Control Serialization Elements

MrBEE — Fri, 24 Mar 2006 23:21:53 GMT

The following article is a response to a number of requests I had from my Students to show them how to intervene in the way a class produces an XML serialized version, of an objects internal state, or how we get an XML document transformed into a type that easily allows us to manipulate it.

In a few words how we can change not the semantics of an object, but the syntax of the XML that is produced by the XMLSerializer class.

I have decided to use an actual project that I have developed recently and contain the code that allows an application to use with ease, some of the services of the WinBank PayCenter.

Background

When we want to use the services of WinBank XML Web Service, it is required by us, in our systems to collect all the information for a transaction. Then the above referenced transaction information must be sent in XML form, to the web service of PayCenter and receive a response again in XML for the successful or not completion of the transaction.

Transactions are send one at a time and the Schema of the Request document should derive from the following XML

REQUEST XML WEB SERVICE

<?xml version="1.0" encoding="ISO-8859-7"?>

</actiontype>

<user/>

</merchantinfo>

</header>

<body>

</transactioninfo>

<emv/>

<cvv2/>

</cardinfo>

</body>

</winbankpos>

Τhe result of the transaction is immediately send to the Merchant in the following form RESPONSE XML

<?xml version="1.0" encoding="ISO-8859-7"?>

</actiontype>

<user/>

</merchantinfo>

</header>

<body>

</transactioninfo>

</body>

</winbankpos>

Iιn order to start working we need to create a Class Library Project called WinBankLib that contain 2 top classes: WinBankRequest and WinBankResponse.

ΒΒoth when serialized follow the above corresponding XML signature.

BΒelow is the actual implementation of the WinBankRequest

‘ WinBankRequest.vb by Byron Thanopoulos

‘Import the necessary namespaces

Imports System

Imports System.Net

Imports System.IO

Imports System.Text

Imports System.Xml.Serialization

‘ since we need to change the Root Element of this class when serialized we need to ‘apply declaratively some attributes

<XmlRoot("winbankpos")> Public Class WinBankRequest

<XmlElement("header")> Public header As HeaderClass = New HeaderClass

<XmlElement("body")> Public body As BodyClass = New BodyClass

Public Function GetResponse(ByVal url As String) As WinBankResponse

' Configure HTTP request

Dim httpRequest As HttpWebRequest

httpRequest = WebRequest.Create(url)

httpRequest.Method = "POST"

'Prepare correct encoding for XML Serialization

Dim encoding As UTF8Encoding = New UTF8Encoding

' Use Xml property to obtain serialized XML data

' convert into bytes using encoding specified above and get length

Dim bodybytes() As Byte = encoding.GetBytes(Xml)

httpRequest.ContentLength = bodybytes.Length

' Get HTTP Request stream for putting XML data into

Dim httpRequestBodyStream As Stream = httpRequest.GetRequestStream()

' Fill Request Stream with Serialized XML data

httpRequestBodyStream.Write(bodybytes, 0, bodybytes.Length)

httpRequestBodyStream.Close()

' Get HTTP response // the Request is actually initiated when we call the httpRequest.GetResponse

Dim httpResponseStream As StreamReader

httpRequest.Credentials = New System.Net.NetworkCredential("username", "password")

Dim httpResponse As HttpWebResponse = httpRequest.GetResponse()

httpResponseStream = New StreamReader(httpResponse.GetResponseStream(), System.Text.Encoding.ASCII)

Dim httpResponseBody As String

' Extract XML from Response

httpResponseBody = httpResponseStream.ReadToEnd

httpResponseStream.Close()

' Ignore everything that is NOT XML by removing Headers

httpResponseBody = httpResponseBody.Substring(httpResponseBody.IndexOf("<?xml"))

' Deserialize XML into WinBankResponse

Dim serializer As XmlSerializer = _

New XmlSerializer(GetType(WinBankResponse))

Dim ResponseReader As StringReader = New StringReader(httpResponseBody)

'********

' Return WinBankResponse

Return CType(serializer.Deserialize(ResponseReader), WinBankResponse)

End Function

<XmlIgnore()> Public ReadOnly Property Xml() ' Simply Serializes the WinBankRequest Instance into XML

Get

' Prepare Xml Serializer

Dim Serializer As XmlSerializer = New XmlSerializer(GetType(WinBankRequest))

' serialize into string builder

Dim bodyBuilder As StringBuilder = New StringBuilder

Dim bodyWriter As StringWriter = New StringWriter(bodyBuilder)

Serializer.Serialize(bodyWriter, Me)

'replace Utf-16 encoding with utf-8

Dim body As String = bodyBuilder.ToString

body = body.Replace("utf-16", "utf-8")

Return body

End Get

End Property

End Class

Following the same principals the WinBankResponse code will be

‘WinBankResponse.vb by Byron Thanopoulos

Imports System

Imports System.Net

Imports System.IO

Imports System.Text

Imports System.Xml.Serialization

<XmlRoot("winbankpos")> Public Class WinBankResponse

<XmlElement("header")> Public header As HeaderClass = New HeaderClass

<XmlElement("body")> Public body As BodyClass = New BodyClass

<XmlIgnore()> Public ReadOnly Property Xml()

Get

' Prepare Xml Serializer

Dim Serializer As XmlSerializer = New XmlSerializer(GetType(WinBankResponse))

' serialize into string builder

Dim bodyBuilder As StringBuilder = New StringBuilder

Dim bodyWriter As StringWriter = New StringWriter(bodyBuilder)

Serializer.Serialize(bodyWriter, Me)

'replace Utf-16 encoding with utf-8

Dim body As String = bodyBuilder.ToString

body = body.Replace("utf-16", "utf-8")

Return body

End Get

End Property

End Class

Within both of the above documents there are more helper classes that their code is included as well in alphabetical order.

'ActionTypeClass.vb

Imports System

Imports System.Net

Imports System.IO

Imports System.Text

Imports System.Xml.Serialization

Public Class ActionTypeClass

<XmlElement("transtype")> Public transtype As String

<XmlElement("transname")> Public transname As String

<XmlElement("method")> Public method As String

End Class

'AssemblyInfo.vb

Imports System

Imports System.Reflection

Imports System.Runtime.InteropServices

' General Information about an assembly is controlled through the following

' set of attributes. Change these attribute values to modify the information

' associated with an assembly.

' Review the values of the assembly attributes

<Assembly: AssemblyTitle("")>

<Assembly: AssemblyDescription("")>

<Assembly: AssemblyCompany("")>

<Assembly: AssemblyProduct("")>

<Assembly: AssemblyCopyright("")>

<Assembly: AssemblyTrademark("")>

<Assembly: CLSCompliant(True)>

'The following GUID is for the ID of the typelib if this project is exposed to COM

<Assembly: Guid("A3C98D9F-7C6F-4B56-9F9C-D492C837F5B0")>

' Version information for an assembly consists of the following four values:

' Major Version

' Minor Version

' Build Number

' Revision

' You can specify all the values or you can default the Build and Revision Numbers

' by using the '*' as shown below:

<Assembly: AssemblyVersion("1.0.*")>

'BodyClass.vb

Imports System

Imports System.Net

Imports System.IO

Imports System.Text

Imports System.Xml.Serialization

Public Class BodyClass

<XmlElement("transactioninfo")> Public transactioninfo As TransactioninfoClass = New TransactioninfoClass

<XmlElement("cardinfo")> Public cardinfo As CardinfoClass = New CardinfoClass

End Class

'CardinfoClass.vb

Imports System

Imports System.Net

Imports System.IO

Imports System.Text

Imports System.Xml.Serialization

Public Class CardinfoClass

<XmlElement("track2")> Public track2 As String

<XmlElement("emv")> Public emv As String

<XmlElement("cardtype")> Public cardtype As String

<XmlElement("cardnumber")> Public cardnumber As String

<XmlElement("expirationmonth")> Public expirationmonth As String

<XmlElement("expirationyear")> Public expirationyear As String

<XmlElement("cvv2")> Public cvv2 As String

End Class

'HeaderClass.vb

Imports System

Imports System.Net

Imports System.IO

Imports System.Text

Imports System.Xml.Serialization

Public Class HeaderClass

<XmlElement("actiontype")> Public actiontype As ActionTypeClass = New ActionTypeClass

<XmlElement("merchantinfo")> Public merchantinfo As MerchantinfoClass = New MerchantinfoClass

<XmlElement("errorcode")> Public errorcode As String

<XmlElement("errordescription")> Public errordescription As String

End Class

'MerchantinfoClass.vb

Imports System

Imports System.Net

Imports System.IO

Imports System.Text

Imports System.Xml.Serialization

Public Class MerchantinfoClass

<XmlElement("merchantid")> Public merchantid As String

<XmlElement("posid")> Public posid As String

<XmlElement("channeltype")> Public channeltype As String

<XmlElement("user")> Public user As String

End Class

'TransactioninfoClass.vb

Imports System

Imports System.Net

Imports System.IO

Imports System.Text

Imports System.Xml.Serialization

Public Class TransactioninfoClass

<XmlElement("merchantreference")> Public merchantreference As String

<XmlElement("currency")> Public currency As String

<XmlElement("amount")> Public amount As String

<XmlElement("installments")> Public installments As String

<XmlElement("preorderdate")> Public preorderdate As String

<XmlElement("entrytype")> Public entrytype As String

<XmlElement("transactionid")> Public transactionid As String

End Class

So now we have the objects that we need to initiate communication with PayCenter system and an example is shown below

‘WinBankTestform.vb

Imports winBankLib

Imports System

Imports System.Net

Imports System.IO

Imports System.Text

Imports System.Xml.Serialization

Public Class WinBankTestform

Inherits System.Web.UI.Page

#Region " Web Form Designer Generated Code "

'This call is required by the Web Form Designer.

<System.Diagnostics.DebuggerStepThrough()> Private Sub InitializeComponent()

End Sub

Protected WithEvents TextBox1 As System.Web.UI.WebControls.TextBox

Protected WithEvents TextBox2 As System.Web.UI.WebControls.TextBox

Protected WithEvents TextBox3 As System.Web.UI.WebControls.TextBox

Protected WithEvents Label1 As System.Web.UI.WebControls.Label

Protected WithEvents Button1 As System.Web.UI.WebControls.Button

Protected WithEvents Label2 As System.Web.UI.WebControls.Label

'NOTE: The following placeholder declaration is required by the Web Form Designer.

'Do not delete or move it.

Private designerPlaceholderDeclaration As System.Object

Private Sub Page_Init(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Init

'CODEGEN: This method call is required by the Web Form Designer

'Do not modify it using the code editor.

InitializeComponent()

End Sub

#End Region

Private Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load

'Put user code to initialize the page here

TextBox1.Text = ""

TextBox2.Text = ""

End Sub

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click

TextBox1.Text = ""

TextBox2.Text = ""

' initialize variables

Dim request As WinBankRequest

Dim requestSerializer As XmlSerializer = New XmlSerializer(GetType(WinBankRequest))

Dim response As WinBankResponse

Dim responseSerializer As XmlSerializer = New XmlSerializer(GetType(WinBankResponse))

Dim xmlBuilder As StringBuilder

Dim xmlWriter As StringWriter

Dim winBankUrl As String = ConfigurationSettings.AppSettings("winBankVerificationUrl") '"https://Paycenter.winbank.gr/webservice/service.asp"

request = New WinBankRequest

request.header.actiontype.transtype = "10"

request.header.actiontype.transname = "CheckTransaction"

request.header.actiontype.method = "Request"

request.header.merchantinfo.merchantid = "xxxxxxxx"

request.header.merchantinfo.posid = " xxxxxxxx "

request.header.merchantinfo.channeltype = " xxxxxxxx "

request.header.merchantinfo.user = ConfigurationSettings.AppSettings("winBankVerificationPWD")

request.header.errorcode = ""

request.header.errordescription = ""

request.body.transactioninfo.merchantreference = Me.TextBox3.Text

request.body.transactioninfo.currency = ""

request.body.transactioninfo.amount = ""

request.body.transactioninfo.installments = ""

request.body.transactioninfo.preorderdate = ""

request.body.transactioninfo.entrytype = ""

request.body.transactioninfo.transactionid = ""

request.body.cardinfo.track2 = ""

request.body.cardinfo.emv = ""

request.body.cardinfo.cardtype = ""

request.body.cardinfo.cardnumber = ""

request.body.cardinfo.expirationmonth = ""

request.body.cardinfo.expirationyear = ""

request.body.cardinfo.cvv2 = ""

'display request

xmlBuilder = New StringBuilder

xmlWriter = New StringWriter(xmlBuilder)

requestSerializer.Serialize(xmlWriter, request)

Me.TextBox1.Text = xmlBuilder.ToString

' get response

response = request.GetResponse(winBankUrl)

If response.header.errorcode = "0" Then

Label2.BackColor = System.Drawing.Color.DeepSkyBlue

Label2.Text = "This OrderID has been succesfully processed by Win Bank"

Else

Label2.BackColor = System.Drawing.Color.White

Label2.ForeColor = System.Drawing.Color.Red

Label2.Text = "This OrderID has NOT been processed by Win Bank"

End If

xmlBuilder = New StringBuilder

xmlWriter = New StringWriter(xmlBuilder)

responseSerializer.Serialize(xmlWriter, response)

Me.TextBox2.Text = xmlBuilder.ToString

End Sub

End Class

This concludes my post.

I hope you will find it useful. Even though I could have produced the necessary classes using the XSD.exe I chose in this example to do it on my own. Please note that this is not a complete solution, but part of it. This does not change the fact that the above code is functional and you could use it straight away to connect your e-commerce application with PayCenter.

Ευχαριστώ πολύ

Θανόπουλος Βύρων – Friend of David Waterston – who ever knows him will know that that’s an honor.

XML / XSLT

Control Serialization Elements