W3C home > Mailing lists > Public > public-html@w3.org > May 2009

HTML interpreter vs. HTML user agent

From: Larry Masinter <masinter@adobe.com>
Date: Tue, 26 May 2009 12:26:14 -0700
To: HTML WG <public-html@w3.org>
Message-ID: <8B62A039C620904E92F1233570534C9B0118CD8A4A30@nambx04.corp.adobe.com>
> By "HTML interpreter" do you mean "HTML user agent"?

The phrase "user agent"  was introduced and used in the
literature as representing a software used by, well,
users: humans or agents representing humans.

The "User-Agent" header was introduced into the HTTP 
protocol at a time when HTTP was thought only to
involve clients (that were user agents) and servers
(that were not user agents.) 

When spiders, search engines, proxies, and other
web intermediaries got added to the web architecture,
the header "User-Agent" remained, even when some of
those agents are not operating directly in service
of a human end user.

For HTML, it seems useful to distinguish between a
HTML "User Agent" -- software that interprets HTML
in service of an individual agent -- from other
applications that need to read and interpret HTML,
such as search engine analyzers, translation tools,

In particular, there are frequently different
security requirements for "User Agents"  vs. other
autonomous tools. For HTTP the distinction can be
made by making reference to the "client".

"HTML interpreter" seems like a more general
term that would include HTML user agents but also
other kinds of agents. "HTML processor" might work,
but an "XML processor" doesn't do any of the
semantic interpretation.

Received on Tuesday, 26 May 2009 19:26:59 UTC

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