T6Uq.png' alt='Sap Visual Studio Server Explorer Install Java Runtime Environment' title='Sap Visual Studio Server Explorer Install Java Runtime Environment' />Architecture Overview.LoadRunner works by creating virtual users who take the place of real users operating client software, such as Internet Explorer sending.BizTalk Server 2013 List of Known Issues and Solutions with Setup and Configuration BizTalk 2010 List of Known Issues and Solutions with Setup and Configuration.Fredi_VS_Net/FrediNet4_40_AdvancedCompilerSettings.gif' alt='Sap Visual Studio Server Explorer Install Java Runtime Environment' title='Sap Visual Studio Server Explorer Install Java Runtime Environment' />Understanding How the Application Servers Web Container Works.To understand how to do proper application server development, you need to understand how the two basic containers of an application server work, namely the Web container and the EJB container.This article will take a look at how a client application interacts with the application servers Web container.By submitting your personal information, you agree that Tech.Target and its partners may contact you regarding relevant content, products and special offers.You also agree that your personal information may be transferred and processed in the United States, and that you have read and agree to the Terms of Use and the Privacy Policy.How does an application servers Web container workLets look at a typical Web based interaction with our application server at runtime.Lets use a typical scenario where the request is coming in from an Internet browser, such as Internet Explorer, Chrome or Safari.Well also simplify the interaction by eliminating the complications presented by workload enhancements such as network sprayers and caching proxies.Well just focus on a typical Web based interaction between a Web based client and our application server.From Client to Web Server.When dealing with Web based requests, before tunneling through to our application server, a client will always hit a Web server first.An application server does not replace the need for a Web server.A Web server remains as pivotal a part of the application server architecture as ever.Web servers are great at doing one thing serving up files.A Web server takes requests from clients, maps that request to a file on the file system, and then sends that file back to the client.If you want an HTML file, a Web server can efficiently and reliably find that file and send it back to you.If you need an image, a Web server can serve it up to you as well.You want to download a.A Web server can make that happen.Unfortunately though, your Web server is about as intelligent as a male model.A Web server can serve up static files until the cows come home, but ask your Web server to add one plus one and youll be waiting there for a very, very long time.If our applications use any images, HTML,.Web server. If we need some logic or dynamic content in our applications, we will delegate to our Servlets, JSPs, EJBs and Java.Beans that are running on our application server.Now here is the dilemma.Our application server contains all of our Servlets and JSPs, but all of the requests go through the Web server, and the Web server, not being a very clever machine, tries to handle all requests, regardless of whether the request is for an image, HTML file, or to our detriment, a Servlet or a JSP.How do you stop a Web server from trying to handle requests for our Servlets and JSPsThe key to stopping a Web server from trying to serve up JSPs or Servlets, is to install something called the application server plug in on the Web server.The general idea, although not a hard and fast rule, is that before you install an application server, you should install your Web server first.Even when you do a full installation of an application server, behind the scenes, the application server typically installs a Web server first, and then installs an application server plug in into that Web server to forward non static request that it cant handle.What exactly does the Web server plug in do As was stated earlier, the Web server tries to handle every single request that it receives.However, when the Application server comes onto the scene, it introduces itself to the Web server and has a conversation that goes something like this Application server Hey, Web.Server. Web Server Yo, whats upApplication server Hey, not much.Web Server What can I do for you Application server Well, I know that youre really great at serving up static files and all, but youre going to get some crazy requests for JSPs and Servlets that you wont be able to find on your file system.Web Server Really What am I going to do I wont be able to find any of these JSPs and Servlets, and Ill end up sending a bunch of 4.Application server Hey, calm down.Heres what you do just take those requests and send them to me.Ill handle the request, generate some HTML, give that HTML back to you, and you can send the HTML back to the client.Web Server Kewl. You do the work, but the client thinks its me handling the request I like this arrangement already.How do I know what files to send to you though Application server Dont worry.Ill make a thorough list and write it all down in a special XML file.Just read that file every once in a while and keep up to date on which files you need to send back to me.Web Server Great.But when I do get a request for an item on the list, how will I know where to send it.Application server Hey, dont worry.Ive got it all covered.That XML file also contains a list of which IP addressesport combinations to send the requests to.Its all right there in that XML file.And if you have a problem understanding how to use it, heres a.Read it every time you start up.Web Server Kewl. I think this is going to be a great relationship.From Web Server to Application Server.When a client makes a request for a JSP or a Servlet, the request initially goes to the Web server.The Web server reads the special XML file the application server provides, and realizes that the request that came in should be sent to the application server for processing.The special XML file also provides the IP addressport combination of listening application servers.The Web server, using the http protocol, then sends the request to the Application server JVM listening on the appropriate port.The JVM listening on the appropriate port represents our application server, and the port the JVM listens on can be configured through that JVMs Web container.The Web server handles the incoming request, and matches that request to the application server set up to handle the given Servlet or JSP.Inside the Web Container.If the Servlet hasnt been called before, the JVM loads the Servlet and then generates a thread to handle the request.Servlets are shy little creatures.They sit on the hard drive just minding their own business, and dont bother anyone until theyve been invoked.However, feed a few drinks to those Servlets get them loaded and they remain resident in memory until the party ends, which happens when someone pulls the plug on the application server.So, the request gets sent from the client, to the Web server, and the Web server passes the request to the application server, who in turn invokes and threads the appropriate Servlet.What does our Servlet do Well, the Servlet can do pretty much anything the developer wants it to do.When programming Servlets, a developer is only limited by their creativity, and more likely, their Java programming skills.Typically, a Servlet implements some control logic.For example, a Servlet might figure out what a user typed into some text fields in a web based form.It might then take that information and save it to a database.Servlets are intended to be controllers.While Servlets can interact directly with a database, theyre not really supposed to.Instead, Servlets are supposed to delegate to a Java.Bean or an EJB to do such things.Lets say, for the sake of argument, our Servlet calls an EJB. 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