Tracking a delivery order (Java)

In this use case, the user requests for a live delivery tracking link that can be rendered on the application.

Code snippets

Client calls the BAP server to trigger track:

    @PostMapping("/delivery/track_order")
    public ResponseEntity trackOrder(
            @RequestHeader HttpHeaders headers,
            @RequestBody ClientOrderRequest request) {
        var response = bapApplicationService.trackOrder(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": "track",
        "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": "2021-06-23T08:29:27.933Z"
    },
    "message": {
        "order_id": "order_1"
    }
}
*/

    public Response trackOrder(ClientOrderRequest request, HttpHeaders headers) {

        // Generate message id
        var messageId = UUID.randomUUID().toString();

        // Check if transaction id exists in the request.
        // Generate if not exists
        var txnId = StringUtils.hasText(request.getTransactionId())
                ? request.getTransactionId()
                : UUID.randomUUID().toString();

        // Construct the Context based on the request parameters
        var context = Context.builder().domain(request.getDomain())
                .action(Context.ActionEnum.track)
                .messageId(messageId)
                .transactionId(txnId)
                .transactionId(UUID.randomUUID().toString())
                .timestamp(new Date().toString())
                .build();

        // Construct the protocol specific object to be passed to the BPP
        // to track the active order
        var trackRequest = TrackRequest.builder()
                .context(context)
                .message(StatusMessage.builder()
                        .orderId(request.getOrderId())
                        .callbackUrl(request.getTrackingCallbackUrl())
                        .build())
                .build();

        return invokeTrack(trackRequest, headers);
    }
}

BAP server calls protocol track to the network

    public Response invokeTrack(TrackRequest request, HttpHeaders headers) {

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

        // Call BPP Track api from the returned endpoint.
        // Construct request headers with the public key
         var responseEntity = apiClient.post(url[0] + Context.ActionEnum.track,
                constructRequestHeaders(),
                request,
                Response.class);

        // Validate the received response
        if (responseEntity.getBody() == null || responseEntity.getBody().getError() != null ||
                "NACK".equals(responseEntity.getBody().getMessage().getAck().getStatus())) {
            // Return custom error to the client
            return null;
        }
        return Response.of("ACK", null);
    }

BAP receives protocol on_track

/*
Example Response JSON:
{
    "context": {
        "domain": "delivery",
        "country": "IND",
        "city": "std:080",
        "action": "on_track",
        "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": "2021-06-23T08:31:04.045Z"
    },
    "message": {
        "tracking": {
            "url": "https://track.bpp.com?order_id=order_1",
            "status": "active"
        }
    }
}
*/
    @PostMapping("/bap/on_track")
    public ResponseEntity onTrack(
            @RequestHeader HttpHeaders headers,
            @RequestBody OnTrackRequest request) {
        var response = bapCallbackApplicationService.onTrack(request, headers);
        return ResponseEntity.ok(response);
    }

    public Response onTrack(OnTrackRequest 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_track results

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