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You may already be using JavaBean, but you don't know it yet. If you have a browser that supports Java, there are no restrictions on using JavaBean on the desktop. The web page you use can include bean as part of the mini-application. You will soon interact with JavaBean, which is the visual part of the browser, and then those JavaBean will interface with EJB on the server. This capability can also be extended to the Internet and intranets.

JavaBean and Server Bean (often referred to as Enterprise JavaBean (EJB)) have some basic similarities. They are all objects or components that are created with a set of properties to perform their specific tasks. They also have the ability to obtain other features from the containers on the current host server. This makes the behavior of bean vary depending on the specific task and environment.

This has opened up huge business opportunities. Because JavaBean is platform-independent, vendors can easily roll out their client-side JavaBean to different users for future solutions without having to create or maintain different versions. These JavaBean can be used in conjunction with EJB that perform business functions such as ordering, credit card processing, electronic remittance, inventory allocation, shipping, and so on. There is great potential here, and this is the kind of potential that component agent (websphere Application Server Enterprise Edition) design provides.

JavaBean is a component that has internal interfaces or related properties so that bean developed by different people at different times can be queried and integrated. You can build a bean and bind it to other bean when you construct it later. This process provides a way to build and then reuse, which is the concept of components. This single application can be deployed as a stand-alone program, an ActiveX component, or in a browser.

JavaBean is different from pure objects because of its external interface (that is, attribute interface). This interface allows the tool to read the functions that the component is going to perform, hook it to other bean, and plug it into other environments. JavaBean are designed to be native to a single process, and they are usually visible at run time. This visual component may be a button, list box, graph, or chart-but this is not required.

Executable component

Server Bean or EJB are executable components or business objects that are deployed on the server. There is a protocol that allows remote access to them or to install or deploy them on specific servers. There are a series of mechanisms that allow them to delegate the main aspects of service security, transactional behavior, concurrency (the ability to be accessed by multiple clients at the same time), and persistence (how long their state can be preserved) to their containers on the EJB server. When installed in a container, they get their own behavior, which provides different quality of service, so it is important to choose the right EJB server. This is the advantage of IBM WebSphere Enterprise Edition.

EJB is a non-visual remote object designed to run on the server and called by the client. EJB can be built from multiple non-visual JavaBean. They have a deployment descriptor for the same purpose as the JavaBean property: it is a description of the bean that can be read later by the tool. EJB is also platform independent and, once written, can be used on any platform that supports Java, including clients and servers.

Because EJB is generated by a toolset such as IBM VisualAge for Java, it is a server-based object and is used for remote calls. They are installed on the EJB server and get the remote interface to make the call just like other Corba remote objects are called.

ActiveX object

You can deploy JavaBean as an ActiveX object, and while EJB's agent can do the same, because ActiveX runs on the desktop, EJB itself cannot be an ActiveX object. To do this on platform-related, windows-only platforms, developers can transform JavaBean into ActiveX components.

Benefits

The main benefit of EJB is that when building a bean, bean developers can specify what type of behavior they need, rather than how to do it. Development is divided into two parts: the programmer develops the bean and then verifies that it works with the build tool and includes deployment descriptors that identify the desired types of quality of service behavior. Next, another programmer can take the bean and use the deployment tool that reads the EJB deployment descriptor, and then install the bean into a container on Enterprise Java Server. In the second step, the deployment tool takes some action-which may mean generating code such as state saving, putting in a transaction hook, or performing security checks. All of these operations are generated by deployment tools, and bean developers and deployers can be different people.

By using deployment tools, any platform-independent JavaBean can be rewritten into a platform-specific EJB with reliable quality of service to meet the specific needs of existing business systems and applications. This is why EJB servers are so important to integrated systems, networks, and architectures.

EJB and IBM WebSphere Enterprise Edition

When used in IBM WebSphere Enterprise Edition, EJB can be configured as a managed business object. The container that accepts their authorized service is the container to which it is installed. Map the persistence portion of EJB to a data or state object. EJB servers provide different quality of service for EJB, and choosing the right EJB server may be critical to meeting complete business needs. The component Agent feature is extremely robust, providing advanced features such as load balancing and supporting multiple machines in the server group. It also goes far beyond the system management capabilities advocated by the Enterprise Java Server (EJS) specification. As a result, JavaBean or EJB written according to basic standards can run on WebSphere Enterprise Edition that uses the component Agent feature and get all those additional features.

EJB servers also provide unique features and quality of service, but they are not exactly the same. The IBM "component agent" has some powerful features-for example, scalability, which allows developers to deploy EJB to different types of servers, from small systems to large networks. Developers can start small, for example, in a department, first deploy on LAN's Java server, and once ready, they know that the JavaBean and EJB created there can be deployed to the global network. Developers can then test and familiarize themselves with the bean, try it out, make samples, and so on. Once satisfied, developers can greatly increase its size by moving it to a high-performance server. JavaBean and EJB are not subject to any computer architecture boundaries. They are written in Java, can run on any system with a Java virtual machine, and can use any Enterprise Java Server (EJS) to deploy objects. As a result, developers can now build on a convenient system and later deploy on a convenient system, without having to be the same or the same type of machine.

IBM WebSphere Enterprise Edition supports the deployment of business objects to multiple servers. EJB is integrated into the component Agent function as a business object and handled as any other business object. As a result, EJB can connect to the selected back-end system and perform any necessary actions to meet its business needs. This becomes the infrastructure provided by the component Agent for EJB. By using the component Agent as an EJB server, developers will be able to continue to use the current legacy system and provide it with the e-commerce interface.

To enable EJB to work in the WebSphere component Agent environment, you can use the component Agent deployment tool to install it on one or more servers, and then add it to the naming server so that it can be found globally. Anyone with access to the public naming server can find it, find its host, and execute methods on the host while creating an EJB. This is what the proxy component does.

Example

Let's give an example of an electronic shopping cart that can be seen on the Web shopping site. The user's shopping cart is a JavaBean. The user puts the items on the shelf into the shopping cart, which themselves are JavaBean. They are all visible and user-oriented. At checkout, the items in the user's shopping cart are sent to the EJB on the server, which performs the necessary actions, such as checking credit card authorization and availability, generating seals, or generating special instructions to the shipping department about what to pick up and where to ship-this is what the business program is already doing.

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