Applying an offer on a mobility service and getting discounted fare (Node.js)

In this use case, the user applies an offer on a mobility service and receives a discounted fare

Code snippets

Client calls the BAP server to trigger select:

    router.post("/mobility/apply_offer", applyOffer);

    async function applyOffer({ body }, res) {
        try {
            //  .. Validate the client request before below function
            await generateSelectRequest(body)
        } catch (error) {
            res.status(500).send(httpResponse("NACK", error));
        }
    };

BAP server generates the protocol request body

    // Code to generate the protocol request body i.e. function generateSelectRequest() specified above

    async function generateSelectRequest(clientRequestBody) {
/*
Example Request JSON :
{
    "context": {
        "domain": "nic2004:60221",
        "country": "IND",
        "city": "std:080",
        "action": "select",
        "core_version": "0.9.1",
        "bap_id": "https://mock_bap.com/",
        "bap_uri": "https://mock_bap.com/beckn/",
        "bpp_id": "https://mock_bpp.com/",
        "bpp_uri": "https://mock_bpp.com/beckn/",
        "transaction_id": "1209849124",
        "message_id": "12341242343",
        "timestamp": "2021-03-23T10:00:40.065Z"
    },
    "message": {
        "order": {
            "offers":[
                {
                    "id": "offer_10"
                }
            ]
        }
    }
}
*/
        //The below code generates the above example JSON.
        const transactionId = _.get(body, "transactionId");
        // Returns the Context including MessageId
        const context = createContext(transactionId);
        // Construct Header
        const headers = constructAuthHeader(); // Auth Header
        const selectRequestBody = {
            context,
            message:  {
                // Construct from the request
            }
        };
        //call protocol select
        const response = await callSelect(selectRequestBody);
        res
        .status(200)
        .send({ ...response.data, messageId: context["message_id"] });
    }

BAP server calls protocol select to the network

    async function callSelect(selectRequestBody) {
        // It lookups the registry for BG OR BPP
        let uri = lookup();
        // Construct Header
        const headers = constructAuthHeader(); // Auth Header with digital Signature
        return axios({ url: `${uri}/mobility/select`, method: "POST", headers, data: selectRequestBody });
    }

BAP receives protocol on_select

/*
Example Response JSON:
{
    "context": {
        "domain": "nic2004:60221",
        "country": "IND",
        "city": "std:080",
        "action": "on_select",
        "core_version": "0.9.1",
        "bap_id": "https://mock_bap.com/",
        "bap_uri": "https://mock_bap.com/beckn/",
        "bpp_id": "https://mock_bpp.com/",
        "bpp_uri": "https://mock_bpp.com/beckn/",
        "transaction_id": "1209849124",
        "message_id": "12341242343",
        "timestamp": "2021-03-23T10:00:40.065Z"
    },
    "message": {
        "order": {
            "provider": {
                "id": "yellow-cabs",
                "locations": [
                    {
                        "id": "closest-sedan-spot",
                        "gps": "12.9349377,77.6055586"
                    }
                ]
            },
            "items": [
                {
                    "id": "sedan_spot",
                    "price" : {
                        "currency": "INR",
                        "value": "170"
                    },
                    "time": {
                        "label": "ETA",
                        "duration": "P13M"
                    },
                    "location_id": "closest-sedan-spot",
                    "quantity": {
                        "selected": {
                            "count": 1
                        },
                        "available": {
                            "count": 4
                        }
                    }
                }
            ],
            "offers":[
                {
                    "id": "offer_10"
                }
            ],
            "quote": {
                "price": {
                    "currency": "INR",
                    "value": "160"
                },
                "breakup": [
                    {
                        "title": "Sedan Spot Booking",
                        "price": {
                            "currency": "INR",
                            "value": "170"
                        }
                    },
                    {
                        "title": "Service Charge",
                        "price": {
                            "currency": "INR",
                            "value": "10"
                        }
                    },
                    {
                        "title": "20 rupees off",
                        "price": {
                            "currency": "INR",
                            "value": "-20"
                        }
                    }
                ]
            }
        }
    }
}
*/
    // Auth middleware authenticates the digital signature of the incoming request
    router.post("/mobility/on_select", auth, onSelect);
    async function onSelect({ body }, res) {
        // Save the response to Database
        await saveToDb(body);
    };

Client polls BAP to get the on_select results

    // Endpoint for the client to poll the search data based on the message id
    async function getMessageById(req) {
        try {
            const messageId = _.get(req, "messageId");
            // Get the data using message Id
            const response = await getData(messageId);
            res.status(200).send(httpResponse('ACK', "", response));
        } catch(error) {
            res.status(500).send(httpResponse("NACK", error));
        }
    };