With little or no tweaking to source code, Java programs can be delivered as Castanet channels. Castanet, therefore, allows Java programs to be delivered across networks without a browser. In this scheme, the Castanet tuner takes the place of the browser. This eliminates the requirement that network-delivered Java programs adopt the browser metaphor, because the program has jumped out of the browser. The channel metaphor The Castanet tuner uses the desktop metaphor rather than the browser metaphor.
Channels look like regular applications on the client's desktop.
Therefore, the developer has free reign in user-interface design. The channel metaphor , then, is one in which network-delivered applications, which are mirrored in entirety on the user's local disk, appear as desktop applications to the user. The main difference from the user's perspective between a Castanet channel and a traditional desktop application is that the channel automatically installs and evolves over time. In this regard channels behave less like traditional desktop applications and more like applets. The channel metaphor represents a new way of using the network, but looks and feels like the old way of using computers.