Error detection (was Re: HTML+ Comments)

Dave_Raggett (
Wed, 21 Jul 93 14:47:30 BST

>> I would like to again bring up the error detection problem. Let's say
>> you are in the middle of transmitting a document and you get some kind of
>> error (disk error, processing error, whatever). There is currently not
>> any clean way to notify the client.

>> We can partially solve this by using the <EMBED> tag, something like this.

> No, this is a transport level problem which shouldn't affect the
> document format at all. Agreed, HTTP currently doesn't have a way to
> tell normal EOF from an error, but HTTP+ will solve this problem and
> then the transport will be able to tell the higher layers that an
> error occurred. Please don't mix layers!

Good in principle, but unfortunately, HTTP 1.0 only passes control information
at the start of data transfer - there isn't a way of intermixing control
and data and subsequently separating them. FTP gets around this problem by
using separate links for control and data.

I think we should consider a transport escaping mechanism for embedding
control info into the data stream. My suggestion for <error> ... </error>
would allow this for HTML/HTML+ and could be stripped out of the data stream
before it gets displayed.

Dave Raggett