4. Connect your service to an OCN Node

If you have followed the previous steps in this tutorial you should now have the following things ready for making your connection to the Open Charging Network:

(TOKEN_A in OCPI Terms)

Follow the steps listed below to connect to your OCN Node

Access the full OCN technical documentation .

1. Get the Public URL of your selected OCN node from the OCN Registry

There are three methods of interacting with the OCN Registry:

Using the CLI

ocn-registry get-node 0xEada1b2521115e07578DBD9595B52359E9900104

Where 0xEada1b2521115e07578DBD9595B52359E9900104 is the operator's public address.

Using the Typescript Library

The Public URL could look something like this: https://test-node.emobilify.com

Once connected to the registry, you can use the getNode method to return the operator's public URL:

     /**
     * Get a registry node listing for a given operator.
     * @param operator Ethereum address of the operator.
     * @returns the domain name/url if listing exists.
     */
    public async getNode(operator: string): Promise<string | undefined> {
        this.verifyAddress(operator)
        const node = await this.registry.getNode(operator)
        return node || undefined
    }

Using the Java Library

2. Get OCN Node versions and endpoints

We will first send a GET request to the OCN Node’s versions endpoint, using the TOKEN_A we received from the faucet. Note that curl requests can be imported into e.g. Postman or Insomnia if desired.

curl https://test-node.emobilify.com/ocpi/versions -H 'Authorization: Token {{TOKEN_A}}'

Do the same for this endpoint:

curl https://test-node.emobilify.com/ocpi/2.2 -H 'Authorization: Token {{TOKEN_A}}'

You should see a long list of OCPI version 2.2 endpoints implemented by the OCN Node. You will want to save these endpoints for future reference in your application’s database.

For now though, we just need one endpoint. Find the endpoint URL for the module identifier “credentials”. This will be the one we use to connect to the node:

{
  "identifier": "credentials",
  "role": "SENDER",
  "url": "https://test-node.emobilify.com/ocpi/2.2/credentials"
}

3. Ensure OCN Node can access our versions and endpoints

The OCN Node needs to know where to contact us in case there is a message from another party that needs to be routed to us. It can also help to filter requests, in the case that we have not implemented a specific OCPI module that another party is requesting from us.

const express = require("express")
const uuid = require("uuid")

const app = express()

const PUBLIC_URL = "https://service.msp.com"
const TOKEN_B = uuid.v4()
console.log("Auth TOKEN_B = " + TOKEN_B)


const authorize = (req, res, next) => {
	if (req.headers.authorization !== `Token ${TOKEN_B}`) {
		return res.status(401).send({
			status_code: 2001,
			status_message: "Unauthorized",
			timestamp: new Date()
		})
	}
	next()
} 


app.get("/ocpi/versions", authorize, async (_, res) => {
	res.send({
		status_code: 1000,
		data: {
			versions: [{
				version: "2.2",
				url: `${PUBLIC_URL}/ocpi/2.2`
			}]
		},
		timestamp: new Date()
	})
})


app.get("/ocpi/2.2", authorize, async (_, res) => {
	res.send({
		status_code: 1000,
		data: {
			version: "2.2",
			endpoints: [
				/* {
					identifier: "locations",
					role: "RECEIVER",
					url: `${PUBLIC_URL}/ocpi/2.2/receiver/locations`
				} */
			]
		},
		timestamp: new Date()
	})
})


app.listen(3000, () => { console.log("Started on port 3000") })

This will create an authorization token that the OCN Node should use to access our own endpoints. It is logged on start. Be sure to make a note of the authorization token as we will need it later.

Note also the PUBLIC_IP. We want the OCN Node to be able to access these endpoints from the outside, so we should make sure that the server is reachable via the public IP we set.

4. Credentials handshake

Now we are ready to connect to the OCN Node.

The credentials request is detailed below. Make sure to replace the variables TOKEN_A, TOKEN_B and PUBLIC_IP, PARTY_ID and COUNTRY_CODE where described:

TOKEN_A should match the one generated for you by the faucet
TOKEN_B should match the authorization token that you have created
PUBLIC_IP should point to your publicly accessible web service

curl https://test-node.emobilify.com/ocpi/2.2/credentials \
  -H 'Authorization: Token {{TOKEN_A}}' \
  -H 'Content-Type: application/json' \
  -d '{
    "token": "{{TOKEN_B}}",
    "url": "{{PUBLIC_IP}}/ocpi/versions",
    "roles": [{
      "party_id": "{{PARTY_ID}",
      "country_code": "{{COUNTRY_CODE}}",
      "role": "EMSP",
      "business_details": {
        "name": "Tutorial MSP"
      }
    }]
  }'

If the request is successful, you should see a response with OCPI status code 1000 and the OCN Node’s credentials returned in the body.

Now that we have connected to the Open Charging Network we can make use of OCPI to find point of interest data, issue remote commands at charge points and authorize RFID cards of any other OCPI party that is connected to the network.

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