Receiving a search intent based on product name and sending list of stores that sell matching items (Node.js)

In this use case, the user types the name of a product on a search bar and expects a list of stores that sell the items matching his search. This sort of result appears in the case of retail aggregator BPPs that have onboarded multiple sellers on their platform

Code snippets

BPP receives protocol search

/*
Example Request JSON:
{
    "context": {
        "domain": "local_retail",
        "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": {
                "descriptor" : {
                    "name" : "Bread and Milk"
                }
            },
            "fulfillment": {
                "end": {
                    "location": {
                        "gps": "12.4535445,77.9283792"
                    }
                }
            }
        }
    }
}
*/
    // Auth middleware authenticates the digital signature of the incoming request
    router.post('/local_retail/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": "local_retail",
        "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": "2021-06-23T09:53:38.872Z"
    },
    "message": {
        "catalog": {
            "bpp/descriptor": {
                "name": "Shop EZ"
            },
            "bpp/providers": [
                {
                    "id": "./retail.kirana/ind.blr/[email protected]",
                    "descriptor": {
                        "name": "Pooja Stores"
                    },
                    "locations": [
                        {
                            "id": "./retail.kirana/ind.blr/[email protected]_location",
                            "gps": "12.9349377,77.6055586"
                        }
                    ]
                },
                {
                    "id": "./retail.kirana/ind.blr/[email protected]",
                    "descriptor": {
                        "name": "Nilgiris"
                    },
                    "locations": [
                        {
                            "id": "./retail.kirana/ind.blr/[email protected]_location",
                            "gps": "12.9349406,77.6208795"
                        }
                    ]
                },
                {
                    "id": "./retail.kirana/ind.blr/[email protected]",
                    "descriptor": {
                        "name": "Food Mall"
                    },
                    "locations": [
                        {
                            "id": "./retail.kirana/ind.blr/[email protected]_location"
                        }
                    ]
                }
            ]
        }
    }
}
*/
        //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}/local_retail/on_search`, method: "POST", headers, data: onRatingResponseBody });
    }