Updated 2018-04-22 12:16:48 by paul â–²

This page describes the Second European Tcl/Tk Users Meeting held June 7-8, 2001 in Hamburg, Germany.

The presentations of this meeting are available at the EuroTcl site.

Here's a report posted by Rolf Ade on comp.lang.tcl: (Too sad, nobody has reported about what has happen at the 2. Tcl/TK European User Meeting at Hamburg-Harburg at the 7th and 8th June 2001. Therefore a few notes at my own. Excuse the clumsy English.)

It was great to be there; thanks again to Carsten Zerbst, for organizing this meeting the second time.

At both days around 40 Tcl'ers met in the rooms of the Technische Universität Hamburg-Harburg. It was truly an European meeting; about half of the participants were Germans, the other half traveled there from England, Italy, Switzerland, Netherlands, Finland and maybe some other countries.

The major general themes of the talks and the private discussions between the talks are not uncommon to the readers of c.l.t. To name a few: Tcl is really, truly great for embedding, there is a pressure need for a central extension repository or a least a batteries included distribution, and what happened to Paul Duffins feather.

Undoubted, there is only a small tcl community. But this doesn't truly reflect the wide spread usage of tcl within the industry. Everybody at the meeting reported about some tcl embedded commercial applications. Do you ever heard about a commercial package, that has an embedded perl interpreter?

In his keynote, Andreas Kupries gave an overview of what has happen in the tcl world in the last year and what is coming in the near future (new alpha/first beta of tcl8.4). He pointed out, that the Tcl Core Team (beside the fact, that a lot, maybe most of the real core development is done by TCT members) isn't the tcl core development team, but more of a coordination and regulation instance. Everyone is invited to involve ideas to make tcl a just more useful thing, writing TIPs and implement the ideas in coordination with the TCT. The closing "Oustervote" was about which extensions should be included within a batteries included distribution.

Andrej Vckovski, from the swiss netcetera, held two impressive talks, the first about Tcl as a strategic development platform and the second about building web applications, especially using the netcetera tool websh (available as Open Source). The history of the at the moment 60 people company netcetera is a clear tcl success story. They use tcl for building web applications, CORBA Services, internal tools, process support, test automation, gluing legacy application, products and embedding. It's unimpossible to summerize in a few words all the good points Andrej made about themes like "selling" tcl and packaging tcl applications. His talks showed very clearly, that the folks at netcetera have deep experiences in building large and complicated web applications. Therefore, if you are in the same area, websh may really worth a try.

Franco Violi presented another impressing example of successful commercial tcl usage. Beside the already last year presented TclCobol (an interface between Cobol and Tcl/Tk) his talk was focused on his [TclDirectory], a Tk Interface to LDAP Servers, and a new toolkit, that is able to generate database GUI's out of a small, compact description, which dramatically simplifies legacy application development. A part of this is a set of "legacy widgets" for special datatypes. Franco promised to publish the code of at least some of his tools to sourceforge within the next weeks and months.

Uwe Zdun's Introduction to the OO package XOTcl triggered probably the most discussions of all talks. In some sense XOTcl is really different from most other tcl OO extensions, including itcl. Uwe and his co-author Gustaf Neumann are claiming their OO system is much more the "tcl way" of doing OO development, than every other tcl OO extension. XOTcl is a "slot based" OO system with a lot of capabilities like introspection, dynamically changeable objects, classes and superclasses, per-object mixin of classes into the precedence order of an object in front of the precedence order implied by the class hierarchy (used for object-specific extensions), and special filter methods, that are automatically invoked, every time an object receives a message. Some yelled "clearly wrong" about some of the ideas, others where thrilled exactly from the same ideas. I'm at least sure really a lot of the tcl european meeting participants will take a closer look at XOTcl at home within the next weeks.

The second day started with a talk from Stefan Finzel about how to write "proved" and certificateable tcl code. He found the Tcl/Tk Engineering Manuals useful, but not specific enough, and defined himself a set of around 200 additional coding rules. He also promoted the use of code checker programs, like frink and procheck. Additional, he has written code checking tools by himself, especially for checking the usage of variables. Stefan promised to publish his coding rules and his code checking tools at the tclers wiki.

Jochen Loewer talked about what has happened with his tDOM package (for easy and powerful XML/DOM processing with an extra focus on expressiveness and performance) since his last year talk. How fast and less memory hungry his tDOM package is showed a few test results compared with the results of the lately published "Java XML Representations Benchmark". Compared with the six most popular Java XML/DOM Implementations, tDOM builds a DOM tree 5 to 15 times faster, while using 3 to 4 times lesser memory. Since the last year, the C coded Xpath implementation included in tDOM was quality improved. Jochen added a HTML reader to the suite, to build DOM trees from HTML files. A fast XML validator module was added to the package, that allows to validate XML documents against their DTD, while building the DOM tree or using the SAX interface of the package. tDOM is thread save now, and work is ongoing, to share DOM trees between threads. Jochen has added a C coded XSLT engine to tDOM, that allows to transform the in memory XML data. Although this is at the moment a work in progress, it has started to be useful for simple XSLT stylesheets and tasks. Although tDOM isn't very present in public perception, there are a few commercial applications, that are using it.

[Carsten Orthbrandt] presented a success story about using tcl in an area you may never have minded: tcl as scripting language for professional game development. Carstens company, SEK-Ost, uses tcl as scripting engine within the game itself and also for workflow tools in the production process. They use tcl only embedded and don't use Tcl DLLs but link statically. They have done a couple of interesting things with and to tcl. For example they added a "pre-processor", to provide a different mechanism for comments, skipping the "not strictly intuitive" way of tcl comments, and to be able to do some C-like conditional inclusion of Tcl sources. They are using one tcl interpreter per game object, that means hundreds or thousands of interpreters at a time. Every created game object calls some class scripts. To circumvent reloading and compiling of otherwise constant scripts, they added a bytecode cache, that keeps all loaded scripts in memory and returns the preprocessed and (if it was evaluated before) compiled Tcl object on successive requests for the same tcl file. For use within the game, they added over 600 custom commands to tcl. They also had some big problems, Carsten said. Handling of C++ object references in Tcl was one of the bigger challenges. A custom type for smart object pointers didn't worked out, because of the limited control over the lifetime of custom type internal representations. On top of there tcl wishlist are a lightweight tcl (because they don't use events, sockets or reg expressions) and the possibility of opaque types. Indeed they are thinking about rewriting tcl for there needs, Carsten told.

Arjen Markus talked about using tcl to generate test programs and libraries written in some other procedural language, lets say Fortran 90 or Java. Basically, Markus tcl program (which he calls Testmake), generates from some skeleton code and the user defined test input (in a very simple "data-like" syntax) full working test programs.

Very promising sounded the talk of Mr. Vogler from the German federal office for environment protection. They developed together with an industry partner some kind of generic database access for tcl. To do this, they defined an abstract layer above existing tcl interfaces for several databases, including Oracle, MySQL, PostgreSQL and ODBC. Since they only manage the abstract layer, they can only build "generic" database commands for the "common denominator" of the functionalities provided by the several underlaying database interfaces. They already have the commitment of the federal office to make the package public available as open source, after they finished. This is remarkable, as they pointed out, because it truly isn't common for German federal offices to do this. 80 to 90 percent of the code are already done, they said. Await the package to be available anytime in august or september.

The maybe most entertaining talk of the meeting was held by Lindsay Marshall. He reported about his experiences using tcl/tk on the iPaq PDA. The first step, if you also want do this, is to replace the standard Win CE (or whatever) OS of the iPaq with a linux installation, which is, according to Lindsay, quite easy. After crosscompiling and copying across, wish worked straight away, he said. The major practical problem while using tk applications is more or less obvious: the iPaq has, as any other PDA, a really small screen, compared to a typical desktop system. After reducing the default button text typeface (and also the width of the scrollbars) Lindsay was able to use his IRC client Zircon at his iPaq. At top of Lindsays wishlist for an "PDA tcl/tk" are anti-aliased fonts support (crucial because of the needed small point sizes of the fonts) and a more easy and centralized way of adjusting some defaults like the font sizes.

Kristoffer Lawson talked about a high-level protocol, object system and related libraries for controlling and building user interfaces to work with a large variety of display platforms, without change to the application. The major point of the hole system is to describe user interfaces in terms of abstract objects forming a tree structure, similar to what LaTeX and XML do in the field of documents. Out of this description a display server is rendering the user interface. Tcl comes into the story if you ask for code. Kristoffer and his co-workers have already a Tcl/XOTcl client library to talk to a display server, and, beside a HTML display server, a basic tk display server.

Unfortunately, David Welton couldn't manage to come to the meeting, to talk about his apache module mod_dtcl.

Andreas Kupries also posted a valuable summary [1] to comp.lang.tcl.