Palm OS Network Programming

Summary

We discussed the two most commonly used Net Library functions for exchanging data over TCP, NetLibSend and NetLibReceive. These functions support either stream or datagram connections.

FTP clients send commands to the server. The server processes the command and returns a response. FTP authentication, or login, requires a username and password. The client sends this information to the server. If the username and password are valid, the client begins an FTP session.

When the client is finished with the server, it logs out. The client sends a QUIT command to the server, and shuts down its end of the connection for sending. The server responds with one or more goodbye messages then shuts down its connection. In the meantime, the client is reading these goodbye messages. When there are no more, the client closes the connection.

Our FTP sample provides an excellent example of how to use the Net Library functions to exchange data across the network. Managing the state of the session that uses the Net Library sockets API is the true challenge of network applications development.

Right now our application has a serious performance problem that makes the device look like it’s hung up. In Chapter 10, we learn techniques for making our application coexist more peacefully on the device and on the network.