It would be a good editorial clarification
to comment that all parameter values should be URL encoded since they will
appear in the URL activated by an End-User interaction. Does anyone object
to adding such a comment?
As to the particular question about
collapsing // into /, the Consumer can easily prevent this by using a construct
such as /_ to separate parameters (or "/ns_" before the navigational
state if so desired). I think we can leave it the Consumer's responsibility
to properly construct its templates.
Rich Thompson
Andre Kramer <>
03/28/2003 10:48 AM
To:
cc:
Subject:
[wsrp] WSRP url parameters and URL Encoding
questions
In 10.2.1.1.4.1 we advice "wsrp-url" values
to be URL Encoded.
However, we are silent on the remaining consumer rewriting tokens and their
producer URL writing counterparts. But the obvious thing to do is to URL
encode them all (i.e. if {wsrp-navigationalState} contains an "&"
or a "/"
etc then URL Encode it. Or encode it anyway just to be safe).
Having URL Encoded all parameters, for producer template URL activation
,
the web server may even help out and do the URL decode for you.
Furthermore, in order to support method GET, URL templates must avoid query
strings. One strategy is to use a path ("/") instead, but I have
found that
(after the above helpful URL decode) some Web Servers will replace any
"//"
with a "/"!
[A valid transformation for file paths as, e.g. file path a///b == file
path
a/b, but not great if one is encoding data as a path. We should not force
consumers to use "#" or ";" instead of "?",
as these also have issues.]
Obviously this corrupts any (URL template) parameters that contain
consecutive back slashes, and we can not expect producers to know what
URL
structure the consumer is using for it's templates. Both the decode and
collapsing consecutive "/"s seem valid things for the Web server
to do but
they are interacting with our method=GET work around. What could we do?
The simplest solution seems to be to *double* URL Encode values when
replacing a {wsp-someparameter} in templates. By double encode I
mean
{wasp-paramValue} =
HttpUtility.UrlEncode(HttpUtility.UrlEncode(RawParamValue)) or
{wsrp-paramValue} = URLEncoder.encode(URLEncoder.encode(rawParamValue));
[A single URL encode should be enough for consumer rewriting. The consumer
can apply a second encode on re-writing (if required).]
This double encode does seem onerous at first, but has the advantage of
being always safe and independent of template schemes and usesMethodGet
(as
well as constant for a Web Server environment & avoids us inventing
a new
encoding scheme).
What do people think?
regards,
Andre
