#

## Chapter 3

## Using the Tuner

With the Castanet Tuner installed, now you can use it to tune into Castanet Transmitters on the Internet, and download and use various channels contained on those transmitters. In this chapter, you'll get a feel for how to use the tuner to do basic tasks including how to manage channels. You'll also learn how to start channels from outside the tuner, including from the desktop and from inside a Web page.

### Starting the Tuner

If you don't have the tuner already running on your system, here's how to start it. Marimba recommends that you run the tuner in the background all the time, so that channels can be automatically updated at regular intervals. (Running the tuner itself all the time does not significantly impact system resources.)

To start the tuner from Windows, navigate through the Start menus (Start | Programs | Castanet Tuner | Castanet Tuner; see Figure 3.1):

Figure 3.1. Starting the tuner.

In Windows, the tuner is running when the tuner icon appears on the right side of the task bar (see Figure 3.2), even if the tuner window does not appear on the desktop or in the task bar. Double-clicking the tuner icon in the task bar causes the tuner window to display on the screen.

Figure 3.2. The Tuner icon.

To start the tuner in Solaris, use the `tuner` command from any UNIX prompt. If the tuner directory is not in your execution path, you'll have to use the full path name of the tuner (in this case, the tuner software has been installed in the `/usr/local/` directory):

`/usr/local/castanet/tuner/bin/tuner`

### Quick Start: The Basics

Want to get started as fast as possible? Read this section for the bare-bones details of how to use the Castanet Tuner.

Castanet channels are broadcast from Castanet Transmitters. To subscribe to a channel–that is, to download that channel to your system–you point the Castanet Tuner to the transmitter that contains that channel.

When you first start up the Castanet Tuner, the default transmitter you'll have available to visit is Marimba's transmitter at `trans.marimba.com`. Choosing the Listing tab will show you that transmitter and the listing of channels available on that transmitter. (See Figure 3.3.)

Figure 3.3. The channel listing for `trans.marimba.com`.

Each line of that listing is a different software channel. To subscribe to it, double-click the channel. That channel will then be downloaded and stored on your local disk. So, for example, to subscribe to the SameGame channel, double-click its icon. SameGame is a game with a set of tiles; you can remove groups of tiles of the same color by double-clicking them. You get points based on how many adjoining tiles you remove. It's very addictive. Watch out!

The tuner will switch panels from the Listing panel to the Channels panel, download that channel, and start it. Figure 3.4 shows the Channels panel after subscribing to the SameGame channel.

Figure 3.4. The SameGame channel, subscribed to in the tuner

Note that whereas the Listing panel shows you all the available channels on a transmitter, the Channels panel shows you the channels you are currently subscribed to and the transmitter where you got them from. You can switch between those two panels to subscribe to new channels or launch channels you've already downloaded.

After you've subscribed to a channel, that channel will remain loaded and stored on your hard drive; you don't have to download it all over again every single time. You can start and stop a channel just as you would any other program installed on your system–just double-click on its icon in the Channel panel to start it.

After they have been subscribed to, channels will update automatically as new data becomes available on the transmitter. Different channels will update at different times; a news channel, for example, might update every few minutes, whereas a channel for a word processor or other sophisticated application might update only when there are significant changes to be made. Channels will update automatically, in the background, as long as the tuner is running, or you can manually update a channel by choosing the Update menu item.

To get rid of a channel, you can either unsubscribe to it (which removes the channel files but not its saved state) or remove it altogether. Both Unsubscribe and Remove are menu items in the Channel menu, as shown in Figure 3.5.

Figure 3.5. The Channel menu.

Got it? Read the rest of this chapter for more details on how to use the tuner to explore transmitters and channels.

### Exploring Transmitters

Channels are located on transmitters, similar to the way that Web pages are located on Web sites. To explore channels, therefore, you must first find a transmitter and get a listing of the available channels from that transmitter.

The Listing Panel

The Listing panel is used to point the tuner to a particular transmitter, show the channels available on that transmitter, and subscribe to those channels. You can get to that Listing panel by choosing the Listing tab or selecting Listing Page from the Tuner menu. Figure 3.6 shows the listing for the transmitter located at `trans.marimba.com`.

Figure 3.6. The Listing panel.

Each channel in the listing has a name, a channel size, and a channel description. The channel size determines how long it will take for that channel to initially download, depending on the speed of your connection.

> ####

> Note

> After you've subscribed to a channel once, you won't have to download it again as you would for an applet or a file on a Web page. If there are updates to that channel, they'll be downloaded as they are needed, but those are usually much smaller than the initial channel. Keep that in mind before becoming nervous about the size of a channel.

The channel description contains information about the channel. The channel description can be as simple as the author's name, or it can include more information about the channel itself so that you can get an idea of what the channel is for before downloading it. You can read channel descriptions by choosing the plus-sign to the left of each channel, and hide the channel description by choosing the minus sign. (See Figure 3.7, which shows the channel description for the Digital Simulator channel.)

Figure 3.7. Channel descriptions.

There are two buttons to the right of the transmitter name: Browse and Refresh. Browse is used to examine the list of channels in a Web browser. Choosing the Browse button starts up your Web browser and displays the listing of channels as a Web page, including each channel's description. (See Figure 3.8.) You can then print that page or bookmark it to visit later on. (You'll learn more about using channels from a browser in "Other Ways of Using Transmitters and Channels," later in this chapter.)

Figure 3.8. Channel listing in a browser.

> ####

> Note

> In Windows, the Browse button will launch your default Web browser. In Solaris, your browser must already be running for Browse to work.

The Refresh button is used to make the tuner contact the transmitter for a new list of channels, just in case new channels have been added since the last time you looked at that transmitter.

Tuning into Different Transmitters

The `trans.marimba.com` transmitter that you get when you start up the tuner isn't the only transmitter you have available to explore. A Castanet Transmitter can be located on any site on the Internet; all you have to do is point your tuner at a transmitter to view or subscribe to the channels available on that transmitter.

To tune into a new transmitter, type its name into the transmitter name field (the one marked "Enter Transmitter Host Name" on the Listing panel, shown in Figure 3.9) and press the Enter or Return key. The tuner will contact that transmitter and give you a list of the channels that transmitter broadcasts.

Figure 3.9. The transmitter name field.

Some transmitter names have a number after them–for example, `trans.havefun.com:5282`. The number is the network port on which that transmitter is located and is important–don't forget it! Your tuner might not be able to get a listing from a transmitter if you leave the number off.

> ####

> Note

> Transmitter names generally begin with the prefix `trans`, as in `trans.marimba.com` or `trans.excite.com`. However, transmitters can be located on any site on the Internet, including Web or FTP sites. Don't let the transmitter name fool you.

If the transmitter name you listed does not exist (for example, if you misspelled the name), you'll get an Unknown Host error at the bottom of the tuner screen. Make sure you've spelled the host name correctly and that there is indeed a transmitter installed on that host and port number.

The field containing the name of the transmitter is actually a pull-down menu that contains all the transmitters you've ever visited. You can choose from that list to get a list of channels from any of those transmitters. (Figure 3.10 shows an example of a few transmitters.)

Figure 3.10. Choose from a list of transmitters.

Once you've subscribed to a channel on a transmitter, you can also get a listing of that transmitter by double-clicking the transmitter name in the Channels panel (more about this later).

The Transmitter Hotlist

Where can you find other transmitters? Often you can find them much the same way you find Web sites–through friends, Web pages, advertisements, or even other transmitters. One of the easiest ways, however, is to use the transmitter hotlist. Choose the Hot tab in the tuner to see a listing of available transmitters that Marimba has designated as having good channels. Figure 3.11 shows an example listing.

Figure 3.11. The transmitter hotlist.

Choosing any of the transmitter icons in the Hot panel tells the tuner to switch to the Listing panel and to contact that transmitter for a list of channels.

The Register button in the top-right corner of this panel gives you information on registering your own transmitter for use in the hotlist. See Chapter 6, "Transmitter Administration and Performance Tuning."

### Working with Channels

Use the Listing panel in the tuner to explore different transmitters and get a listing of the channels available on those transmitters. Then, double-click a channel to subscribe to it. The tuner will switch to the Channels panel, and then download and run the channel you've just subscribed to. Then, from the Channels panel, you can get a listing of the channels you're currently subscribed to and maintain those channels. From the Channels panel, you can

- Subscribe, unsubscribe, or resubscribe to channels
- Start or stop channels
- Update channels
- Remove channels

Figure 3.12 shows a sample Channel panel, with multiple channels from multiple transmitters available. The status column shows the current status of a channel, whether it is subscribed to or not, whether it is running or not, and any interim status (whether or not the channel is downloading, launching, or stopping, for example). It'll also show the word `error` if there was a problem downloading or updating the channel, with the actual `error` as a tooltip. (Move your mouse over the channel name; the error will appear in a little pop-up window.). Errors usually result because a connection to the transmitter could not be made but sometimes because there's an actual error in the channel.

Figure 3.12. The Channel panel.

Subscribing and Unsubscribing to Channels

To subscribe to a channel, start at the Listing panel with a transmitter listing and double-click the icon for the channel you want to subscribe to (or, select the name of the channel and choose Subscribe or Start from the Channel menu). The tuner will switch to the Channels panel and begin downloading the channel from the transmitter. As the download progresses, the tuner will keep you updated on the progress of the channel both in the Channel panel itself and in the status bar at the bottom of the window. (See Figure 3.13.)

Figure 3.13. Channel in the process of downloading.

When the channel has fully downloaded, it will appear listed in the Channel panel.

> ####

> Note

> Channels are stored on your local disk. In Windows, you had the option of where to install those channels; by default on Windows 95, they're stored in `C:\Windows\.marimba\`; on Windows NT, in `C:\WINNT\.marimba\`. On Solaris, channels are stored in your home directory, in the `.marimba` directory. Inside the channel directory, channels are organized by transmitter name, and each channel has its own directories for channel files and for data. Note that the channel files are actually stored in a special database-like format so they can be shared between channels; if you browse the channel directories, chances are you won't find anything useful. Most of the time you won't need to know this; channels will simply work as you expect when you launch them from the tuner.

Quick Subscription Using the New Channel Panel

If you already know the name of a channel and the transmitter it is located on (for example, if someone told you to check out a cool new channel), you can use the New Channel menu item from the Tuner menu (see Figure 13.14) to quickly subscribe to that channel. New Channel brings up the panel shown in Figure 3.15.

Figure 3.14. New Channel from the Tuner menu.

Figure 3.15. Subscribing to new channels.

From this panel, you can enter the name of the transmitter (and the port number, if necessary), and the name of the channel. Choosing Subscribe takes you to the Channels panel, where the channel is subscribed to, downloaded, and run.

If you know the name of the transmitter but not the name of the channel, you can enter the name of the transmitter into the field marked Transmitter and choose the List button. The tuner will switch to the Listing panel and display the channels available on that transmitter just as if you had entered the name of the transmitter here.

Starting and Stopping Channels

The first time you download a channel, that channel will also start running, so you can see what it is you've downloaded. Channels run in their own windows, just like regular applications.

To stop a channel from running, you can quit it from that channel's menu bar or use the close box, just as you would any other application. In addition, you can select that channel from the tuner's Channel panel and choose the Stop menu item.

To restart a channel, double-click its icon in the Channel panel, or select it and choose Start from the Channel menu.

> ####

> Note

> There are also other ways to start channels, including from the Start menu and from shortcuts in Windows. You'll learn about these later in this chapter in the section titled "Other Ways of Using Transmitters and Channels."

Updating Channels

Probably the niftiest feature of channels is that the tuner will update them automatically if there is new information available for that channel on the transmitter. New information for a channel can be anything from something as simple as a new quote in a quote-of-the-day channel, to an updated database of books for a library channel, all the way up to an entirely new revision of the channel itself. The Castanet tuner keeps track of updating the channels you are subscribed to, whether or not they are currently running; you never have to do anything to make sure any of your channels is up to date.

There are two ways to update channels:

- You can let the tuner update all your channels automatically, in which case you don't have to do anything at all (although you can configure the tuner to update your channels more or less often or turn off updating altogether; see "Controlling Updates" for more information). The tuner must be running for automatic updates to occur.
- You can update a channel manually at any time.

To update a channel yourself, select that channel from the Channels panel and choose Update from the Channel menu. The tuner will contact that channel's transmitter, check for new information, and download and install it if there is any.

> ####

> Note

> The tuner is smart about updates. A channel becomes updated only if the new data on the transmitter can be fully downloaded. If an update is aborted either because of a network failure or because you stopped an update in the middle, the old version of the channel will continue to work. There will never be a point where a channel is in an in-between state and cannot run. And, if an update is interrupted for any reason, the tuner will pick up where it left off, rather than restarting from the beginning every time.

Note that in the Channels panel, the Updated column shows when the channel was last updated.

Channel Properties

On the Listing panel in the tuner, you can get some summary information about a channel by selecting the plus sign to the left of the channel name. Once you've subscribed to a channel, however, there are several other properties you can examine.

To display a channel's properties, select the channel from the Channels panel and choose Channel Properties from the Channel menu. A window similar to the one shown in Figure 3.16 is displayed. (This one is for the SameGame channel.)

Figure 3.16. Channel Properties.

Channel properties include information about the channel and its transmitter, when it was last updated, its current size, the type of channel it is (application, applet, presentation, HTML), and how often that channel should be updated. Finally, it also includes information about the author and the administrator of the channel (which can be different people).

Unsubscribing and Removing Channels

What if you've played with a channel and decided you don't like it any more? You can do one of two things: You can unsubscribe from that channel, or you can remove that channel.

To unsubscribe from a channel, select that channel's name from the Channels panel and choose Unsubscribe from the Channel menu. The channel will continue to be listing in the Channels panel, but both its status and updated column will be empty. (See Figure 3.17.)

Figure 3.17. An Unsubscribed channel.

Unsubscribing from a channel means that the channel is no longer active; it will not be updated by the tuner, and the files that make up that channel are deleted from your hard drive. Unsubscribed channels, however, continue to be listed in the tuner and in the Start menu, and any data or information you have saved along with that channel will also continue to exist. After you've unsubscribed from a channel, you can resubscribe to it at any time, and the tuner will de-download the channel's files and let the channel pick up where it left off. Unsubscribing to channels is useful for channels that you use infrequently; the tuner won't tie up your network connection updating these channels, and you won't need to set aside disk space to store them.

Removing a channel is how you get rid of a channel altogether. To remove a channel, select its name from the Channels panel and select the Remove item from the Channel menu. Removing a channel deletes the channel from your tuner, removes all its files from your hard drive, and deletes any data you may have saved with that channel.

> ####

> Caution

> Use Remove only when you truly never want to use a channel ever again; to get it back, you'll have to go back to that channel's transmitter and redownload it.

### Using HTML Channels

In Castanet, most of the channels you download and use will be based on Java applets, applications, or presentations created using Bongo. They'll run in their own windows on your desktop. HTML channels are a special kind of channel which looks and acts just like a normal Web site–except its downloaded and stored on your local disk as a whole, rather than page by page.

HTML channels are subscribed to and updated exactly in the same way that regular channels are, so that new data on a Web site is always available on your local system for browsing. Contrast this with the "normal" way of viewing Web sites, where you must revisit and redownload all the data on a Web page each time to see any new information.

After you've subscribed to and downloaded an HTML channel, you use your default Web browser to view that HTML channel. There's a catch, however; because HTML channels are managed through the tuner instead of through a regular Web server, you have to configure your browser in a special way in order to view them.

To view HTML channels in your browser, set up your browser such that the Castanet Tuner is your HTTP proxy. Then, each request the browser makes to a Web page in an HTML channel can be redirected to the channel stored on your local disk (or passed back out to the Web at large for Web sites that are not HTML channels).

To configure Netscape to view HTML channels, select Options | Network Preferences | Proxy, choose Manual Proxy Configuration, and click the View button. A window similar to the one shown in Figure 3.18 will appear.

Figure 3.18. Proxy configuration in Netscape.

The line marked HTTP Proxy should have the host name `localhost`, and the Port should be `5283` (as shown in Figure 3.18). If your HTTP proxy had been set to some other value, you might want to mark down that proxy and port in case you end up removing the tuner at some later date.

To configure Internet Explorer to view HTML channels, select View | Options | Connection, choose "Connect Through a Proxy Server," and click the Settings button. Figure 3.19 shows the window that appears.

Figure 3.19. Proxy configuration in Internet Explorer.

As with Netscape, the line marked HTTP Proxy should have `localhost` as the host and `5283` for the port. If you've already got values for that line, you'll want to save those in case you need them at a later time.

Note that setting the HTTP proxy of the browser to be the tuner will not interfere with your normal Web browsing of pages that are not HTML channels. As long as the tuner is running each time you use your Web browser, requests to the Internet at large will be passed on by the tuner.

This is true even if your organization uses a firewall and you were required to have a host and port in your HTTP proxy configuration of your browser. As long as the tuner has been configured to use your organization's HTTP proxy, Netscape will still work even when configured in this way.

> ####

> Note

> If you find that your browser has suddenly stopped working–that it can't find any hosts, or tries to save all the pages you access–make sure the tuner is running, or reset your proxy information back to its original state.

After your browser has been correctly configured, you should be able to launch HTML channels from within the tuner, and view and navigate them inside your browser. Note that on Windows, if your browser isn't running when you launch an HTML channel, your default browser will start up automatically. On Solaris, you must have a browser running ahead of time to be able to launch HTML channels from the tuner.

> ####

> Note

> Obviously, setting up the tuner as a proxy is not the most ideal solution for browsing HTML channels. Marimba is exploring other options for browsing these channels for later versions of the Castanet software.

### Controlling Updates

Updates to channels happen automatically. Each channel has an update interval that determines how often the tuner tries to update that channel. (For example, a channel to display news headlines or stock data would update fairly frequently, whereas a game or spreadsheet channel might not update very often at all.) As long as the tuner is running, the tuner will attempt to update each channel at its proper time by contacting the transmitter and checking for new data.

If you have a slow or intermittent network connection, you might not want the tuner to spend a lot of time doing updates. Or, you might want to have the full bandwidth of your connection for more important work during the day.

You can configure the tuner to update channels only at certain times of the day or not to update automatically at all. To configure tuner updates, choose the Configure tab from the tuner (and the Loading tab, if the Loading panel is not already displayed).

The Loading panel contains two drop-down lists: one for the time automatic updates can occur and one for the frequency of those updates.

The first menu (shown in Figure 3.20) determines the time of day you would like updates to occur. For example, if you use the network a lot during the work day, you might want to restrict updates to nonworking hours so you can have the full network bandwidth for your own work. Or, you might want to turn off automatic updates altogether (in which case you'll have to update each channel automatically to make sure it gets all its new information).

Figure 3.20. Update times.

> ####

> Tip

> If you have Internet software that automatically dials your ISP each time you attempt to make a network connection, you might want to choose Never to prevent the tuner from dialing your ISP for you at unexpected times. Keep in mind that if your tuner does dial your ISP for you, you can configure it to disconnect itself after being idle for some time. Choose the Configure panel, and then the Network subpanel, to change the configuration for your connection.

The second menu on this panel (shown in Figure 3.21) determines how often updates can be made. By default, updates are made every 15 minutes if you have a direct connection or once an hour if you have a modem connection. If you set the defaults to update more often, updates are made as often as the channels you have subscribed to need them. By limiting the frequency of updates, however, you can prevent the tuner from making too-frequent network connections and potentially slowing down your machine or your network.

Figure 3.21. Update frequency.

###
Interrupting Tuner Downloads

When a tuner is downloading a channel, updating that channel, or getting a listing of channels from a transmitter, the satellite dish on the top-right corner of the tuner will animate, and the status of the connection will appear along the bottom of the screen. (See Figure 3.22.) If you want to interrupt any of these connections for any reason (perhaps the network is being unbearably slow or has stopped working altogether, as networks are sometimes prone to do), you can stop the download in one of two ways:

- Choose Cancel Transfers from the Tuner menu.
- Press Ctrl+C on the keyboard.

Figure 3.22. Tuner in the process of downloading a channel.

> ####

> Note

> If you stop downloading a channel in the middle of subscribing to it, that channel will still appear in the Channels panel. The next time you try to run that channel, it will restart the downloading process. If you try downloading it again within a few minutes, the download will begin where it left off, rather than restarting again from scratch (a useful feature for when you have a flaky network connection as well; if you keep trying eventually the full channel will get downloaded).

If you interrupt an update in the middle of downloading, the channel will revert to its original state. Castanet is designed so that interrupting an update in the middle will never break what you already have.

### Other Ways of Using Transmitters and Channels

Although the Castanet Tuner is your primary interface for exploring and using channels, there are several other ways you can browse and use Castanet Transmitters and channels, including browsing transmitters and launching channels from a Web browser, and accessing channels from the desktop.

Exploring Transmitters and Channels Using a Web Browser

You can use your Web browser instead of the tuner to explore a transmitter's channel listing and to subscribe to and launch channels from that browser.

You've already seen one way to do this. If you enter a transmitter name in the field at the top of the Listing panel in the tuner, you can then choose the Browse button to see a listing of that transmitter's channels.

Outside of the tuner, if you know the name of the transmitter you want to browse, you can use the name of that transmitter in your browser as if it were a Web site. (For example, to contact the transmitter at `trans.marimba.com`, use the URL `http://trans.marimba.com/`.)

In either case, the browser will display a listing of the available channels on the transmitter as a Web page, with each channel as a link. (See Figure 3.23.) Clicking the links downloads and subscribes you to the channel (if it's not yet subscribed to).

Figure 3.23. Transmitter listings in browsers.

> ####

> Note

> With Netscape, clicking a channel link will launch the tuner as a helper application automatically. If you're using Internet Explorer, you'll need to configure that browser by hand to launch the tuner when you select a link to a channel. To do, this, select View | Options| Programs and select the File Types button. From the File Types window, choose New Type, and enter `Marimba Channel` into the "Description of Type" field, `.chn` into the "Associated Extension" field, and `application/marimba` into the Content Type field. Then, click the New button. A New Action window will appear; enter `Open` into the Action field and then use the Browse button to navigate to the location of the tuner. (By default, it's `in C:\Marimba\Castanet Tuner\Tuner.exe`.) Choose OK all the way back up to browser to finish up.

Note that because you can get access to a transmitter and a channel in this way, you can also create links to channels in your own HTML Web pages–for example, to create a list of cool channels for others to browse. Just link to the channel using an `<A>` tag, the same way you would any other link, where the destination URL is the name of the transmitter, the name of the channel, a question mark, and the word `start`. For example, to link to the SameGame channel on Marimba's transmitter, use HTML code something like this:

`Warning! <A HREF="``http://trans.marimba.com/SameGame?start``">The SameGame`

`channel</A> is extremely addictive!`

Launching Channels from the Desktop

In Windows, you can launch channels from outside the tuner itself through the use of the Start menu or with shortcuts. On Solaris, you can start or subscribe to channels from the command line.

Channels in the Start Menu (Windows only)

When the tuner is installed, the installer program adds an item to the Start menu for channels. That menu contains all the channels you have subscribed to, arranged by transmitter. (See Figure 3.24.) To launch a channel, simply select its name from the Channels menu.

Note that channels are only removed from the Start menu when you actually remove them; an unsubscribed channel will continue to appear in the start menu.

Figure 3.24. Start menu channels.

If you don't want channels to be added to the Start menu when you subscribe to them, you can turn off this option in the tuner by choosing the Configure panel and then the Options panel. Deselect the checkbox for "Add Subscribed Channels to Start Menu."

### Channel Shortcuts (Windows only)

You can also create shortcuts to channels, put those shortcuts on your desktop or in folders on your hard disk and launch channels from those shortcuts.

To create a shortcut, go to the Channels panel in the tuner and select the channel you're interested in. Then choose Create Shortcut from the Channel menu. The shortcut to that channel will appear on the desktop (Figure 3.25); you can then drag and drop it anywhere you want.

Figure 3.25. Channel shortcuts.

Channels from the Command Line (Solaris Only)

On Solaris, you can start channels from the UNIX command line, which allows you to create aliases or menu items for those channels. To start a channel from the command line, you must know the name of the transmitter and the name of the channel. If the channel name contains spaces, substitute underscores for those spaces (for example, `My_Cool_Channel` for "My Cool Channel").

Then use the tuner command to start the channel, like this:

`tuner -start` transmitter`` channelname

If the tuner isn't running, the tuner will start. If the tuner is running but the channel has not yet been subscribed to, the tuner will download the channel and run it. If the tuner is running and you've already subscribed to that channel, the tuner will just start it. If you get an error when you try to launch the channel, make sure you're using all the same upper- and lowercase letters as the actual name of the channel, and watch out for those spaces.

You can also use the tuner command to stop a channel, like this:

`tuner -stop` channelname

### Other Tuner Features

This last section is a catch-all for the other tuner features that didn't fit anywhere else.

Updating the Tuner

Just as channels are updated automatically, the tuner itself it also a form of channel and can be updated when there is new information (new features or fixes) available at Marimba.

The tuner will attempt to update itself once a week. (There won't necessarily be changes to be made every week, of course, but that's how often the tuner will check back to Marimba.) As with channels, however, you can always update the channel manually by choosing Update Tuner from the Tuner menu. The tuner will exit and display the Tuner Update box shown in Figure 3.26.

Figure 3.26. The Tuner Update box.

Choose the Next button to update the tuner, or Skip to skip updating this time. Note that the tuner always contacts Marimba's site for updates, so even if you use your tuner exclusively on an internal network, you will need an external Internet connection to successfully update the tuner.

Changing the Configuration Information

When you installed the tuner initially, you entered in information about you and your network. You can change that information at any time by selecting the Configuration tab from the tuner and then selecting any of the subpanels on this window. See the previous chapter for information on the information contained in these tabs.

Getting Help

As you explore various aspects of the tuner, you might notice various Help buttons in various windows. In addition, the tuner itself has a Help menu with various items. (See Figure 3.27.)

Figure 3.27. The Help menu.

Selecting any Help button or any of the items in the Help menu brings up the online help for the tuner. Most of the Help files for the tuner are written as Web pages and stored on Marimba's Web site as both regular pages and as a channel. (The channel is called Tuner doc; its contained on `trans.marimba.com`.) When you choose a Help item, the tuner launches your default browser and displays the relevant Help file–either the local version, if you've subscribed to the Tuner doc channel, or the version stored on Marimba's Web site.

For more immediate help, Marimba provides a number of discussion lists and groups. The Marimba Forum channel from `trans.marimba.com` provides a forum in which you can post questions and comments and get help from both Marimba folk and others who are using the technology. For support and help over e-mail, consult the page at `http://www.marimba.com/developer/support.html` for information about discussion and support lists.

### Java Console

Some channels might make use of a text console to display messages, information about the channel, or, most often, errors and debugging information. If a channel you've subscribed to prints these messages, they will appear in the Tuner's Java console. You can display this console by selecting Show Console from the Tuner menu. Figure 3.28 shows the console.

Figure 3.28. The Tuner's Java console.

> ####

> Note

> The Java console is most useful to developers working on creating new channels. It would be unusual for a channel to intentionally print output to the Java console.

### Tuner Extensions & CDROM Files

Some special kinds of channels may require you to do extra work in order for you to be able to running: channels that use local libraries and channels that read files from CDROM.

The former are channels that require you to install special software on your machine before you can run them, similarly to how Netscape uses plug-ins to extend the features of the browser. That special software, called an extension, is usually specific to your system, so it cannot be automatically downloaded as part of the channel itself. Usually a channel that uses these kinds of extensions will let you know the first time you run it how to get those files and how to install them so you can use the channel.

The most important thing to keep in mind about tuner extensions is that those files that you download and install yourself are not subject to the security constraints that normal channels have -- so those files can do just about anything they want to your system. Make sure before you install tuner extensions that you trust the company or organization that has made them available and that you understand what the extensions will be used for; you are responsible for the safety of your system.

The second kind of special channel is one that reads files contained on a CDROM -- for example, you might have a very sophisticated game channel that stores its very large images and video files on a CDROM to save on downloading time. If you run across this kind of channel, you'll have to not only purchase the CDROM, but you'll also have to specially configure your tuner to use that CDROM.

By default, channels aren't allowed to look at any files on your local system other than in one specific directory. This includes examining the disk in your CDROM drive. However, using the option in Figure 3.29, which you can get to from the Configure panel and the Options panel under that, allows the channel to make an exception for the CDROM. Generally its a good idea not to enable this option until you run into a channel that actually needs it.

Figure 3.29. Allow the tuner to read from the CDROM

### Finding Channels

Looking for new transmitters and channels to play with? There are a number of places you can look:

- The tuner Hotlist, described earlier in this chapter, is a great place to start looking for channels.
- The transmitter at `trans.havefun.com:5282` is a public transmitter for channels developed by various people around the world.
- Excite, the popular search engine, has a terrific channel guide at `trans.excite.com`.
- Gamelan, known mostly for their very complete resource for Java, has a section for transmitters and channels at `http://www.gamelan.com/`. They also run a Gamelan channel at `trans.gamelan.com`.
- Marimba's Web site has a Channel of the Week page at `http://www.marimba.com/channels/` with reviews and links to interesting channels.

### Quitting the Tuner

The tuner is designed to run all the time on your system so that it can keep your channels up to date and so that it can serve as a proxy for your Web browser (assuming you've set your browser up to view HTML channels).

On Windows, the tuner is running as long as the tuner icon appears in the task bar. Closing the tuner window using the close box hides the tuner but does not quit it; by double-clicking the tuner's icon, you can make the tuner visible again.

To actually quit the tuner, use the Tuner | Quit menu item (shown in Figure 3.30. The tuner will be relaunched if you start it by hand, if you start any subscribed channels, or if you reboot your system and the tuner has been configured to start when the system starts.

Figure 3.30. Quitting the tuner.

### Keyboard Shortcuts

Many menu items in the tuner have keyboard shortcuts, which you can use in place of selecting the menu item itself. Tables 3.1 shows a summary of those shortcuts.

Table 3.1. Tuner keyboard shortcuts.

Menu | Item Shortcut
New Channel | Ctrl+N
Listing Page | Ctrl+L
Channels Page | Ctrl+T
Channel Description | Ctrl+D
Channel Properties | Ctrl+P
Subscribe | Ctrl+S
Update | Ctrl+U
Start | Ctrl+X
Remove | Ctrl+R
Cancel Transfers | Ctrl+C
Quit | Ctrl+Q

### Summary

The Castanet Tuner is used on your local desktop to download, launch, and manage various channels stored on various Castanet Transmitters on the Internet. It also keeps those channels up to date and lets you visit transmitters to download new channels. Throughout this chapter you've learned how to use the tuner to do all these things: to find new channels, to subscribe to and run those channels, to update them once you've subscribed to them, and to unsubscribe to them or remove them when you've had enough. You also learned how to use channels in conjunction with a Web browser–both to view HTML channels and to create links to real channels from inside a Web page.

Congratulations on finishing Part I! You now know nearly everything there is to know about the Castanet Tuner. In Part II, we'll move to the transmitter side of the process, and you'll learn how to install and use the transmitter as well as how to publish channels.