Web Components and EJB
Together, servlets and JSP provide a powerful platform for generating web pages dynamically. Servlets and JSP, which are collectively called web components, can access resources like JDBC and enterprise beans. Because web components can access databases using JDBC, they allow an enterprise to expose its business systems to the Web through an HTML interface. HTML interfaces have several advantages over more conventional client interfaces. The most important advantages have to do with distribution and firewalls. Conventional clients need to be installed and distributed on client machines: they require additional work for deployment and maintenance. Applets, which are dynamically downloaded, can eliminate the headache of installation, but applets have their own limitations—such as sandbox restrictions and lengthy downloads. In contrast, HTML is extremely lightweight, does not require prior installation, and does not suffer from security restrictions. In addition, HTML interfaces can be modified and enhanced at their source without having to update the clients.
Firewalls present another significant problem in e-commerce. HTTP, the protocol over which web pages are requested and delivered, can pass through most firewalls without a problem, but protocols such as IIOP or JRMP cannot. This limitation is extremely important. It means that a client usually cannot access a server using IIOP or JRMP without modifications to the firewall. And the firewall is usually ...