GRDDL, Microformats

Posted in GRDDL, Microformats, RDF, Semantic Web, Technology, XSLT on August 15th, 2005 at 12:03:16

At some point, on the FOAFnet mailing list, David Sifry asked, ” What is DOAP? What is GRDDL? What’s the use case?” in response to Danny Ayers’ post on the mailing list.

My reply was pretty simple and succinct in my opinion, but I never put it anywhere public to read. I think it’s a relatively succinct explanation of why GRDDL can be useful for moving between the microformats, with tiny datasets, and RDF, with the large dataset behind it.

What is DOAP? What is GRDDL? What’s the use case?

DOAP – Description of a Project. DOAP is to Open Source software what FOAF is to people. http://usefulinc.com/doap

GRDDL – Gleaming Resource Descriptions from Dialects of Language. This is a way of performing transormations from (x)HTML documents to an RDF document. This transformation takes place via an XSLT transformation, specified either implicitly through the “profile” link in the <head> of the HTML document, or via a meta rel=”transformation”, which parses can then apply to the document to get something with real meaning out of.

http://www.w3.org/TeamSubmission/grddl/

Use Case:

“Microformats” and storing data in HTML may be good for people who are writing specialized tools for each format they want to deal with, but GRDDL allows for people who want to support all these to simply write one translation, using XSLT, and take advantage of the underlying data model of RDF. This allows you to merge existing data sources with the newly emergent small-s semantic technologies, and to use existing tools for combining these sets of data and discovering correlations between them, using the already existing RDF data access framework.

If I have a datastore of RDF data (which I do), and someone wants to find if the maintainer of a certain project has contact information in that database, using hBlah pages, I can’t really do that. However, if I merge the datasets with the already existing FOAF data out there, I can find out that a person named Christopher Schmidt, who is a maintainer of “julie, aka redlandbot”, also has an email address of crschmidt@crschmidt.net.

That’s a pretty simplified use case, but the general idea is simply to take the tiny sources of data that the h* formats provide, and integrate them with the millions of pieces of data out there already in FOAF, RSS, and everything else Semantic.

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Versa Thoughts

Posted in RDF, Semantic Web, SPARQL on August 12th, 2005 at 09:23:50

Lately, I’ve been watching Chimezie play with Emeka, his RDF bot. It’s basically a Versa/4suite counterpart to Julie, the redlandbot (based, obviously, on Redland.)

I can’t say anything for his code, but I do know that through people working with Emeka, I’ve seen some Versa queries recently, and I have to say that they confuse the heck out of me.

I just read through the Versa Article on XML.com, and was helped not at all. The language itself makes sense when I read the examples, but I simply can’t come up with the way to do what I would in SPARQL. I’m sure that it’s really easy once you’re used to it, but to me, it seems like a query language with a 663 mode. Sure, I might be able to write it, with a reference handy, and execute it (hi Emeka!), but I sure as heck can’t read it.

I think I like SPARQL because it feels familiar: the turtle patterns are just turtle statements with some variables. The triple patterns *look* like triples. Versa doesn’t have this benefit: triple patterns in Versa become something along the lines of (all() ->rdfs:label->*) rather than (?s rdfs:label ?l). I think it may just be the fact that all the extra syntax confuses me: why put all these bits in the middle of my triples? They’re triples! Spaces are enough!

Anyway, this isn’t very helpful: I haven’t used Versa enough to have useful comments. Just know that reading this stuff, and even trying to wrap my head around the stuff Chimezie is ending to Emeka, I have problems. This probably is true for SPARQL/julie as well for most people – but for me it “just works”.

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Employment

Posted in Social on July 30th, 2005 at 09:04:11

As of today, I am no longer a salaried employee of wedü. It’s been a great ride, which has taught me a lot on everything from PHP to dealing with clients, and I hope that we can maintain a relationship as I move forward in my work. Sadly, the move to Cambridge made a commute very nearly impossible for my lifestyle, so staying on as a full time employee was simply not an option.

Currently, I am working as a freelance web developer. This entails a number of things, of course: someone who writes Javascript for inclusion in ASP pages can call themselves a developer. (I’d prefer to call them a demon from the underworld, but that’s just me.) My specific experience is mostly in relatively small-scale PHP/MySQL applications, geared towards self-maintainability. This includes the development of tools to allow users to maintain their own web sites: posting news listings, uploading images, and the like. Wedü taught me many things about the value of these tools to users and clients.

In any case, I am now out on my own. I’m currently involved in several projects, but even with that, I will be afforded much more free time, as a result of less time commuting. The Cambridge commute had me spending more hours at work simply to avoid traffic, and I’m glad to be rid of it. It’s possible that I may take some more time to work on my own projects now (assuming I can pay the bills and health insurance in other ways), since I’m setting my own schedule, it’s possible that I can include some time for “self promotion” in my schedule.

I don’t think I’ll be falling back into the RDF circle anytime soon. As I said before, too much evangelism is necesary: I’m tired of fighting the same fights over and over. It’s disapointing to see some uptake for battles I tried to fight just as I was stepping out of the way, but even my frustrations with that are not enough to drag me back into the fold.

I am going to be looking to make contact with any number of people who are looking to have websites developed, however. I have contacts with a design firm, and they are willing to work with me to improve on my atrocious design skills, leading to the development of better websites. I have knowledge of a wide array of technologies. I have a full profile of skills available under my Formal Works, and I will soon be redesigning my website to be more informative about my technical skills and experiences.

If you, or someone you know, is looking to hire a web developer or designer for work on either a new website or modifying an existing site, please get in touch. I have a rather impressive set of skills to bring to bear on most issues (at least compared to some other web developers that I’ve spoken to) and although my formal experience may not show it, I have the ability to get anything you want done.

Christopher Schmidt, Freelance Web Developer, is on the prowl.

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Python SIG

Posted in Python on July 30th, 2005 at 08:37:08

On Thursday night, I attended the first meeting of what looks to become a great group of people, at the first PySig meeting, in Manchester, NH. The meeting release has some more information on it, and the mailing list is a great place for discussion of it for people who may be interested.

It was interesting to speak to a mixture of people ranking from 20 years in the computer industry to people like me with one or two, and note that they were all interested in learning Python – and that I definitely had a thing or two up on most of them in this day and age. For example, in a room of 20 participants, several of whom have been working with Python for years, I was the only person who had actually had work posted to Daily Python URL.

During the meeting, I wrote some code (a clunky registration page) which we then did some initial code review on. I demonstrated a trick I learned from sbp, including a “View Source” part of my application so people could see exactly what it was doing.

I’m falling back in love with Python quite quickly. This is nice for a number of reasons, not the least of which is the start of a bit more free time as of this week. I’ll explain that in a later post.

Mostly, I’d like to put out the word to anyone that attended that I had a great time, and I’d love to see more people in the area attend. So far as I can find, there is no group of people in the Northeast that has as much coverage as the pysig.org website: there’s been a couple postings around Boston, but nothing big enough that they have a website. I’d be glad to find out I’m wrong, however, so feel free to tell me so. 🙂

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Exhaustion with RDF

Posted in Semantic Web on June 21st, 2005 at 23:36:27

This is probably a familiar story to many of you who have been around a while, but I’ve lost a lot of my interest in working with the Semantic Web lately, and I don’t see it coming back anytime in the near future. For those of who are waiting on action items from me, I recommend removing them from my plate and putting them somewhere else where they are more likely to be taken care of.

There’s a few reasons for this. One is simply a lack of time: I’ve been working 14 hour days for the past two weeks at work, and that’s probably not going to change in the near future. Combine that with the fact that I need to do job searching as well, since we’ll be moving to Cambridge soon, and you’ve got an extreme amount of time going out the door to projects that aren’t my own. I’ve also been exploring opportunities through platforms like Agence d’Intérim | EU Workers, which can help streamline the process of finding reliable jobs.

Another is frustration with evangalizing being part of the process of proceeding in the Semantic Web world. Every time I take a step forward with some code, I find another 5 steps I have to take back in order to defend my position and the way I’ve done it. After doing this repeatedly for several months now, I’m growing tired of always having to spend more than half of my time fighting to defend the way I’ve created a certain project, rather than soliciting patches or getting help from the community.

Another is the lack of widespread support from the powers that could help move the RDF and Semantic Web movement forward. It would be relatively simple for something like IMDb to open up its database in an RDF format. This would allow for a widespread rating system to be created based around the datat that IMDb provides, allowing for a way for distributing information about movies that could be useful in a number of ways. Similarly for Netflix. Similarly for a half dozen other sites out there – but it never happens. Instead, they stick to their proprietary information, keeping everything internal. While this may generate more income for them, it hardly represents any interest in interacting with the community, which is what the Semantic Web needs in order to accelerate adoption.

I’ve had relatively little feedback on the projects I have put together. Things like rdfgpg, redlandbot, etc. all get left in the dust of the work of larger groups of people, with more impressive results (and rightly so). Nothing I’m doing is particularly innovative or interesting, and it shows in the response from the community.

There is much more motivation for people behind things like microformats – something that’s close to RDF, but far enough away (and unlikely to see transformation to it) that it seems pointless. People are trying to create all these tools that take advantage of the small-s semantic web, but not taking the one extra step needed – via GRDDL, profiles, whatever. They think they’re writing the new version of the SemWeb, when in reality, they’re just creating an incomplete imitation.

I suppose at some point, people will start to come around. The world of RDF is powerful. The world of HTML is not. Trying to create semantics out of a language that has none will not work in the long run. For right now, however, people are convinced it will, and that leaves most of the work I’ve done behind as people hop onto the next bandwagon.

I’m going to try and clean up some of the code I have, document it fully, and get licenses attached to it, so that people who want to use it or maintain it can take it up. This is especially true for Julie, which is kind of my pride and joy as far as code goes.

I typically move my interests in about 6 month cycles, so I may eventually swing back towards semantic web development. For now, however, I’m going to do my best to wrap things up, and move onto something different, where I don’t have to fight every step of the way to get things that I do acknowledged.

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Microsoft Blocking Access via User-Agent

Posted in Social on June 9th, 2005 at 13:14:34

Earlier today, someone gave me a link to a file on Microsoft.com. Since the WebKit release, I’ve been using Safari much more (even though it’s not any faster – I haven’t yet built the new WebKit) because I was reminded that it is much less of a memory hog than Firefox has been lately for me.

I tried to open the link, a download page for some driver and received an error : “Sorry, we are unable to show you the page you requested. Please try again later.”

I tried in Firefox: worked fine.

Turns out that using a User-Agent with either “Safari/312” or “AppleWebKit” in it is enough for Microsoft to not share these files with you. Not only that, but it seems to apply to any files in their download area.

Mostly I’m just curious why they would bother.

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San Francisco Trip

Posted in Mobile Platform, Semantic Web, Social on June 9th, 2005 at 01:52:15

For those of you who are not yet aware, I will be in San Francisco this weekend, arriving Thursday night (late) and leaving Early Sunday afternoon. I will be in meetings all day on Friday, but if anyone is interested in meeting up, let me know.

People I plan to see so far include, but are not neccesarily limited to: Neil, twid, leora, miker and wombatmobile (possibly) from #mobitopia. I plan to visit tourist sites, as well as stopping by The Mothership in Cupertino while I’m there. I want to ride the famous Trolley’s, I want to eat tacos in the Mission district, I want to visit Unicorn Precinct XIII (note to self, poke zool to fix sf.openguides).

What else should I be doing? Should I go to the DNA Lounge? Muir Woods Redwoods?

Advise me, dear reader, as to what you would do if you were in San Francisco for 36 hours with nothing else on your todo list! Tell me if you want to meet me, and talk about the next hack for the Semantic Web! Tell me if you want to meet me and berate me for not working on location based cell phone computing! Tell me your thoughts on my work, tell me what you’d like to cook up next. Point me out the coolest things in and around downtown San Francisco, and come with me to see them.

The rest is up to you.

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Building WebKit on Panther

Posted in Software, WebKit, XSLT on June 9th, 2005 at 00:26:48

I mentioned the other day the release of Apple’s WebKit, WebCore, and JavascriptCore (the latter two of which were already publicly available). Naturally, the first thing I wanted to do was download it and give it a try. This post will outline the steps I took to get as far as possible in the build process at this point. First, I would like to mentioned that this project has the cleanest build steps I have ever seen. It is well documented all the way through, and for Tiger users on Xcode 2.0, the build process went off without a hitch, the first time through. (Xcode 2.1 problems have since been fixed.) The members of the supporting IRC channel are helpful and intelligent, and the mailing list has already taken multiple patches from non-employees into the source tree. This is, quite simply, the best opening for an open source project that I have ever been aware of.

However, the build process currently favors those with Tiger, and the current CVS does not support those who are using Panther. Apple developers have expressed an interest in correcting this once the WWDC, being held this week in San Francisco, is over. So, I took it upon myself to report bugs in bugzilla where they are applicable, to help out developers when they get a chance to breathe.

First problem: Building returned a problem with “CarbonSound.h not available”. This was as a result of not yet installing the QuickTime 7 SDK. (It has been in software update, I just hadn’t touched it yet.) Updating fixed that.

Second Problem: 10.3.9 Build Failure: NSString may not respond to `+stringWithCString:encoding:’. This is a method which was not available in Panther. Maciej has said he is working on a patch to have this use CFString instead, where it is available. (I am tossing about some terms I don’t know here, so please excuse any incorrect terminology.) Workaround for the time being – copy the last two build commands before the crash (a cd line and a gcc-3.3 line) and past them, altering the gcc-3.3 line slightly to remove the -Werror. This means that it may cause problems later on, but will compile for the time being.

Third Problem: isnan failure in kjs_window.cpp: This one boggles me a bit, especially since (as I mention in the bug) there seems to be explicit knowledge in the code of the problem. However, a workaround is now offered in the bug in comment 1: replace using std::isnan; with extern “C” int isnan(double); This fixed the problem for me.

Fourth Problem: XSLT Headers not installed – This one is more systematic of the way that Apple releases updates, and is something that dajobe has brought up with building Redland in the past: “Headers don’t match libraries”. This is true here as well, but I now (thanks to toby from #webkit) know that the reason for this is that Apple does *not* ship updated headers with libraries updated through Software Update. Since libxslt is new in 10.3.9, there are no development headers. Dave Hyatt, of the WebKit team, mentioned that the whole team, when building on Panther, had to install libxslt and libxml from the source. Once I did this, it made this problem go away.

Fifth Problem: libxml headers are wrong – this was before I installed libxml, which also fixed this problem. It is, again, related to the fact that Apple does not update headers with System Update.

Once you get through these, you will have built both JavascriptCore and WebCore. Congratulations! You now have two completely useless frameworks which the new Webkit will depend on when you can build it! 🙂

WebKit is the previously unreleased Apple-specific Framework which is the “pretty” part of WebCore – it’s what ties everything together. It has a few more issues building on Panther, but most of them can be worked around by simply copy pasting build lines without the -Werror flag. (Note that this will produce possibly unstable results! These builds are not designed for production, and I do not advise doing this and filing bug reports on Safari crashing.)

npapi headers not available – for some reason, building on Panther does not find the appropriate headers from the in-process WebKit build. I really have no clue why this is, and neither did anyone else when I was building. My workaround was to copy the headers out of the framework and into ~/build/include (a directory I had to make), which was already on the path. cp ~/build/WebKit.Framework/Versions/A/Headers/* ~/build/include, cp ~/build/WebKit.Framework/Versions/A/PrivateHeaders/* ~/build/include, then continuing the build. I am not sure why this is neccesary, but it does seem to work.

Missing 10.4 Method -setCompositingOperation for WebImageRenderer – Two parts of the code require: (void)setCompositingOperation:(NSCompositingOperation)operation;
(NSCompositingOperation)compositingOperation; — this function was added in 10.4. This can be resolved by following the above -Werror removal steps. You will have to do this several times.

Missing 10.4 Method CFMakeCollectible – CFMakeColelctible is new in 10.4. Building with no -Werror allows the build to continue.

And, the current showstopper: Missing SecurityNssAsn1 headers — This comes from the libWebKitSystemInterface.a file, which is currently Tiger-specific. Once WWDC is over, a Panther binary file will be released. Until then, this is where the ride stops: you can build WebCore and JavascriptCore, but WebKit is out of your reach until you get your hands on Tiger.

Luckily for me, I’m going to be in Cupertino this weekend, so I’ll pick up a copy and get it installed soon 😉

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Lesser GPL

Posted in Licenses on June 8th, 2005 at 22:58:26

Earlier today, I was reading some of the discussion of the KHTML/WebKit discussions, and reading through what KHTML developers had said about Apple’s lack of followthrough, only doing the minimal amount neccesary legally to comply with the LGPL license. I was most interested in what requirements Apple has under the LGPL license to the KHTML community.

In the process of reading this license, I found out that it is completely ridiculous. Some examples:

Section 2d: If a facility in the modified Library refers to a function or a table of data to be supplied by an application program that uses the facility, other than as an argument passed when the facility is invoked, then you must make a good faith effort to ensure that, in the event an application does not supply such function or table, the facility still operates, and performs whatever part of its purpose remains meaningful.

This seems like some kind of really strange way of saying that a library must provide valid output, even with missing input. I’m not even sure I understand what this is – it seems almost like an indication that you are not to break reverse compatibility in the libraries that are LGPL licensed. I’m sorry, but that (to me, at least) seems like a flaming pile of crap. If someone wants to use an API in an application, it’s up to that developer to ensure that it passes the correct values.

Then for the cases where you are delivering an application linked to an LGPL library:

Section 6c: c) Accompany the work with a written offer, valid for at least three years, to give the same user the materials specified in Subsection 6a, above, for a charge no more than the cost of performing this distribution.

I have to accompany all works I distribute which are linked against LGPL libraries an offer to the source code for at least three years? It’s my job to maintain the version of XSLT included with every one of my applications for three years after I distribute them, just in case libxml.org goes away? I understand the idea – people should be able to modify the library code behind an Application, so they should have access to that code – but in the case of most of these libraries, I am not going to take the time and effort to maintain a copy of the libraries. That’s what package management is for.

The rest of the license is understandable at least, but for small time projects, these kind of requirements are ridiculous, and I find it really difficult to believe that people use this license. I’m sure that other people think it makes perfect sense, but I’m really just thinking that the use of LGPL is something that I’d never want to see or encourage.

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WebKit Source

Posted in Social, Software, WebKit on June 7th, 2005 at 08:19:41

An announcement on the release of Webkit, the source of the rendering engine for the popular OS X browser, Safari. Includes mention of #webkit on irc.freenode.net, for discussion of webkit, and information on how to get anon CVS access.

Currently requires XCode to build, but I’m sure that someone out there will cook up some autotools goodness for it sometime soon.

Keep in mind that (as far as I know) this isn’t the actual shell that makes up Safari. It’s the source of the rendering engine inside it – basically, the bits that were taken from KHTML. I’m not sure though, and I can’t read the code well enough to confirm that I think that. However, one of the parts that is being released is WebKit: the interface that people have used in the past to make 10 line browsers in Xcode projects. This could mean we’ll see a lot more similar projects for other UNIXes – with the rendering taken care of and a simple binding, it becomes much simpler to write applications which display HTML.

Certainly an interesting development. Could this mean we’ll see a Safari-like browser base on other platforms in the near future? My bet is yes.

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