Marimba's Castanet applies a new broadcasting paradigm to Web-based publishing and software and software distribution.
Pete Loshin
Change is the only constant in the world of the Internet. Keeping up with it is tedious and inconvenient; whether you're after news or the latest browser release, downloading the necessary files and pages repeatedly can get tiresome. Marimba, a start-up company run by former members of Sun's Java development team, may have the least-effort answer for keeping current with Web updates. A unique architecture embodied in Marimba's new Castanet Software Distribution System combines server "push" and browser "pull" to get around the Web's growing bandwidth problems. The
result is
fast, efficient distribution of Web pages and Java programs.
Castanet borrows somewhat from the cable TV model. With TV, you need a cable box that's fed by a transmitter, you sign up to receive specific channels of programming, and you tune in whenever you want. With Castanet, instead of a cable box you use the free Castanet tuner client. On the server side, a Castanet transmitter delivers the information (software for a repeater and proxy server are expected to be available by the time this rev
iew sees print). The channels deliver Java applets, applications, or Web pages, and you receive only those you've subscribed to. Mac versions of all products will eventually join those for Windows 95 and NT and Solaris.
Using beta versions of the Castanet transmitter and Bongo, Marimba's channel-building tool, I brought up a simple channel in less than an hour.The Castanet tuner is about as easy to use as an average stereo system. Download and install it, fill out a dialog box with a bit of network and personal information, and you can "
subscribe" to channels -- that is, download software and/or data. Channels are downloaded through Web pages like Marimba's (
http://www.marimba.com/channels/
) or by connecting directly to a Castanet transmitter through the tuner control panel.
Most controls are clearly marked on the front of the box.
You control
frequency and schedule channel updates by clicking on the Configure Loading tabs of the tuner control panel. You can easily create a desktop icon for a Castanet channel by selecting the channel and then choosing Create Shortcut from the Channel pull-down menu.
Castanet adds a Channels option to the Windows taskbar through which you can start all subscribed channels whether or not you're connected to the Internet or an intranet. The default is for a channels option to
appear at the top of the Windows taskbar, with each transmitter listed separately and all channels appearing as suboptions under their respective transmitters. If you don't care for that arrangement, you can move the icons anywhere on the taskbar.
Turning On, Tuning In
Underneath the hood, the cable-TV analogy is less appropriate. The tuner regularly polls all transmitters that carry channels to which it's subscribed, and each transmitter responds by sending the latest versions of those channels if they differ from the tuner's current version. Update frequency varies, depending on the end-user configuration as well as on the channel itself.
Castanet uses Application Distribution Protocol (ADP), a protocol for mirroring code and data over network connections, to improve performance and optimize bandwidth. Where possible, updates are done incrementally to save on bandwidth. In all cases, users get the most recent update available.
The transmitter is as easy to administer as the
tuner. It involves setting a root directory, host name and port number, and password and trusted hosts for administration. Advanced settings include the number of concurrent processes and threads, as well as the size of the memory cache for each process. Once the transmitter is configured and launched, you can add, remove, or modify channels with the putback program, even while the transmitter is running. You don't need to bring the system down for updates.
Putback is fairly easy to use once you've figured out the steps. This is where you can enter a channel's description, author, and administrator. You can also set the update frequency for specific channels. For example, if the channel is a stock-ticker applet, you can set it to look for updates frequently; if it's a daily crossword puzzle, there's no need to update it more than once a day. You can also set the update frequency for inactive channels -- that is, how often the channel should be updated even when it's not being used.
Banging on
the (Bongo) Drums
Bongo is a visual tool for authoring Java applets and for creating GUIs, called presentations, which are Castanet's basic building blocks for turning data and applets into channels. Bongo includes a full toolbox of GUI widgets and a framework for integrating them.
Bongo was easy enough even for this nonprogrammer. It's evocative of HyperCard in its extensive use of containers and scripting. You edit presentations in two separate windows: a control panel for opening files and editing properties and scripts, and another window for visually editing or browsing the presentation itself.
Adding a GUI component is as simple as choosing one from the editing window's New pull-down menu. You can resize it or drag it around the window with your mouse in the browsing/editing window. You can also edit a widget script and modify appearance properties, such as labels, patterns, and text alignment, in the other window. Marimba adds plenty of sample code and a simple tutorial to the gen
erous helping of GUI widgets -- enough to get started with Bongo, at least. It took me only a few minutes to dope out where all the software controls were and roughly what they did, and I was able to intelligently modify samples almost from the start.
The Bottom Line
The Castanet tuner is so unprepossessing on installation that some users will forget it's there until they need to use a channel, and then they may need a moment to remember how to use it. The transmitter and putback interfaces take a little getting used to, and Bongo presents a slightly steeper learning curve. Once these products emerge from beta testing, I expect that they will have easier-to-use knobs and buttons.
Castanet's scalability is an unanswered question. Marimba claims that Castanet exceeds the company's expectations and should be able to handle millions of users through a single uniform resource locator (URL), although I wasn't able to test this claim. The bigger question is whether Castanet will catch th
e fancy of end users and content providers. But with clever, paradigm-shifting technology and Marimba's knack for capturing mind share, Castanet has as good a chance as any to be the vehicle that brings Web applications to the masses.
Product Information
Castanet and Bongo Tuner.....................free
Transmitter..................................$995 for 100 users per hour per
channel; $15,000 for
unlimited license.
Bongo........................................$495 (Windows 95 or NT 4.0, or
Solaris 2.4 or higher).
Marimba, Inc.Palo Alto, CA
Phone: (415) 328-5282
Fax: (415) 328-5295
E-mail:
info@marimba.com
Internet:
http://www.marimba.com/
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screen_link (102 Kbytes)
Users configure the Castanet tuner to update Castanet channels as often (or
as rarely) as desired.
Pete Loshin is a technical editor for BYTE reviews and author of TCP/IP Clearly Explained (Academic Press Professional, 1997). You can reach him at
ploshin@bix.com
.
Tune In, Turn On the Web
