在c＃控制台应用程序中使用WCF Royal Mail API

Question

I am trying to consume Royal Mail shipping API in my C# Console Application but I am stuck. When I make a call to the API, it says Invalid Request..

This is what I did so far

RoyalMailMessage.cs

 class RoyalMailMessage : Message
    {
        private readonly Message message;

        public RoyalMailMessage(Message message)
        {
            this.message = message;
        }
        public override MessageHeaders Headers
        {
            get
            {
                return this.message.Headers;
            }
        }
        public override MessageProperties Properties
        {
            get
            {
                return this.message.Properties;
            }
        }
        public override MessageVersion Version
        {
            get
            {
                return this.message.Version;
            }
        }
        protected override void OnWriteStartBody(XmlDictionaryWriter writer)
        {
            writer.WriteStartElement("Body", "http://schemas.xmlsoap.org/soap/envelope/");
        }
        protected override void OnWriteBodyContents(XmlDictionaryWriter writer)
        {
            this.message.WriteBodyContents(writer);
        }
        protected override void OnWriteStartEnvelope(XmlDictionaryWriter writer)
        {
            writer.WriteStartElement("s", "Envelope", "http://schemas.xmlsoap.org/soap/envelope/");
            writer.WriteAttributeString("xmlns", "v2", null, "http://www.royalmailgroup.com/api/ship/V2");
            writer.WriteAttributeString("xmlns", "v1", null, "http://www.royalmailgroup.com/integration/core/V1");
            writer.WriteAttributeString("xmlns", "xsi", null, "http://www.w3.org/2001/XMLSchema-instance");
            writer.WriteAttributeString("xmlns", "xsd", null, "http://www.w3.org/2001/XMLSchema");
            writer.WriteAttributeString("xmlns", "xsd", null, "http://www.w3.org/2001/XMLSchema");
        }
    }

RoyalMailMessageFormatter.cs

public class RoyalMailMessageFormatter : IClientMessageFormatter
    {
        private readonly IClientMessageFormatter formatter;

        public RoyalMailMessageFormatter(IClientMessageFormatter formatter)
        {
            this.formatter = formatter;
        }

        public object DeserializeReply(Message message, object[] parameters)
        {
            return this.formatter.DeserializeReply(message, parameters);
        }

        public Message SerializeRequest(MessageVersion messageVersion, object[] parameters)
        {
            var message = this.formatter.SerializeRequest(messageVersion, parameters);
            return new RoyalMailMessage(message);
        }
    }

RoyalMailIEndpointBehavior.cs

 class RoyalMailIEndpointBehavior : IOperationBehavior
    {

        public RoyalMailIEndpointBehavior() { }

        public void ApplyClientBehavior(OperationDescription description, ClientOperation proxy)
        {
            IClientMessageFormatter currentFormatter = proxy.Formatter;
            proxy.Formatter = new RoyalMailMessageFormatter(currentFormatter);
        }

        public void AddBindingParameters(OperationDescription operationDescription, BindingParameterCollection bindingParameters)
        {

        }

        public void ApplyDispatchBehavior(OperationDescription operationDescription, DispatchOperation dispatchOperation)
        {

        }

        public void Validate(OperationDescription operationDescription)
        {

        }

    }

Program.cs

class Program
    {
        static void Main(string[] args)
        {

            try
            {

                using (var shippingService = new shippingAPIPortTypeClient())
                {
                    shippingService.ClientCredentials.UserName.UserName = "xxxx";
                    shippingService.ClientCredentials.UserName.Password = "xxxxx";

                    foreach (OperationDescription od in shippingService.Endpoint.Contract.Operations)
                    {
                        od.Behaviors.Add(new RoyalMailIEndpointBehavior());
                    }


                    var createShipment = new createShipmentRequest()
                    {
                        integrationHeader = new integrationHeader()
                        {
                            dateTime = DateTime.Now,
                            dateTimeSpecified = true,
                            debugFlag = false,
                            debugFlagSpecified = false,
                            identification = new identificationStructure()
                            {
                                applicationId = "xxxx",
                                endUserId = "Sandra",
                                intermediaryId = "null",
                                transactionId = "123456789"
                            },
                            performanceFlag = false,
                            performanceFlagSpecified = false,
                            testFlag = false,
                            testFlagSpecified = false,
                            version = 1,
                            versionSpecified = false


                        },
                        requestedShipment = new requestedShipment()
                        {
                            bfpoFormat = new bFPOFormatType()
                            {
                                bFPOFormatCode = null,
                            },
                            customerReference = "",
                            departmentReference = "",

                        }
                    };

                    shippingService.createShipment(null, createShipment);
                }

            }
            catch (Exception ex)
            {
                Console.WriteLine(ex.Message);
            }
        }
    }

App.Config

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
  <startup>
    <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.5" />
  </startup>
  <system.serviceModel>
    <bindings>
      <basicHttpBinding>
        <binding name="shippingAPISoapBinding">
          <security mode="Transport">
            <transport clientCredentialType="Certificate"></transport>
          </security>
        </binding>

      </basicHttpBinding>
    </bindings>
    <client>
      <endpoint address="https://api.royalmail.com/shipping/onboarding" binding="basicHttpBinding"
          bindingConfiguration="shippingAPISoapBinding" contract="ShippingService.shippingAPIPortType"
          name="shippingAPIPort" behaviorConfiguration="CustomBehavior" />
    </client>
    <behaviors>
      <endpointBehaviors>
        <behavior name="CustomBehavior">
          <clientCredentials>
            <clientCertificate findValue="RM10001815" x509FindType="FindBySubjectName"
              storeLocation="CurrentUser" storeName="My" />
          </clientCredentials>
        </behavior>
      </endpointBehaviors>
    </behaviors>

  </system.serviceModel>
</configuration>

Now, when I make a call to the API, it says "Invalid Request"..I am not sure if I missing anything, may be adding credentials in Soap Envelop header like below?

<soapenv:Header>
<wsse:Security xmlns:wsse="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-secext-1.0.xsd" xmlns:wsu="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-utility-1.0.xsd">
<wsse:Username>xxxx</wsse:Username>
<wsse:Password Type="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-username-token-profile-1.0#PasswordDigest">xxxx</wsse:Password>
<wsse:Nonce EncodingType="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-soap-message-security-1.0#Base64Binary">xWstjXG0iUxbv3NH/fX+kw==</wsse:Nonce>
<wsu:Created>2014-08-16T15:29:42</wsu:Created>
</wsse:UsernameToken>
</wsse:Security>
</soapenv:Header>

Answer 1

Firstly you are missing the security header as you have already identified, plus a whole host of other fields in your createShipment request such as address, service code etc. I would strongly suggest using fiddler to capture your SOAP requests and responses, they will give you a lot more insight into what is happening. You can also compare the requests you are generating with the example requests provided by royal mail onboarding.

Looking at your code, you are not attaching the security tokens (the wsse) which needs to be unique for every request you make (The nonce token that is). You are also missing a variety of other required fields for the createShipemt request such as address, service code and type etc.

I had to attach the certificate and key to the request to make it work as well. Below are some fragments of the code I created to make this work, it's not a copy paste solution but better than anything else you will find out there with regards to Royal Mail and C# and should point you in the right direction.

Please note, I have config class which loads a lot of the settings from an sqlite database (not posted). The values for the createShipment request are coming from a form (not posted) which is pre-populated with the data but allows the user in our warehouse to alter and adjust accordingly. You have already made use of my custom message formatter example from post ( C# WCF (Royal Mail SOAP API) Declare Namespace In Header ) to handle the namespace issue. Royal Mail API is not easy to implement in C#, took me nearly 2 days to get a valid request and response and as I say, you really need to capture the requests and responses to work out what is going on.

private X509Certificate2 certificate;
private Config config;

    public RoyalMail() {

        // Load The Config
        config = new Config();
        config.loadConfig();

        // Load The SSL Certificate (Check The File Exists)
        String certificatePath = (Path.GetDirectoryName(System.Reflection.Assembly.GetExecutingAssembly().Location) + @"\" + config.GetCertificateName());

        if (!System.IO.File.Exists(certificatePath))
        {
            throw new Exception(@"The Royal Mail Certificate Is Missing From The Plugins Directory. Please Place The File " + config.GetCertificateName() + " In The Same Directory As The Plugin DLL File & Relaunch FileMaker.\n\n" + certificatePath);
        }

        certificate = new X509Certificate2(certificatePath, config.GetCertificatePassword());

        // Check It's In The Certificate 
        X509Store store = new X509Store(StoreName.My, StoreLocation.CurrentUser);
        store.Open(OpenFlags.ReadWrite);
        if (!store.Certificates.Contains(certificate))
        {
            store.Add(certificate);
            MessageBox.Show("Certificate Was Installed Into Computer Trust Store");
        }
        store.Close(); 

    }


    /*
     * 
     * SOAP Service & Methods
     * 
     */

    private shippingAPIPortTypeClient GetProxy()
    {

        BasicHttpBinding myBinding = new BasicHttpBinding(BasicHttpSecurityMode.Transport);
        myBinding.MaxReceivedMessageSize = 2147483647;
        myBinding.Security.Transport.ClientCredentialType = HttpClientCredentialType.Certificate;

        shippingClient = new shippingAPIPortTypeClient(myBinding, new EndpointAddress(new Uri(config.GetEndpointURL()), EndpointIdentity.CreateDnsIdentity("api.royalmail.com"), new AddressHeaderCollection()));
        shippingClient.ClientCredentials.ClientCertificate.Certificate = certificate;

        foreach (OperationDescription od in shippingClient.Endpoint.Contract.Operations)
        {
            od.Behaviors.Add(new RoyalMailIEndpointBehavior());
        }
        return shippingClient;
    }


    private SecurityHeaderType GetSecurityHeaderType()
    {
        SecurityHeaderType securityHeader = new SecurityHeaderType();

        DateTime created = DateTime.Now;

        string creationDate;
        creationDate = DateTime.UtcNow.ToString("yyyy-MM-ddTHH:mm:ssZ");

        string nonce = nonce = (new Random().Next(0, int.MaxValue)).ToString();

        byte[] hashedPassword;
        hashedPassword = GetSHA1(config.GetPassword());

        string concatednatedDigestInput = string.Concat(nonce, creationDate, Encoding.Default.GetString(hashedPassword));
        byte[] digest;
        digest = GetSHA1(concatednatedDigestInput);

        string passwordDigest;
        passwordDigest = Convert.ToBase64String(digest);

        string encodedNonce;
        encodedNonce = Convert.ToBase64String(Encoding.Default.GetBytes(nonce));

        XmlDocument doc = new XmlDocument();
        using (XmlWriter writer = doc.CreateNavigator().AppendChild())
        {
            writer.WriteStartDocument();
            writer.WriteStartElement("Security");
            writer.WriteStartElement("UsernameToken", "http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-secext-1.0.xsd");
            writer.WriteElementString("Username", config.GetUsername());
            writer.WriteElementString("Password", passwordDigest);
            writer.WriteElementString("Nonce", encodedNonce);
            writer.WriteElementString("Created", creationDate);
            writer.WriteEndElement();
            writer.WriteEndElement();
            writer.WriteEndDocument();
            writer.Flush();
        }

        doc.DocumentElement.RemoveAllAttributes();

        System.Xml.XmlElement[] headers = doc.DocumentElement.ChildNodes.Cast<XmlElement>().ToArray<XmlElement>();

        securityHeader.Any = headers;

        return securityHeader;

    }

    private integrationHeader GetIntegrationHeader()
    {
        integrationHeader header = new integrationHeader();

        DateTime created = DateTime.Now;
        String createdAt = DateTime.UtcNow.ToString("yyyy-MM-ddTHH:mm:ssZ");

        header.dateTime = created;
        header.version = Int32.Parse(config.GetVersion());
        header.dateTimeSpecified = true;
        header.versionSpecified = true;

        identificationStructure idStructure = new identificationStructure();
        idStructure.applicationId = config.GetApplicationID();

        string nonce = nonce = (new Random().Next(0, int.MaxValue)).ToString();

        idStructure.transactionId = CalculateMD5Hash(nonce + createdAt);

        header.identification = idStructure;

        return header;
    }

    private static byte[] GetSHA1(string input)
    {
        return SHA1Managed.Create().ComputeHash(Encoding.Default.GetBytes(input));
    }

    public string CalculateMD5Hash(string input)
    {
        // step 1, calculate MD5 hash from input
        MD5 md5 = System.Security.Cryptography.MD5.Create();
        byte[] inputBytes = System.Text.Encoding.ASCII.GetBytes(input);
        byte[] hash = md5.ComputeHash(inputBytes);

        // step 2, convert byte array to hex string
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < hash.Length; i++)
        {
            sb.Append(hash[i].ToString("X2"));
        }
        return sb.ToString();
    }



    /*
     * Check Response Footer For Errors & Warnings From Service
     * If Error Return True So We Can Inform Filemaker Of Error
     * Ignore Warnings For Now
     * 
     */
    private bool checkErrorsAndWarnings(integrationFooter integrationFooter)
    {
        if (integrationFooter != null)
        {
            if (integrationFooter.errors != null && integrationFooter.errors.Length > 0)
            {
                errorDetail[] errors = integrationFooter.errors;
                for (int i = 0; i < errors.Length; i++)
                {
                    errorDetail error = errors[i];
                    MessageBox.Show("Royal Mail Request Error: " + error.errorDescription + ". " + error.errorResolution, "Royal Mail Request Error", MessageBoxButtons.OK, MessageBoxIcon.Error, MessageBoxDefaultButton.Button1);
                }
                if (errors.Length > 0)
                {
                    return true;
                }
            }

            if (integrationFooter.warnings != null && integrationFooter.warnings.Length > 0)
            {
                warningDetail[] warnings = integrationFooter.warnings;
                for (int i = 0; i < warnings.Length; i++)
                {
                    warningDetail warning = warnings[i];
                    //MessageBox.Show("Royal Mail Request Warning: " + warning.warningDescription + ". " + warning.warningResolution, "Royal Mail Request Warning", MessageBoxButtons.OK, MessageBoxIcon.Warning, MessageBoxDefaultButton.Button1);
                }
            }
        }

        return false;

    }

    /*
     * Show Message Box With SOAP Error If We Receive A Fault Code Back From Service
     *
     */
    private void showSoapException(FaultException e)
    {
        MessageFault message = e.CreateMessageFault();

        XmlElement errorDetail = message.GetDetail<XmlElement>();

        XmlNodeList errorDetails = errorDetail.ChildNodes;

        String fullErrorDetails = "";

        for (int i = 0; i < errorDetails.Count; i++)
        {
            fullErrorDetails += errorDetails.Item(i).Name + ": " + errorDetails.Item(i).InnerText + "\n";
        }

        MessageBox.Show("An Error Occured With Royal Mail Service: " + message.Reason.ToString() + "\n\n" + fullErrorDetails, "Royal Mail SOAP Error", MessageBoxButtons.OK, MessageBoxIcon.Error, MessageBoxDefaultButton.Button1);
    }

    public createShipmentResponse SendCreateShipmentRequest(CreateShipmentForm shippingForm)
    {

        shippingAPIPortTypeClient client = GetProxy();

        try
        {

            createShipmentRequest request = new createShipmentRequest();
            request.integrationHeader = GetIntegrationHeader();

            requestedShipment shipment = new requestedShipment();

            // Shipment Type Code (Delivery or Return)
            referenceDataType shipmentType = new referenceDataType();
            shipmentType.code = shippingForm.GetShippingType();
            shipment.shipmentType = shipmentType;

            // Service Occurence (Identifies Agreement on Customers Account) Default to 1. Not Required If There Is There Is Only 1 On Account
            shipment.serviceOccurrence = config.GetServiceOccurance();

            // Service Type Code (1:24H 1st Class, 2: 48H 2nd Class, D: Special Delivery Guaranteed, H: HM Forces (BFPO), I: International, R: Tracked Returns, T: Tracked Domestic)
            referenceDataType serviceType = new referenceDataType();
            serviceType.code = shippingForm.GetServiceType().GetServiceTypeCode();
            shipment.serviceType = serviceType;

            // Service Offering (See Royal Mail Service Offering Type Codes. Too Many To List)
            serviceOfferingType serviceOfferingTypeContainer = new serviceOfferingType();
            referenceDataType serviceOffering = new referenceDataType();
            serviceOffering.code = shippingForm.GetServiceOffering().GetCode();
            serviceOfferingTypeContainer.serviceOfferingCode = serviceOffering;
            shipment.serviceOffering = serviceOfferingTypeContainer;

            // Service Format Code
            serviceFormatType serviceFormatTypeContainer = new serviceFormatType();
            referenceDataType serviceFormat = new referenceDataType();
            serviceFormat.code = shippingForm.GetServiceFormat().GetFormat();
            serviceFormatTypeContainer.serviceFormatCode = serviceFormat;
            shipment.serviceFormat = serviceFormatTypeContainer;

            // Shipping Date
            shipment.shippingDate = shippingForm.GetShippingDate();
            shipment.shippingDateSpecified = true;

            // Signature Required (Only Available On Tracked Services)
            if (shippingForm.IsSignatureRequired())
            {
                shipment.signature = true;
            }
            else
            {
                shipment.signature = false;

                // Leave In Safe Place (Available On Tracked Non Signature Service Offerings)
                shipment.safePlace = shippingForm.GetSafePlaceText();
            }
            shipment.signatureSpecified = true;

            // Sender Reference Number (e.g. Invoice Number or RA Number)
            shipment.senderReference = shippingForm.GetInvoiceNumber();

            /*
             * Service Enhancements
            */

            List<serviceEnhancementType> serviceEnhancements = new List<serviceEnhancementType>();

            List<dataObjects.ServiceEnhancement> selectedEnhancements = shippingForm.GetServiceEnhancements();

            for (int i = 0; i < selectedEnhancements.Count; i++)
            {
                serviceEnhancementType enhancement = new serviceEnhancementType();
                referenceDataType enhancementCode = new referenceDataType();
                enhancementCode.code = selectedEnhancements.ElementAt(i).GetEnhancementType().ToString();
                enhancement.serviceEnhancementCode = enhancementCode;
                serviceEnhancements.Add(enhancement);
            }

            shipment.serviceEnhancements = serviceEnhancements.ToArray();


            /*
             * Recipient Contact Details
            */

            contact recipientContact = new contact();
            recipientContact.complementaryName = shippingForm.GetCompany();
            recipientContact.name = shippingForm.GetName();

            if(!shippingForm.GetEmailAddress().Equals("")) {
                digitalAddress email = new digitalAddress();
                email.electronicAddress = shippingForm.GetEmailAddress();
                recipientContact.electronicAddress = email;
            }

            if(!shippingForm.GetMobileNumber().Equals("")) {
                telephoneNumber tel = new telephoneNumber();

                Regex phoneRegex = new Regex(@"[^\d]");
                tel.telephoneNumber1 = phoneRegex.Replace(shippingForm.GetMobileNumber(), "");
                tel.countryCode = "00" + shippingForm.GetCountry().GetDialingCode();
                recipientContact.telephoneNumber = tel;
            }

            shipment.recipientContact = recipientContact;

            /*
             * Recipient Address
             * 
            */
            address recipientAddress = new address();
            recipientAddress.addressLine1 = shippingForm.GetAddressLine1();
            recipientAddress.addressLine2 = shippingForm.GetAddressLine2();
            recipientAddress.addressLine3 = shippingForm.GetAddressLine3();
            recipientAddress.addressLine4 = shippingForm.GetCounty();
            recipientAddress.postTown = shippingForm.GetTown();
            countryType country = new countryType();
            referenceDataType countryCode = new referenceDataType();
            countryCode.code = shippingForm.GetCountry().getCountryCode();
            country.countryCode = countryCode;
            recipientAddress.country = country;
            recipientAddress.postcode = shippingForm.GetPostCode();

            recipientAddress.stateOrProvince = new stateOrProvinceType();
            recipientAddress.stateOrProvince.stateOrProvinceCode = new referenceDataType();

            shipment.recipientAddress = recipientAddress;

            // Shipment Items

            List<RoyalMailAPI.RoyalMailShippingAPI.item> items = new List<RoyalMailAPI.RoyalMailShippingAPI.item> ();

            foreach(dataObjects.Item i in shippingForm.GetItems()) {
                RoyalMailAPI.RoyalMailShippingAPI.item item = new RoyalMailAPI.RoyalMailShippingAPI.item();
                item.numberOfItems = i.GetQty().ToString();
                item.weight = new dimension();
                item.weight.value = (float) (i.GetWeight() * 1000);
                item.weight.unitOfMeasure = new unitOfMeasureType();
                item.weight.unitOfMeasure.unitOfMeasureCode = new referenceDataType();
                item.weight.unitOfMeasure.unitOfMeasureCode.code = "g";

                items.Add(item);
            }

            if (shippingForm.GetServiceType().GetDescription().ToLower().Contains("international"))
            {
                internationalInfo InternationalInfo = new internationalInfo();
                InternationalInfo.shipperExporterVatNo = "GB945777273";
                InternationalInfo.documentsOnly = false;
                InternationalInfo.shipmentDescription = "Invoice Number: " + shippingForm.GetInvoiceNumber();
                InternationalInfo.invoiceDate = DateTime.Now;
                InternationalInfo.termsOfDelivery = "EXW";
                InternationalInfo.invoiceDateSpecified = true;
                InternationalInfo.purchaseOrderRef = shippingForm.GetInvoiceNumber();

                List<RoyalMailShippingAPI.parcel> parcels = new List<parcel>();
                foreach (dataObjects.Item i in shippingForm.GetItems())
                {
                    parcel Parcel = new parcel();
                    Parcel.weight = new dimension();
                    Parcel.weight.value = (float)(i.GetWeight() * 1000);
                    Parcel.weight.unitOfMeasure = new unitOfMeasureType();
                    Parcel.weight.unitOfMeasure.unitOfMeasureCode = new referenceDataType();
                    Parcel.weight.unitOfMeasure.unitOfMeasureCode.code = "g";

                    Parcel.invoiceNumber = shippingForm.GetInvoiceNumber();
                    Parcel.purposeOfShipment = new referenceDataType();
                    Parcel.purposeOfShipment.code = "31";

                    List<contentDetail> Contents = new List<contentDetail>();
                    foreach (RoyalMailAPI.dataObjects.ProductDetail product in i.GetProducts())
                    {
                        contentDetail ContentDetail = new contentDetail();
                        ContentDetail.articleReference = product.Sku;
                        ContentDetail.countryOfManufacture = new countryType();
                        ContentDetail.countryOfManufacture.countryCode = new referenceDataType();
                        ContentDetail.countryOfManufacture.countryCode.code = product.CountryOfManufacture;

                        ContentDetail.currencyCode = new referenceDataType();
                        ContentDetail.currencyCode.code = product.CurrencyCode;
                        ContentDetail.description = product.Name;
                        ContentDetail.unitQuantity = product.Qty.ToString();
                        ContentDetail.unitValue = Convert.ToDecimal(product.Price);
                        ContentDetail.unitWeight = new dimension();
                        ContentDetail.unitWeight.value = Convert.ToSingle(product.Weight * 1000);
                        ContentDetail.unitWeight.unitOfMeasure = new unitOfMeasureType();
                        ContentDetail.unitWeight.unitOfMeasure.unitOfMeasureCode = new referenceDataType();
                        ContentDetail.unitWeight.unitOfMeasure.unitOfMeasureCode.code = "g";


                        Contents.Add(ContentDetail);
                    }

                    //Parcel.contentDetails = Contents.ToArray();

                    parcels.Add(Parcel);

                }

                InternationalInfo.parcels = parcels.ToArray();

                shipment.internationalInfo = InternationalInfo;
            }
            else
            {
                shipment.items = items.ToArray();
            }

            request.requestedShipment = shipment;

            createShipmentResponse response = client.createShipment(GetSecurityHeaderType(), request);

            // Show Errors And Warnings
            checkErrorsAndWarnings(response.integrationFooter);

            return response;

        }
        catch (TimeoutException e)
        {
            client.Abort();
            MessageBox.Show("Request Timed Out: " + e.Message, "Request Timeout", MessageBoxButtons.OK, MessageBoxIcon.Error, MessageBoxDefaultButton.Button1);
        }
        catch (FaultException e)
        {
            client.Abort();
            showSoapException(e);
        }
        catch (CommunicationException e)
        {
            client.Abort();
            MessageBox.Show("A communication error has occured: " + e.Message + " - " + e.StackTrace, "Communication Error", MessageBoxButtons.OK, MessageBoxIcon.Error, MessageBoxDefaultButton.Button1);
        }
        catch (Exception e)
        {
            client.Abort();
            MessageBox.Show(e.Message, "Royal Mail Error", MessageBoxButtons.OK, MessageBoxIcon.Error, MessageBoxDefaultButton.Button1);
        }

        return null;
    }