmax: -106, ymax: 50,
spatialReference: { wkid: 4326 },
},
geometryType: 'esriGeometryEnvelope',
spatialRel: 'esriSpatialRelContains',
outFields: '*',
returnGeometry: true,
outSR: 102100, // output spatial reference
returnIdsOnly: true,
returnCountOnly: true,
orderByFields: 'Full/Part_COUNT DESC',
groupByFieldsForStatistics: 'Full/Part',
outStatistics: {
statisticType: 'count',
onStatisticField: '<field>',
outStatisticFieldName: 'name'
},
returnDistinctValues: true,
resultOffset: 0,
resultRecordCount: 0,
f: 'pjson'
}
FeatureServer.query(geojson, options)
Generate version 10.51
Geoservices server info
const server = {
description: String // Describes the collection of layers below,
copyrightText: String // Optional copyright text
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
hasAttachments: Boolean // whether or not the server contains any attachments for this layer
layers: [{ // A collection of all the layers managed by the server
type: 'FeatureCollection',
metadata: {
id: number, // The unique layer id. If supplied for one layer, you should supply for all layers to avoid multiple layers having the same id.
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,
geometryType: String, // REQUIRED if no features are returned with this object Point || MultiPoint || LineString || MultiLineString || Polygon || MultiPolygon
maxRecordCount: Number, // the maximum number of features a provider can return at once
limitExceeded: Boolean, // whether or not the server has limited the features returned
timeInfo: Object, // describes the time extent and capabilities of the layer
renderer: Object, // provider can over-ride default symbology of FeatureServer output with a renderer object. See https://developers.arcgis.com/web-map-specification/objects/simpleRenderer, for object specification.
defaultVisibility: boolean, // The default visibility of this layer
minScale: number, // The minScale value for this layer
maxScale: number // The maxScale value for this 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'
}
}]
}
}],
tables: [{ // A collection of all the tables managed by the server
type: 'FeatureCollection',
metadata: {
// see layer metadata
}
}],
relationships: [{ // A collection of all relationships manged by the server
id: number, // The unique relationship id.
name: String, // The name of the relationship
}]
}
FeatureServer.serverInfo(server)
Generate version 10.51
Geoservices information about a single layer
FeatureServer.layerInfo(geojson, options)
Note that the layer info is modified with properties metadata
and capabilites
found at the top-level of the GeoJSON object.
GeoJSON property | Layer info result |
---|---|
metadata.id |
overrides default |
metadata.name |
overrides default |
metadata.description |
overrides default |
metadata.geometryType |
overrides value determined from data |
metadata.extent |
overrides value determined from data |
metadata.timeInfo |
overrides default |
metadata.maxRecordCount |
overrides default (2000) |
metadata.displayField |
overrides default (OBJECTID ) |
metadata.objectIdField |
overrides default (OBJECTID ) |
metadata.hasStaticData |
overrides default (false ) |
metadata.hasAttachments |
overrides default (false ) |
metadata.renderer |
overrides default |
metadata.defaultVisibility |
overrides default |
metadata.minScale |
overrides default |
metadata.maxScale |
overrides default |
metadata.relationships |
overrides default |
capabilities.extract |
when set to true , Extract added to capabilites (e.g., capabilities: "Query,Extract" ) |
capabilities.quantization |
when set to true , supportsCoordinatesQuantization: true |
This defined the server managed relationships for the layer
e.g.
const metadata = {
//...
relationships: [{ // A collection of all relationships manged by the server
id: number, // The unique relationship id.
name: String, // The name of the relationship
relatedTableId: number, // Id of the layer/table related records are found
cardinality: String, // esriRelCardinalityOneToMany | esriRelCardinalityManyToMany
role: String, // esriRelRoleOrigin | esriRelRoleDestination
keyField: String, // key field name in the related Table
composite: Boolean // likely to false
}]
//...
}
Generate version 10.51
Geoservices information about one or many layers
Can pass a single geojson object or an array of geojson objects
FeatureServer.layers(geojson, options)
Pass in geojson
and options
, and the function will return a valid generateRenderer object. Two classificationDef
classification types are supported, classBreaksDef and uniqueValueDef.
classBreaksDef is used to classify numeric data based on a number of breaks and a statistical method. Features can also be normalized before being classified. uniqueValueDef is used to classify data based on a unique field(s). If classification breaks are not supplied through in statistics
, they will be generated using classificationDef
options. The output is a generateRenderer object.
In addition to class breaks as input statistics: []
, the following is an example of all classBreaksDef options
that can be passed into the generateRenderer route: '/FeatureServer/:layer/generateRenderer'
e.g.
const options = {
*'classificationDef': {
*'type': 'classBreaksDef',
*'classificationField': '<field1>',
*'classificationMethod': 'esriClassifyEqualInterval' | 'esriClassifyNaturalBreaks' | 'esriClassifyQuantile' | 'esriClassifyStandardDeviation',
*'breakCount': 9,
'normalizationType': 'esriNormalizeByField' | 'esriNormalizeByLog' | 'esriNormalizeByPercentOfTotal',
'normalizationField': '<field2>' // mandatory if 'normalizationType' === 'esriNormalizeByField'
'baseSymbol': {
'type': 'esriSMS',
'style': 'esriSMSCircle',
'width': 2
},
'colorRamp': {
'type': 'algorithmic',
'fromColor': [115,76,0,255],
'toColor': [255,25,86,255],
'algorithm': 'esriHSVAlgorithm'
}
},
'where': '<field2> > 39'
}
FeatureServer.generateRender(geojson, options)
*required
Output:
{
type: 'classBreaks',
field: '<field1>',
classificationMethod: 'esriClassifyEqualInterval',
minValue: 0,
classBreakInfos: [
{
classMinValue: 0,
classMaxValue: 5,
label: '0-5',
description: '',
symbol: {
type: 'esriSMS',
style: 'esriSMSCircle',
width: 2,
color: [115, 76, 0]
}
},
{
classMinValue: 6,
classMaxValue: 11,
label: '6-11',
description: '',
symbol: {
type: 'esriSMS',
style: 'esriSMSCircle',
width: 2,
color: [156, 67, 0]
}
},
...
]
}
The following is an example of all uniqueValueDef options
that can be passed into the generateRenderer route: '/FeatureServer/:layer/generateRenderer'
e.g.
const options = {
*'classificationDef': {
*'type': 'uniqueValueDef',
*'uniqueValueFields': ['Genus', '<field2>', '<field3>'],
*'fieldDelimiter': ', '
'baseSymbol': {
'type': 'esriSMS',
'style': 'esriSMSCircle',
'width': 2
},
'colorRamp': {
'type': 'algorithmic',
'fromColor': [115,76,0,255],
'toColor': [255,25,86,255],
'algorithm': 'esriHSVAlgorithm'
}
},
'where': 'latitude > 39'
}
FeatureServer.generateRender(geojson, options)
*required
Output:
{
type: 'uniqueValue',
field1: 'Genus',
field2: '',
field3: '',
fieldDelimiter: ', ',
defaultSymbol: {},
defaultLabel: '',
uniqueValueInfos: [
{
value: 'MAGNOLIA',
count: 5908,
label: 'MAGNOLIA',
description: '',
symbol: {
type: 'esriSMS',
style: 'esriSMSCircle',
width: 2,
color: [115, 76, 0]
}
},
{
value: 'QUERCUS',
count: 12105,
label: 'QUERCUS',
description: '',
symbol: {
type: 'esriSMS',
style: 'esriSMSCircle',
width: 2,
color: [116, 76, 0]
}
},
...
]
Pass in an outgoing response object and an authentication success object and this function will route and return a formatted authentication success response.
FeatureServer.authenticate(res, auth, ssl = false)
auth
is the result of a successful authentication attempt that returns a token and expiration timessl
is a boolean flag indicating if token should always be passed back via HTTPS. Defaults tofalse
e.g.,
const auth = {
"token":"elS39KU4bMmZQgMXDuswgA14vavIp4mfpiqcWSr0qM6q4dFguTnnHddWqbpK5Mc3HsCN8XghlwawUUYApOOcxKNyg_9WqTofChJXxxD058_rL1HZkM5PDhUOh9YYQn1K",
"expires":1524508236322
}
FeatureServer.authenticate(res, auth)
{
"token":"elS39KU4bMmZQgMXDuswgA14vavIp4mfpiqcWSr0qM6q4dFguTnnHddWqbpK5Mc3HsCN8XghlwawUUYApOOcxKNyg_9WqTofChJXxxD058_rL1HZkM5PDhUOh9YYQn1K",
"expires":1524508236322,
ssl: false
}
Pass in an outgoing response object and this function will route and return a formattted authorization error.
FeatureServer.error.authorize(res)
{
"error": {
"code": 499,
"message": "Token Required",
"details": []
}
}
Pass in an outgoing response object and this function will route and return a formatted authentication error.
FeatureServer.error.authenticate(res)
{
"error": {
"code": 400,
"message": "Unable to generate token.",
"details": ["Invalid username or password."]
}
}
Pass in geojson
and options
, and the function will return a valid queryRelatedRecords object. Required attributes within options
are objectIds
and relationshipId
.
The geojson
should be in the special FeatureCollection of FeatureCollections format to show the relationship between requested Features within the layer/table and the referenced relatinoship's features.
e.g.
const geojson = {
"type": "FeatureCollection",
"features": [ // Array of FeatureCollections by objectId with the related records as features
{
"type": "FeatureCollection",
"properties": {
"OBJECTID": 37
},
"features": [
{
"type": "Feature",
"geometry": {...},
"properties": {...}
}
]
}
]
}
const options = {
objectIds: "37, 462", // comma separated string of object ids within the layer to get related records
relationshipId: 4, // relationship Id of the server manged relationship of the layer, see FeatureServer.layerInfo
}
FeatureServer.queryRelatedRecords(geojson, options)
Output:
{
"geometryType": "esriGeometryPolygon",
"spatialReference": {
"wkid": 4267
},
"fields": [
{
"name": "OBJECTID",
"type": "esriFieldTypeOID",
"alias": "OBJECTID"
},
{
"name": "FIELD1",
"type": "esriFieldTypeString",
"alias": "FIELD1",
"length": 25
}
],
"relatedRecordGroups": [
{
"objectId": 37,
"relatedRecords": [
{
"attributes": {
"OBJECTID": 5540,
"FIELD1": "1000147595"
},
"geometry": {...}
}
]
}
]
}