Sending the latest delivery order with status (Node.js)

In this use case, the user requests the delivery agency to get the latest status of a confirmed delivery. Sometimes, the delivery agency also sends multiple status updates as and when the status of delivery changes like "Agent has picked up package", "Agent is en-route", "Agent has delivered package" etc.

Code snippets

BPP receives protocol status

/*
Example Request JSON:
{
    "context": {
        "domain": "delivery",
        "country": "IND",
        "city": "std:080",
        "action": "status",
        "core_version": "0.9.2",
        "bap_id": "https://mock_bap.com/",
        "bap_uri": "https://mock_bap.com/beckn/",
        "transaction_id": "1239890342",
        "message_id": "123793824",
        "timestamp": "2021-06-23T07:59:13.950Z"
    },
    "message": {
        "order_id": "order_1"
    }
}
*/
    // Auth middleware authenticates the digital signature of the incoming request
    router.post('/delivery/status', auth, status);

    function status({ headers, body }, res) {
        try {
            const message = _.get(body, "message");
            const context = _.get(body, "context");
            if (!context) {
                return res.status(400).send(httpResponse("NACK", "Missing Context"));
            }
            if (!message) {
                return res.status(400).send(httpResponse("NACK", "Missing Message"));
            }
            // ... Returns the ack immediately and continue the processing after validation
            res.status(200).send(httpResponse("ACK"));
            processStatus(headers, body)
        } catch (error) {
            res.status(500).send(httpResponse("NACK", error));
        }
    };

BPP processes the status

    function processStatus(requestHeaders, statusRequestBody) {
        // Execute business logic here
        let statusResponse = {}
        generateResponse(requestHeaders, statusResponse)
    }

BPP generates response

    function generateResponse(requestHeaders, rawResponse){

/*
Example Request JSON :
{
    "context": {
        "domain": "delivery",
        "country": "IND",
        "city": "std:080",
        "action": "on_status",
        "core_version": "0.9.2",
        "bap_id": "https://mock_bap.com/",
        "bap_uri": "https://mock_bap.com/beckn/",
        "transaction_id": "1239890342",
        "message_id": "123793824",
        "timestamp": "2021-06-23T08:02:07.788Z"
    },
    "message": {
        "order": {
            "id": "order_1",
            "state": "Agent is en-route",
            "items": [
                {
                    "id": "standard",
                    "quantity": {
                        "count": 1
                    }
                }
            ],
            "billing": {
                "name": "John Doe",
                "address": {
                    "door": "21A",
                    "name": "ABC Apartments",
                    "locality": "HSR Layout",
                    "city": "Bengaluru",
                    "state": "Karnataka",
                    "country": "India",
                    "area_code": "560102"
                },
                "email": "[email protected]",
                "phone": "+919876543210",
                "created_at": "2021-06-15T07:08:36.211Z",
                "updated_at": "2021-06-15T07:08:36.211Z"
            },
            "fulfillment": {
                "type": "home-delivery",
                "tracking": false,
                "start": {
                    "location": {
                        "gps": "12.9349377,77.6055586"
                    },
                    "time": {
                        "range": {
                            "start": "2021-06-15T07:09:30.000Z",
                            "end": "2021-06-15T07:10:30.000Z"
                        }
                    },
                    "instructions": {
                        "name": "pick up instructions",
                        "short_desc": "Don't ring doorbell"
                    },
                    "contact": {
                        "phone": "+919999999999",
                        "email": "[email protected]"
                    }
                },
                "end": {
                    "location": {
                        "gps": "12.914028, 77.638698",
                        "address": {
                            "door": "21A",
                            "name": "ABC Apartments",
                            "locality": "HSR Layout",
                            "city": "Bengaluru",
                            "state": "Karnataka",
                            "country": "India",
                            "area_code": "560102"
                        }
                    },
                    "time": {
                        "range": {
                            "start": "2021-06-15T07:11:36.212Z",
                            "end": "2021-06-15T07:12:36.212Z"
                        }
                    },
                    "instructions": {
                        "name": "drop off instructions",
                        "short_desc": "Leave at door step"
                    },
                    "contact": {
                        "phone": "+919876543210",
                        "email": "[email protected]"
                    }
                }
            },
            "quote": {
                "price": {
                    "currency": "INR",
                    "value": "40"
                },
                "breakup": [
                    {
                        "title": "Standard delivery",
                        "price": {
                            "currency": "INR",
                            "value": "40"
                        }
                    }
                ],
                "ttl": "P4D"
            },
            "payment": {
                "uri": "https://api.bpp.com/pay?amt=$amount&txn_id=ksh87yriuro34iyr3p4&mode=upi&vpa=bpp@upi",
                "tl_method": "http/get",
                "params": {
                    "transaction_id": "ksh87yriuro34iyr3p4",
                    "amount": "40",
                    "mode": "upi",
                    "vpa": "bpp@upi"
                },
                "type": "ON-ORDER",
                "status": "PAID"
            },
            "created_at": "2021-06-23T07:33:02.655Z",
            "updated_at": "2021-06-23T07:33:02.655Z"
        }
    }
}
*/
        //The below code generates the above example JSON.
        let onStatusResponseBody = {

        }
        //call protocol on_status
        await callOnStatus(requestHeaders, onStatusResponseBody);
    }

BPP calls protocol on_status

    function callOnStatus(requestHeaders, onStatusResponseBody) {
        // Take the subscriber Id from the header and calls the registry to get the url. If already cached it need not to call again
        const uri = await lookup(requestHeaders);
        // Construct Header
        const headers = constructAuthHeader(); // Auth Header with digital Signature
        return axios({ url: `${uri}/delivery/on_status`, method: "POST", headers, data: onStatusResponseBody })
    }