Making Things Talk

174 MAKING THINGS TALK

Conclusion

The client should also place a priority on listening, but

it has to juggle listening to the server with listening to

the physical inputs. It should always give a clear and

immediate response to local input, and it should indicate

the state of the network connection at all times.

The protocol that the objects in this system speak to each

other should be as simple and as flexible as possible.

Leave room to add commands, because you never know

when you might decide to add something. Make sure to

build in responses where appropriate, like the “hi” and

“bye” responses from the server. Keep the messages

unambiguous, and if possible, keep them short as well.

Finally, make sure you’ve got a reliable way to test the

system. Simple tools like the telnet client and the test

server will save you much time in building every multi-

player server, and help you get to the fun sooner.

Now you’ve seen examples of both asynchronous client-

server exchanges (the HTTP system in Chapter 4) and

synchronous exchanges (the chat server here). With those

two tools, you can build almost any application in which

there’s a central server and a number of clients. For the

next chapter, you’ll step away from the Internet and take a

look at various forms of wireless communication.

X

The basic structure of the clients and server in this chapter can be used any time that

you want to make ...