Invoking Other Web Resources
Web components can invoke other Web resources in two ways: indirect and direct. A Web component indirectly invokes another Web resource when it embeds in content returned to a client a URL that points to another Web component. In the Duke’s Bookstore application, most Web components contain embedded URLs that point to other Web components. For example, ReceiptServlet indirectly invokes the CatalogServlet through the embedded URL /bookstore1/catalog.
A Web component can also directly invoke another resource while it is executing. There are two possibilities: it can include the content of another resource, or it can forward a request to another resource.
To invoke a resource available on the server that is running ...