If you’ve paid any attention to the web standards discussions, you may have heard the phrase “Semantic Web”, or perhaps even been pressured to use standards with names like “Dublin Core Metadata” or “RDF”. If you’ve attempted to read any of the available documentation on these topics, you were probably intimidated by terms such as “reify” and all sorts of artificial intelligence concepts. This document attempts to explain what all of this chatter really means, and help you decide which parts you should care about and why. I have tried to use common-sense, real-world examples and stay away from complicated terminology. Please contact me if you find significant omissions that you would like me to correct, or if you find certain portions of the explanation unnecessarily complex.
Disclaimer: I am not responsible for evaluating any business strategies related to the subjects covered here. I was not asked by my employer to create this document, and nobody at my company endorsed or reviewed it. This is simply my own personal perspective after recently researching this topic, and I reserve the right to completely change my mind about the opinions expressed here at any time. It is nearly Valentine’s Day, and nowhere in this document do I use the word decommoditize. This paper is copyright Joshua Allen. I wrote this, and if you try to change it or claim credit, you will be taunted mercilessly.

Reinvigorating the Web

The web was pretty revolutionary, right? Before the web, we had systems like HyperCard which let us create documents and hyperlink those documents together. But the web was world-wide. Anyone with a server could publish documents for the rest of the world to see, and you could hyperlink any document to any other document. It didn’t matter if the page you were browsing was being served up by some guy in Kuwait from a Unix server, and your web site was running on a Macintosh in Boston; if you could browse the page, you could link to it. These early days were exciting indeed, but we’ve been excited about what is basically the same old web for the past ten years. Hyperlinking to everything in the universe is cool, but it’s become rather boring. Now that we have all of these document linked together every which way, isn’t there something more we can do with them?

Some Examples

Here are some examples of things that could be done to make the web a better place.

Context-aware Links

Suppose that you are browsing a web page that uses the word “reify”, and you want to know what that means. You also happen to know that you can look up any word by using a URL like http://www.dictionary.com/cgi-bin/dict.pl?term=someword (Replace someword with the word you want to look up). If the author of the page had added a hyperlink like this to the word “reify”, you would be able to click on it to look it up. But why depend on the author? Why doesn’t your web browser let you highlight a word, and then allow you to select a command to define the word, which just replaces someword in the URL above with the text you have highlighted? Then you would automatically be taken to the definition of the word “reify”. After looking at the definition, you might still be confused by what that word really means, but it would be a neat feature, right? Suppose that the web browser could go a step further, and recognize that the phrase Grateful Dead refers to a music group. It could then link you to RollingStone.com, even if the original author of the page hadn’t bothered. In fact, such tools are available today. Though it is not the first or the only example, Comet Systems Smart Cursors is one such rudimentary tool.

Site Information

Now consider the case of browsing a page like www.news.com. What if the browser were able to detect that you were at a news.com site, and provide you with a menu option “About the owner of this site” that could pull up company information about CNET (the owner of news.com). This is similar to the above, but in this case the browser is being smart about the whole site or domain instead of words within a page.

Continue to read this article on Net Crucible…

Forms are for collecting data, so it’s not surprising that the most important concept in XForms is “instance data”, an internal representation of the data mapped to the familiar “form controls”. Instance data is based on XML and defined in terms of XPath’s internal tree representation and processing of XML.

It might seem strange at first to associate XPath and XForms. XPath is best known as the common layer between XSLT and XPointer, not as a foundation for web forms. As XForms evolved, however, it became apparent that forms needed greater structure than was possible with simple name-value pairs. With structured data comes the need to reach into the instance data to connect or “bind” form controls to specific parts of the data structure, hence XPath.

Since XForms and XSLT are related through XPath, it is interesting to compare the two technologies. XSLT is usually described in terms of three trees, usually produced by parsing XML documents: XSLT with labeled’source tree’, ’stylesheet tree’, and ‘result tree’ and arrows

1. From input sources, typically documents, a “source tree” and “stylesheet tree” are parsed into memory.
2. Processing of these two trees forms a third tree, the “result tree”.
3. Upon completion of processing, the result tree is serialized, typically to a new XML document.

XForms processing is similar, but combines input and output into the same tree:
a single tree, labeled ‘instance data’, with arrows in and out

1. From an input source, either inline or an XML document on a server, “instance data” is parsed into memory.
2. Processing of the instance data involves interacting with the user and recording any changes in the data.
3. Upon submit, the instance data is serialized, typically as XML, and sent to a server.

Continue reading this great article on XML.com

The Web Consortium’s XML Linking working group is developing specifications to enable more advanced hypertext functionality on the Web: in particular fine-grained anchors, external annotation, and bi-directional links. This paper examines basic goals and approaches; describes HTML linking limitations XML Linking seeks to overcome; and surveys the Working Group’s primary specifications: XPath, XPointer, and XLink. As of this writing, the last two, while well advanced, are not final recommendations, and so are subject to change. Consult the W3C Web site for the latest versions.

Background of XML Linking

The HTML tag set and its hypertext element types such as A are very useful and popular, yet have difficulties apparent at larger scale and for more diverse data. These include practical matters such as divergence of implementations and mixing of formatting with structure (I, TT, HR versus H1, OL, BODY); but also more fundamental limitations:

• Element types only of certain kinds, which do not model novel kinds of information (say, PRICE for a mail-order catalog).
• Links only of particular kinds (coarse-grained, inline, one-way, and bound up with specific behaviors).

Information modelling

XML permits creating new element types, and trees of them. These can model information structures, moving markup beyond the realm of formatting [Coombs 1987]. This benefits many aspects of document development including hypertext, since documents as structures are processable for more purposes than formatting or printing: retrieval, linguistic and thematic analysis, database interchange, querying, etc. (a list of purposes is less important than the notion of arbitrary processing — [DeRose 1990]). Ordered hierarchies are particularly adept at modelling largely linguistic objects such as documents.

“Generalized”, “generic”, or “descriptive” markup has been discovered several times, apparently independently. Scribe [Reid 1981] is an early formatter based on structure rather than formatting commands. IBM’s GML fed into the SGML standard [ISO 1986]. SGML achieved widespread adoption in high-tech industries and introduced document grammars or schemas (called “Document Type Definitions” or “DTDs”) — HTML, for example, is defined by a DTD. See [Reid 1981] and [Furuta 1992] for more information.

XML [Bray 1998] is a meta-language like SGML, not a specific tag language like HTML. It shares SGML’s abstract model while removing abbreviatory features and simplifying parsing. A comparative analysis is [DeRose 1997]. Documents are ordered hierarchies of typed “element” nodes, each type supporting particular named “attributes” (in addition to its hierarchical “content”). Character data and references to non-XML data objects reside at leaves. Intra-document links can use an ID attribute type. The W3C “XML Information Set” working draft [Cowan 1999] is formalizing the structure, but an approximate example of an XML document structure is:

Read article completely on Brown University Website

Human interactions are multimodal in nature. From simple to complex forms of transferal of information, human beings draw on a multiplicity of communicative modes, such as intonation and gaze, to make sense of everyday experiences. Likewise, the learning process, either within traditional classrooms or Virtual Learning Environments, is shaped by learners’ perceptions of what is being communicated multimodally to them intentionally or not, and by the perceptible pedagogical affordances of the environment.

This paper examines the specific place of action and multimodal interaction within the learning process. It starts by defining learning and multimodal interaction. Next, it expands on an existing methodological framework for analyzing multimodal interaction in order to include affordances for learning and to visually map the central role of action to learning. Finally, it makes use of the reviewed methodological framework to analyze a video ethnographic study of interactions that take place within a graduate Design classroom.

Any view of learning reflects its underlying theories. In (he present study, it is assumed that learning is situated in particular socioculturel contexts, and it is the result of mediated experiences that are afforded (Gibson, 1986) or constrained by interactions with the situation (King et al., 2001). In this way, the possibilities and limitations for action in particular situations affect learning. Furthermore, learning takes place whenever and wherever the individual is receptive. It can have different purposes or intentions, which, according to King, Young, Drivere-Richmond and Schrader (2001), can be classified into: a) objective-driven learning, such as in instruction; b) non-objective driven learning, such as in exploration; and c) unintended learning. With regard to the relation between learning and multimodal interaction, it is possible to affirm that learning is woven with multimodal interaction. Discourse analysis studies in educational settings (Cazden, 2001; Adger, 2001; Mehan, 1979; Gumperz and Herasimrhuk, 1975) have been trying to uncover the way in which talk in school is unique, helping to explicate the actions in which learning is realized. The emphasis on the linguistic aspect of classroom interaction, however, fails to account for the multiple fused semiotic modalities that together, rather than separately, help extend the understanding of the learning that takes place.

Continue to read Abstract on Find Articles

In a sense, nobody is in charge of the web. The web is an open standard, with no restrictions on who can post content, or what that content should be about. The web belongs to everybody, and so it belongs to nobody. The openness and decentralization of the web is one of its greatest strengths. But it wouldn’t work at all without some sort of standard way of encoding the information. That’s where the World Wide Web consortium (W3C) comes in.

The W3C is an international, vendor-neutral group that determines the protocols and standards for the web. They invented HTML, XHTML, XML, CSS, SMIL, SVG, and a host of other acronyms that stand for different kinds of markup languages. Most people have at least heard of HTML (HyperText Markup Language). All basic web documents are written in HTML (or XHTML—or eXtensible HyperText Markup Language—which is a modified, XML-based version of HTML).

As the web matured, the members of the W3C realized that they needed to make provisions to ensure that people with disabilities were not excluded from accessing it. From this realization, the Web Accessibility Initiative (WAI) was born. The WAI formed a working group to draft some guidelines for ensuring disability access to Web content. These guidelines are known as the Web Content Accessibility Guidelines, or WCAG.

Continue to read this introduction on WebAim

PICS works by comparing PICS information from an HTML META tag or HTTP header with a rating file installed in the browser. Typically, the rating file is provided by a Rating Service, who also provide a script to generate PICS headers suitable for inclusion in a document.

• PICS for Users (Parents and Educators)
• PICS for Content Providers
• Tools for Content Providers

PICS for Users

While PICS is vendor and platform-independant, the major browser currently with PICS support is Internet Explorer.

In Internet Explorer, the PICS settings are found under View –> Options –> Security: Content Advisor. Internet Explorer comes preloaded with the RSAC ratings file, which is usually located in C:\WINDOWS\System\Rsaci.rat. You should be able to view this file with Notepad or other text editor; the syntax is described here at W3.org.

More than one ratings file can be installed

To install a new ratings file, download the file from the ratings service (for example, VWP1.0.rat here) into the C:\WINDOWS\System directory (actually, it doesn’t matter where, but this is the default). It should have a .rat extension. Next, in Content Advisor –> Settings –> Advanced –> Ratings Systems, select Add, then the new ratings file, then OK. Returning to the Content Advisor –> Ratings menu, you will see entries for the new ratings scheme. Typically a list of topics is presented with a slider bar for each. Move the slider bar to the highest setting in each category you wish to be able to view. You should be able to contact the ratings service for more information by clicking the More Info button (for example, VWP1.0 here).

When the Content Advisor is enabled, you can select (in Settings –> General) whether to allow viewing of unrated sites. If you select Yes, then only pages with a PICS rating exceeding your preset limits will be blocked. Unrated sites will not be blocked, no matter what their content.

If you select No, then only pages with a PICS rating can be viewed. If a page is rated with a scheme you do not have installed, you will see a message telling you how to contact the rating service. You should then receive instructions on downloading the ratings files; if not, try here at W3.org. If a page is rated with two schemes, and you have only one installed, you will not see any message. If you have both schemes installed, then the limits of both schemes must be met before a page can be viewed. A message will be shown explaining which limit(s) are exceeded. If the header for one scheme is invalid or has expired, but the other is valid, you will see no message (unless the ratings are over limit). If all the headers are invalid or expired, you will see a warning message.

At this time (IE version 3.0), only Web pages appear to be checked by Internet Explorer, though the PICS protocol may be applied to other media such as Usenet messages, IRC channels, chat rooms, etc.. As a rating method, it is sufficiently flexible to be extended to other electronic media such as CD-ROMs, and conceivably audio CDs, television programs and the like.

PICS for Content Developers

For a content developer, installing PICS usually means running a PICS generator such as this one, and including the resulting META data in the document header.

PICS allows for generic and specific labels. Generic labels apply to any document whose URL begins with a specific string of characters. Specific labels apply only to a given file.

In version 3.0 of Internet Explorer, the browser first checks the document itself for PICS data as Metadata in the document head, and also as an HTTP header. If this does not exist, it gets the homepage for the site (formed by stripping all path and filenames from the URL) and checks that. It does not check for an index page in the current directory. Thus in Internet Explorer, specific labels override generic labels. The only generic label is that of the homepage. Note that where a for option is used, in declaring a generic label, that the specified URL must match the one that the user sees. This may not always be the case when a server has more than one name, or is addressed by a short from from within the users domain.

Using more than one rating service

PICS labels may be concatenated, for instance:

<HTML><HEAD><TITLE>Joes Bookstore</TITLE>
<META http-equiv=”PICS-Label” content=’(PICS-1.1
“http://www.service1.org/v1.0″
labels on “1996.10.05T05:15-0500″
for “http://www.my.org/etc/mypage.html”
ratings (s 0 v 0 g 0)
“http://www.service2.org/v1.2″
labels on “1996.10.05T08:15-0700″
for “http://www.my.org/etc/mypage.html”
ratings (com 2 edu 1)
)’>
</HEAD>

Although HTML allows more than one META tag of one type, Internet Explorer does not currently support this.

Note that if the user only has one scheme installed, that no message will be generated if that one is under limits (the second scheme will be ignored).

Applying PICS headers to a non-HTML document

It is possible to apply a PICS header to a file such as a movie, PDF or VRML file by generating an HTTP header. Some servers, such as Apache or CERN httpd allow the use of a metafile attached to a document which contains extra HTTP headers not normally generated by the server. A header such as

PICS-Label: (PICS-1.1 “http://www.service2.org/v1.2″ r (s 0 v 0 g 0))

may be specified. Internet Explorer does not appear to support this use inside a /cgi-bin/ directory, though. (A METAdata header may be generated instead).

Tools

• add-PICS.pl - Perl script to add/replace generic PICS METAdata
• rat2html.pl - Perl script to generate an HTML form from a .rat ratings file (limited subset only)
• mk-PICS.pl - Perl script to generate HTML METAdata and HTTP headers from the abovementioned form.

This page is an attempt to provide an easily digested PNG status board–basically a place to come and see how PNG currently fares for those who haven’t been keeping up with the news page or mailing lists. It grew out of an article submitted to Slashdot in February 1999 (with a followup in June 2000), but it is intended to be more dynamic and has been redesigned accordingly.

Stability: excellent * * * * *

The PNG specification has proven to be exceptionally solid. There have been two minor updates since the 1.0 release–to clarify gamma handling and to add some new chunk types for precision color and international text–but the design of PNG is such that these additions do not prevent older apps from displaying images that contain the new chunks. In addition, PNG finally emerged from the amazingly slow process of ISO/IEC standardization in March 2004, which assures its long-term stability as an image format. It is also a required part of both VRML97/X3D and the vector-based image standard, SVG.

User acceptance: very good to excellent * * * *

Among those who are familiar with PNG, acceptance is excellent, and the most recent Unisys flap (late August 1999) further increased the level of awareness of PNG. While there are still many people who are barely aware of the difference between GIF and JPEG, much less who have heard of PNG, the number of non-PNG-Group folks who regularly post useful and accurate information about PNG (e.g., to Usenet newsgroups and mailing lists) is impressively high. In addition, application support is no longer considered extraordinary but rather is expected. Indeed, applications that do not support PNG are criticized both by users and by the trade press. And in 1999, technical publisher O’Reilly and Associates felt the market was ready for a book devoted entirely to the subject; PNG: The Definitive Guide was published in June 1999. (It turned out to be too narrow a topic to sell well and went out of print in late 2001, but it was relicensed under the GNU FDL, and the full text has been online since July 2003.)

Application support (quantity): excellent * * * * *

Virtually all graphics-related applications these days are at least able to read or write basic PNG images, and many can do both. See the PNG-supporting applications pages and freshmeat.net for details; several “new” apps are announced, discovered and/or listed every week.

Application support (quality): good * * *

The quality of PNG support in applications varies widely, but overall it is improving at a reasonable rate. Many applications now support both basic GIF-like transparency (palette-based with a single, fully transparent color index) and full alpha transparency (32-bit RGBA); a handful also support PNG’s “RGBA palette” mode (8-bit with a multi-entry tRNS chunk). A number of high-end applications now support 16-bit color channels in PNG. Support for gamma correction continues to be uneven, with many applications failing to honor the gamma information when reading images, and most of them not making a distinction between recording gamma-related information about the user’s display (lossless) and modifying the image data directly (lossy). Compression support is also uneven, with a surprisingly large number of applications writing overly large palettes, misusing PNG’s compression filters, and often providing no way of setting the maximum possible compression level.

Among PNG-supporting image editors, Macromedia’s Fireworks 2.0 and later, available for Windows and Macintosh, remains the best overall, with excellent support for PNG transparency, good compression, and support for text annotations. The GIMP, available primarily for Unix systems but now also for Windows, has reasonable alpha support, good gamma and text support, and excellent compression. Adobe’s Photoshop, considered by many to be the preeminent image-editing application, is slowly improving but still is not at the level one might expect given its price tag. PS 7.0 fixes all known PNG bugs in previous versions, but its compression remains poor (reportedly), it cannot write 16-bit color channels (in PNG images, that is), and it has no support at all for RGBA palettes or text annotations. (It also silently “flattens” color data in areas where the image’s alpha channel indicates complete transparency, which is a lossy operation and which may surprise users who expected truly lossless storage. Adobe does not consider this a bug.)

Browser support: very good to excellent * * * *

Web-browser support for PNG–or the incomplete implementation thereof–was, for more than a decade, a major thorn in the side of PNG developers and web designers who wanted to use PNG. While most browsers supported PNG images natively since the late 1990s–the “Big Two” (Netscape and Internet Explorer) having finally caught up in late 1997 (early 2000 for MSIE on the Macintosh)–the level of support was downright pathetic until 2001 or so and didn’t achieve “ubiquitous goodness” until late 2006. Users want alpha transparency, which allows one to do nifty effects like drop-shadows and anti-aliasing against any background, but users of the now-dominant web browser, MSIE for Windows, were locked in the dark ages of GIF-style binary transparency until the release of MSIE 7.0 in October 2006. (Previous versions implemented PNG transparency in such a way that any palette index that wasn’t completely opaque was treated as completely transparent–depending on your image, say goodbye to most of it! To make up for that, MSIE for Windows didn’t support 32-bit RGBA transparency at all.) And even the newest version still has multiple bugs in its gamma support (screenshots).

Meanwhile, most other browsers–including Microsoft’s now-defunct MSIE 5 for Macintosh (screenshots)–have had excellent PNG support for years. (MSIE/Mac’s only real downsides from the PNG perspective were that (1) the Mac development team and code base apparently were largely independent of the Windows side, and (2) they were disbanded entirely since the release of Apple’s KHTML-based Safari browser, with the obvious corollary that there will never be any more updates.) However, both Safari and another Mac browser, iCab, also have excellent transparency support (though no gamma support in the latter), as do NetPositive for BeOS, OmniWeb for Mac OS X Server, the Sega Dreamcast browser, and the CSCMail e-mail client for Linux. Netscape’s Navigator 6 and later (plus Mozilla, its open-source code base, and derivatives such as Firefox, Galeon and K-Meleon) has had very good transparency support since April 2000, with the exception of 8- and 16-bit X on Unix (mediocre quality); it also has full gamma support and even, for a brief period, native MNG support. (Navigator 4.x had no transparency support whatsoever, but virtually all users have since upgraded to one of the Mozilla-based releases.) Recent releases of Dillo for Linux and Opera for Windows and Linux and are likewise fully capable of both transparency and gamma correction (though Dillo doesn’t yet handle background images). Konqueror 3, KDE’s native browser, has full 32-bit RGBA support but, at least through version 3.2.2, only binary transparency support for palette-based images. (Like older versions of Mozilla, it supports MNG natively.) WebTV does both gamma and transparency reasonably well, although versions before July 2000 had serious problems with palette-based transparency; there’s also a WebTV Viewer test browser for Windows that has excellent PNG support. The W3C’s Amaya browser was provided with a patch against version 2.1, which was supposed to give the Windows port some level of alpha support, but there’s no mention of it in the new-features list for versions released since then. And Webster XL for RISC OS and the ICE Browser for Java are both supposed to have full transparency support, although these claims have not been verified.

On the less lively side, the nearly defunct Acorn Browse for RISC OS had full, flawless support for all forms of PNG transparency, not to mention gamma-correction and progressive display of interlaced PNGs. The fully defunct Arena also had decent alpha support, though it always used its own background pattern.

What will it take to move the Browsers rating firmly into the “Excellent” category? Leaving aside the issue of Windows users’ migration to browsers with good PNG support (e.g., Firefox, MSIE 7, or Opera)–which may take another year or two–Microsoft needs to fix MSIE’s broken gamma support; Mozilla/Firefox still lead in this regard. (And while Microsoft is at it, how about color correction? This falls into the “put up or shut up” category, since Microsoft was a founding member of the International Color Consortium more than a decade ago, before PNG even existed. See the screenshots page for details and links to test pages.) Beyond that, it would be nice to see some of the other actively developed browsers like Amaya (and Konqueror?) learn how to do all forms of PNG transparency correctly; that goes for most of the embedded browsers, like ANT Fresco and ViewML, as well.

As a related item, note that Microsoft’s Internet Information Server (a.k.a. IIS) shipped by default without an explicit MIME type for PNG images until version 6, which effectively meant that it treated PNGs as application/octet-stream rather than image/png. Not surprisingly, this affected only non-Microsoft web browsers connecting to IIS servers; they rightly refused to display such mislabelled PNGs. Fortunately, Microsoft did finally correct the problem with the release of IIS 6.0 in 2003, and a fix is available for older versions (at least for version 4.0).

Animation support: poor to fair *

Animation and other forms of multi-image storage were intentionally excluded from the PNG specification; at the time (early 1995), animated GIFs were almost unheard of, MPEG was well established in the video realm, and the PNG Group felt (and still feels) that multi-image applications would be better served by a PNG-like meta-format. MNG, short for Multiple-image Network Graphics, is precisely that format. It uses exactly the same chunk architecture as PNG and actually shares many of the same chunks, but it supports looping, objects, and JPEG image data, among other things. See the MNG web site for details.

Prior to mid-1999, animation support was rather abysmal. But with the freezing of the MNG spec in May 1999 and the continued development of several MNG-supporting applications (e.g., ImageMagick, MNGeye, eMNGma, and PNG/MNG Construction Set Pro) since then, the rating has moved up a notch. In February 2001, Gerard Juyn’s free libmng achieved 1.0 status, and it is (or was) being used not only in a pair of browser plug-ins, a couple of Java applets, and in the Qt GUI toolkit, but also in Mozilla, Navigator 6 and later, Konqueror 3, and NetFront 3 and later. Unfortunately, MNG support was subsequently removed from Mozilla and its relatives (except as a separate “XPI” add-on), and MNGeye and eMNGma are no longer being developed, so the rating has moved back down a notch.

More apps and better browser support will be necessary in order to move beyond “fair” status. Currently more than four dozen are listed, a number that continues to increase slowly but steadily.

Source : LibPNG

Looking back over the last six years, it is hard to imagine networked computing without the Web. The reason why the Web succeeded where earlier hypertext schemes failed can be traced to a couple of basic factors: simplicity and ubiquity. From a service provider’s (e.g. an e-shop) point of view, if they can set up a web site they can join the global community. From a client’s point of view, if you can type, you can access services. From a service API point of view, the majority of the web’s work is done by 3 methods (GET, POST, and PUT) and a simple markup language. The web services movement is about the fact that the advantages of the Web as a platform apply not only to information but to services.

By “services”, I don’t mean monolithic coarse-grained services like Amazon.com, but, rather, component services that others might use to build bigger services. Microsoft’s Passport, for instance, offers an authentication function exported on the Web. So hypothetically, an electronic newspaper like the Washington Post can avoid creating its own user authentication service, delegating it to Passport.

Oracle’s dynamic services whitepaper provides other examples of component services that are reusable building blocks: currency conversion, language translation, shipping, and claims processing, A more formal definition of a web service may be borrowed from IBM’s tutorial on the topic.

Web services are a new breed of Web application. They are self-contained, self-describing, modular applications that can be published, located, and invoked across the Web. Web services perform functions, which can be anything from simple requests to complicated business processes…Once a Web service is deployed, other applications (and other Web services) can discover and invoke the deployed service.

Continue to read article on XML.com

An important application of XML is the interchange of electronic data (EDI) between multiple data sources on the Web. As XML data proliferates on the Web, applications will need to integrate and aggregate data from multiple source and clean and transform data to facilitate exchange. Data extraction, conversion, transformation, and integration are all well-understood database problems, and their solutions rely on a query language. We present a query language for XML, called XML-QL, which we argue is suitable for performing the above tasks. XML-QL is a declarative, “relational complete” query language and is simple enough that it can be optimized. XML-QL can extract data from existing XML documents and construct new XML documents.
Keywords: XML, query languages, electronic-data interchange (EDI)

The goal of XML is to provide many of SGML’s benefits not available in HTML and to provide them in a language that is easier to learn and use than complete SGML. These benefits include user-defined tags, nested elements, and an optional validation of document structure with respect to a Document Type Descriptor (DTD).

One important application of XML is the interchange of electronic data (EDI) between two or more data sources on the Web. Electronic data is primarily intended for computer, not human, consumption. For example, search robots could integrate automatically information from related sources that publish their data in XML format, e.g., stock quotes from financial sites, sports scores from news sites; businesses could publish data about their products and services, and potential customers could compare and process this information automatically; and business partners could exchange internal operational data between their information systems on secure channels. New opportunities will arise for third parties to add value by integrating, transforming, cleaning, and aggregating XML data. In this paper, we focus on XML’s application to EDI. Specifically, we take a database view, as opposed to document view, of XML. We consider an XML document to be a database and a DTD to be a database schema.

EDI applications require tools that support the following tasks:

• extraction of data from large XML documents,
• conversion of data between relational or object-oriented databases and XML data,
• transformation of data from one DTD to a different DTD, and/or
• integration of multiple XML data sources.

Data extraction, conversion, transformation, and integration are all well-understood database problems. Their solutions rely on a query language, either relational (SQL) or object-oriented (OQL). We present a query language for XML, called XML-QL, which we argue is suitable for performing the above tasks. XML-QL has the following features:

• It is declarative.
• It is “relational complete”; in particular, it can express joins.
• It is simple enough that known database techniques for query optimization, cost estimation, and query rewriting could be extended to XML-QL.
• It can extract data from existing XML documents and construct new XML documents.
• It can support both ordered and unordered views on an XML document.

Continue to read article on W8.org

The Web, for better or worse, has arguably become the equivalent of a massive public agency. It is the repository for consumer information and services of the most sensitive and important nature, ranging from medical records to financial investments.

Web-based services are supplanting traditional desktop software at a blinding pace, taking over terabytes of personal data in the process. Unlimited e-mail storage and Web 2.0-style start-ups will accelerate that trend even more.

Yet access to those massive and indispensable resources is generally gated by a handful of large, profit-driven corporations. Microsoft, Google, Yahoo, America Online and other leading companies have largely built the services that much of the world has come to rely on in everyday life–making them, in effect, the guardians of our most sensitive information.

Which raises an obvious question: Is that a good idea? The most disturbing answer, if history is any guide, is that we may not have much of a choice.

It’s disturbing on many levels, but mostly because the industry is basically making up Web security as it goes along. As security executives from Microsoft, Google and Yahoo attest, the companies are in many cases adapting standard desktop security techniques to new Web applications. Sometimes that works; sometimes it doesn’t.

“Data is now available online, all the time,” said Billy Hoffman, lead researcher at Web security specialist SPI Dynamics. “It’s a great big target.”

Hoffman’s job is to understand where Web security breaks down. The way he sees it, the Big Three Web properties are doing a fairly good job with security, at least on the server end of the equation. The wild card is what happens to that data once it leaves the Googleplex, travels across the network, and gets cached on users’ desktops.

Since 1999, more than 90 percent of all documents have been produced digitally; more than 42 percent of all U.S. Internet users have Web-based banking services; and more than 160 billion e-mail messages are sent daily, according to computer services firm CSC and other sources. As the data piles up, it becomes harder to secure bits flowing between servers and desktop Web applications, not to mention the additional complexity of mashups and other Web 2.0 technologies. Simultaneously, attacks are on the rise.

The bottom line is that we’re entering unexplored territory where an unprecedented number of people depend on a growing number of relatively new applications, some built with still-evolving technologies, to handle enormous amounts of personal data fragmented across a multiplicity of servers and networks worldwide. Against this daunting backdrop–and amid concerns over corporate control–calls for some kind of independent oversight are inevitable.

“We have information on security practices out there. The disconnect is that we don’t have an intermediary that says how these things apply to you as you build Web 2.0 or other applications,” Hoffman said. “Will a nonprofit or some other group arise that tries to publish standards? Probably. We definitely need a central clearing house of good information, because there is a lot of bad information out there.”

Continue reading article on News.com