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With the advent of Microsoft Windows NT and Web servers that run on that platform, setting up and configuring Web servers has become much easier. I have attempted to write this chapter for the novice, but as with any technology it is always desirable to get as much information as possible before diving right into the fray. I recommend reading and understanding the available documentation for your Web before proceeding with this chapter. Although I have found the documentation that comes with Web servers I have configured to usually be adequate, there are additional books that may help. I am told that the Que Special Edition book on the Oracle WebServer is quite good.
Now that you have created your application system in Oracle Developer 2000, wouldn't it be nice if you could just push a button and move the application to the World Wide Web? Well, it is not quite as simple as that yet, but with Oracle Developer 2000, it is surprisingly easy to get the Forms and Reports to run from the Web once a few configuration snags are removed. In this chapter, I will cover what software is required to make this all work and give details on configuring and running Web applications, and identifying quirks and confusing items that I ran into along the way.n
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Before we dive into all the messy details about configuring Developer 2000 applications to run on the Web, I thought it would be helpful to give a high-level description of what makes all this magic work. Oracle describes the Web implementation as a three-tiered approach to delivering an application (as opposed to the two-tiered approach of client/server).
So what exactly is the three-tiered approach, and how does it differ from the common two-tiered client/server implementation are two questions you may have. On a two-tiered configuration, an application runs on the end-user desktop and accesses data located on the database server. The three-tiered approach inserts an additional layer, as its name implies. The end-user desktop is used only for the application presentation and input retrieval. The application actually runs on an application, or in this case Web, server. Table 19.1 briefly explains where each piece may be loaded and its function as follows:
Table 19.1 Three-Tiered Architecture
There are several advantages to delivering applications via the Web. First, the client or front-end piece of the implementation does not require a heavily configured workstation to run these applications. All that is required is a Java-enabled Web browser (see the following section on required software for details on the Java version requirements). As mentioned before, the front-end handles mainly the presentation or display of the forms and reports, along with gathering user input.
Second, deployment of applications to the user community should be greatly eased. This is one feature that I personally am interested in. Currently, to move client/server systems out to the user community, I have to do the following:
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With a Web deployment, I configure the Web or Application server with the proper versions of the runtime executables, move over the necessary FMX files (for forms) and RDF files (for reports), and set up HTML hyperlinks on my Web site. True, these steps are the same or at least similar to the steps outlined earlier for the individual desktops, but the main difference here is that I do these steps in one place (on the Web/Application server) as opposed to many times (possibly thousands of times) with the two-tiered client/server approach.
And now for some detail on the software requirements for moving Oracle Designer 2000 forms and reports to the Web. Just because the implementation is called three-tiered does not mean that it must reside on three different machines; the configuration I used for this chapter loaded all components (browser, application, and database) onto one machine. While the front-end piece will be via a Java-capable browser usually on the end-user desktop, the middle and back-end pieces may be on the same or different machines. If multiple application servers are to be used, each application server must have a Web server (also called a Web Listener) installed.
This piece of the three-tiered puzzle is at the end-user's workstation. As mentioned before,
a Java-enabled browser is all that is required here. However, the Java requirements for
the Oracle Web implementation is version 1.1.2. The problem with this is that, as of the writing
of this chapter, no available Web browser supports this version of Java.
Oracle informed me that they are currently working with the major browser vendors (Netscape and Microsoft) to get this version of Java into the new versions of their products. To Oracle's credit, they have worked with Sun on making their additions to Java part of the standard version of Java. Hopefully, this Java release will be the version that all browser vendors will implement in their products, or at least include as a minimum set of functionality. As for when you will be able to get your hands on one of the new browsers, Oracle said it is hoping that these browsers will be on the market by October 1997. For an exact date of Web browser availability supporting Java version 1.1.2, bug Netscape and Microsoft. To keep track of browser advances yourself, Cnet provides an excellent site that keeps track of the various browser advances at http://www.cnet.com/Content/Browser/?ctb.browser.
So until a Java 1.1.2 browser is available, what does this mean to you when looking at implementing Developer 2000 on the Web? It means you will not likely be doing the forms piece until Java 1.1.2 browsers are available. The reports piece will work fine without the Java 1.1.2 support in a browser (I used Microsoft Internet Explorer 3.0 during my experimentation).
You are probably asking yourself, "Just how are you going to tell me how the forms piece works if you cannot use a browser?" For this chapter, I used the Java Development Kit and the appletviewer application that is included. This development kit is included on the Developer 2000 CD-ROM, or a more recent version of the kit may be downloaded from Oracle's Developer 2000 page on the Internet at http://www.oracle.com/products/tools/dev2k/.