HTTP-EQUIV

Roedy Green · Sep 3, 2008

Microsoft sometimes responds to my probes like this . What does it
mean? I am familiar with Refresh with an URL. Is it just asking you
to try again later?

<HTML><HEAD><META HTTP-EQUIV="Refresh" CONTENT="0.1">
<META HTTP-EQUIV="Pragma" CONTENT="no cache">
<META HTTP-EQUIV="Expires" CONTENT="-1">
</HEAD></HTML>

Isn't Java supposed to follow such redirects on its own?

Tom Anderson · Sep 3, 2008

Microsoft sometimes responds to my probes like this . What does it mean?
I am familiar with Refresh with an URL. Is it just asking you to try
again later?

<HTML><HEAD><META HTTP-EQUIV="Refresh" CONTENT="0.1">

It's telling you to reload the same page 0.1 seconds later.

<META HTTP-EQUIV="Pragma" CONTENT="no cache">
<META HTTP-EQUIV="Expires" CONTENT="-1">

And not to cache it.

That's quite bizarre behaviour.

Isn't Java supposed to follow such redirects on its own?

This is happening at the HTML level, not the HTTP level. An HTTP client
(like URLConnection) can handle redirects and refreshes at the HTTP level,
but if it's not parsing the HTML (which it's not), it won't be able to
handle those.

Meta HTTP-equiv tags are generally a sign of poor site design - if one has
some HTTP-level metadata, one should be saying it in HTTP, not HTML.

tom

Joshua Cranmer · Sep 3, 2008

Roedy said:
Microsoft sometimes responds to my probes like this . What does it
mean? I am familiar with Refresh with an URL. Is it just asking you
to try again later?

<HTML><HEAD><META HTTP-EQUIV="Refresh" CONTENT="0.1">

From the HTML 5 definition of 'Refresh' (it's not a standard HTTP header):
<http://www.whatwg.org/specs/web-apps/current-work/#refresh>
[If only a number is present], the integer represents a number of
seconds before the page is to be reloaded; [if a URL is present] the
integer represents a number of seconds before the page is to be replaced
by the page at the given URL.

<META HTTP-EQUIV="Pragma" CONTENT="no cache">

§14.32 of RFC 2616 says that a value of "no-cache" (should have a hyphen
there) means that it should request from the server again

<META HTTP-EQUIV="Expires" CONTENT="-1">

§14.21, ibid., except this is also malformed (it's not a valid date
parameter).

What the page is probably trying to say is "Busy, please try again
[automatically] in 100ms."

Isn't Java supposed to follow such redirects on its own?

If they were sent as actual HTTP response headers, maybe (doubtful,
though), but these are specified in HTML. And HTTP is content-agnostic.

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HTTP-EQUIV

Roedy Green

Tom Anderson

Joshua Cranmer

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