NET Interaction With J2EE

Introduction

Enterprise Application Integration is a major order of the day, and making varied technology applications to talkbetween them is an uphill task. This article describes on how a .NET based application could talk to a j2EE basedapplication run on WebLogic behind a security wall posed by �Webseal�. The major tasks identified to have aseamless working application developed with a j2EE based application run on Weblogic and a .NET applicationare:

Maintenance of session between j2EE based application and .NET application.Maintenance of security framework as existing in j2EE based application.Exchange of data without any binding on data types.Exchange of data without much restriction on protocol layers and ports.

Background

Framework at Web Server application:

VB.NET Windows client application exchanges data and user interface with j2EE based web application developedin STRUTS framework, with the application server as Weblogic 7.0. All the resources (Java class files) deployedin app server have to be accessed via Sun One Portal with �Webseal� as its security feature.

Approach to Solution:

Session Maintenance:

Weblogic servers maintain their session with a unique identifier jsessionid. Every HTTP request from the

client is identified with this jsessionid for tracking the session with client. This session tracking is done

in two aspects, either:

As a cookie sent from the browser

or

As URL rewriting by appending the jsessionid as a query string in each request

a.

Security Maintenance:

The security feature implemented in this case along with Weblogic and Sun One portal is �Webseal�.Webseal authorizes each of the resources it allows to access by generating a webseal identifier aftersuccessful login, and sending it as a cookie (PD-H-SESSION-ID) for tracking the subsequent requests. Ifthe cookie is not identified properly in the subsequent request for the session, access to resources is deniedby �Web Seal�.

Cookies Values:

Cookie Name Value Remarks

PD-H-SESSION-ID Randomly generated for each session Generated by WebSeal

Cookie Name Randomly generated for each session Generated by WebLogic

b.

Exchange of data:

Since the .NET application accessing web resources may come behind a firewall, it was decided to make allthe requests as HTTP requests. The output response from web server will be either a HTML page for userinterface, or an XML document over HTTP which will be parsed at the VB.NET application end to process thedata.

c.

Solution:

The .NET application is a Windows based application developed in VB.NET. IE control andSystem.web.HTTPUtility namespace are used for accessing the j2EE based web application.

IE control is used for making a HTTP request to j2EE based web application and displaying it in browser window if

CodeProject: .NET Interactions with j2EE based Web Applications. Free... http://www.codeproject.com/KB/dotnet/NET_Interact_j2EE.aspx

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IE control is used for making a HTTP request to j2EE based web application and displaying it in browser window ifneeded.

System.web.HTTPUtility is used for making HTTP request and getting the required data in an XML format asa response stream from j2EE based web application.

Using the code

A new IE process is initiated to have the control of browser window targeted at Login screen of the application.

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'//Code snippet

'//

'DLL References

' 1) Microsoft.mshtml

' 2) SHDocVw.dll

'Declarations

'Declare libraries...

Friend libSWs As SHDocVw.ShellWindows Friend libDoc As mshtml.HTMLDocument Friend WithEvents libIE As SHDocVw.InternetExplorer Friend objIE As New Object

Private Function InitiateIE () Try

Dim strIEExecutablePath As String = "" StrIEExecutablePath = GetBrowserName ()

If Trim (strIEExecutablePath) <> "" Then

'Initializing shellwindows ...

libSWs = New SHDocVw.ShellWindows

A new process is created for control of removing all resources when the browser window is closed. This is neededbecause, IE control otherwise holds the resource since it associates with existing IExplore.exe process if anybrowser window is already open.

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'Start the process Info

prcStartInfo = New ProcessStartInfo (strIEExecutablePath,<LOGIN URL>)prcStartInfo.WindowStyle = ProcessWindowStyle.MinimizedprcStartInfo.UseShellExecute = True

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'Create a new process...

SetStatusText(DOWNLOADING_IN_PROGRESS)prcInitprocess = New ProcessprcInitprocess.StartInfo = prcStartInfoprcInitprocess.Start()prcInitprocess.WaitForInputIdle () 'Get the handle of the window

pWHnd = prcInitprocess.MainWindowHandlehWndIe = pWHnd.ToInt64

For Each objIE In libSWs If TypeName(objIE) = "IWebBrowser2" Then 'Condition checking for getting a specific IE

'Checking based on window handle information

libIE = objIE

If hWndIe = libIE.HWND Then 'Hide the addressbar, MenuBar and toolbar.

'The Browser application is without address bar,

'menu bar and toolbar...

libIE.AddressBar = False libIE.MenuBar = False libIE.ToolBar = False libIE.Visible = True

'Set the Browser Window in the front in normal state...


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'Set the Browser Window in the front in normal state...

SetWindowFront (hWndIe)

While libIE.ReadyState <> READYSTATE_COMPLETE 'Lock the thread

End While If libIE.ReadyState = READYSTATE_COMPLETE Then 'setting the document object

libDoc = libIE.Document SetStatusText(DOWNLOADING_COMPLETED) blnSessionflg = False blnIsLoginEnabled = True blnTimerEnabled = True End If End If End IfNext

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End If Catch exp As Exception MessageBox.Show(exp.ToString) End TryEnd Function'//

Login credentials are filled and submitted for authentication. Webseal authenticates valid users and sends asecurity cookie () along with the home page/initial page of the application. In the download event of homepage/initial page of the application in the browser, the security cookie is read from document cookie and storedfor further requests through System.Web.httputility. In the following code snippet, Weblogic session

(jsessionid) is also tracked, since after login, home page from Weblogic is accessed, thus creating a new

session.

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'//Code snippet'//

'This function is called in the download event of the'browser window. It retrieves the webseal and weblogic'cookie values for appending it in subsequent requests'for maintaining the session values...

Public Function TrackSession() Try For Each objIE in libSWs If TypeName(objIE) = "IWebBrowser2" Then 'if this is an HTML page, navigate. libIE = objIE 'Checking whether same window handle If hWndIe = libIE.HWND Then libIE.AddressBar = False libIE.MenuBar = False libIE.ToolBar = False libIE.Visible = True

'See if the weblogic session has been created and track the'cookie information required for authentication... 'setting the document object libDoc = libIE.Document Dim title As String'Capture the browser instance that has this title 'and use the same for future calls. title = "MY title" If libDoc.title = title Then

'Get the cookie val. strCookieVal = libDoc.cookie 'SetNetCookieCollection(strCookieVal) str_g_cookieval = strCookieVal

'Parse and assign the cookie val.... ParseCookie(strCookieVal)

'set the session value as on blnSessionflg = True Exit For End If End If End If Next Catch exp as Exception End TryEnd Function

Private Function ParseCookie (ByVal strCookie As String) As String 'Assigns webseal and jession identifier values... Dim arrCookieVal() As String Dim strWebLogicCookie As String Dim arrWebLogicCookie() As String


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Dim arrWebLogicCookie() As String Dim strWebSealCookie As String Dim arrWebSealCookie() As String

Dim intCounter As Integer arrCookieVal = strCookie.Split(";") For intCounter = 0 To arrCookieVal.Length - 1 If InStr(arrCookieVal(intCounter), "SESSION_IDS_OF_ADAPTER") Then strWebLogicCookie = arrCookieVal(intCounter) arrWebLogicCookie = strWebLogicCookie.Split("#") JSESSION_ID = JSESSION_ID & arrWebLogicCookie(1) strMethodUrl = strMethodUrl & JSESSION_ID ElseIf InStr(arrCookieVal(intCounter), "PD-H-SESSION-ID") Then strWebSealCookie = arrCookieVal(intCounter) arrWebSealCookie = strWebSealCookie.Split("=") WEB_SEALCOOKIE_NM = arrWebSealCookie(0) WEB_SEALCOOKIE_VAL = arrWebSealCookie(1) End If NextEnd Function

Once the security and session cookies are obtained in the VB.NET application, j2EE based application could beaccessed as below:

Through initiated browser window as normal web application, by appending jessionid in URL.

A JSESSIONID cookie value is appended to the URL as a query string parameter.

Example: http://www.yyyy.com/UI123?JSESSIONID=xxxxx.

a.

Through System.web.httputility for getting XML data over HTTP response.

Webseal session cookie value (PD-H-SESSION-ID) is set initially on the requesting URL, and method callrequest is made appending JSESSIONID cookie value to the URL as a query string parameter.

Example: http://www.yyyy.com/MC123?JSESSIONID=xxxxx.

b.

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'//Code snippet

'//

'Accessing web application through initiated browser window:

NavigateToUrl(http://www.yyyy.com/UI123?JSESSIONID=xxxxx.)

'Navigates to the specified url in IE browser window...

Public Function NavigateToUrl(ByVal strUrl As String, _ ByVal blnAsync As Object, ByVal trgFrame As Object, _ ByVal objPostData As Object, ByVal objHeader As Object) 'Navigates to the specified url in IE browser window...

Try For Each objIE In libSWs 'Checking based on window handle information

If TypeName(objIE) = "InternetExplorerClass" _ Or TypeName(objIE) = "IWebBrowser2" Then libIE = objIE 'Checking whether same window handle

If hWndIe = libIE.HWND Then libIE.AddressBar = False libIE.MenuBar = False libIE.ToolBar = False libIE.Visible = True 'Navigate to the specified URL

libIE.Navigate(strUrl, blnAsync, _ trgFrame, objPostData, objHeader) 'Track the download status and

'if download is complete

'display the page

While libIE.ReadyState <> READYSTATE_COMPLETE Application.DoEvents() End While Exit For End If End If Next Catch exp As Exception Messagebox(exp.ToString) End TryEnd Function

Accessing web application through System.web.httputility


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Source code snippet for making method calls (XML over HTTP).

This class is representing the same functionality of xmlHTTP object in MSXML.XMLHTTP.

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Imports System.NetImports System.Web.HttpUtility

''Sample Execution flow

Function main () 'Setting Method Call URL

StrMethdoURL ="http://www.yyy.com/ IntegrationServlet;" & _ " jsessionid=AhFj18NaW5AEe1o0EvNH1u1gw8P3Yjq" & _ "1TMNUyWiSI1t2ce0TJL9Y!567889692! 1075906019681"

'Setting Post Data

PostData = "TargetName=GetPreOrders&FromDate=&ToDate=&ReferenceNo=1"

'XML Response in string

response = ProcessData(strMethdoURL,PostData)

End Function

Public Function ProcessData(ByVal strUrl As String, _ ByVal postdata As String) As String 'Opens an url connection, posts the parameters,

'gets the response as XML string

'Validated XML is displayed.

Dim xmlHTTP As New XMLHTTP Dim strXML As String xmlHTTP.open("POST", strUrl) xmlHTTP.Send(postdata) strXML = xmlHTTP.ResponseText() DisplayXML(ParseXML(strXML)) ProcessData = strXMLEnd Function

Public Class XMLHTTP'Makes an internet connection to specified URL

Public Overridable Sub open(ByVal bstrMethod As String, _ ByVal bstrUrl As String, Optional ByVal varAsync As _ Object = False, Optional ByVal bstrUser _ As Object = "", Optional ByVal bstrPassword As Object = "") Try strUrl = bstrUrl strMethod = bstrMethod

'Checking if proxy configuration

'is required...(blnIsProxy value

'from config file)

If blnIsProxy Then 'Set the proxy object

proxyObject = WebProxy.GetDefaultProxy()

'Finding if proxy exists and if so set

'the proxy configuration parameters...

If Not (IsNothing(proxyObject.Address)) Then uriAddress = proxyObject.Address If Not (IsNothing(uriAddress)) Then _ProxyName = uriAddress.Host _ProxyPort = uriAddress.Port End If UpdateProxy() End If urlWebRequest.Proxy = proxyObject End If

'Make the webRequest...

urlWebRequest = System.Net.HttpWebRequest.Create(strUrl) urlWebRequest.Method = strMethod

If (strMethod = "POST") Then setRequestHeader("Content-Type", _ "application/x-www-form-urlencoded") End If

'Add the cookie values of jessionid of weblogic

'and PH-Session value of webseal


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'and PH-Session value of webseal

'for retaining the same session

urlWebRequest.Headers.Add("Cookie", str_g_cookieval)

Catch exp As Exception SetErrStatusText("Error opening method level url connection") End Try End Sub 'Sends the request with post parameters...

Public Overridable Sub Send(Optional ByVal objBody As Object = "") Try Dim rspResult As System.Net.HttpWebResponse Dim strmRequestStream As System.IO.Stream Dim strmReceiveStream As System.IO.Stream Dim encode As System.Text.Encoding Dim sr As System.IO.StreamReader Dim bytBytes() As Byte Dim UrlEncoded As New System.Text.StringBuilder Dim reserved() As Char = {ChrW(63), ChrW(61), ChrW(38)} urlWebRequest.Expect = Nothing If (strMethod = "POST") Then If objBody <> Nothing Then Dim intICounter As Integer = 0 Dim intJCounter As Integer = 0 While intICounter < objBody.Length intJCounter = _ objBody.IndexOfAny(reserved, intICounter) If intJCounter = -1 ThenUrlEncoded.Append(System.Web.HttpUtility.UrlEncode(objBody.Substring(intICounter, _ objBody.Length - intICounter))) Exit While End IfUrlEncoded.Append(System.Web.HttpUtility.UrlEncode(objBody.Substring(intICounter, _ intJCounter - intICounter))) UrlEncoded.Append(objBody.Substring(intJCounter, 1)) intICounter = intJCounter + 1 End While

bytBytes = _ System.Text.Encoding.UTF8.GetBytes(UrlEncoded.ToString()) urlWebRequest.ContentLength = bytBytes.Length strmRequestStream = urlWebRequest.GetRequestStream strmRequestStream.Write(bytBytes, 0, bytBytes.Length) strmRequestStream.Close() Else urlWebRequest.ContentLength = 0 End If End If rspResult = urlWebRequest.GetResponse() strmReceiveStream = rspResult.GetResponseStream() encode = System.Text.Encoding.GetEncoding("utf-8") sr = New System.IO.StreamReader(strmReceiveStream, encode)

Dim read(256) As Char Dim count As Integer = sr.Read(read, 0, 256) Do While count > 0 Dim str As String = New String(read, 0, count) strResponseText = strResponseText & str count = sr.Read(read, 0, 256) Loop Catch exp As Exception SetErrStatusText("Error while sending parameters") WritetoLog(exp.ToString) End Try End Sub 'Setting header values...

Public Overridable Sub setRequestHeader(ByVal bstrHeader _ As String, ByVal bstrValue As String) Select Case bstrHeader Case "Referer" urlWebRequest.Referer = bstrValue Case "User-Agent" urlWebRequest.UserAgent = bstrValue Case "Content-Type" urlWebRequest.ContentType = bstrValue Case Else urlWebRequest.Headers(bstrHeader) = bstrValue End Select End Sub

Private Function UpdateProxy() Try If Not (IsNothing(uriAddress)) Then If ((Not IsNothing(_ProxyName)) And _ (_ProxyName.Length > 0) And (_ProxyPort > 0)) Then proxyObject = New WebProxy(_ProxyName, _ProxyPort) Dim strByPass() As String = Split(strByPassList, "|") If strByPass.Length > 0 Then proxyObject.BypassList = strByPass End If proxyObject.BypassProxyOnLocal = True If blnNetworkCredentials Then If strDomain <> "" Then


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If strDomain <> "" Then proxyObject.Credentials = New _ NetworkCredential(strUserName, _ strPwd, strDomain) Else proxyObject.Credentials = New _ NetworkCredential(strUserName, _ strPwd) End If End If End If End If Catch exp As Exception SetErrStatusText("Error while updating proxy configurations") WritetoLog(exp.ToString) End Try End Function 'Property for setting the Responsetext

Public Overridable ReadOnly Property ResponseText() As String Get ResponseText = strResponseText End Get End Property

Private urlWebRequest As System.Net.HttpWebRequest Private urlWebResponse As System.Net.HttpWebResponse Private strResponseText As String Private strUrl As String Private strMethod As String Private proxyObject As WebProxy Private intCount As Integer Private uriAddress As Uri Private _ProxyName As String Private _ProxyPort As IntegerEnd Class

'//

Points of Interest

The data integrity between the two applications is maintained by defining an XML schema of the data exchangedthrough XML over HTTP which could be also a webservice. If the access to j2EE is through secured protocol layer,System.Security.Cryptography.X509Certificates namespace could be used and HTTPS request could be

authorized through.

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'//Authorizes SSL Trust Certification

System.Net.ServicePointManager.CertificatePolicy = New CertificatePolicy

The above could also be followed for ASP.NET applications to interact with j2EE based applications or any webservices that could be accessed with port 8080 or 443.

History

This is the initial version. All comments are welcome.

License

This article has no explicit license attached to it but may contain usage terms in the article text or the downloadfiles themselves. If in doubt please contact the author via the discussion board below.

A list of licenses authors might use can be found here

About the Author

Chellam

Member

I am a software engineer from India working inMS technologies

Occupation: Web Developer

Location: India


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NET Interaction With J2EE