Explain Message Beans with respect to EJB?
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Oracle9iAS Containers for J2EE - Release 2Date: 06/27/02\n\nHow-To: Message-Driven BeansAfter completing this how-to you should be able to: \nUnderstand how Message-Driven Beans (MDBs) work and why they're useful. \nBuild, deploy and run the sample application code. \nSoftware RequirementsOracle9iAS Containers for J2EE (9.0.3) Developer Preview is installed, available from OTN \nJakarta Ant 1.4, to build the application example, available here \nSun's JDK 1.3_01 or above, available here \nIntroductionThe EJB 2.0 specification provides for a new EJB component, the Message-Driven Bean. MDBs are not accessed directly, as are other EJBs, but instead listen on a message queue and respond to the arrival of appropriate messages. MDBs provide a simple and powerful paradigm for implementing asynchronous transactional applications in Java. You'll notice from the code that MDBs are simpler than Entity and Session Beans with respect to the fact that since they are not accessed directly, they do not require local, remote, or home interfaces. They only need a bean implementation class.\n\nIn the example below, you will build, deploy, and test a simple J2EE application to OC4J. The application comprises an MDB and a small web-application that enables you to insert messages onto a queue via your web browser. The MDB is only a single Java class. When the MDB receives messages off of the queue, it will report its findings to the command-line via standard output.\n\n\n\nPrerequisites for running the exampleTo run the sample application you must have: \nAdd the following JMS topic and topic connection factory in the jms.xml file in the $OC4J_HOME/config directory: \n<topic name="Demo Topic" location="jms/theTopic">\n<description>A dummy topic</description>\n\n</topic>\n\n<topic-connection-factory name="Demo Topic Connection Factory" location="jms/theTopicConnectionFactory">\n<description>A dummy topic connection factory</description>\n</topic-connection-factory>\nAlternatively, you may use the jms.xml file provided in the example files discussed below.\n\nUnpack example filesDownload the examples files (messagelogger.zip) and unzip it into a directory of your choice <example_home>.  The zip file contains the following files and directories:\n\nsrc/ - contains all Java source code for the example. \nejb/ \nmdb/ \nMessageLogger.java - Message-Driven Bean. \nweb/ \nlogmessageform.htm - HTML file. \nlogmessage.jsp - JSP that puts message on the queue. \netc/ \napplication.xml - Standard J2EE Application descriptor file. \nejb-jar.xml - Standard EJBs descriptor file. \nweb.xml - Standard Web Application description file. \norion-ejb-jar.xml - OC4J-specific EJB decriptor file. (Holds the MDB <-> Topic mapping. See below.) \njms.xml - Example for modifying OC4J config file. \ndoc/ \nreadme.htm- This document. \nbuild.xml - An Ant build file. \nThe orion-ejb-jar.xml file holds the Topic and TopicConnection mappings that tell the container how to associate the MDB with a message service. Here is part of the configuration presented in orion-ejb-jar.xml:\n\n<enterprise-beans><message-driven-deployment name="MessageLogger" \ndestination-location="jms/theTopic" \nconnection-factory-location="jms/theTopicConnectionFactory"></message-driven-deployment></enterprise-beans>\n\nCompiling and deploying the applicationUsing Ant and admin.jarFrom the root of the example directory [the directory where the build.xml file is located] execute the following command:  ant \n\n\nYou should now have a newly created messagelogger.ear file in your <example_home>&#92;lib directory. \n\n\nDeploy this J2EE application to a running instance of OC4J R2 by executing the following command from the <example_home>directory: \nant deploy-usingadmin.jar \n\nTest the application by accessing the web app at the URL
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Application server :- jboss,weblogic,websphere etc.These servvers implements J2EE standards  Webserver :- Apache webserver.Generally holds static html,images etc.\ndead lock occures in Threads
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http://www.jbc.org/cgi/content/full/276/39/36303
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You can get the latest version of the JRE (Java Runtime Environment), which is what its asking for, directly from Sun Microsystems, the creators of Java:\n\nhttp://java.com/en/download/manual.jsp
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Too many questions.\n\n- You know that Java is a programming language. The essential portion of the language is core java. Everything else is to enrich the java.\n\n- J2EE - Stands for Java 2 Enterprise Edition downloadable from Sun Microsystem's site. You install it on your computer so that you can create, compile, and run Java programs on your computer. There is also J2SE - stands for Jaa 2 Standard Edition -- this just the scaled down version of J2EE.\n\n- Struts is open source frameworks and toolkits that help developers build applications for the web. This is not essential for Java programming -- It just makes programing easier.\n\n- Writing a program to create a screen like the one you are looking at now with buttons, menu, etc is not easy. Swing helps in creating Java user interface.\n\n- If understand how HTML is used to create a web page, you know what tags are. Tags are embedded with text to modify them. Tags are also used in JavaServer Pages. A tag library is a collection of tags.\n\n- Web applications are stored in web servers so that users can access the resources through their browsers. Right now you are accessing the resources sitting in Yahoo web server. WebLogic is a  server made by a company called BEA. Other popular web servers are IIS made by Microsoft, Apache, WebSphere made by IBM, etc etc.
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http://java.sun.com/developer/Books/JDBCTutorial/
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Its mainly for Webapplications,\n\nSo COBRA, DCOM, and RPC are component based models that are very important for software engineers... \n\nLook them up in the Java sun website..\nhttp://java.sun.com
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The first step in this technique is to create a dialog within an internal frame. To do this, you need to create the JOptionPane, and then use one of the createInternalXXX methods to create and show the necessary message component. For instance, the following creates a message dialog within an internal frame:\n\n  JOptionPane optionPane = new JOptionPane();\n  optionPane.setMessage("Hello, World");\n  optionPane.setMessageType(\n    JOptionPane.INFORMATION_MESSAGE);\n  JInternalFrame modal = \n    optionPane.createInternalFrame(desktop, "Modal");\n\n\n\nThe next step is to place the component in the glass pane of the window where the desktop pane is located. The glass pane can be any component. So, the easiest way to do this is to create a transparent JPanel:\n\n  JPanel glass = new JPanel();\n  glass.setOpaque(false);\n  glass.add(modal);\n  frame.setGlassPane(glass);\n  glass.setVisible(true);\n  modal.setVisible(true);\n\n\n The last steps are to set up the glass pane to intercept events, and to hide the glass pane when the internal frame closes. In order for the glass pane to intercept events, you have to attach a MouseListener and MouseMotionListener. To hide the glass pane when the internal frame closes, you need to attach an InternalFrameListener to the internal frame:\n\n  class ModalAdapter extends InternalFrameAdapter {\n    Component glass;\n\n    public ModalAdapter(Component glass) {\n      this.glass = glass;\n\n      // Associate dummy mouse listeners\n      // Otherwise mouse events pass through\n      MouseInputAdapter adapter = new MouseInputAdapter(){};\n      glass.addMouseListener(adapter);\n      glass.addMouseMotionListener(adapter);\n    }\n\n    public void internalFrameClosed(InternalFrameEvent e) {\n      glass.setVisible(false);\n    }\n  }\n\n\nRead the link
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http://java.sun.com/\nhttp://www.jguru.com/\nhttp://www.jchq.net/\n\n\nYou can download book Mastering EJB third edition from \nhttp://www.theserverside.com/
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Go back to Sun's Java site and head for the forums; that's the ideal place to get answers to questions of that nature. In fact, somebody asked a similar question in said forum:\n\nhttp://forum.java.sun.com/thread.jspa?threadID=460113&messageID=2107071
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Java Mail is an API for sending emails, emails with attachment, reading emails, etc. This API is meant as an API for sending automated emails like the one you recieve when you register for an account. The JMS is the Java Messaging Service which is capable of exchanging messages between applications. An example would be my authomated ordering system will find the JMS queue for my Vendor and places an XML message that contains an order. In this case the recieving party is another application. Similarly an application that displays quotes may be listening to a JMS queue to update the status of a stock. JMS is more like a database - the messages (can be configured) to be drained if and only if the recipient system reads it. In other words the delivery can be guarrenteed.\n\nIn simple:\nJMS - Inter and Intra Company Application to Application Messaging. Delivery can be guarenteed\nJava Mail - Application to a person or person to application. Delivery not guaranteed
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I believe chat2.0 is java based, and yahoo took away the java support about a month ago.l
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Here you go\nhttp://www.webdeveloper.com/java/java_programming_grounds_up.html\n///
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JWebMail\nWebMail is a www-frontend to IMAP/POP3 mailboxes. You can compare it to the systems Hotmail, YahooMail etc use. It allows a user to access his mailbox via the world wide web and do most things other mail programs allow to do, even if he is not sitting on his own personal computer or corporate LAN. \nhttp://java-source.net/open-source/web-mail/jwebmail
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if ur messages are read on what/
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I'm not exactly sure what you mean?\n\nAre you trying to run a Java application and the main method can not be found?\n\nIs there a specific error message you are seeing that you can add to the details of this question?
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I agree with Mallik, but this will let you know a bit more !\n\nEach time you make changes, or more clearly each time when you access the JSP, the server will make changes in the corresponding \nservlet and is reloaded.(But beware of borwser cache, if you make changes and there is content at cache, then it 'll be displayed).\n\nTry the following to get a better understanding.\n\nfirst  create a jsp named one.jsp\ncall it in IE\nrename one.jsp to two.jsp\nrefresh the IE, you will still get one.jsp\n\nnow restart IE and try to access one.jsp, you'll get an error msg.\ni.e., each time the server searches for the file and proceses it and converts it to .java file(servlet).\n\ngood luck.