Java I/O, 2nd Edition

Chapter 22. The Java Communications API

This chapter covers the Java Communications API, a standard extension that can send data to and receive data from RS-232 serial ports and IEEE 1284-parallel ports. This allows Java programs to talk to essentially any device connected to a serial or parallel port, like a printer, a scanner, a modem, a tape backup unit, and so on. The Communications API operates at a very low level. It only understands how to send and receive bytes to these ports. It does not understand anything about what these bytes mean. Doing useful work generally requires not only understanding the Java Communications API (which is actually quite simple) but also the protocols spoken by the devices connected to the ports (which can be almost arbitrarily complex).

The Architecture of the Java Communications API

Because the Java Communications API is a standard extension, it is not installed by default with the JDK. You have to download it from http://java.sun.com/products/javacomm/ and install it separately. The current version is 3.0. However. this is only available for Linux and Solaris. Version 2.0 was also available on Windows. However, Sun recently retired that version. At the time of this writing you can find it at http://javashoplm.sun.com/ECom/docs/Welcome.jsp?StoreId=22&PartDetailId=7235-javacomm-2.0-spec-oth-JSpec&SiteId=JSC&TransactionId=noreg but I wouldn’t count on that URL lasting forever. If you can find a copy, the difference between 2.0 and 3.0 is not huge ...