Integration with CORBA

Integration with CORBAIntegration with CORBA Page Page 11

Integration with CORBAIntegration with CORBA

Liang TianLiang Tian

April 23, 2001April 23, 2001


OutlineOutline

J2EE and CORBAJ2EE and CORBA

IntegrationIntegration

JSP and CORBA Objects JSP and CORBA Objects

EJB and CORBA ObjectsEJB and CORBA Objects

SummarySummary

Servlet and CORBA ObjectsServlet and CORBA Objects



J2EE and CORBA architectures both can provide developing environment for distributed applications.

Each of the two architectures can provide multi-platform support, which makes application running in heterogeneous environment possible and easier.

The implementation language is different.



J2EE: entirely in Java.

Application components benefit from “Write Once, Run Anywhere” model.

Difficult in using the existing third-party non-Java code and making components running in non-Java client environments.



CORBA: any one of supported programming languages.

APIs written in different languages.

Difficult in moving non-Java CORBA components from one platform to another.

Flexible in implementation language and portability is not very good.



Integration of J2EE and CORBA architectures.

Share the benefits and reduce the limitations.

J2EE and CORBA can work together very well.

Our objective is to show how objects in CORBA architecture can be accessed from various J2EE application components.


Set Initial Object Reference PortSet Initial Object Reference Port

WroxQuotes CORBA Object DemoWroxQuotes CORBA Object Demo


Server RunningServer Running

WroxQuotes CORBA Object DemoWroxQuotes CORBA Object Demo


WroxQuotes CORBA Object DemoWroxQuotes CORBA Object DemoClient OutputClient Output



Web ContainerWeb Container

EJB ContainerEJB Container

Servlet

JSP

EJB

CORBA ServerCORBA Server

WroxQuotes

CORBAObject



Creating a Java Servlet that retrieves quotes information from WroxQuotes CORBA Object.

Constructing a JavaServer Page that retrieves quotes information from WroxQuotes CORBA Object .

Constructing Enterprise JavaBean that “wrap” CORBA Object and provide information to client.


Servlets and CORBA ObjectsServlets and CORBA Objects

HTML FormHTML Form ServletServlet CORBACORBAObjectObject



Initializing ORB

Accessing Naming Services

Locating the Object

Invoking the Method on Object

Constructing resulting HTML Page

Servlet.javaServlet.java


……. String port = getServletContext().getInitParameter("ORBInitialPort" );

String host = getServletContext().getInitParameter("ORBInitialHost" );

Properties orbProps = new Properties();

orbProps.put("org.omg.CORBA.ORBInitialPort", port);

orbProps.put("org.omg.CORBA.ORBInitialHost", host);

orb = org.omg.CORBA.ORB.init(args, orbProps); …….


Initializing ORBInitializing ORB




Accessing Naming Services & Locating the ObjectAccessing Naming Services & Locating the Object

org.omg.CORBA.Object contextObj = orb.resolve_initial_references("NameService");

NamingContext rootContext = NamingContextHelper.narrow (contextObj);

NameComponent name = new NameComponent("WroxQuotes", ""); NameComponent namePath[] = { name };

org.omg.CORBA.Object obj = rootContext.resolve(namePath); quoteObj = WroxStocks.WroxQuotesHelper.narrow(obj);Servlet.javaServlet.java



Invoking the Method on CORBA ObjectInvoking the Method on CORBA Object

…… String symbolList = request.getParameter("Symbols");String symbols[ ] = parseSymbolList(symbolList);

try { if (quoteObj != null) { quotes = quoteObj.getQuoteList(symbols); }

response.setContentType("text/html");……



…… if (quotes != null) {

out.println("<td align=\"center\">" + quotes[i].symb + "</td>"); out.println("<td>" + quotes[i].volume + "</td>"); out.println("<td>" + quotes[i].bid + "</td>"); out.println("<td>" + quotes[i].ask + "</td>");

}……


Constructing Resulting HTML PageConstructing Resulting HTML Page



…… <form method=GET action="servlet/WroxQuotesServlet">

<br/><h3>WroxStocks Quote Service</h3><p>Symbol(s): <input type="TEXT" name="Symbols" size=30><p><p>Enter stock symbol or multiple symbols delimited by spaces<p><input type="SUBMIT" name="SUBMIT" value="Get"><input type="RESET" name="RESET" value="Reset">

</form>……


HTML FormHTML Form

Form.htmlForm.html


java -jar orion.jar

tnameserv -ORBInitialPort 1100

java -cp %CLASSPATH% WroxQuotesServer -ORBInitialPort 1100

Servlets and CORBA Objects DemoServlets and CORBA Objects Demo

web.xml, application.xml, server.xml, default-web-site.xml

http://localhost/WroxQuotes/






HTML FormHTML Form JSPJSP

JavaBeanJavaBean

CORBACORBAObjectObject



Initializing ORB


Locating the Object


Bean.javaBean.java




Resulting PageResulting Page

Quotes.jspQuotes.jsp

<%@ page import="WroxStocks.WroxQuotesPackage.Quote" errorPage="WroxQuotesError.jsp"%>

<jsp:useBean id="WroxQuotesBean" scope="application" class="WroxQuotesBean" ><% String port = application.getInitParameter("ORBInitialPort" ); String host = application.getInitParameter("ORBInitialHost" ); WroxQuotesBean.init(port, host ); %></jsp:useBean><% String symbols = request.getParameter( "Symbols" );%>



Resulting PageResulting Page

Quotes.jspQuotes.jsp

……<td align="center"> <%= quotes[i].symb %> </td>

<td> <%= quotes[i].volume %> </td>

<td> <%= quotes[i].bid %> </td>

<td> <%= quotes[i].ask %> </td>

<td align="center">04/23/2001 20:59:00</td>……



HTML FormHTML Form

Form.htmlForm.html

…… <form method=GET action="WroxQuotes.jsp">

<br/><h3>WroxStocks Quote Service</h3><p>Symbol(s): <input type="TEXT" name="Symbols" size=30><p><p>Enter stock symbol or multiple symbols delimited by spaces<p><input type="SUBMIT" name="SUBMIT" value="Get"><input type="RESET" name="RESET" value="Reset">

</form>……


java -jar orion.jar



web.xml, application.xml, server.xml, default-web-site.xml

http://localhost/WroxQuotes/

JSP and CORBA Objects Demo JSP and CORBA Objects Demo






EJB and CORBA Objects EJB and CORBA Objects

ClientClientApplicationApplication

EJBEJB CORBACORBAObjectObject



…… public interface WroxQuotes extends EJBObject {

public StockQuote getQuote(String symbol) throws UnknownSymbolException, RemoteException;

public StockQuote[] getQuoteList(String[] symbols) throws UnknownSymbolException, RemoteException;

}……

Remote InterfaceRemote Interface

Quotes.javaQuotes.java


import javax.ejb.EJBHome;

import javax.ejb.CreateException;

import java.io.Serializable;

import java.rmi.RemoteException;

public interface WroxQuotesHome extends EJBHome { WroxQuotes create() throws RemoteException, CreateException;}


Home InterfaceHome Interface

QuotesHome.javaQuotesHome.java



QuotesEJB.javaQuotesEJB.java

Initializing ORB


Locating the Object





Initializing ORBInitializing ORB

Accessing Naming Services Accessing Naming Services

Locating the ObjectLocating the Object

public class WroxQuotesEJB implements SessionBean { WroxQuotesBean quotesBean;

public WroxQuotesEJB() { …… quotesBean = new WroxQuotesBean(); quotesBean.init("1100", "localhost"); } ……


Invoking the Method on CORBA ObjectInvoking the Method on CORBA Object



…… q = quotesBean.getQuotes(symbolList);

result.symbol = q[0].symb;

result.volume = q[0].volume;

result.bid = q[0].bid;

result.ask = q[0].ask;……


Constructing ResultConstructing Result



…… for (int i = 0; i < q.length; i++) { result[i] = new StockQuote(); …… result[i].symbol = q[i].symb; result[i].volume = q[i].volume; result[i].bid = q[i].bid; result[i].ask = q[i].ask; …… cal.set(q[i].asOf.year, q[i].asOf.month, q[i].asOf.day, q[i].asOf.hour, q[i].asOf.minute, q[i].asOf.second); ……


EJB and CORBA Objects Demo EJB and CORBA Objects Demo

java -jar orion.jar



java -cp %CLASSPATH% WroxQuotesClient


EJB and CORBA Objects Demo EJB and CORBA Objects Demo


SummarySummary

Initialize ORB

Connect & Access Naming Services

Obtain Object Reference & Locating the Object

Invoke the Method on Remote Object

Basic StepsBasic Steps


SummarySummary

“With the integration of J2EE and CORBA, we can easily build n-tier applications where Java and non-Java clients objects can seamlessly interact.”

“By combining the benefits of Java and CORBA, our n-tier application can now be both accessible to new clients and able to accommodate new distributed objects without considering their implementation languages.”

-- Professional Java Server Programming. -- Professional Java Server Programming.

J2EE Edition. p.1423J2EE Edition. p.1423





EJB and CORBA ObjectsEJB and CORBA Objects

SummarySummary

Servlet and CORBA ObjectsServlet and CORBA Objects

SummarySummary


ReferenceReference

[1] Professional Java Server Programming. J2EE Edition. Chapter 29. Wrox Press. 2000.

[2] Source Code of Professional Java Server Programming. J2EE Edition. Chapter 29. Wrox Press. 2000. Available at http://www.wrox.com


Integration with CORBAIntegration with CORBA

Liang TianLiang Tian

April 23, 2001April 23, 2001

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Integration with CORBA