Cancel a trip (Java)

in this use case, the user cancels a trip before it starts

Code snippets

Client calls the BAP server to trigger cancel:

    @PostMapping("/mobility/cancel_order")
    public ResponseEntity cancelOrder(
            @RequestHeader HttpHeaders headers,
            @RequestBody ClientOrderRequest request) {
        var response = bapApplicationService.cancelOrder(request, headers);
        return ResponseEntity.ok(response);
    }

BAP server generates the protocol request body

/*
Example Request JSON:
{
    "context": {
        "domain": "nic2004:60221",
        "country": "IND",
        "city": "std:080",
        "action": "cancel",
        "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": "1234124234237",
        "timestamp": "2021-03-23T10:00:40.065Z"
    },
    "message": {
        "order_id": "trip_1",
        "cancellation_reason_id": "reason_3"
    }
}
*/

    public Response cancelOrder(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.cancel)
                .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 cancel the order of given order id
        // The valid cancellation reasons will be fetched by the BPP's /get_cancellation_reasons endpoint
        var cancelRequest = CancelRequest.builder()
                .context(context)
                .message(CancelMessage.builder()
                        .orderId(request.getOrderId())
                        .cancellationReasonId(request.getCancellationReason())
                        .build())
                .build();

        return invokeCancel(cancelRequest, headers);
    }
}

BAP server calls protocol cancel to the network

    public Response invokeCancel(CancelRequest 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 Cancel api from the returned endpoint.
        // Construct request headers with the public key
        var responseEntity = apiClient.post(url[0] + Context.ActionEnum.cancel,
                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_cancel

/*
Example Response JSON:
{
    "context": {
        "domain": "nic2004:60221",
        "country": "IND",
        "city": "std:080",
        "action": "on_cancel",
        "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": "12341242345",
        "timestamp": "2021-03-23T10:00:40.065Z"
    },
    "message": {
        "order": {
            "id":"trip_1",
            "state":"Cancelled",
            "items":[
                {
                    "id": "sedan_spot",
                    "quantity": {
                        "count": 1
                    }
                }
            ],
            "billing": {
                "name": "John Doe",
                "address": {
                    "door": "21A",
                    "name": "ABC Apartments",
                    "locality": "HSR Layout",
                    "city": "Bengaluru",
                    "state": "Karnataka",
                    "country": "India",
                    "area_code": "560102"
                },
                "email": "[email protected]",
                "phone": "+919876543210"
            },
            "fulfillment": {
                "tracking": true,
                "start": {
                    "location": {
                        "id": "user-location",
                        "descriptor": {
                            "name": "Current user location"
                        },
                        "gps": "12.9349377,77.6055586"
                    },
                    "instructions": {
                        "name": "pick up instructions",
                        "short_desc": "Ask doorman to ring 21A"
                    },
                    "time": {
                        "label": "ETA",
                        "duration": "P12M"
                    },
                    "contact": {
                        "phone": "+919999999999",
                        "email": "[email protected]"
                    }
                },
                "end": {
                    "location": {
                        "gps": "12.914028, 77.638698"
                    }
                }
            },
            "quote": {
                "price": {
                    "currency": "INR",
                    "value": "180"
                },
                "breakup": [
                    {
                        "title": "Sedan Spot Booking",
                        "price": {
                            "currency": "INR",
                            "value": "170"
                        }
                    },
                    {
                        "title": "Service Charge",
                        "price": {
                            "currency": "INR",
                            "value": "10"
                        }
                    }
                ]
            },
            "payment": {
                "uri": "https://api.bpp.com/pay?amt=$180&mode=upi&vpa=bpp@upi",
                "tl_method": "http/get",
                "params": {
                    "amount": "180",
                    "mode": "upi",
                    "vpa": "bpp@upi"
                },
                "type": "ON-FULFILLMENT",
                "status": "NOT-PAID"
            }
        }
    }
}
*/
    @PostMapping("/bap/on_cancel")
    public ResponseEntity onCancel(
            @RequestHeader HttpHeaders headers,
            @RequestBody OnCancelRequest request) {
        var response = bapCallbackApplicationService.onCancel(request, headers);
        return ResponseEntity.ok(response);
    }

    public Response onCancel(OnCancelRequest 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_cancel results

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