Brief Overview of WebLogic Server
WebLogic Server 8.1 is based on providing support and handling issues such as security, fault tolerance, and implementing the J2EE technology from the Sun specifications. This section gives an overview of WebLogic for different areas, such as the J2EE specifications supported, WebLogic framework, security, and handling traffic.
The J2EE Specification
The Java 2 Enterprise Edition (J2EE) specification was created to address the needs of these new multi-tiered Web applications. This specification comes from the Java Community Process, a group of more than 100 companies that meet to form open computing standards for information technology problems such as database connectivity and the generation of dynamic HTML.
The latest version of the J2EE specification, 1.3, contains many new features, especially in the areas of enterprise integration. WebLogic Server 8.1 fully supports the entire J2EE 1.3 spec and in doing so, provides developers with the engine, tools, and APIs to build secure, enterprise-level applications that can scale with user load, connect to legacy systems, and provide the high availability that your customers expect.
BEA WebLogic Server has always been a world-class, enterprise-level J2EE application server that has focused on open standards, high performance, and time-to-market features. By being a J2EE application server, WebLogic Server has passed the rigorous J2EE Compatibility Test Suite, containing more than 5,000 tests for J2EE compliance.
Because WebLogic Server is entirely written in Java (except for native drivers for performance purposes), it is available for many platforms including Unix, Windows, and the mainframe. Companies can upgrade their hardware as their needs change without having to worry about their software infrastructure.
Companies using WebLogic Server can hire experienced J2EE developers and be sure that can be productive from the first day. They can also utilize existing J2EE in-house or third-party application components with minimal effort.
The full list of technologies in the J2EE 1.3 specification is the following:
Java Authentication and Authorization Service (JAAS) 1.0 Java Transaction API (JTA) 1.0.1b Java Database Connectivity (JDBC) 2.0 Enterprise JavaBeans (EJB) 2.0 JavaServer Pages (JSP) 1.2 Java Servlet 2.3 Java Messaging Service (JMS) 1.0.2b Java API for XML Parsing (JAXP) 1.1 Remote Method Invocation (RMI)/Internet Inter-Orb Protocol (IIOP) 1.0 J2EE Connector Architecture (J2EE-CA) 1.0 Java Naming and Directory Interface (JNDI) 1.2
BEA WebLogic Server provides a framework on which to build today's technically demanding Internet-based applications. It supplies tools to make building these applications easier. After these applications are built, WebLogic Server provides the engine to run them.
The WebLogic Server Framework
Building applications that span multiple machines, connect legacy systems, and service the multitudes of users on the Internet can be a nightmare for developers. Thankfully, WebLogic Server provides building blocks for the
Presentation layer—
JavaServer Pages and servlets
Business layer—
EJBs and Web Services
Back-end layer—
JDBC and J2EE Connector Architecture
This gives developers a head start in the development process.
Presentation Layer
Currently, the Internet browser is the most common way that customers connect to Web applications. Therefore, the capability to deliver customized, dynamic HTML is critical in the overall acceptance and usage of Web applications. WebLogic Server offers two options for creating this presentation layer: JavaServer Pages and Java servlets.
WebLogic Server also supports thick clients such as Java standalone applications and applications written in Visual Basic and Visual C++. These clients can connect using many communication methods such as CORBA, RMI, SOAP, and COM+.
Although customers using devices such as PDAs and wireless phones are in the minority, their numbers are growing. WebLogic Server can handle their needs by dynamically rendering JavaServer Pages and servlets to communicate in their language, Wireless Markup Language (WML) or any other WAP compatible language, much as it dynamically creates HTML pages for Web browsers on personal computers.
Business Layer
To support the presentation layer, WebLogic Server provides a strong, stable business layer through the use of Enterprise JavaBeans (EJB). EJBs provide reusable scalable business objects that supply business logic and access to EIS and database information. By implementing the J2EE EJB 2.0 specification, WebLogic Server enables developers to create three different types of EJBs: Session, Entity, and Message-Driven.
Session beans represent workers that can perform business processes, such as determining the sales tax of a purchase, determining the risk of insuring an automobile driver, and transferring funds between accounts. Entity beans represent data within a business process, such as a customer, an account, or an insurance policy. WebLogic Server helps developers by automating code generation for this type of EJB to save itself to and retrieve itself from a database. Message-Driven beans work with message queues that receive and hold messages from other applications or other parts of the same application. For instance, a queue can be set up to receive requests for information. Message-Driven beans remove messages from their assigned queue and process them according to the business logic within them.
Also contained in the business layer are Web Services. Although Web Services are in their infancy, many industry experts agree that their usage will grow tremendously in the next several years. The technologies behind Web Services include Universal Description, Discovery and Integration (UDDI) and Web Services Description Language (WSDL). Not only does WebLogic Server come with all the technologies and tools required for Web Services, it also provides an incredible way for creating them from existing application components without requiring any new code to be written.
The Back-End Layer
WebLogic Server provides many options for connecting to legacy systems and databases across vendor, hardware, and operating system chasms. Creating applications comprising data and program logic from various ERP, CRM, and mainframe applications has never been easier. Other services provided by the back-end layer including creating and maintaining topics and queues to hold messages, sending email messages, and connecting to native applications such as Microsoft COM programs and BEA Tuxedo.
By supporting Java Database Connectivity (JDBC), WebLogic Server can connect to every major database on the planet. Database vendors supply JDBC drivers that hide their implementation details, and developers can write code that connects to databases without being concerned with low-level communication details.
WebLogic Server implements the J2EE Connector Architecture (J2EE-CA) and thus supports J2EE-CA resources adapters from EIS vendors such as SAP, PeopleSoft, SeeBeyond, and JD Edwards. Java developers can connect to and communicate with these systems without having to understand their whole infrastructure. Transactional integrity and security credentials can span between WebLogic Server and these EIS systems as if they were all one big application.
The WebLogic Server Engine
When WebLogic Server executes Web applications, it provides a multitude of services for
This means that developers do not have to write these services and administrators merely have to configure them. These services let Web applications handle large amounts of Internet traffic, keep the application running despite hardware and software failures, and improve their response time to customer requests.
Security
Security is becoming the number one concern for companies doing business on the Internet and WebLogic Server provides many mechanisms for securing access to the applications it's running. WebLogic Server can work with your existing security infrastructure or provide one for your Web applications and possibly the rest of your IT infrastructure.
WebLogic Server employs security at many levels such as how customers log on to a Web site, who can access a Web page, and when can these pages be accessed. The WebLogic Server plug-and-play security model makes it simple to introduce third-party modules that perform security-specific tasks and thus expand Weblogic Server's already rich set of security functionality.
Handling the Traffic
When developers write code, they're usually concerned about business logic, which keeps them quite busy. Having to consider varying amounts of web traffic at different times of the day, week, and year, could be overwhelming.
With WebLogic Server, developers can create Web applications for a single machine and these applications can be recompiled at a later time to run on a cluster of machines. By splitting the work among many machines, response times will be greatly improved.
WebLogic Server handles clustering at the application component level by providing services for clustering EJBs and JMS queues and destination. WebLogic Server supports commonly used load balancers, but a Web server can act as a proxy to redirect customer requests to the instances of WebLogic Server running in your cluster.
Clustering is not your only option. However, WebLogic allows even a single server to handle high traffic by adding processors or configuring worker threads.
Keeping the Application Running
Web applications can go down because of hardware and software failures or because of negligent coding. In all cases, WebLogic Server does its best to keep things running by providing features such as hardware clustering, clustering of application components, and transparent failover.
Clustering not only improves performance, it also provides redundancy in the infrastructure. If an instance of WebLogic Server that's servicing a customer request fails, it will transparently failover to another instance in the cluster.
WebLogic can also be enabled to restart based on health monitoring configuration. This enables the administrator to configure a health check interval that checks for the server's availability. If there's a problem, WebLogic automatically restarts to avoid long periods of downtime.
Improving Response Time
WebLogic Server employs many methods for increasing performance that reduces response time for Web application customers. Caching of often-used resources occurs with EJBs, servlets, and JSPs. Connections to EIS systems and databases are pooled and reused as needed, avoiding the overhead of constantly reconnecting.
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