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Re: [Uri-review] New posting of the "jms" URI scheme

From: Bjoern Hoehrmann <derhoermi@gmx.net>
Date: Tue, 21 Sep 2010 20:06:29 +0200
To: Eric Johnson <eric@tibco.com>
Cc: SOAP-JMS <public-soap-jms@w3.org>, uri-review@ietf.org
Message-ID: <6oqh96l1ueqfflnfsu5e22abej534hrbja@hive.bjoern.hoehrmann.de>
* Eric Johnson wrote:
>We discussed this in the SOAP-JMS working group, and don't quite
>understand your concern.

Say you have a SVG vector graphic that embeds a PNG bitmap graphic. That
would look more or less like this:

  <svg ...>
    <image xlink:href='data:image/png;base64,xxxxxxxxxxxxxxxxxxxxxxxxx
                       xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
                       ...' .../>

So you have a lot of spaces and line breaks. The XML specification de-
fines the line breaks are turned into spaces and the XLink specification
defines that spaces, being disallowed in proper resource identifiers,
are percent-encoded, so you get

  data:image/png;base64,xxxxxxxxxxxxxxxxxxxxxxxxx%20%20...

Now Base64 does not allow spaces, and RFC 2045 addresses this by man-
dating that characters not part of the Base64 alphabet are ignored. So
this has well-defined behavior and works fine in implementations.

Now my concern is that "jms" identifiers may be used in a similar en-
vironment, and someone might embed them in an XML document like

   <example foo="jms:jndi:REQ_QUEUE?jndiURL=file:/C:/JMSAdmin
                 &amp;jndiInitialContextFactory=com.sun.jndi....
                 &amp;jndiConnectionFactoryName=CONNFACT
                 &amp;jndi-com.example.jndi.someParameter=someValue"/>

... where there are similar rules for the interpretation of the "foo"
attribute as there are for XLink, i.e., this ends up being

  jms:jndi:REQ_QUEUE?jndiURL=file:/C:/JMSAdmin%20%20...

and some implementers of the scheme come across this, and then strip
the spaces so this kind of wrapping works properly, and other imple-
menters don't come across this kind of situation, and their imple-
mentation does not strip the spaces.

I am entirely ignorant about the details of the scheme, I just saw
the draft had a number of examples where the identifers are wrapped
across multiple lines, and checked if it said anything about handling
white space in identifiers. I could not find anything, so I wanted to
point that out.

>Are there other URI schemes that address the question of spaces in
>URIs?  Can you point to the text in those specs, so I can get a feel for
>the character possible textual changes we might make?  I just don't
>recall tripping over language like that before.

Saying that all white space is significant and must be passed on un-
modified to "the next layer" would work for me, to give an example.
-- 
Björn Höhrmann · mailto:bjoern@hoehrmann.de · http://bjoern.hoehrmann.de
Am Badedeich 7 · Telefon: +49(0)160/4415681 · http://www.bjoernsworld.de
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Received on Tuesday, 21 September 2010 18:07:10 GMT

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