HTML 5

Topics this week include microdata, video and audio, and spec licensing.

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Topics this week include microdata, events, and document.head.

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Topics this week include parsing, accessibility, security, semantics, video, and web forms.

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Topics this week include keygen, dialog, and the pros and cons of including examples in specs.

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Welcome back to “This Week in HTML 5,” where I’ll try to summarize the major activity in the ongoing standards process in the WHATWG and W3C HTML Working Group.

This big news this week is the <datagrid> element. This is a brand spanking new element introduced in r2962.

In the datagrid data model, data is structured as a set of rows representing a tree, each row being split into a number of columns. The columns are always present in the data model, although individual columns might be hidden in the presentation.

Each row can have child rows. Child rows may be hidden or shown, by closing or opening (respectively) the parent row.

Rows are referred to by the path along the tree that one would take to reach the row, using zero-based indices. Thus, the first row of a list is row “0″, the second row is row “1″; the first child row of the first row is row “0,0″, the second child row of the first row is row “0,1″; the fourth child of the seventh child of the third child of the tenth row is “9,2,6,3″, etc.

The chains of numbers that give a row’s path, or identifier, are represented by arrays of positions, represented in IDL by the RowID interface.

The root of the tree is represented by an empty array.

Each column has a string that is used to identify it in the API, a label that is shown to users interacting with the column, a type, and optionally an icon.

The possible types are as follows:

Keyword	Description
text	Simple text.
editable	Editable text.
checkable	Text with a check box.
list	A list of values that the user can switch between.
progress	A progress bar.
meter	A gauge.
custom	A canvas onto which arbitrary content can be drawn.

Each column can be flagged as sortable, in which case the user will be able to sort the view using that column.

Columns are not necessarily visible. A column can be created invisible by default. The user can select which columns are to be shown.

When no columns have been added to the datagrid, a column with no name, whose identifier is the empty string, whose type is text, and which is not sortable, is implied. This column is removed if any explicit columns are declared.

Each cell uses the type given for its column, so all cells in a column present the same type of information.

The other major change to the spec this week is the <keygen> element. As I mentioned in episode 12, someone went to the trouble of documenting the <keygen> element, and there has been a surprising amount of discussion about it in the past six months. Simply put, the keygen element represents a key-pair generator control. You include it in a <form>. When your browser submits the form, the private key is stored in the local keystore, and the public key is packaged and sent to the server. [r2960]

Not much else went into the spec this week, but there’s been a lot of interesting activity around the web.

• A new W3C Working Draft of HTML 5 is out. As I’ve mentioned before, this is just a snapshot of progress-to-date. By its very nature, it is out of date as soon as it’s published, since the working group continues to progress while the webmaster gnomes are publishing.
• Also published: the latest draft of “HTML 5 differences from HTML 4″, compiled by Opera’s Anne van Kesteren.
• Mozilla bug 465007: “Harmonize content sniffing in HTML 5 and Firefox.” The next version of Firefox will sniff images the way the HTML 5 specification recommends. I am still opposed to content sniffing on philosophical grounds, but philosophy doesn’t get you very far on the open web, and documented heuristics are better than undocumented heuristics. And interoperable, documented heuristics are even better!
• Speaking of content sniffing, Adam Barth’s [PDF] whitepaper, Secure Content Sniffing For Web Browsers, is an excellent read.
• Henri Sivonen’s The Last of the Parsing Quirks is equally fascinating.
• Superset encodings [Re: ISO-8859-* and the C1 controlrange] is an incredibly detailed look into the insane world of character encoding.
• You can still help us review HTML 5! Your input is important!

Tune in next week for another exciting episode of “This Week in HTML 5.”

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Welcome back to “This Week in HTML 5,” where I’ll try to summarize the major activity in the ongoing standards process in the WHATWG and W3C HTML Working Group.

There has been very little spec-related activity this week, so I will briefly repeat Ian Hickson’s request to Help us review HTML5 and then turn to a fascinating debate happening right now on the WHATWG mailing list.

The debate revolves around perceptions and expectations of privacy. Brady Eidson (Apple/WebKit) kicks off the discussion with Private browsing vs. Storage and Databases:

A commonly added feature in browsers these days is “private browsing mode” where the intention is that the user’s browsing session leaves no footprint on their machine. Cookies, cache files, history, and other data that the browser would normally store to disk are not updated during these private browsing sessions.

This concept is at odds with allowing pages to store data on the user’s machine as allowed by LocalStorage and Databases. Sur[e]ly persistent changes during a private browsing session shouldn’t be written to the user’s disk as that would violate the intention of a private browsing session. …

1. Disable LocalStorage completely when private browsing is on. Remove it from the DOM completely.
2. Disable LocalStorage mostly when private browsing is on. It exists at window.localStorage, but is empty and has a 0-quota.
3. Slide a “fake” LocalStorage object in when private browsing is enabled. It starts empty, changes to it are successful, but it is never written to disk. When private browsing is disabled, all changes to the private browsing proxy are thrown out.
4. Cover the real LocalStorage object with a private browsing layer. It starts with all previously stored contents. Any changes to it are pretended to occur, but are never written to disk. When private browsing is disabled, all items revert to the state they were in when private browsing was enabled and writing changes to disk is re-enabled.
5. Treat LocalStorage as read-only when private browsing is on. It exists, and all previously stored contents can be retrieved. Any attempt to setItem(), removeItem(), or clear() fail.

Ian Fette (Google/Chrome) explains how Google Chrome handles LocalStorage in “incognito” mode:

[W]hilst the [incognito] session is active, pages can still use a database / local storage / … / and at the end of the session, when that [temporary] profile is deleted, things will go away. I personally like that approach, as there may be legitimate reasons to want to use a database even for just a single session.

Darin Fisher (Google/Chrome) follows up to clarify Google Chrome’s behavior:

Chrome’s “incognito mode” means — is defined as — starting from a clean slate (as if you started browsing for the first time on a new computer), and when you exit incognito mode, the accumulated data is discarded. That’s all there is to it. The behavior of LocalStorage and Database in this mode is deduced easily from that definition.

Jonas Sicking (Mozilla/Firefox) explains his opposition to option 5:

My concern with this is the same as the reason we in firefox clear all cookies when entering private browsing mode. The concern is as follows:

• A search engine stores a user-id token in a cookie. They then use this token to server side store the users 10 last searches.
• A user uses this search engine to search for various items. Doing this causes the user-id token to be stored in a cookie.
• The user then switches to private browsing mode.
• The user makes a search for a present for his wife.
• The user switches back into normal browsing mode.

At this point it is still possible to see the search for the wifes present in the websites store of recent searches.

Something very similar could happen for localStorage I would imagine, where the user-identifing information is stored in the localStorage rather than a cookie.

Josh “timeless” Soref (core Firefox developer) explores the privacy implications of different options:

[Option 1: Disabling LocalStorage won't work because] Many sites will just assume that they know a given useragent supports localstorage, so they’ll be surprised and break. This will mean that a user can’t use certain sites.

[Option 2: Enabling LocalStorage with 0 quota] will enable sites to know that the user is browsing in private, which is probably also a violation of the user’s trust model. If I were to be browsing in private, I wouldn’t want most sites to know that I’m doing this.

[Option 4 or 5: Starting with existing LocalStorage data] means the site will know who you are (on average), and is almost certainly never what the user wants.

Jonas Sicking (Mozilla/Firefox) tentatively states

For what it’s worth, I believe we’re currently planning on doing 2 in firefox.

Brady Eidson concludes:

I strongly share Jonas’ concern that we’d tell web applications that we’re storing there data when we already know we’re going to dump it later. For 3 and 4 both, we’re basically lying to the application and therefore the user.

… So far I’m standing by WebKit choosing #5 for now.

Drew Wilson summarizes his thoughts on the matter:

I think the #1 goal for incognito mode has to be “maximum compatibility” — let sites continue to work, which kills options #1 & 2. A secondary goal for incognito mode would be “don’t let sites know the user is in incognito mode” — this kills approach #1 and #5, and possibly #2 (depending on whether there are significant non-incognito use cases that also have 0 local storage quota).

For my part, I agree with Drew, and I would add this: I use Google Chrome’s “incognito mode” quite frequently when I’m developing websites. It’s an easy way to test from a “blank slate” with no cookies and no cache, and it’s much easier than juggling multiple profiles. If data in my LocalStorage “bleeds” into incognito mode, this use case would become unreliable and web development would be harder for me. (Bil Corry makes this point too.)

On a more philosophical level, it’s nobody’s business that I’m in private browsing mode. (Scott Hess makes this point too.) If authors can detect it, I consider that a serious bug. (Imagine the ha.ckers.org headline: “Safari Hole Allows Sites To Detect ‘Private’ Browsing, Punish Users.”) Even worse, if LocalStorage could be used as a “super-cookie” for less-than-honorable sites to track me from normal usage to incognito usage, then it’s not really “private browsing” in any sense of the word that matters.

In the early days of Greasemonkey, there were discussions of whether Greasemonkey should send or provide some detectable signal to page authors that Greasemonkey was running and the user had active scripts modifying the current page. To which I replied:

If Greasemonkey makes any overtures towards allowing web publishers to “opt out” or override my browsing experience in any way, I will immediately fork it and make it my life’s mission to maintain the fork as long as possible.

Tune in next week for another exciting episode of “This Week in HTML 5.”

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Welcome back to “This Week in HTML 5,” where I’ll try to summarize the major activity in the ongoing standards process in the WHATWG and W3C HTML Working Group.

The big news for the week of March 30^th is the addition of a synchronous database API to the Web Storage spec (which was split out from the HTML 5 spec a few weeks ago). This new API defines a DatabaseSync object whose methods return SQLTransactionSync objects. This directly mirrors the asynchronous database API, which had already defined a Database object whose methods return SQLTransaction objects. [r2958]

Another interesting change this week is r2921, which adds the placeholder attribute to the <textarea> element. I tracked the initial discussion of the placeholder attribute in episode 8 and noted its appearance in HTML 5 in episode 13. Previously you could only use the placeholder attribute on <input type=text>, <input type=email>, <input type=url>, and <input type=password>, but Thomas Broyer pointed out that Google Code (among others) uses placeholder text on <textarea> elements. Such sites could now theoretically migrate their current script-based solutions to HTML 5 markup.

Other interesting changes this week:

• r2928 recommends that browsers should reset the text-indent property when rendering a <textarea> element.
• r2930 notes a strange edge case where paragraphs (<p> elements) can end up overlapping each other if they are used as fallback content within an <object> element.
• r2933 adds event handler DOM attributes like onclick to the WebIDL definition of the document object.
• r2936 allows the spellcheck attribute to be present with no value, as a synonym for spellcheck="true". I first mentioned the spellcheck attribute in episode 23, and again in The Road to HTML 5: spellchecking.
• r2937 allows <textarea wrap=off>.
• r2941 further tweaks the algorithm for parsing legacy color attributes, which is trickier than you might think.
• r2943 allows the width and height attributes of an <img> element to be 0.

Around the web:

• Jacob Seidelin posts a <canvas> cheat sheet.
• Peter-Paul Koch knows way more about dates than you do.
• Eric Meyer uses HTML 5 to present the results of the “A List Apart Survey 2008.”
• Alex Nicolaou explains how the new versions of Google Mail and Google Calendar use HTML 5 for offline functionality.
• Jon Tan talks about practical ways to tweak your markup now to migrate to HTML 5 later.
• addfullsize.com is an entire site devoted to adding an attribute to the <img> element.
• Anne van Kesteren thinks URLs are tough, and he’s right.

Tune in next week for another exciting episode of “This Week in HTML 5.”

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Welcome back to “This Week in HTML 5,” where I’ll try to summarize the major activity in the ongoing standards process in the WHATWG and W3C HTML Working Group.

The big news for the week of March 23^rd is that SVG can once again be included directly in HTML 5 documents served as text/html:

I’ve made the following changes to HTML5:

• Uncommented out the XXXSVG bits, reintroducing the ability to have SVG content in text/html.
• Defined <script> processing for SVG <script> in text/html by deferring to the SVG Tiny 1.2 spec and blocking synchronous document.write(). The alternative to this is to integrate the SVG script processing model with the (pretty complicated) HTML script processing model, which would require changes to SVG and might result in a dependency from SVG to HTML5. Anne would like to do this, but I’m not convinced it’s wise, and it certainly would be more complex than what we have now. If we ever want to add async="" or defer="" to SVG scripts, then this would probably be a necessary part of that process, though.
• Added a paragraph suggesting: “To enable authors to use SVG tools that only accept SVG in its XML form, interactive HTML user agents are encouraged to provide a way to export any SVG fragment as a namespace-well-formed XML fragment.”
• Added a paragraph defining the allowed content model for SVG <title> elements in text/html documents.

r2904 (and, briefly, r2910) give all the details of this solution. There are still a number of differences between the text in HTML 5 and the proposal brought by the SVG working group. Some of these are addressed further down in the announcement:

• SVG-in-XML is case-preserving; SVG-in-HTML is not.
• SVG-in-XML requires quoted attribute values; SVG-in-HTML does not.
• When SVG-in-XML uses CDATA blocks, they show up as CDATA nodes in the DOM; when SVG-in-HTML uses CDATA blocks, they show up in the DOM as conventional text nodes. [Clarified based on Henri's feedback]
• The <svg> element can not be the root element of a text/html document.

Doug Schepers, who has been the SVG working group’s HTML 5 liason, does not like this solution:

To be honest, I think it’s not a good use of the SVG WG’s time to provide feedback when Ian already has his mind made up, even if I don’t believe that he is citing real evidence to back up his decision. What I see is this: one set of implementers and authors (the SVG WG) and the majority of the author and user community (in public comments) asking for some sort of preservation of SVG as an XML format, even if it’s looser and error-corrected in practice, and a few implementers (Jonas and Lachy, most notably) disagreeing, and Ian giving preference to the minority opinion. Maybe there is sound technical rationale for doing so, but I haven’t been satisfied on that score.

Turning to technical matters, one of the features of web forms in HTML 5 is allowing the attributes for form submission on either the <form> element (as in HTML 4) or on the submit button (new in HTML 5). Originally, the attributes for submit buttons were named action, enctype, method, novalidate, and target, which exactly mirrored the attribute names that could be declared on the <form> element.

However, in January 2008, Hallvord R. M. Steen (Opera developer) noted that “INPUT action [attribute] breaks web applications frequently. Both GMail and Yahoo mail (the new Oddpost-based version) use input/button.action and were seriously broken by WF2’s action attribute.”

Following up in November 2008, Ian Hickson replied, “I notice that Opera still supports ‘action’ and doesn’t seem to have problems in GMail; is this still a problem?” to which Hallvord replied, “GMail fixed it on their side a while ago. It is still a problem with Yahoo mail, breaking most buttons in their UI for a browser that supports ‘action’. We work around this with a browser.js hack. (’Still a problem’ means ‘I tested this again a couple of weeks ago and things were still broken without this patch’.)”

Ian replied, “This is certainly problematic. It’s unclear what we should do. It’s hard to use another attribute name, since the whole point is reusing existing ones… can we trigger this based on quirks mode, maybe? Though I hate to add new quirks.” Hallvord did not like that idea: “In my personal opinion, I don’t see why re-using attribute names is considered so important if we can find an alternative that feels memorable and usable. How does this look? <input type="submit" formaction="http://www.example.com/">“

Finally, in March 2009, Ian replied:

That seems reasonable. I’ve changed “action”, “method”, “target”, “enctype” and “novalidate” attributes on <input> and <button> to start with “form” instead: “formaction”, “formmethod”, “formtarget”, “formenctype” and “formnovalidate”.

And thus we have r2890: Rename attributes for form submission to avoid clashes with existing usage.

Other interesting changes this week:

• r2889 adds support for select.add(e) and select.options.add(e) with no second argument.
• r2888 defines how to determine the character encoding of Web Worker scripts. Briefly, it says to look for a Byte Order Mark, then look at the Content-Type HTTP header, then fall back to UTF-8.
• r2898, r2899, r2901, r2914, and r2916 define a locking mechanism to allow thread-safe read/write access to document.cookie and .localStorage. The lock is acquired during page fetching (which sets the cookie based on HTTP headers) and released once the cookie is set. It is also released automatically whenever something modal happens (such as window.alert()). (I first mentioned the discussion of this issue in episode 27. The problem is that Web Workers allows threaded client-side script execution, which means access to shared storage like document.cookie needs to be made explicitly thread-safe with some sort of locking mechanism.)

Tune in next week for another exciting episode of “This Week in HTML 5.”

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Welcome back to “This Week in HTML 5,” where I’ll try to summarize the major activity in the ongoing standards process in the WHATWG and W3C HTML Working Group. In this episode, I’d like to highlight some of the discussions that I’ve missed in previous episodes.

• Greg Millam writes, “I’m one of the main engineers responsible for captioning support on YouTube, and I’ve joined the Chrome team at Google to attempt to help drive video captions and subtitling forward.” Henri Sivonen replies, “I agree it makes sense to start with something simple. The markupless flavor of SRT would be such a format. However, supporting the formatting tags in later flavors of SRT is a can of worms.” [full thread: Captions, Subtitles, and the Video Element]
• Robert O’Rourke writes, “Are there any plans to bring list headers from HTML3 into HTML5?” Ian Hickson replies, “You can do this in HTML5, using <figure> and <legend>.” The thread continues in a number of directions. Marcus Ernst writes, “Anyway I would consider it even more appropriate to allow the list inside a paragraph,” to which Ian replies, “We had this in the spec originally, but we dropped it due to a variety of issues (it made life harder for editors, it didn’t work in text/html even when it looked like it did, people got confused…).” [full thread: List Headers]
• Drew Wilson writes, “There’s currently no way to set or get cookies from workers, which makes various types of cookie-based operations problematic.” Jonas Sicking replies, “Allowing cookie to be set would unfortunately create a synchronous communication channel between the worker and the main window.” The discussion continues, focusing on issues of multi-threaded updates to document.cookie. Drew Wilson again: “Following up on this. I created two pages, one that tests cookies in a loop, and one that sets cookies in a loop, and ran them in separate windows in Firefox 3, IE7, and Chrome. Chrome and IE7 currently allow concurrent modification of document.cookies (i.e. the test loop throws up an alert). Firefox does not.” [full thread: Accessing cookies from workers]
• There have been a number of overlapping discussions on whether and how to allow authors to embed RDFa in HTML 5 documents. See 1, 2, 3, and followups. Besides the technical arguments about how it would work, much of the discussion centers around the concept of distributed extensibility, which I’ve touched on before. For example, here is Chris Wilson (of the Microsoft IE development team): “We have had (in the past as well, imo, in the future) a requirement for decentralized extensibility – that is, that document/content authors can extend the set of elements with their own semantic or behavioral elements. I continue to think there is a requirement for that. (One might well ask why we didn’t implement full XML in that case; I’ll politely not answer from a historical context, but will point out that the draconian error handling and poor fallback story make delivering content in XML in the browser a poor solution in the ecosystem today.)”
• Steven Faulkner writes, “I have … taken a stab at a RFC 2119 compatible definition for table summaries: http://esw.w3.org/topic/HTML/SummaryForTABLE/SummarySpecification.” [full thread: Draft text for summary attribute definition, continued in March archives]

There has also been a vigorous debate about the license of the specification itself.

• Sam Ruby writes, “In my discussions with Ian and at Mozilla, I gathered that it was a shared understanding that by October that the license for the W3C license would be somehow open source friendly, and specifically that a Creative Commons Attribution license was something that was of common and general interest.” The “open source friendly” clause is a reference to the fact that the spec does actually contain some code (in the form of WebIDL declarations), and vendors of open source browsers would like to include this code (or derive code from it) into their products.
• After much discussion, Philippe Le Hegaret (of the W3C) writes, “In response to requests from developers to make it easier to include portions of W3C specifications in software documentation, bug reports, code, and test cases, W3C have drafted a new Excerpt & Citation License. … Uses like forking of a specification would remain prohibited to protect the due process and the consensus found in a chartered Working Group.”
• Ian Hickson immediately replies, “Increasing license proliferation is a really bad idea here. I would be opposed to introducing yet another license. … [The forking] use case is the main one that I’m concerned about, FWIW.”
• Jonas Sicking explains his reasoning about allowing forking: “I think it would gain W3C a tremendous amount of trust if it were to allow [forking]. To many people, me included, having the gurentee that W3C can’t go off ‘into the weeds’ means that I have don’t have to worry about my time being wasted when I contribute. I think many people feel the same when they contribute to the forkable software I represent.”
• Philippe notes that the W3C “isn’t used to the concept of allowing a fork” of their specifications, which is one of the requirements of any “open source friendly” license.
• I believe Maciej Stachowiak (WebKit developer at Apple) best summarized the group’s objections: “1) Preventing specification forks is not achievable through license terms; a sufficiently motivated party can create a new spec from scratch. 2) Preventing specification forks is probably not necessary; the one time it happened, the outcome was good and the effort merged back into a realigned W3C. 3) Due to 1 and 2, we should give more consideration to LGPL/GPL compatibility than prevention of forks via licensing terms.”
• Ian Hickson agrees: “I do agree that the original use cases are (intentionally and explicitly) not all met by the proposal that was put forward, and I do think the original use cases were an accurate portrayal of the use cases that this working group has consensus on. Compatibility with open source (including GPL and LGPL projects), clear license terms (ideally reusing an existing license), and the ability to fork are all issues that working group members discussed and considered important previously.”

[Further reading: Discussions with plh, Draft W3C Excerpt License]

Tune in next week for another exciting episode of “This Week in HTML 5.”

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Welcome back to “This Week in HTML 5,” where I’ll try to summarize the major activity in the ongoing standards process in the WHATWG and W3C HTML Working Group.

The big news for the week of March 16^th is this announcement from Ian Hickson:

I’ve now split out the Server-sent Events and Storage APIs out of HTML5, and I’ve removed the text for Web Sockets, which was split out earlier. By popular demand I’ve also done some tweaks to the styling of these specs.

HTML5

http://dev.w3.org/html5/spec/

Server-Sent Events

http://dev.w3.org/html5/eventsource/

Web Storage

http://dev.w3.org/html5/webstorage/

Web Workers

http://dev.w3.org/html5/workers/

Web Sockets

http://dev.w3.org/html5/websockets/
http://tools.ietf.org/html/draft-hixie-thewebsocketprotocol

It is my understanding that the desire is to publish the Server-Sent Events, Web Storage, Web Workers, and Web Sockets specs through the Web Apps working group, so that is what I put into the “status of this document” sections.

I would like to be able to put more permissive licenses (ideally MIT) on these drafts, rather than the W3C license.

The following sections still haven’t been split out:

URLs

I’ll remove this section as soon as DanC’s draft is published.

Content-Type sniffing

I’ll remove this section once Adam’s draft is on a standards track.

Timeout API

This section is lacking an active editor.

Origin

I’m unsure what will happen with this section.

In IRC, Ian explained that all of these documents are generated from one master file:

# [21:02] <hixie> the source document is run through a bunch of scripts to generate the output documents
# [21:03] <hixie> from that one file i now generate one whatwg spec, four w3c specs, and an rfc

In other news, r2876 (WARNING: VERY LARGE) adds user stylesheets to the HTML 5 specification itself. If you view it in a browser that support switching stylesheets (such as Firefox, under the View → Page Style submenu), you can choose between “Complete specification” (default), “Author documentation only,” or “Highlight implementation requirements.” The “Author documentation only” stylesheet hides all of the client parsing algorithms and focuses on the elements, attributes, and scripting features that web authors need to know about.

For example, the “author documentation” of the <img> element highlights the required attributes, how to create a new Image() dynamically, and the detailed requirements for providing alternate text, while completely hiding any mention of how image fetching fits into the client’s task queue, the gory details of how clients resolve image URLs, or the security risks of allowing pages on the public internet to attempt to load images on the local network. On the flip side, “highlight implementation requirements” highlights these exact issues.

Critics who complained that the HTML 5 specification should be “just a markup language” will be able to have their cake and eat it too. Those who complained that HTML 5 was “too bloated” will have a little less to complain about now that several parts of it have been published as separate documents. On the other hand, critics who complained about these things as a cover for other agendas will have to continue complaining a little while longer.

Tune in next week for another exciting episode of “This Week in HTML 5.”

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