Smalltalk and Object Orientation: an Introduction - Free

Compatibility (or code generation) for Smalltalk. For Smalltalk to continue as a commercial success it
is essential that it gains a similar level of support in this area as C++.
33.4 The internet and objects
The world wide web (or just the Web for short) is one of the phenomena of the last few years. It is set to
revolutionize the way we think about computers and computing. However, at present most information
available on the web is in the form of static web pages. These are useful in providing information but
are fairly limited in their ability to do much more. Java has of course allowed Web pages to possess at
least some dynamic element, however the majority of Java applets on the Web make little cartoon
characters do something. To gain the full benefits of the Web it is necessary to be able to connect
applets, downloaded form the Web, into corporate databases or to existing programs. Such an ability
will open the Web up to a huge range of applications both within and between corporations.
Java, of course, has already guaranteed that object technology will play an important role in the
development of such applications. Java is in many ways just another object oriented language, which
like Smalltalk, is not compiled into an executable but into byte codes which are then “executed” by an
interpreter (or virtual machin e). Thus any Java applet is an object or set of objects which communicate
with each other via message passing. Thus these applets should be capable of communicating, relatively
easily, with a distributed object system. Indeed developments are already under way to link Java applets
to CORBA compliant ORBs, and to OLE/COM.
To simplify this sort of task, special OO WEB site development tools will be (and are being)
developed. It is also likely that many of the existing OO CASE tools will provide Web additions s o that
they too can be used with the Web and for Web development.
However, which language will dominate, and which type of distributed system will be adopted, are
two different questions. Java will certainly be the dominant Web language, although there is no great
reason why Java should be any better as a Web language than Smalltalk or any other interpreted OO
languages such as Objective-C or Eiffel, other than the fact that Java got there first and has the backing
of both Netscape and Sun. However, in earl y 1996, ParcPlace-Digitalk released VisualWave. This is an
application development environment (ADE) for building live applications on the Web. VisualWave
runs on VisualWorks and hides all the HTML (Hyper Text Markup Language) and CGI (Common
Gateway Interface) details from the developer. Instead, the developer can concentrate on creating Web
applications in a Smalltalk environment. This allows the user to access multiple databases, use
interactive window building tools, Smalltalk classes and the VisualWork s browsers to develop
applications. At present VisualWave relies on the use of a CORBA compliant ORB, however it claims
that it will be able to access OLE components soon.
It is interesting to compare and contrast Java and Smalltalk. Smalltalk appears to be the better OO
language for the internet as it is not a hybrid language and has many features built into it which would
work well with the Web. This means that it is likely that companies which already have significant
Smalltalk experience will stick with Smalltalk and use VisualWave, although many others will swallow
the hype surrounding Java, and go with it.
The question of which distributed object technology will be adopted is more complex. OMG would
certainly like CORBA to be adopted as the accepted standard, while Microsoft would prefer their own
OLE/COM infrastructure standard. An open question is what will Netscape do? It is probable that
Netscape will do both. For examp le, Sun have already linked Java with CORBA and Sun and Netscape
are closely linked, but a great deal of the world uses Microsoft products.
33.5 Object oriented databases
An object oriented database system is one which relies on an object-oriented view of the world, that is,
uses classes and objects as the basic storage mechanism rather than forms and tables. In general these
databases are also quite flexible about the type of data they hold including text, programs, graphics,
video and sound. However OO databases have been fairly thin on the ground until recently. The main
players in this field have tended to concentrate on Smalltalk based systems. Either providing Smalltalk
binding or in some cases implementing the system in Sm alltalk and treating Smalltalk as the database
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