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RE: A newer's question.

From: Jim Whitehead <ejw@ics.uci.edu>
Date: Thu, 22 Jan 1998 08:57:58 -0800
Message-ID: <01BD2713.D6FB57A0.ejw@ics.uci.edu>
To: "'Markus Fleck'" <fleck@xmailer.informatik.uni-bonn.de>, Wang HanMin <whm@sic.ml.org>
Cc: "w3c-dist-auth@w3.org" <w3c-dist-auth@w3.org>
I agree with Markus Fleck's response -- some amplifications below:

On Thursday, January 22, 1998 2:21 AM, Markus Fleck 
[SMTP:fleck@xmailer.informatik.uni-bonn.de] wrote:
> Wang HanMin:
> > I am a newer to this list,for I am considering to implement the cscw =
> > under web.
>
> So am I. ;-) [1]

Please keep me (and the list) informed of your progress implementing the 
WebDAV protocol.  The IETF procedures are set up such that we need multiple 
independent implementations of the protocol to advance from Proposed 
Standard to Draft Standard, and even having implementations going to 
Proposed Standard helps a lot.

> I am probably not an expert on WebDAV, but I hope that I have
> grasped enough of it to be able to contribute some thoughts.
>
> I have several question below,I donot know whether it should =
> > be debated:
> > 1.When one use put an object to the server,how to let the other users =
> > know the changes immediately?For example,when one create a image,the =
> > other uesrs' screen should also show the image.As I know,http does not 
=
> > support the push now.So,how to do that?
>
> I do not think that WebDAV will be able to accomplish that.
>
> I could think of at least three ways to get this functionality:
>
>  (1) setting up a push channel (could also be a custom udp or
>      multicast mechanism) for update notifications
>  (2) polling the web server for changes at certain intervals
>  (3) using a session-based protocol (such as e.g. IRC =:-) that
>      offers update "channels" where changes are "broadcast"
>
> While I will probably try the last solution, the first (and
> possibly second) alternatives might be "cleaner" solutions
> from a protocol design standpoint.

I have also heard people discuss using email (SMTP) or netnews (NNTP) for 
sending notification messages.  One current solution to this problem is 
employed by the BSCW group (http://bscw.gmd.de/) which created a separate 
notification protocol, which is received by a helper application.

>
> > 2.I have read the WebDAV protocol-06 document,I think it is mainly 
based =
> > on html editor.I think using html has many shortcoming.
>
> Actually, WebDAV can be used to store and
> retrieve any type of document content.

Very, very true.  WebDAV is based on the HTTP protocol which has no 
restrictions on the type of content it can transmit.  For example, it would 
not be difficult at all to implement a word processor which uses the WebDAV 
protocol for remote storage of word processing documents.

> > well,we can also use the Java and the Activex technology,and I think =
> > using Java is more efficient then using HTML.
>
> The versioning working group might come up with some ideas as to
> how to calculate differences (diffs) between revisions - this might
> help to implement some mechanism for displaying changes incrementally.

Jeff Mogul (and others, including Yaron) have recently submitted proposals 
on delta encoding and instance digests which address transmission of 
changes between versions of a resource:

  ftp://ietf.org/internet-drafts/draft-mogul-http-delta-00.txt
  ftp://ietf.org/internet-drafts/draft-mogul-http-digest-00.txt

- Jim
Received on Thursday, 22 January 1998 12:09:05 GMT

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