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Current economic demands require that Web and e-commerce applications help accelerate awareness of companies in growing markets and help them discover new means to reach customers and retain them, as well as ways to introduce new products and provide services to their customers quickly and effectively.

To achieve all these goals, solutions need to be built, developed, and deployed that target effective service to customers. This is possible with the help of proven and reliable e-commerce platforms that allow companies to integrate corporate data, legacy applications on mainframes, and other enterprise applications. That’s where WebLogic Server comes into play.

WebLogic Server is an industry-leading e-commerce platform. With WebLogic, it is possible to develop and deploy applications that are reliable, scaleable, secure, manageable, and maintainable. WebLogic facilitates the complexities of system-level details, allowing the user to focus on building a business rather than running a server.

WebLogic Server is also the leader in implementing features of J2EE 1.3, a standard for developing multi-tier enterprise applications. J2EE provides a complete set of services, such as Java servlets; JSP; EJB; HTTP; Java Message Service (JMS); Java Transaction Service (JTA); Java Naming and Directory Interface (JNDI); Java Connection Architecture (JCA); Internet Inter-ORB Protocol (IIOP); Java Authentication and Authorization Service (JAAS); Java Database Connectivity (JDBC); Simple Object Access Protocol (SOAP); Extensible Markup Language (XML); Universal Description, Discovery, and Integration (UDDI); and Web Services Description Language (WSDL). Table 1-2 lists various services provided by WebLogic Server.

WebLogic Server is referred to as middleware because it is responsible for connecting the client with the database servers and for serving the information contained in the databases. WebLogic Server is needed in an enterprise for several reasons. For one, when companies want to decrease the size and complexity of client programs, they need to cache and control data flow for better performance and to enhance the

Table 1-2. WebLogic Server Services
EJBEJB specification, version 2.0, Second Public Draft; EJB provides a mechanism that contains business logic for building reusable Java components. It also helps users build component-based distributed applications.
HTTPHTTP specification, version 1.1; WebLogic complies with the HTTP V1.1 specifications.
JAASA package that enables services to authenticate the users and enforce access control upon them. It is integrated into Java SDK version 1.4.
JCAJCA specification, version 1.0; when implemented in WebLogic and Resource Adapters, JCA facilitates connectivity with Enterprise Information Systems (EIS)
JDBCJDBC specification, version 2.0; JDBC is a Java standard for allowing Java applications to communicate with databases.
JMSJMS, version 1.02; aids communication between applications with the help of message exchanges.
JNDIJNDI, version 1.2.1; naming services as a means for locating objects over the network.
JSPJSP specification, version 1.2; JSPs are used for generating dynamic Web content.
JTAJTA, version 1.0.1; in a Distributed Transaction System (DTS), JTA is a standard Java interface between the transaction manager and the parties involved.
ServletServlet specification, version 2.3; servlets are server-side Java programs that act as clients to EJB components and have the ability to generate dynamic Web content, process client requests, and communicate with databases.
SOAPSOAP, version 1.1; a protocol providing an XML/HTTP-based solution for accessing services, objects, and servers in a platform-independent manner.
UDDIUDDI, version 1.0; UDDI is an industry-standard initiative that enables businesses to locate and communicate with each other. UDDI allows businesses to describe their services, locate businesses that offer desired services, and integrate these services with other businesses. It opens a world of opportunities for enterprises in exchanging services.
WDSLWSDL, version 1.0; an XML format for specifying Web services as a set of endpoints operating on messages. It’s a specification for describing networked XML-based services.
XMLJAXP, version 1.0, SAX version 2.0, DOM Level 2, and W3C Schema; XML is a standard markup language for describing data in structured fashion.
performance of the entire system, while providing security for both data and users of the system.

In client/server applications, the business logic is split across the client and server, but it usually resides in the client application. This increases the complexity of software. In addition, upgrading software or applying any changes is a huge job in itself, as these changes have to be managed with all client systems on the network. This creates the need for software that helps connect the two pieces—client application and databases— while managing all business logic and providing seamless connectivity to the front and back ends.

The architecture of Web-based applications is both two and three tiered (see Figures 1-4 and 1-5). In a scenario that involves simply a Web client and a Web server, the architecture is two tiered: client and server. However, if the services are extended to provide the client information from various sources, such as a database, a third tier is added.

Web servers do have limitations. They cannot provide more elaborate service to the client other than static pages with static information. To resolve this, a typical piece of software and a development language is needed that helps build logical pages and that contains not only data for presentation but a way to gather information dynamically from the back-end systems and build pages on the fly to deliver to the client.

The role of the application server differs from application to application. Not every application requires the same functionality and set of services from an application server. Take scalability, for example. Smaller companies might want an application server that helps them organize their applications for the Web, that provides better control over the way business logic is contained and managed, and that makes it easier to monitor and secure the data. They don’t need multiple servers. On the other hand, large corporations or enterprises may need to manage multiple servers. For them, the scalability of an application server is crucial because they are expecting a huge number of users to visit their Web sites and do business online. WebLogic Server provides everything that’s needed for such business needs; it’s up to the user to make appropriate use of what is provided.

Before deciding on an application server, an organization must conduct an in-depth and accurate study of its requirements. Look into factors such as security, scalability, business logic management, and database connectivity to decide which server is appropriate.

Keep in mind that not all products from the same family of application servers are written using the same programming framework. While many—though not all—
products are written in Java, some are Microsoft friendly and others are not. However, there is room for all, including support for Java, CORBA, or Microsoft COM+ and the .NET Framework of distributed application development infrastructures.

If you are working for an organization that’s looking to run enterprise Java applications in n-tier architecture, you’re going to need to work with an application server, and a place for it in the infrastructure is an inevitable necessity. The application server is the cornerstone of a software architecture designed to tie together different components of a complex application, yet maintain a fundamental modularity in the software. First and foremost, application servers provide the glue that connects information from a database with the end user or client program, which is often running on a Web browser.

WebLogic Server provides the means to cache and control data flow for better overall performance and scalability of applications in production. It has the potential to provide security for both data and user traffic. WebLogic Server extracts data from the database to individual applications instead of requiring that each of those applications make a call to the database directly, thereby reducing direct database hits, which adds to the overall performance of the entire system.

The Web is automatically three tiered, with a client-centered application, a Web server, and one or more databases. Therefore, managing data along with application functionality is not only an exercise in better application design, but also a downright necessity.
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