GeoJSON

GeoJSON

GeoJSON geospatial data can be exposed as a feature service through configuration.

Assuming your data looks similar to the following:

{
  "envelope": {
    "header": {
      "type": "geojson", 
      "ctsRegion": "POINT (125.6, 10.1)",
      "pointId": 12312
    },
    "instance": {
      "type": "Feature",
      "geometry": {
        "type": "Point",
        "coordinates": [125.6, 10.1]
      },
      "properties": {
        "name": "Dinagat Islands"
      }
    }
  }
}

Reference: https://geojson.org/

Add Geospatial Data Services to your Gradle Project

Create a schema's database for your application. Add the marklogic-geo-data-services mlBundle. See the project README

dependencies {
  mlBundle "com.marklogic:marklogic-geo-data-services-modules:1.1.0"
}

Define your Feature Service

You first define your feature service.

{
  "info": {
    "name": "MyGeoData",
    "description": "My GeoJSON data"
  },
  "layers": [
    {
      "id": 0,
      "name": "GeoJSON Data",
      "description": "My data in GeoJSON",
      "geometryType": "Polygon",
      "idField": "OBJECTID",
      "extent": {
        "xmin": 8,
        "ymin": 119,
        "xmax": 14,
        "ymax": 128,
        "spatialReference": {
          "wkid": 4326,
          "latestWkid": 4326
        }
      },
      "schema": "GeoLocation",
      "view": "GeoJSON",
      "geometry": {
        "type": "Polygon",
        "format": "geojson",
        "coordinateSystem": "wgs84",
        "source": {
          "xpath": "/envelope/instance/boundary"
        }
      }
    }
  ]
}

A few notes on the Feature Service configuration:

• You can have multiple layers, each layer must have a unique incrementing id
  • Multiple layers may be defined in the layers array but do not need to make use of the same extent, schema, view, or geometry index. Increment the id for each layer.
• If you are supporting Esri products, uou must identify an idField with a unique number for each document's data points. See the README for more information.
• The feature service needs to identify the geospatial area (e.g. geospatial extent) the layer should return data for.
• schema identifies the schema-name of the TDE used for this layer
• view identifies the view-name of the TDE used for this layer
• geometry specifies the geospatial index to use for geospatial queries and point responses

Define your Template (TDE)

The Template Driven Extraction (TDE)

For the Feature Service defined above, the following TDE will extact data into the view used to return relevant feature data. Notice the context of the template identifies envelope data with a type of "geojson".

<template xmlns="http://marklogic.com/xdmp/tde">
   <description>Example template for GeoJSON documents</description>
   <context>/envelope[header/type="geojson"]</context>
   <collections>
      <collection>example-geojson</collection>
   </collections>
   <templates>
    <template xmlns:tde="http://marklogic.com/xdmp/tde">
      <context>./instance</context>
      <rows>
        <row>
          <schema-name>GDS_Sample</schema-name>
          <view-name>GeoJSON</view-name>
          <view-layout>sparse</view-layout>
          <columns>
            <column>
              <name>OBJECTID</name>
              <scalar-type>long</scalar-type>
              <val>../header/pointId</val>
            </column>
            <column>
              <name>feature</name>
              <scalar-type>string</scalar-type>
              <val>type</val>
              <nullable>true</nullable>
            </column>
            <column>
              <name>name</name>
              <scalar-type>string</scalar-type>
              <val>properties/name</val>
              <nullable>true</nullable>
            </column>
          </columns>
        </row>
      </rows>
    </template>
   </templates>
</template>

Please refer to the MarkLogic Documentation on TDE's for more information.

After deploying the template and some sample code, you can use MarkLogic Query Console to verify the TDE is extracting your data.

Verify the provided sample data and TDE.

SELECT * FROM GDS_Sample.GeoJSON

Result (raw):

[["GDS_Sample.GeoJSON.OBJECTID","GDS_Sample.GeoJSON.feature","GDS_Sample.GeoJSON.name"],[12312,"Feature","Dinagat Islands"]]

Result (as table):

GDS_Sample.GeoJSON.OBJECTID	GDS_Sample.GeoJSON.feature	GDS_Sample.GeoJSON.name
12312	Feature	Dinagat Islands

Deploy your application

Using mlGradle, deploy to your MarkLogic system.

gradle mlDeploy -PenvironmentName=local

Ingest your data

You can ingest your data using MarkLogic Content Pump mlcp, Apache Nifi processors, MarkLogic Data Hub input flow, and a several other methods.

Test your data

Now that you have your application deployed with your verified TDE, you should be able to add marklogic-geo-data-services via an mlBundle to your application.

Consult the README on the marklogic-geo-data-services to configure and test your Feature Services.