Things you might ask.

General questions.

How can I set up my computer to run Java?

You need to install a Java runtime. If you run Mac OS, install Apple's MRJ 2.1.4 or later. (If you have Mac OS 9 or later, you've already got it.) On Windows or Unix, install Sun's JRE.

How can you do MP3 stuff in Java? I thought Java was slow.

Java is faster than you think, although it's no match for C at number-crunching. But while encoding or decoding MP3 audio is hard, MP3 streaming is quite easy -- it just reads the raw MP3 data from files and transmits it over TCP connections. Very little CPU horsepower is required.

How many listeners can connect at a time?

That depends mostly on your network bandwidth. A consumer grade 128kbps-upstream DSL connection can really only host one 64kbps stream. (But see the note on bandwidth, above.) A 1mbps T-1 line can host 15 of those or seven 128kbps streams. A 10mbps Ethernet LAN could host over 70 128kbps streams. In the real world, network congestion and the efficiency of your net interface will reduce this. Java performance isn't really an issue; the server spends nearly all of its time waiting for network I/O to complete.

How many stations can I serve?

As many as you have RAM and disk space for, pretty much. The RAM is needed for Java threads and I/O buffers; a few hundred kilobytes per station. The disk space, of course, is for the station's MP3 files.

What's the legality of broadcasting copyrighted music?

Most importantly, you need to legally own the music you're streaming (but if you're the kind who downloads pirated MP3s from the net, you've probably already ignored this paragraph.) You also need to pay for a license from music publishers like ASCAP and/or BMI to broadcast material published by their artists. Alternatively, if you use a legit replicator site like Live365.com, they're probably already licensed to serve your stream.

Troubleshooting.

I set up RadioStation at work, but no one outside my company can connect to my server, even though I gave them my correct IP address.

Your workplace is almost certainly behind a network firewall. Firewalls are designed precisely to prevent outside computers from connecting to machines on the inside -- this helps deter malicious attacks. But it also means you can't run a public server from within the firewall. You'll have to convince your network administrator either to tweak the firewall configuration to allow connections to your machine, or to let you run RadioStation from a machine that's not behind the firewall. The bigger your company, the slimmer your chances of success.

I set up RadioStation at home, but no one elsewhere can connect. We have several computers sharing a single Internet connection.

This is almost the same situation as above. IP-address sharing is done using network address translation, which is much like a packet-filtering firewall. The result is the same: no outside computer can connect to any computer on your network except the one that has the physical Internet connection (modem). You'll have to run RadioStation on that computer. If even that doesn't work, you might have a dynamic IP address, as in the next Q&A:

The station address that gets printed out when I start the server isn't always the same. This makes it hard for people to connect, because I have to keep telling them the new address.

Your computer must have a dynamic IP address. It might be using PPP or DHCP. You might be able to get a static IP address from your ISP, but it'll cost more. (If you're at work, ask your network administrators if you can switch to a static address.) Or you might be able to get away with just never rebooting your computer, since usually your dynamic address only changes when you re-connect to the net.