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Although a huge engine and a 53-foot trailer might be essential to the efficient operation of some companies, you wouldn't make such an investment if your company's needs could be met by a minivan. Information-technology investments require similar choices. You need to carefully evaluate even very promising, widely used technology against your firm's technical needs, corporate culture, and future plans to make sure that its strengths will really benefit your organization.
Enterprise JavaBeans (EJB) technology, for example, is a promising specification that many companies have already adopted. The EJB specification offers potential benefits such as portability, ease of development, and reusability - all excellent features.
But should you base your Internet applications on EJB? It may indeed be the appropriate choice for your system, but in some cases, you may be investing in a tractor-trailer when a minivan might serve you better. In order to determine whether your organization will really benefit from EJB, you must understand its strengths and weaknesses and evaluate them against your company's needs. You may ultimately decide to implement a simpler solution, such as Java Server Pages (JSP) and Servlets with pure JavaBeans components. Or, introducing strategic changes in your company's software practice may be necessary in order to reap the full benefits of your investment in EJB.
The Benefits of EJB
EJB offers many benefits. As a server-side component model for developing Java-based, multitier distributed component applications, EJB architecture can make development faster and cheaper. EJB-enabled servers automate lower-level services such as transactions, security, state management, and persistence. Therefore, developers don't have to build those services as part of an application and can concentrate on business logic. Because you don't have to recreate those commonly used system services with each application, you can greatly reduce time-to-market and development costs. Additionally, because the applications rely on the well-tested code of a commercial EJB-compliant application server, they will be much more robust.
You can further reduce time-to-market by purchasing and deploying off-the-shelf components to meet your application's needs. Today, for example, you can buy a set of EJB components such as BEA Systems Inc.'s Commerce Server Components, modify or enhance them to suit your needs, and assemble an e-business application. You can reuse purchased or specially developed EJB components, further increasing the long-term efficiency of EJB-based development.
EJB is based on the portable Java programming language, and you can deploy software components on any EJB-compliant server and operating system. That portability really adds to the cost-effectiveness of building e-business applications with EJB and frees companies from vendor lock-in.
Is EJB Right for You?
With EJB's potential for ease of development, portability, and reusability, why wouldn't you use it for your Internet application? You should consider several business and technical elements when deciding on which technology to use for your Internet applications. Ask yourself the following questions:
- How frequently will your business logic change? Flexibility is one of the greatest strengths of EJB. Will users browse your catalog and buy products online from your site? To what extent do you expect your business rules to change? If new marketing campaigns are likely to hatch and require immediate, major changes to your Internet application's code and data model, then EJB's added flexibility would be very valuable to your application's maintenance. By separating the process components (Session Beans) from the data components (Entity Beans), EJB enforces sound object-oriented (OO) design techniques, which make changes to business rules relatively easy to implement.
For example, if your shopping site is an assembly of BEA Commerce Components and you are adding a new product category with new pricing rules, the implementation of such a change - an otherwise daunting task - is quite easy. You simply enhance your unified modeling language model, generate the skeleton code, fill in the business logic such as pricing rules, and deploy your components. In the absence of a well-planned OO design and EJB persistence services (especially container-managed services), changing a single database column is very complex. It requires changing each line of client code that relied on that column. A developer could potentially break multiple lines of code and find it impossible to keep up with new marketing programs.
However, if your product offerings and pricing do not change frequently or your site is simply a publish-and-subscribe type without a realtime shopping experience, then EJB's flexibility may not be essential to your organization. You may be served just as well with simpler technologies such as JSP and Servlets with JavaBean components.
  
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