Weblogic - WEBLOGIC WEB SERVERWeb server software runs HTTP services and is able to host one or more Web sites. Each site is a collection of various documents and applications that form the Web content. This content needs to be delivered to Web clients over the network using HTTP. Various HTTP servers are available on the market today, and most are similar in terms of what they provide because HTTP service is a standard feature of the Web. The WebLogic Web server is a Java-powered server capable of delivering not only static content, but also dynamic content with the help of Java-enabled technologies such as JSP and Java servlets. WebLogic Web server hosts and delivers static HTML/HTM files, images, Java applets, XML (Extensible Markup Language) documents, JSP, Java servlets, multimedia files, and other types of files. The way Web servers and browsers communicate is represented in Figure 1-1. The client running the browser software sends a user request to the server using HTTP. The server software (in our case, the WebLogic Server) examines and interprets the request, prepares to locate the appropriate information, locates the information, and then sends an HTTP response to the client. This response is either an HTML document or an image file, which is then interpreted by the client’s browser software and presented on the client’s interface accordingly. NOTE Web server software such as Apache, Microsoft Internet Information Services (IIS), IBM HTTP server, WebLogic Server, JRun, and many others are available to provide HTTP services. Presently, because HTTP services have become a subset of application servers, each vendor dealing with application servers has built-in support for Web content handling and management. Let’s break it down even further. The Web server serves requested contents to the client—contents that are either statically available as HTML or dynamically generated using JSP and servlets. When a client sends a request for information to the Web server, the server maps the URL (Uniform Resource Locator) to a file with the given name on the local file system. Then either it reads the content from the disk and serves it out to the network with the aid of HTTP, or the server-side program generates it dynamically. For example, in the case of a URL that reads www.javatechnologycenter.com the Web server software will serve index.html after locating and loading the file from disk to client. The information contained in the document is placed between HTML tags that, along with the requested information, are carried over the network using HTTP. The client software interprets these tags and presents the information in a fashion appropriate for the user. Static Web documents are always placed in the respective folder in the appropriate directory. For example, all the static Web documents for the default Web app are placed in the default Web application folder. (Figure 1-2 shows the directory structure of WebLogic 6.1 and 7.0.) The default Web application directory contains documents delivered when the browser doesn’t specify a URI (Uniform Resource Identifier). In other words, if the server is listening on http://server:7001, that URL will respond with documents from the default Web application directory. If the browser requests http://server:7001/otherdocs, another Web application directory serves the otherdocs URI. Ports WebLogic Server typically listens on port 80, but it can be set to listen on port 7001 instead. You can assign the listener port address to any value ranging between 1024 and 65536 (0–1023 are reserved). Figure 1-3 demonstrates the various communication ports available. If you already have a running server installed at port 80, WebLogic Server can be installed to listen on a port other than 80. It is not possible for WebLogic Server to listen to your client’s requests on the same port as another server. For example, if you are using Windows NT/2000, Microsoft IIS will already be installed and running on port 80. In this case, you will either have to stop (shut down) IIS to free up port 80 for WebLogic Server or you must configure the server to listen on another port. NOTE No two Web servers can be configured to listen at the same HTTP port at the same time, but every Web service can be listened to on a particular port over the network. To access the home page of your WebLogic server, enter the following link into the browser’s address bar: http://localhost:7001. Here, http:// is the protocol, localhost is the computer on which the Web site is hosted, and 7001 is the port at which the WebLogic Web server will be ready to listen for a client’s request. Other HTTP Servers Table 1-1 provides information about other HTTP servers. For Administrators If you use WebLogic Server as a Web server, you should be interested in the following aspects of its functionality:
NOTE WebLogic provides plug-ins for Apache, Microsoft IIS, and Netscape Enterprise Server. A WebLogic plug-in is a small piece of software that extends the boundaries and capacities of WebLogic Server implementation. It allows WebLogic Server to communicate with other Web servers, as well as access Web applications that have been deployed on those servers. |
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