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Re: [APPS-REVIEW] Review of HTTP Binding for DSKPP
Hi Lisa,
Hi Chris,
Hi all,
thank you Chris for the pointer to RFC 3205 (BCP 56). I now read it and
it is indeed a very interesting document. Too bad that I didn't came
across it earlier.
Reading through that document I got the impression that the suggestions
that can be found in there are not exercised by today's protocol designs.
There are a couple of issues that require consideration when defining an
HTTP transport:
(a) MIME-types. I believe we are doing fine with the usage of XML and
the registration of a new mime type.
http://tools.ietf.org/html/draft-ietf-pkix-scvp-33 on the other hand
uses different mime types for request and resonse messages. I don't
think that this is necessary.
(b) No new HTTP method seems to be needed
(We don't do that in the DSKPP draft anyway)
(c) New port number for DSKPP since the usage is so different from
ordinary HTTP webbrowsing
(This is quite controversal when it comes to firewall traversal and
might require more discussions. See
http://www1.ietf.org/mail-archive/web/apps-review/current/msg00090.html)
None of the protocols I have been working on defines a new port. Can you
give a reference to a recently developed protocol that carries XML on
top of HTTP that uses a new port number?
(d) New URI scheme
(Currently we use the HTTP/HTTPS schemes but that does not seem to be
inline with the recommendations in BCP 56.)
Neither HELD, SCVP, LoST nor DSKPP define a new URI scheme. In LoST we
had a URL registration in the document once, see Section 16.5 of
draft-ietf-ecrit-lost-03, but removed it later (co-author of that
document is Ted Hardie, the former Applications Area Director).
(e) WSDL Usage: Lisa and Chris do not see WSDL as something being
useful. In fact, I haven't found a person who argued in favor of WSDL.
Hence, I believe we should avoid it.
(f) Error Codes: RFC 3205 points to the problems of defining error codes
when applications are layered on top of HTTP. The suggestion is to
essentially only use 200 (for complete success) and 500 (for complete
failure) at the HTTP layer and to use "application" specific error codes
inside the layer application itself. We are essentially doing this. The
only other error message that is being mentioned is 403 and since it is
independent of the DSKPP protocol interaction it should be fine as well.
(g) HTTP client, proxy and server code: We added text regarding the
expected behavior of clients, proxies and server in Section 5 of
http://www.ietf.org/internet-drafts/draft-ietf-keyprov-dskpp-00.txt. I
guess we are doing fine there.
I am OK with (a), (b), (e), (f) and (g). I am not sure about (c) and
(d). Help needed.
Ciao
Hannes
PS: Regarding Mime-Types:
In KEYPROV with the DSKPP document we should use application/dskpp+xml
instead of application/vnd.ietf.keyprov.dskpp+xml
The IANA registry for the MIME type should look similar to the one in
Section 17.2 of draft-ietf-ecrit-lost-06.
We also need to add a registry for the schema and the namespace (see
Section 11.1 of draft-ietf-geopriv-http-location-delivery-02.txt for the
URN sub-namespace registration, and Section 11.2 of for the XML schema
registration).
Chris Newman wrote:
I expect HTTP bindings to address the concerns raised in BCP 56.
Unless the primary client for your protocol is a web browser, I would
strongly encourage registering a separate port. In the SMTP world,
the primary source of interoperability problems is application-level
gateways/firewalls. At this point it's inevitable we'll end up with
intrusive firewalls on port 80 that will break anything beyond stock
browser-based HTTP. I encourage new HTTP-based protocols to register
a separate port so they have the opportunity to avoid such damage and
interoperability problems. It also simplifies responsible firewall
operation by enabling port-based service restrictions that are more
scalable and less intrusive.
I have yet to see any evidence that WSDL is useful in practice but
that may be due to my lack of experience with web services.
I find Relax NG and/or XML schema useful for XML-based
protocols/formats whether or not they are built on top of HTTP. My
understanding is that Relax NG is better for extensible entity-based
XML formats, whereas XML Schema is better for XML formats with strong
value typing.
I haven't reviewed the DSKPP draft yet.
- Chris
Hannes Tschofenig wrote on 9/13/07 14:56 +0200:
Hi all,
I would like to solicit feedback regarding the HTTP binding described in
DSKPP:
http://www.ietf.org/internet-drafts/draft-ietf-keyprov-dskpp-00.txt
I went through a couple of documents that describe an HTTP binding and
noticed all of them are slightly different. If you, for example, take
a look
at another recent work, namely HELD, from the GEOPRIV working group
then you
will notice that the author incorporated a WSDL binding. The draft is
here:
http://www.ietf.org/internet-drafts/draft-ietf-geopriv-http-location-delivery
-01.txt
Do people on this list have an opinion about the content they would
like to
see in these type of documents?
What is the opinion regarding the usage of WSDL?
Ciao
Hannes
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