Apple WebObjects 5 - Manual (Page 17)

C H A P T E R 2
What Is WebObjects?
Web-Enabled Client-Server Applications 17
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Apple Computer, Inc. January 2002
buttons, checkboxes, and tables) to complex ones (for example, toolbars). The set of
components that you can use with WebObjects is extensible, so you can create
components that can be reused across all of your Web applications.
Your application isn’t entirely built out of components. You create WebObjects
applications from a combination of components and Java classes. You put your
application-specific business logic in some of these classes. WebObjects provides
the rest of them.
The basic structure of an HTML-based Web application matches that of a dynamic
publishing site that uses WebObjects. Thus,
Figure 2-2 (page 15) applies to
HTML-based Web applications as well.
Java Client Applications
When you need the fast and rich user interface of desktop client-server applications,
you can partition your application so that a portion of it—including all or part of the
user interface—runs in Java directly on the client. Client-server communication is
handled by WebObjects. WebObjects applications that are partitioned in this way
are known as
Java Client applications.
Java Client distributes the objects of your WebObjects application between the
application server and one or more clients—typically Java applications. It is based
on a distributed multi-tier client-server architecture where processing duties are
divided between a client, an application server, a database server, and an HTTP
server. With a Java Client application, you can partition business objects containing
business logic and data into a client side and a server side. This partitioning can
improve performance and at the same time help to secure legacy data and business
rules.
Figure 2-3 (page 18) illustrates a Java Client application in which the client portion
is running as an application installed on the user’s computer. As with an
HTML-based WebObjects application, the application can communicate with the
server side using HTTP. In addition, Java Client passes objects between a portion of
your application residing on the user’s computer and the portion of your
application that remains on the application server.