Palm OS Programming, 2nd Edition

TCP/IP Communications

Now it is time to look at TCP/IP. In this section, we will do the following:

• Discuss the API for networking on a Palm device

• Give you some programming tips for using TCP/IP

• Use TCP/IP in a small sample application that sends email to a Simple Mail Transfer Protocol (SMTP) server

Network API

The Palm OS (2.0 or later) contains a net library that provides network services, such as TCP/IP, to applications. With this library, an application on the Palm device can connect to any other machine on a network using standard TCP/IP protocols. The API for this library is a socket interface modeled closely on the Berkeley Sockets API.

Tip

This section provides a brief introduction to network programming on the Palm OS. For more in-depth coverage, see Palm OS Network Programming, by Greg Winton (O’Reilly).

Berkeley Sockets API

Sockets are a communication mechanism. Information is sent into a socket on one machine and comes out of a socket on a remote machine (and vice versa). With a connection-oriented socket interface, you can establish the connection between the two machines prior to sending data. The connection stay opens whether or not data is sent. A good example of this is TCP. Sockets also allow a connectionless mode for sending datagrams. These can be sent to an address without any prior connection using a protocol such as the User Datagram Protocol (UDP).

Tip

For a brief introduction to Berkeley Sockets and socket programming, see http://www.ibrado.com/sock-faq/ ...