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Re: [Fwd: W3C and APIs -- request for agenda item]

From: <noah_mendelsohn@us.ibm.com>
Date: Fri, 19 Jun 2009 17:38:04 -0400
To: ashok.malhotra@oracle.com
Cc: "www-tag@w3.org" <www-tag@w3.org>
Message-ID: <OF73CC06FC.50275ECF-ON852575DA.0072E82C-852575DA.00734691@lotus.com>
It occurs to me that one of the most significant "API" interfaces that the 
W3C is contemplating for a Recommendation is the 2D Graphics [1] context 
of the proposed HTML 5 Canvas tag [2].  I see no reason why the W3C should 
not be in the business of specifying such APIs in situations where they 
seem to be the technically appropriate means of, in this case, encoding a 
Web representation. 

As an aside, The Rule of Least Power [3] suggests that more declarative 
approaches might be attractive if they prove practical, but that certainly 
doesn't in any way discourage W3C from being involved in situations where 
this more imperative style of interface is indeed the best.


[1] http://dev.w3.org/html5/spec/Overview.html#the-2d-context

[2] http://dev.w3.org/html5/spec/Overview.html#the-canvas-element

[3] http://www.w3.org/2001/tag/doc/leastPower.html

Noah Mendelsohn 
IBM Corporation
One Rogers Street
Cambridge, MA 02142

ashok malhotra <ashok.malhotra@oracle.com>
Sent by: www-tag-request@w3.org
06/18/2009 03:12 PM
Please respond to ashok.malhotra
        To:     "www-tag@w3.org" <www-tag@w3.org>
        cc:     (bcc: Noah Mendelsohn/Cambridge/IBM)
        Subject:        [Fwd: W3C and APIs -- request for agenda item]

Forwarding to www-tag

-------- Original Message --------
Subject:                 W3C and APIs -- request for agenda item
Date:            Sun, 14 Jun 2009 06:23:09 -0700
From:            ashok malhotra <ashok.malhotra@oracle.com>
Reply-To:                ashok.malhotra@oracle.com
Organization:            Oracle
To:              tag@w3.org <tag@w3.org>

The attached writeup is from Larry, John and me.
All the best, Ashok

All the best, Ashok
W3C and APIs 
Historically, the W3C has focused primarily on developing clearly 
declarative languages (such as HTML, and the XML-based languages) and 
syntactic elements used in protocols. The AWWW [1] says “The Web follows 
Internet tradition in that its important interfaces are defined in terms 
of protocols, by specifying the syntax, semantics, and sequencing 
constraints of the messages interchanged.” 
But over time, use of scripting languages (and Javascript in particular) 
and event-based APIs (such as DOM) has increased; today’s HTML 
specification focuses more on the DOM2 HTML API than it does on the 
declarative syntax of HTML itself, for example. 
Recently, the W3C has greatly increased its focus on defining APIs [2,3]. 
This raises the question of whether the W3C TAG should offer further 
guidance to the developers of APIs, and whether (or how) that guidance 
should differ from that offered to the developer of a declarative language 
or protocol. 
APIs are often described by means of an interface definition language 
(such as WebIDL[6]) adding yet another language to the heady mix available 
on the Web today. 
At this point a sceptic might say the W3C offers little guidance to the 
developers of declarative languages and protocols -- why need we do 
something different for API developers? But this is not quite true. We do 
offer some guidance and best practices to developers of declarative 
languages and protocols: use namespaces for extensibility, use http 
namespaces, plan for extensibility and versioning, etc. So here are some 
suggested changes: 
1.      Revise the AWWW [1] to discuss the role of APIs and active content 
in general. 
2.      The process document [4] says “ … , the Working Group SHOULD be 
able to demonstrate two interoperable implementations of each feature.” 
Clarify what this means for APIs insofar as APIs are often embedded in, or 
used in context with, other languages. 
3.      Think through what we want to say about versioning and 
extensibility. It may be even more important for extended versions of APIs 
to work with old devices than for HTML to work with old browsers. 
4.      The failure model may be different. If the implementation does not 
understand a statement, what does it do: error, crash and burn, ignore? In 
typical interface definition languages, this is handled by describing 
exception cases which are documented for a particular interface. 
5.      Subverting the traditional client-server model of the Web (by 
allowing a client to effectively serve Web content via an API call) has 
implications (particularly in the areas of security and privacy) for the 
relationship between a client and a server. 
The Geolocation API [3] and the Device APIs Charter [2] both mention 
security and privacy policies but, as yet there are large disagreements on 
what shape such policies should take. This seems an important, fundamental 
area for future work. (One problem with policy is that in a web of 
autonomous, often anonymous agents, who will enforce policy and where will 
it be enforced? For example, is it sufficient for GPS devices just have a 
switch to turn off location broadcasting?) 
6.      There may be a need for guidance on how an API should be embedded 
in other Web content. 
For example, in Geolocation the host language identifies the device while 
the API specifies operations on the device. Similarly, if there is an 
error during the processing of an API request, how is that reported to the 
host content? 
7.      Testing APIs is different from testing protocols at least, in part 
due to wide variability in features between implementations of the API. 
For example, the Mobile Test Initiative has made a good start by 
publishing a note on how to write device-independent tests for mobile 
devices [5]. 
[1] http://www.w3.org/TR/webarch/#protocol-interop 
[2] http://www.w3.org/2009/05/DeviceAPICharter 
[3] http://www.w3.org/2008/geolocation/drafts/API/ 
[4] http://www.w3.org/2005/10/Process-20051014/tr#rec-advance 
[5] http://www.w3.org/TR/2009/NOTE-di-testing-20090512/ 
[6] http://dev.w3.org/2006/webapi/WebIDL/ 

Received on Friday, 19 June 2009 20:59:44 UTC

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