Receiving the search intent based on availability timings and sending a list of delivery service options (Node.js)

In this use case, the user searches for delivery services by specifying some details about the package, where it needs to be picked up from and dropped including the time of pickup. As a result, the user sees a list of available delivery options to choose from and some associated costs involved.

Code snippets

BPP receives protocol search

/*
Example Request JSON:
{
    "context": {
        "domain": "delivery",
        "country": "IND",
        "city": "std:080",
        "action": "search",
        "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": {
        "intent" : {
            "item": {
                "time" : {
                    "start" : "2019-10-12T011:00:50.52Z",
                    "end" : "2019-10-13T00:20:50.52Z"
                }
            },
            "fulfillment": {
                "start" : {
                    "location" : {
                        "gps" : "12.4535445,77.9283792"
                    }
                },
                "end" : {
                    "location" : {
                        "gps" : "12.4535445,77.9283792"
                    }
                }
            }
        }
    }
}
*/
    // Auth middleware authenticates the digital signature of the incoming request
    router.post('/delivery/search', auth, search);

    function search({ 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"));
            processSearch(headers, body)
        } catch (error) {
            res.status(500).send(httpResponse("NACK", error));
        }
    };

BPP processes the search

   function processSearch(requestHeaders, searchRequestBody) {
        // Execute business logic here
        let searchResponse = {

        }
        generateResponse(requestHeaders, searchResponse)
    }

BPP generates response

    async function generateResponse(requestHeaders, rawResponse){
/*
Example Request JSON :
{
    "context": {
        "domain": "delivery",
        "country": "IND",
        "city": "std:080",
        "action": "on_search",
        "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": {
        "catalog" : {
            "bpp/descriptor": {
                "name": "Fast Logistics"
            },
            "bpp/providers" : [
                {
                    "id": "fast-logistics",
                    "descriptor" : {
                        "name": "Fast Logistics"
                    },
                    "items" : [
                        {
                            "id": "standard",
                            "descriptor" : {
                                "name" : "Standard Delivery"
                            },"price" : {
                                "currency": "INR",
                                "value": "40"
                            },
                            "matched": true
                        },
                        {
                            "id": "express",
                            "descriptor" : {
                                "name" : "Express Delivery"
                            },
                            "price" : {
                                "currency": "INR",
                                "value": "60"
                            },
                            "recommended": true
                        }
                    ]
                }
            ]
        }
    }
}
*/
        //The below code generates the above example JSON.
        let onSearchResponseBody = { }
        //call protocol on_search
        await callOnSearch(requestHeaders, onSearchResponseBody);
    }

BPP calls protocol on_search

    async function callOnSearch(requestHeaders, onSearchResponseBody) {
        // 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_search`, method: "POST", headers, data: onRatingResponseBody });
    }