Overview of SENTRY Redirect Link

3. Processing Methods

3.6 Overview of SENTRY Redirect Link

To implement the Redirect Link method, a developer would need to create an HTML form that would post all of the information needed to process a transaction to the system. The fields contained in the posted form would be all of the information necessary to process a transaction, minus the card detail fields.

Once the gateway server receives all of the transaction information, the transaction is processed. Once the transaction is processed, an HTTPS form POST is sent to the MerRespURL specified, along with the results of the transaction. The receiving script or program at the merchant side listens for the results at the specified MerRespURL, and then decides what type of response to display to the cardholder‟s browser.

3.6.1 Example - Minimum Requirements for Redirect Link

The following are the minimum requirements for an ADC Relay Response transaction. It assumes the merchant is using the generic Payment Form defined by the SENTRY provider. If the merchant does not wish to use the generic payment form, the merchant would then need to customize the Checkout page

PurchaseAmt Purchase Amount as calculated by the merchant‟s checkout system

PurchaseCurrency The currency value of the purchase in ISO Numeric value.

Only values permitted by acquirer are allowed.

PurchaseCurrencyExponent The number of decimal digits of the purchase currency.

OrderID The transaction ID of the order that uniquely identifies the transaction in the merchant‟s system.

Signature The hash signature for the order request

The following code sample is written in VB.NET. It prepares a String containing all the necessary HTML code to place an order request: it contains the mandatory Redirect fields and their values, along with a Javascript function that submits the HTML form to the SENTRY PG listener URL (in the sample, the URL comes from a textbox located on the webpage).

The string containing the HTML form and javascript is then written directly to the output stream of a .NET HttpResponse object and is flushed to the browser, which then executes the javascript and submits the HTML form to SENTRY PG for processing.

NOTE: The limitation of this approach is that if browser has disabled javascript, this code will not function properly. It is assumed that the merchant developer is aware of the appropriate coding approach to use.

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Page 35 of 72 Private Sub Send_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Send.Click

Dim ReqString As String = Nothing

Dim PurcAmount As String = GetAmtFillZeros(PurchaseAmount.Text.Trim) Dim GOrderId As String = GenerateOrderId()

' Calculate the Hash with SHA ...

Dim MerchantHash As String

MerchantHash = MerchantPassword.Text.Trim & MerchantId.Text.Trim & AcquiredId.Text.Trim & GOrderId.Trim & PurcAmount.Trim &

PurchaseCurrency.Text.Trim

Dim Signature = Me.ComputeHash(MerchantHash)

ReqString = "<HTML><body><form id='FrmHtmlCheckout' name='FrmHtmlCheckout' action='' method='post'>" & vbNewLine ReqString &= "<input id='Version' type='hidden' name='Version' value='" & Version.Text.Trim & "'> " & vbNewLine ReqString &= "<input id='MerID' type='hidden' value='" & MerchantId.Text.Trim & "' name='MerID' > " & vbNewLine ReqString &= "<input id='AcqID' type='hidden' value='" & AcquiredId.Text.Trim & "' name='AcqID' > " & vbNewLine

ReqString &= "<input id='MerRespURL' type='hidden' value='" & MerRespUrl.Text.Trim & "' name='MerRespURL'> " & vbNewLine ReqString &= "<input id='PurchaseAmt' type='hidden' value='" & PurcAmount.Trim & "' name='PurchaseAmt'> " & vbNewLine

ReqString &= "<input id='PurchaseCurrency' type='hidden' value='" & PurchaseCurrency.Text.Trim & "' name='PurchaseCurrency'>

" & vbNewLine

ReqString &= "<input id='PurchaseCurrencyExponent' type='hidden' value='" & PurchaseCurrencyExponent.Text.Trim & "' name='PurchaseCurrencyExponent'> " & vbNewLine

ReqString &= "<input id='OrderID' type='hidden' value='" & GOrderId.Trim & "' name='OrderID' > " & vbNewLine

ReqString &= "<input id='SignatureMethod' type='hidden' value='" & SignatureMethod.Text.Trim & "' name='SignatureMethod'> "

& vbNewLine

ReqString &= "<input id='Signature' type='hidden' value='" & Signature & "' name='Signature'> " & vbNewLine

ReqString &= "<input id='CaptureFlag' type='hidden' value='" & CaptureFlag.Text.Trim & "' name='CaptureFlag' > " &

vbNewLine

(sample continued on next page)

Page 36 of 72 ReqString &= "</form>" & vbNewLine

ReqString &= "<script language='javascript'> " & vbNewLine ReqString &= " CheckOut(); " & vbNewLine

ReqString &= "function CheckOut(){" & vbNewLine

ReqString &= "document.FrmHtmlCheckout.action = '" & SentryHostUrl.Text.Trim & "';

" & vbNewLine

ReqString &= "document.FrmHtmlCheckout.submit();" & vbNewLine ReqString &= "}</script></body></HTML>" & vbNewLine

Response.Write(ReqString) Response.Close()

End If End Sub

Page 37 of 72

In document SENTRY Payment Gateway (Page 34-37)