Sending the latest order with status (Node.js)

In this use case, the user refreshes the order screen to get the latest updates. On the other hand, the pharmacy pushes updates to the application as and when there is a change to the fulfillment status of the order.

Code snippets

BPP receives protocol status

/*
Example Request JSON:
{
    "context": {
        "domain": "nic2004:52311",
        "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": "2021-03-23T10:00:40.065Z"
    },
    "message": {
        "order_id": "order_1"
    }
}
*/
    // Auth middleware authenticates the digital signature of the incoming request
    router.post('/health_pharmacy/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": "nic2004:52311",
        "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": "2021-03-23T10:00:40.065Z"
    },
    "message": {
        "order": {
            "id": "order_1",
            "state": "Time slot blocked",
            "items": [
                {
                    "id": "vit_c",
                    "price" : {
                        "currency": "INR",
                        "value": "500"
                    },
                    "quantity": {
                        "selected": {
                            "count": 1
                        }
                    }
                },
                {
                    "id": "a_500",
                    "price" : {
                        "currency": "INR",
                        "value": "500"
                    },
                    "quantity": {
                        "selected": {
                            "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"
            },
            "fulfillment": {
                "type": "HOME-DELIVERY",
                "start": {
                    "location": {
                        "id": "abc_medicines_koramangala",
                        "descriptor": {
                            "name": "ABC Medicines"
                        },
                        "gps": "12.9349377,77.6055586"
                    },
                    "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]"
                    }
                },
                "customer": {
                    "person":{
                        "name": "John Doe",
                        "image": "https://mock_bap.com/prescription1.jpg",
                        "dob": "1991-08-12"
                    }
                }
            },
            "quote": {
                "price": {
                    "currency": "INR",
                    "value": "1100"
                },
                "breakup": [
                    {
                        "title": "Vitamin C",
                        "price": {
                            "currency": "INR",
                            "value": "500"
                        }
                    }, 
                   {
                        "title": "Antibiotics",
                        "price": {
                            "currency": "INR",
                            "value": "500"
                        }
                    },
                    {
                        "title": "Delivery Charge",
                        "price": {
                            "currency": "INR",
                            "value": "100"
                        }
                    }
                ],
                "ttl": "P1H"
            },
            "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": "1100",
                    "mode": "upi",
                    "vpa": "bpp@upi"
                },
                "type": "ON-FULFILLMENT",
                "status": "NOT-PAID"
            }
        }
    }
}
*/
        //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}/health_pharmacy/on_status`, method: "POST", headers, data: onStatusResponseBody })
    }