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RE: What is "server-safe HTTP"?

• From: Michael Brennan <Michael_Brennan@A...>
• To: XML DEV <xml-dev@l...>
• Date: Tue, 13 Mar 2001 13:22:17 -0800

I believe the XMLHTTPRequest object also can run afoul of multi-threading
issues more easily than the ServerXMLHTTP object. It is problematic using
XMLHTTPRequest within ASP pages.

Unfortunately, there is an extremely annoying bug in both implementations
(and it is a bug that is pervasive among XML messaging toolkits). The
component does not properly identify the character encoding used in the
Content-Type header. It should be sending something like:
  Content-Type: text/xml; charset="utf-8"
Instead, it simply sends:
  Content-Type: text/xml

So the recipient is left to guess what character encoding is used. Not good.
Setting the header explicitly doesn't necessarily work, either. If you do
so, then use a DOM document as the parameter to the "send" method, it
overwrites the header and sets it back to the default "Content-Type:
text/xml". The work around is to explicitly set the header, then get the XML
from the DOM as text and send the text. When doing this, it does not reset
the header (and it seems to use appropriate character encoding for the
actual transmission, as well).

Regrettably, this problem is pervasive among the XML messaging toolkits
available to developers. Very few developers understand character encoding
issues, and very few of the toolkits they look to for assistance deal with
character encoding properly. It's a crap shoot, as well, as to what
character encoding gets actually used. Pre-2.0 versions of the Microsoft
SOAP toolkit always used ISO-8859-1 for the character encoding. Supposedly,
that is getting addressed in 2.0 (though I haven't kept close tabs, so I
don't know if it has been fixed). Early version of Apache SOAP simply used
the default platform-dependent encoding of the underlying JVM, creating
considerable interoperability problems. (Fortunately, that problem has long
since been addressed, to the best of my knowledge.)

I believe this problem is a deep one. It threatens interoperability and
jeopardizes the heavily hyped vision of a global network of collaborative
web services. It would be nice if the large vendors would make commitment to
properly support the specs they helped to produce.

> -----Original Message-----
> From: Simon St.Laurent [mailto:simonstl@s...]
> Sent: Tuesday, March 13, 2001 7:10 AM
> To: Rick Jelliffe; XML DEV
> Subject: Re: What is "server-safe HTTP"?
> 
> 
> At 11:15 PM 3/13/01 +0800, Rick Jelliffe wrote:
> >Any hints or URLs on what is "server-safe HTTP",
> >as supported in MSXML 3?
> 
> Microsoft re-built their XMLHTTP library so that servers 
> wouldn't be using 
> the Internet Explorer HTTP classes as a foundation.  While 
> those work well 
> for client use, they weren't intended to have 10,000 simultaneous 
> connections, and have lots of features (and overhead) servers 
> don't need.
> 
> The ServerXMLHTTP classes (if I got that right) use a smaller 
> foundation 
> that lets them manage a lot more simultaneous connections.  
> If I remember 
> correctly, it only works on Windows 2000, but it does seem to 
> work really 
> well.  Simple XML messaging with them is pretty easy stuff!
> 
> 
> Simon St.Laurent - Associate Editor, O'Reilly and Associates
> XML Elements of Style / XML: A Primer, 2nd Ed.
> XHTML: Migrating Toward XML
> http://www.simonstl.com - XML essays and books
> 
> 
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