Sep 96 Dialog Box
Volume Number: 12
Issue Number: 9
Column Tag: Dialogue Box
Dialog Box 
By Matt Neuburg, letters@mactech.com
Hello Java, Good-bye OLE and OpenDoc
Sometimes, when we are lucky, reality sneaks up and screams “Hello!” when we most
need it.
Thinking about how to write extensible applications in Java, I was listing
requirements, procedures, and issues for communication and control between the main
application and the extensions. What is the minimum core of OLE and OpenDoc? Does
it really have to be as complicated as OpenDoc?
Then reality suddenly screamed, “Hello! Isn’t a Java-enabled browser one of the
most extensible applications we have ever seen? How is that done?”
A browser can load and run essentially “anonymous” applets, of any complexity,
that can do just about anything - even bring up windows and work with files (when
permitted). What more could we want?
Well, for extensible applications in general, we could want custom menus, closer
integration into the application, and more access to the application’s data. As it
happens, all this is possible - right now - with Java; the implementation of a browser
shows us how.
We extend the Applet class to make our own applets. The Applet class establishes
a few “entry points” (methods) through which a browser can tell the applet to
initialize itself, run, update, and so on. The applet can do whatever else you want in
addition to these few responsibilities.
For its part, the browser must implement the AppletContext interface, which
dictates the services the browser must provide to any applet. If both sides fulfill these
contracts, the browser can use Java’s ClassLoader to load an applet from a local or
remote file, place it into the browser’s own window, and run it.
To implement our own extensible applications, we don’t have to use applets
(although we certainly can); we just need to set up the kind of contracts established by
the Applet class and the AppletContext interface. Perhaps we will include ways to
share menus and application data; the particular methods are our call (so to speak).
Now think of the silliness of first implementing a Java-enabled OpenDoc part,
then rewriting applications to accept OpenDoc parts! Or just rewriting for OpenDoc in
general. Why not rewrite the applications in Java, and get straight to the point?
“Hello!” Which is the actually existing revolution - Java, or OLE/OpenDoc?
It’s time to tell OLE and OpenDoc (and VBXs, OCXs, XFCNs, MOBJs, XTNDs, and so
on) “Good-bye!”
“Uncle Dave” Moffat
Mac Web Tools Redux
In the May 1996 Dialogue Box, Ziya Oz writes:
“At the last Macworld Expo in Boston, I asked myself: If Ceneca was not formed
by ex-Taligent people, would they have developed Page/SiteMill for the Mac OS first?
Would they even have developed for the Mac at all? My answers are: No and No
again.”
His conclusions are erroneous. Ceneca initially planned to write PageMill for
Windows. However, when they spoke to Web authors at several companies, they found
out that Macintosh was the dominant platform for creating Web content. Ceneca
therefore changed their strategy and developed a Mac version instead. (I learned this
from Robert Seidl of Ceneca/Adobe at the WWDC.)
The majority of Web content is created on Macs. Macintosh is also the second
most popular Web server, after UNIX. A developer writing content tools would be wise
to publish a Mac version of his product.
Terry Morse
Language Wars Redux
Many Mac OS programmers still code in Pascal - and that’s OK. But they (and MacTech
Magazine, too) should give another language a try. No, I’m not talking about C++ or
Java; I’m talking about Oberon-2 (Pascal’s grandchild, so to speak). Interested?
Then read on.
MacOberon, Oberon System 3, and Oberon/F generate 68K code. PowerOberon
generates PowerPC code, but has no linker yet. Or you can use MPW. The URLs are:
ftp://ftp.inf.ethz.ch/pub/Oberon/
ftp://oberon.ssw.uni-linz.ac.at/pub/Oberon/PowerMac/
http://frodo.informatik.uni-ulm.de/projekte/MPWOberon/
As a CodeWarrior, I hope that Metrowerks will integrate this fantastic language
into their IDE. But, till then, I’m perfectly happy with C++ and PowerPlant.
By the way, to “serious” Oberon users I recommend Programming in Oberon and
Object-oriented Programming in Oberon-2 (both from Addison-Wesley).
Paul E. Sevinc
[Our paucity of articles written in Oberon is not due to any want of trying. In fact, we
have a review of Oberon/F in the works; watch for it in a future issue. As always, the
best way to ensure coverage of your favorite area of expertise is to participate by
writing us an article yourself - man]