Using SOAP Header and SOAP Extensions in a Web Service

12. Now we will change the SoapMessageStage.BeforeDeserialize case in the ProcessMessage method as below. In the client side the portion of the code within

case SoapMessageStage.BeforeDeserialize:
readStr = new StreamReader(outwardStream);
writeStr = new StreamWriter(inwardStream);
soapMsg1 = readStr.ReadToEnd();
if ( message is System.Web.Services.Protocols.SoapClientMessage)
{
// this is executed at client side
xDoc.LoadXml(soapMsg1);
XmlNodeList xResult = xDoc.GetElementsByTagName("AuthenticateResult");
xResult[0].InnerXml = decrypt(xResult[0].InnerXml);
}
else if( message is System.Web.Services.Protocols.SoapServerMessage)
{
// this is executed at server side
xDoc.LoadXml(soapMsg1);
XmlNodeList xSiteID = xDoc.GetElementsByTagName("siteID");
xSiteID[0].InnerXml = decrypt(xSiteID[0].InnerXml);
XmlNodeList xSitePwd = xDoc.GetElementsByTagName("sitePwd");
xSitePwd[0].InnerXml = decrypt(xSitePwd[0].InnerXml);
XmlNodeList xUserID = xDoc.GetElementsByTagName("UserID");
xUserID[0].InnerXml = decrypt(xUserID[0].InnerXml);
XmlNodeList xPwd = xDoc.GetElementsByTagName("Password");
xPwd[0].InnerXml = decrypt(xPwd[0].InnerXml);
}
soapMsg1 = xDoc.InnerXml;
writeStr.Write(soapMsg1);
writeStr.Flush();
inwardStream.Position = 0;
break;

13. Now we will change the SoapMessageStage.AfterSerialize case in the ProcessMessage method as below.

case SoapMessageStage.AfterSerialize:
inwardStream.Position = 0;
readStr = new StreamReader(inwardStream);
writeStr = new StreamWriter(outwardStream);
soapMsg1 = readStr.ReadToEnd();
if ( message is System.Web.Services.Protocols.SoapClientMessage)
{
// this is executed at client side
xDoc.LoadXml(soapMsg1);
XmlNodeList xSiteID = xDoc.GetElementsByTagName("siteID");
xSiteID[0].InnerXml = encrypt(xSiteID[0].InnerXml);
XmlNodeList xSitePwd = xDoc.GetElementsByTagName("sitePwd");
xSitePwd[0].InnerXml = encrypt(xSitePwd[0].InnerXml);
XmlNodeList xUserID = xDoc.GetElementsByTagName("UserID");
xUserID[0].InnerXml = encrypt(xUserID[0].InnerXml);
XmlNodeList xPwd = xDoc.GetElementsByTagName("Password");
xPwd[0].InnerXml = encrypt(xPwd[0].InnerXml);
}
else if( message is System.Web.Services.Protocols.SoapServerMessage)
{
// this is executed at server side
xDoc.LoadXml(soapMsg1);
XmlNodeList xResult = xDoc.GetElementsByTagName("AuthenticateResult");
xResult[0].InnerXml = encrypt(xResult[0].InnerXml);
}
soapMsg1 = xDoc.InnerXml;
writeStr.Write(soapMsg1);
writeStr.Flush();
break;

14. We write two methods for encryption and decryption. These methods call encrypt or decrypt methods in the EncryptClass class. These methods are as below

private string encrypt(string message)
{
EncryptClass ec = new EncryptClass();
string encryStr = ec.custEncrypt(message);
return encryStr;
}
private string decrypt(string message)
{
EncryptClass ec = new EncryptClass();
string decryptStr = message;
return ec.custDecrypt(decryptStr);
}

15. The EncryptClass.cs file will have methods to encrypt or decrypt a string. To this file add the following code at the top.

using System;
uing System.Security.Cryptography;
using System.IO;
using System.Text;
using System.Xml;

16. To this file add a class call it EncryptClass. The code to add this class is as follows.

namespace WebServiceHeaderExtension
{
public class EncryptClass
{
DESCryptoServiceProvider des;
private Byte[] key = {0x01, 0x23, 0x45, 0x67, 0x89, 0xab, 0xcd, 0xef};
private Byte[] IV = {0x12, 0x34, 0x56, 0x78, 0x90, 0xab, 0xcd, 0xef};
public EncryptClass()
{
des = new DESCryptoServiceProvider();
}
// for encryption
public string custEncrypt(string message)
{
}
// for decryption
public string custDecrypt(string message)
{
}
}
}

17. We will modify the custEncrypt method so that it encrypts the passed message.

// for encryption
public string custEncrypt(string message)
{
//create a memory stream
MemoryStream memStrm = new MemoryStream();
//create a crypto stream in write mode
CryptoStream crystm = new CryptoStream(memStrm, des.CreateEncryptor
key,IV),CryptoStreamMode.Write);
//Encode the passed plain text string into Unicode byte stream
Byte[] plaintextbyte = new UnicodeEncoding().GetBytes(message);
//Write the plaintext byte stream to CryptoStream
crystm.Write(plaintextbyte,0,plaintextbyte.Length);
//don't forget to close the stream
crystm.Close();
//Extract the ciphertext byte stream and close the MemoryStream
Byte[] ciphertextbyte = memStrm.ToArray();
memStrm.Close();
//Encode the ciphertext byte into Unicode string
string ciphertext = new UnicodeEncoding().GetString(ciphertextbyte);
return XmlConvert.EncodeName(ciphertext)}

18. We will modify the custDecrypt method so that it decrypts the passed message.

// for decryption
public string custDecrypt(string message)
{
message = XmlConvert.DecodeName(message);
//Create a memory stream from which CryptoStream will read the cipher text
MemoryStream memStrm = new MemoryStream(new UnicodeEncoding().GetBytes
message));
//Create a CryptoStream in Read Mode; initialise with the Rijndael's Decryptor
CryptoTransform
CryptoStream crystm = new CryptoStream(memStrm, des.CreateDecryptor
key,IV),CryptoStreamMode.Read);
//Create a temporary memory stream to which we will copy the
//plaintext byte array from CryptoStream
MemoryStream plaintextmem = new MemoryStream();
do
{
//Create a byte array into which we will read the plaintext
//from CryptoStream
Byte[] buf = new Byte[100];
//read the plaintext from CryptoStream
int actualbytesread = crystm.Read(buf,0,100);
//if we have reached the end of stream quit the loop
if (0 == actualbytesread)
break;
//copy the plaintext byte array to MemoryStream
plaintextmem.Write(buf,0,actualbytesread);
}while(true);
//don't forget to close the streams
crystm.Close();
memStrm.Close();
//Extract the plaintext byte stream and close the MemoryStream
Byte[] plaintextbyte = plaintextmem.ToArray();
plaintextmem.Close();
//Encode the plaintext byte into Unicode string
string plaintext = new UnicodeEncoding().GetString(plaintextbyte);
return plaintext;
}

19. Save the file and compile the project.

To create the web service project: -

1. To the solution add a new C# project of type web service name it AuthneticateUser.
2. To this project add an asmx file call it AuthenticateService.asmx.
3. At the top of the file add the following lines of code

using System;
using System.Collections;
using System.ComponentModel;
using System.Data;
using System.Diagnostics;
using System.Web;
using System.Web.Services;
using System.Web.Services.Protocols;

4. Now we will add a class for the SOAP header within the AuthenticateService.asmx file

public class AuthenticateHeader : System.Web.Services.Protocols.SoapHeader
{
public string siteID;
public string sitePwd;
}

5. Now we will add a declaration for the SOAP header within the existing web services class as below

public class AuthenticateService : System.Web.Services.WebService
{
public AuthenticateHeader authHeader;
}

6. After this we will add the authenticate method. This will be added in the AuthenticateService.asmx file.

WebMethod]
[SoapHeader("authHeader", Direction=SoapHeaderDirection.In)]

public string Authenticate(string UserID, string Password)
{
return authHeader.siteID + " " + authHeader.sitePwd + " " + UserID + " " +
password;
}

This method doesnt do much to authenticate a user. However our own custom code can be added.

7. Now we need to add a reference to the WebServiceHeaderExtension project.

8. Now the Web.config file of the web service has to be edited. Within the

<System.Web> tag add the following code

<system.web> tag
<webServices>
soapExtensionTypes>
<add type="WebServiceHeaderExtension.WebServcSoapExt,
WebServiceHeaderExtension" priority="1" group="0" />
</soapExtensionTypes>
</webServices>

9. Compile the project.

To create the web project: -

1. To the solution add a new C# ASP.NET project, name it UserWebSite.

2. To this project add an aspx file or use the default WebForm1.aspx page.

3. To this file add two text boxes one for the user id and other for the pass word.

4. Add a button to this page.

5. Add 3 labels to the page. Label them as User ID, Password and leave the third as blank. Make sure the Label1 is the one that is blank. As this is where we are going to write the web service response.

6. Now we need to add reference to the web service and the SOAP extension. For adding reference to the web service we add a web reference. While for the SOAP extension we can add a project reference to the WebServiceHeaderExtension project.

7. Once that is done. We will double click the button on the design page and within the event handler we will add the following code.

// create an instance of the web service
localhost.AuthenticateService auth = new localhost.AuthenticateService();
// create an instance of the soap header
localhost.AuthenticateHeader authHeader = new localhost.AuthenticateHeader();
// add the site's ID to the Soap header
authHeader.siteID="MySite";
// add the site's password to the Soap header
authHeader.sitePwd = "MySitePwd";
// attach the soap header to the soap message
auth.AuthenticateHeaderValue = authHeader;
// call the authenticate method in the web service
Label1.Text = auth.Authenticate(TextBox1.Text, TextBox2.Text);

8. We are done with the aspx file. Now we need to modify the Web.config file so that it calls the SOAP extension. We will add the following line of codes within the

<system.web> tag
<webServices>
soapExtensionTypes>
<add type="WebServiceHeaderExtension.WebServcSoapExt,
WebServiceHeaderExtension" priority="1" group="0" />
</soapExtensionTypes>
</webServices>

9. Compile the project.

Now we are all set to test the application. Set the web project as the startup project and execute it. You should see the result in the label in your web page.