nodejs-read-versioned-layer.md

Example how to read the layer data on Node.js using @here/olp-sdk-dataservice-read and @here/olp-sdk-authentication

This example shows how to retrieve partition metadata, and partition data using the OLP SDK for TypeScript.

Build and running on Node.js

Requirements:

Node.js 10+ TypeScript: 3.5+

Start by creating a simple Node.js app:

mkdir example-app && cd example-app && npm init

Then initialize a TypeScript project:

tsc --init

Also, install node types:

npm install --save-dev @types/node

Then install SDK modules:

npm install --save @here/olp-sdk-authentication @here/olp-sdk-dataservice-read @here/olp-sdk-dataservice-api

Now everything is set to create the app.

Create index.ts file add app skeleton:

/**
 * Example Node.js app for reading versioned layer from datastore
 */

class App {
    run() {
        console.log("App works!");
    }
}

const app = new App();
app.run();

Compile and run the app:

tsc && node .

After a successful run, the console displays the following message:

App works!

Log into the data store

The first thing you need is https://account.here.com account. Log into your account and create a test app to get app access key id and secret access key at https://platform.here.com/admin/apps

Now you can obtain the token for requests to the datastore by using the @here/olp-sdk-authentification.

Log into the api. Modify our app to the following state:

/**
 * Example Node.js app for reading versioned layer from datastore
 */
import { UserAuth } from "@here/olp-sdk-authentification";

const userAuth = new UserAuth({
    env: "here",
    credentials: {
        accessKeyId: "your-access-key-id",
        accessKeySecret: "your-access-key-secret"
    }
});

Context

Now you can initialize DataStore client for here environment and, for example, list catalogs. To do so you need a DatastoreContext. It contains look up api functionallity to get the base urls to the services.

/**
 * Example Node.js app for reading versioned layer from datastore
 */
import { UserAuth } from "@here/olp-sdk-authentification";
import { DataStoreContext } from "@here/olp-sdk-dataservice-read";

const userAuth = new UserAuth({
    env: "here",
    credentials: {
        accessKeyId: "your-access-key-id",
        accessKeySecret: "your-access-key-secret"
    }
});

const context = new DataStoreContext({
    environment: "here",
    getToken: () => userAuth.getToken()
});

VersionLayerClient

Therefore, when you have context, you can get catalog clients for different catalogs and read the information. You can get more information about Version Layer following the link. To create VersionLayerClient, run:

import { UserAuth } from "@here/olp-sdk-authentification";
import { DataStoreContext, VersionLayerClient } from "@here/olp-sdk-dataservice-read";
import * as utils from "@here/olp-sdk-dataservice-read";

const userAuth = new UserAuth({
    env: "here",
    credentials: {
        accessKeyId: "your-access-key-id",
        accessKeySecret: "your-access-key-secret"
    }
});

const context = new DataStoreContext({
    environment: "here",
    getToken: () => userAuth.getToken()
});

//  Client for "protobuf-example-berlin-v1" layer from "sensor-data-sensoris-versioned-example" catalog
const versionClient = await new VersionLayerClient({
    context,
    hrn: "hrn:here:data:::sensor-data-sensoris-versioned-example",
    layerId: "protobuf-example-berlin-v1",
    version: 0
});

// Get partition "23618173" by id
const partition = await versionClient.getPartition('23618173');

// Get tile using QuadKey
const tile = await versionClient.getTile({
    row: 1,
    column: 2,
    level: 3
});

// Get tile using mortonCode
const tile = await versionClient.getTile(utils.quadKeyFromMortonCode("1476147"));

// Get aggregated tile using mortonCode
const aggregatedTile = await versionClient.getAggregatedTile(utils.quadKeyFromMortonCode("1476147"));

// Get all partitions metadata for this layer
const partitions = await versionClient.getPartitionsMetadata();

// Get data coverage bitmap for this layer
const bitmap = await versionClient.getDataCoverageBitMap();

// Get data coverage sizemap for this layer
const sizeMap = await versionClient.getDataCoverageSizeMap();

// Get data coverage timemap for this layer
const timeMap = await versionClient.getDataCoverageTimeMap();

// Get index metadata for layer by QuadKey
const index = await versionClient.getIndexMetadata({
    row: 1,
    column: 2,
    level: 3
});

// Get layer summary metadata
const summary = await versionClient.getSummary();