Searching by pickup and drop location of a package and receiving list of delivery service options (Java)

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. As a result, the user sees a list of available delivery options to choose from and some associated costs involved.

Code snippets

Client calls the BAP server to trigger search:

    @PostMapping("/delivery/search_by_pickup_and_drop_location")
    public ResponseEntity searchByPickupDrop(
            @RequestHeader HttpHeaders headers,
            @RequestBody ClientSearchRequest request) {
        var response = bapApplicationService.generateSearchRequest(request, headers);
        return ResponseEntity.ok(response);
    }

BAP server generates the protocol request body

/*
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" : {
            "fulfillment": {
                "start" : {
                    "location" : {
                        "gps" : "12.4535445,77.9283792"
                    }
                },
                "end" : {
                    "location" : {
                        "gps" : "12.4535445,77.9283792"
                    }
                }
            }
        }
    }
}
*/

    public Response generateSearchRequest(ClientSearchRequest request, HttpHeaders headers) {

        var messageId = UUID.randomUUID().toString();

        // Check and create transaction id if not passed
        var txnId = StringUtils.hasText(request.getTransactionId())
                ? request.getTransactionId()
                : UUID.randomUUID().toString();

        // Construct the request similar to the example given above
        var context = Context.builder().domain(request.getDomain())
                .action(Context.ActionEnum.search)
                .messageId(messageId)
                .transactionId(txnId)
                .transactionId(UUID.randomUUID().toString())
                .timestamp(new Date().toString())
                .build();
        var intentBuilder = Intent.builder();

        // Construct fulfilment object for the request from the pickup location gps
        intentBuilder = intentBuilder.fulfillment(ClientAssembler.of(request.getFulfilment()));

        // Construct the protocol specific object to be passed to the BPP/BG
        var searchRequest = SearchRequest.builder()
                .context(context)
                .message(SearchMessage.builder()
                        .intent(intentBuilder.build())
                        .build())
                .build();

        return invokeSearch(searchRequest, headers);
    }
}

BAP server calls protocol search to the network

    public Response invokeSearch(SearchRequest request, HttpHeaders headers) {

        // Call to look up function which returns the the public key and BPP/BG Endpoint to be called
        var url = lookUp(headers);

        //Call BPP Search api
        var searchResponse = apiClient.post(url[0] + Context.ActionEnum.search,
                constructRequestHeaders(),
                request,
                Response.class);

        if (responseEntity.getBody() == null || responseEntity.getBody().getError() != null ||
                "NACK".equals(responseEntity.getBody().getMessage().getAck().getStatus())) {
            // Return custom error to the client
            return null;
        }
        return searchResponse.getBody();
    }

BAP receives protocol on_search

/*
Example Response 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
                        }
                    ]
                }
            ]
        }
    }
}
*/
    @PostMapping("/bap/on_search")
    public ResponseEntity onSearch(
            @RequestHeader HttpHeaders headers,
            @RequestBody OnSearchRequest request) {
        var response = bapCallbackApplicationService.onSearch(request, headers);
        return ResponseEntity.ok(response);
    }

    public Response onSearch(OnSearchRequest request, HttpHeaders headers) {
        // Validate the headers received
        var isHeadersValid = validateHeaders(headers);
        // Construct and return error if the received headers are invalid
        if (!isHeadersValid) return null;

        // Store the data received based on message id for the client to poll
        saveToDB(request);

        return Response.of("ACK", null);
    }

Client polls BAP to get the on_search results

    // Endpoint for the client to poll the search data based on the message id
    @GetMapping("/delivery/on_search")
    public ResponseEntity searchByMessageId(
            @PathVariable(ClientRoutes.PARAM_MESSAGE_ID) String messageId,
            @RequestHeader HttpHeaders headers) {
        var data = bapApplicationService.getSearchData(messageId);
        return ResponseEntity.ok(data);
    }