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Newsletter
November 1997

A Renaissance for AI
Visual Prolog goes for the Internet
TCP/IP
Intelligent Agents
Put your Applications on the Web
Juggling RTF- and HTML Documents

Debugger
Objects in Visual Prolog

Linker
Visual Prolog "Timelocked"
Short News

SCO UNIX / Linux
New Features for Fail Detection
Embed Visual Prolog into your Applications!
Expert System Shell included with Visual Prolog
New ODBCBIND
thinker.jpg (22055 bytes)

 

A Renaissance for AI

These years, the whole AI-area is undergoing some very exiting changes – in fact some have called this A renaissance of AI. The reason for this renaissance is closely connected to the development of Internet and Intranets. Intelligence on homepages is one of the hottest topics right now, and nothing looks like this will become less important. Intelligent agents will play a major part in the development of the net. As the web grows, we need more and more tools to extract the information we need. Another very important issue in the commercial breakthrough of the net is the ability to buy, pay and receive goods. Before the net can turn into a virtual shopping center, we need good tools to attach applications to homepages. Everyone will then be able to buy consultant help, for your homepage or use an expert system to choose from the millions of products on the web.

Of course, all these trends are being followed very closely by the development team behind Visual Prolog, so that Visual Prolog, probably the worlds best visual development tool, can meet all these new demands.

Visual Prolog goes for the Internet

An example: Your support team would be relieved by an intelligent web site, which can diagnose and give advice for the 10 most common problems (that causes 90% of the phone calls). Another example could be an intelligent web site that could help customers make the right decision about which product to choose. In both cases, a Visual Prolog application attached to the homepage can do the trick. The new Visual Prolog version 5.0 includes lots of tools for applying logic to the web: agent-technology, good document handling tools, facilities for publishing applications on the web and of course support for the basis protocols. With Visual Prolog, you can develop Prolog applications and attach them to the web. This gives possibility for customers to use Visual Prolog programs through their browsers.

TCP/IP
TCP/IP is the protocol, that is be used to establish a communication between programs over the Internet as well as internally in an Intranet or between two programs on the same computer. Visual Prolog contains bindings to Sockets, the API to the TCP/IP-protocol.

Both FTP (file transfer protocol) and HTTP, the basic protocol used by the World Wide Web, is supported in Visual Prolog 5.0. You can use the Internet FTP to send and receive Files from an Internet server, as well as you can use the Internet Hyper Text Transfer Protocol.

Intelligent Agents

agenthead.gif (6142 bytes)  (The picture is designed by John Burman)

Visual Prolog is an excellent tool for designing Internet agents, because of its rule based nature and good web support. On the Visual Prolog CD, you will find the source code for two Internet agents, that can easily be modified to your purposes. Being able to easily retrieve, parse and analysis pages from the Internet opens up for many interesting applications.

 

Put your Applications on the Web
CGI-bin is supported and gives possibilities for creating Visual Prolog programs that generate dynamic WEB pages with forms. You can also make a Prolog server that communicates with JAVA applets. These features all meet coming demands for trade and advertisement on the net!

Visual Prolog can also take advantage of the Internet Server API (ISAPI) frame work , that allows higher performance scripts on the Microsoft Information Server. You can get much higher speed on the web through ISAPI than CGI, because the program is placed in a .DLL that does not need to be started each time like a CGI executable.

Juggling RTF- and HTML Documents
Good document handling tools are as important as ever when developing web sites in HTML, making multimedia or constructing Windows help files, Word documents, Internet assistants etc. In Visual Prolog these different document types can all be represented in one common structure. This makes it easy to handle and convert documents, totally independent of the actual format, whether it is .RTF, HTML or .IPF. You can generate and import these formats easily with the build-in Visual Prolog documents handling tools.

 

Debugger

Programming in Prolog is usually quite easy, but when you work with larger Prolog programs, you will find the Visual Prolog debugger an indispensable tool. The debugger has all the facilities of debuggers in other modern development environments. It works on the compiled code. This makes the program very stable and completely independent of the Visual Prolog development environment and the program, being debuggeds behavoir.

The browser will be welcomed by many users. This gives a fine and very good view over the modular structure of a project. Here you can examine the program in a tree, similar to the windows File Manager/Explorer.

As in other debuggers, you can of course set breakpoints, at any place in the program. Of course the debugger also supports some of the special features of Prolog. You can set up a goal tree, and you can specify how deep you will allow you program to fail and exit. You can debug the predicates, set a maximum backtracking level, a very usefull run-until-fail-facility, and if this exceeds, the debugger will start single stepping. At any point in the program, you can single step through the execution, or ignore certain predicates.

This, combined with the very nice view facts, call stacks- and variables-dialogs will give you maximum overview over your program. Actual values of variables can be obtained just by moving the mouse over a variable, like the windows-style tooltips. All in all - a very nice tool for debugging prolog programs!

A user, who has been doing largescale programming for lots of years, told us:" I used a debugger back in the UNIX-day, but I never cared much about the debuggers, that is normally supplied with the traditional graphics development tools. The VIP is though a very useful tool, because the semantics of Prolog can be more complicated. I use the Facts-window a lot! The Visual Prolog Debugger has reminded me of the value of good debuggers."

Another user: "I actually just use the setting of breakpoints and viewing local variables. Just these 2 small features has made my development time much shorter".

The Debugger is included in the Professional version only, and can debug 32-bit applications in Win NT and 95 mode (not OS/2 at the moment).

(More detailed information about Debugger)

 

Objects in Visual Prolog

Object orientated programming is a nice way to model real-world problems. In Visual Prolog 5.0 we include support for Objects and Classes. The new object-mechanism in Visual Prolog will put an end to the struggle between logic programming- versus object oriented programming-addicts. Visual Prolog does now, as professional development environment offers both object-oriented and declarative methods. The design is similar to the design in standard object-oriented programming languages, so if you know how it is done in one of these languages, you will immediately be acquainted with Visual Prologs object-orientation.

Example:

CLASS Truck

PREDICATES

Calculate_max_speed()

ENDCLASS Truck

IMPLEMENT Truck

Calculate_max_speed():-

ENDCLASS Truck

GOAL

Object = truck::new,

Object:calculate_max_speed(),

(More detailed information about Objects)

Linker

Visual Prolog 5.0 contains a new linker which is able to generate 32 bit Windows-NT and Windows 95 as well as 32 bit OS/2 programs without the use of an external C compiler.

 

Visual Prolog "Timelocked"

We are happy to present you to the Visual Prolog 5.0 trial version! The timelocked version includes the complete Visual Prolog compiler and development environment for you to study and work with.

Comprehensive demo programs and examples are also included, and if you are not already familiar with Visual Prolog - you will realize that it is a powerful language with unlimited possibilities.

You can download Visual Prolog "Timelocked" for free from PDC's Homepage (www.pdc.dk). You can use this version within 30 days and we hope you will enjoy it and you will want to obtain the full version.

 

Short News

SCO UNIX / Linux

The Professional version of Visual Prolog does now support SCO UNIX and LINUX. It contains a command-line compiler so it is possible to create command-line textmode utilities under SCO UNIX and LINUX. This makes it possible Visual Prolog to make portable programs between the operating systems: SCO UNIX, LINUX, OS/2, Windows 3.1/95/NT and DOS. Note that VPI is not supported.

New Features for Fail Detection
In the traditional programming languages, a "spaghetti program", is a program where the programmer does not have a clear structure in the program. The equivalent problem in Prolog, is a program where the Programmer has no clear knowledge about whether the predicates are non-deterministic, whether they can fail or whether they behave like regular procedures. In Visual Prolog it is now possible to specify whether predicates are non-determ, determ or procedures, and the compiler will check and warn you if you make a mistake. Such checking can save many debugging hours!

Embed Visual Prolog into your Applications!
I version 5.0 (professional version only) there is an example on how you can include the Visual Prolog compiler in your programs. This can be an extremely strong feature, in situations where your design "rule compilers". You can design applications, that can take rules as input and compile these to new, very fast DLL’s, using Visual Prologs powerful rule based kernel. Note that it requires a runtime fee to include the Visual Prolog compiler and linker.

Expert System Shell included with Visual Prolog
The well-known expert system shell, ESTA has now been reprogrammed to the VPI layer and included, with source code, in Visual Prolog version 5.0. ESTA can be customized to various purposes. It has previously been modified to an environment for generating on-demand special insurance's.

New ODBCBIND
We have added full bindings to the ODBC API allowing Windows applications to take advantage of all the features in the ODBC API. Some programs need to use every special feature, and if portability is of no concern, it might be desirable to use ODBCBIND instead of the more portable SQLBIND!