[Part 1 of this article begins by defining "middleware" and looking at some networking middleware driver examples. Part 2 offers pseudocode examples for PPP Link Control Protocol states and a look at the IP networking layer protocol. Part 3 looks at a transport layer middleware example using the User Datagram Protocol, as well as examples of embedded Java and networking middleware.]
10.4 Application Layer Software Examples
In some cases, applications can be based upon industry-accepted standards, as shown in Figure 10-27. For example, for devices that need to be able to connect to other devices to transfer data or to have the remote device perform functions on command, an application networking protocol must be implemented in some form in the application layer.
Figure 10-27: Application software and networking protocols
Networking protocols at the application level are independent of the software that they are implemented in, meaning an application-specific protocol can be implemented within a stand-alone application whose sole function is the implementation of that protocol, or can be implemented as a sub-unit of a larger application that provides many functions, as shown in Figure 10-28.
10-28: Application software and networking protocols
The next three examples demonstrate networking protocols implemented in both general-purpose and market-specific applications.