[OSGeo-Standards] HTML and GeoWeb Re: Was: "file" formats. Is: GeoWeb

Rushforth, Peter Peter.Rushforth at NRCan-RNCan.gc.ca
Tue Jul 16 08:45:58 PDT 2013

Hi Mr Takagi,

Thanks for taking the time to respond.  I agree with having
SVG representations for tiles, as these are nice vector graphics

I will have to take the time to look into the references you've

It seems our philosophies are well aligned, in general, in that we
both conclude that html is the dominant hypermedia format.  It would
be nice to see maps have a more prominent place in
the html vocabulary than they currently have.  I think the spatial
data/software community will need time to come to the same 
conclusion, however.

I hope that the geospatial services community will conclude that
hypermedia is an excellent architecture for consideration, too.
I see Atom as being an excellent choice for that community to begin
working with hypermedia architectures directly.

Peter Rushforth

> -----Original Message-----
> From: Satoru Takagi [mailto:sa-takagi at kddi.com] 
> Sent: July 16, 2013 01:43
> To: Rushforth, Peter; standards at lists.osgeo.org
> Subject: HTML and GeoWeb Re: [OSGeo-Standards] Was: "file" 
> formats. Is: GeoWeb
> Hi, Mr. Peter Rushforth,
> It is a interesting discussion. Though I am not good at 
> English, I would like to comment your post as one of a W3C 
> member working on standardization of Web mapping.
> >The idea behind that constraint is that the specification of a format
>  which contains links ( hypermedia ) , can be 'easier ' to 
> standardize  than interfaces .
> I agree.
> >Currently the only RESTful system which matters is the html Web. 
> I agree too.
> >It is my personal professional belief that the only practical way to
> build a GeoWeb is to add map ( client ) semantics to directly 
> into html , and thereby build it ( html ) into the GeoWeb .
> I think so.
> >add a "geo map " tag to html .
> A format for presentation of the hyper-documents is the 
> origin of the HTML. And various presentation methods have 
> been expanded for HTML such as CSS, forms, bitimages, audio, 
> video, vector graphics etc. I like that geo map was strongly 
> related with those a variety of existing expression. If I 
> express it a little more deeply, I like geo map as the 
> expansion that utilized these standards well.
> >We need to specify a browser -provided ( js ) API for maps around a "
> geo map " tag .
> Only JS? In the W3C, I think that declarative data is 
> respected than API.[1] The reason is your indication. 
> Hyper-document as declarative data may be one reason.
> >Browsers are not going to guess / build URI from component
> hierarchies.  They want links, preferably fully formed.
> Good point. And, you may be interested in Fragment Identifier.[2]
> >the only practical way to do this is with hypertext .
> I think so.
> >I suggest Atom , because it is a widespread ( community ) standard
> hypertext base , having ( appropriate ) collection / member 
> semantics .
> Is Atom regarded as HTML (in wide sense)? In the standards considered 
> to be HTML5 of the wide sense[3], Atom does not seem to come up very 
> much. Atom is found in the chapter of Link of the HTML.[4]
> If Atom is regarded as a part of HTML, is only Atom usable 
> for geo map?
>  There may be specifications to be related to presentation of geo map 
> closely more.
> I think that SVG, canvas, Geolocation APIand CSS become the starting 
> point more closer for geo map in HTML. This is because they are 
> enumerated more definitely as HTML5 of the wide sense. And this is 
> because they are strongly related to the existing behavior of the Web 
> browser more.
> >tiling
> I also think that the tiling is strongly related with ultra high-
> resolution graphics and level of detail controlling of it. And I 
> consider that ultra high-resolution graphics is related to the 
> responsive images[5] and  CSS media queries[6] for such a usecases as 
> Pano JS.[7]
> I push forward standardization activity of mapping based on such a 
> concept in W3C.[8], [9]
> Please comment if you are interested in these activities.
> 1: Web Apps Powered by Linked Data : http://www.w3.org/QA/2012/07/
> interview_ora_lassila.html
> 2: Fragment identifier
> 2-1: http://en.wikipedia.org/wiki/Fragment_identifier
> 2-2: Media Fragments URI : http://www.w3.org/TR/media-frags/
> 2-3: SVG fragment identifiers: http://www.w3.org/TR/SVG/linking.html#
> IntroFragmentsViews
> 3: HTML5 in wide sense
> 3-1: W3C's HTML5 logo: http://www.w3.org/html/logo/ :In this page's 
> class section, the followings are enumerated.
> HTML5, RDFa, microdata, microformats, App Cache, Local Storage, 
> Indexed DB, File API, Geolocation API, audio/video input, contacts & 
> events, tilt orientation, Web Sockets, Server-Sent Events, Audio, 
> video, SVG, Canvas, WebGL, CSS3 3D, Web Workers, XMLHttpRequest 2, 
> 3-2: W3C's Standards for Web Applications on Mobile: current state and
>  roadmap : http://www.w3.org/2013/06/mobile-web-app-state/
> 4: References about Atom in HTML(5)
> 4-1: (@WHATWG) : http://www.whatwg.org/specs/web-apps/current-work/
> multipage/links.html#rel-alternate
> 4-2: (@w3c) : http://www.w3.org/html/wg/drafts/html/master/links.html#
> rel-alternate
> 5: Responsive Images Community Group: http://www.w3.org/community/
> respimg/
> 6: Media Queries: http://www.w3.org/TR/css3-mediaqueries/
> 7: PanoJS3: http://www.dimin.net/software/panojs/
> 8: slides:proposal-of-svg-map : http://www.slideshare.net/totipalmate/
> proposal-of-svg-map-8157601
> 9: Tiling and Layering Module for SVG 1.2 Tiny Submission http://www.
> w3.org/Submission/2011/04/
> Regards,
> Satoru Takagi
> > Hi,
> > 
> > tl;dr ... apologies!  I'm keeping this to the standards list out of 
> respect for people's in-baskets.
> > 
> > I did not mean to instigate a discussion of file formats.  I have my
>  favourite formats too!  And, I don't want to lecture expert 
> technologists on technology, so I apologize if I seem to be 
> doing that.
> ..
> > 
> > Fifteen years ago or so, I thought "Web" Map Service was going to be
>  "it".  It was how I understood you put maps and the Web 
> together. But,
>  it turns out, there's not enough Web in that or any other geo service
>  I know of.  The Web has gone on to scale up exponentially in the 
> interim, leaving behind those parochial services we thought 
> were "Web".
>   Yet we have kept on repeating the same pattern.  More of the same is
>  not going to help.  
> > 
> > REST built the Web, and the GeoWeb needs REST in order to be built. 
>  Without REST, there will be no 'Web' in Geo.   
> > 
> > The reader's digest nature of REST, as originally specified, and why
>  it is important for geographic services:
> > Hypermedia As The Engine Of Application State is the key constraint 
> identified by Fielding which constitutes REST.  Everything else is 
> just not REST.
> > 
> > The idea behind that constraint is that the specification of a 
> format which contains links (hypermedia), can be 'easier' to 
> standardize than interfaces.   The format can then be served by many 
> servers, and consumed by many clients.  The contract is not between 
> the client and the server.  There are two contracts, one between the 
> client and the format and another between the server and the format.  
> The result is the de-coupling of client and server.  If I change my 
> web site, you can still read it, iff I respect the contract between 
> the server and the format (html).  
> > 
> > In order to 'be RESTful', a client application reads the "file" 
> (really the entire response, including headers) which is transferred 
> to it over HTTP, and, discovering links therein, either follows them, 
> thereby replacing/changing its state, or loads the resource, 
> augmenting/changing its current state.  
> > 
> > To try to shorten a long story...
> > 
> > Currently the only RESTful system which matters is the html Web.  
> > 
> > It is my personal professional belief that the only practical way to
>  build a GeoWeb is to add map (client) semantics to directly 
> into html,
>  and thereby build it (html) into the GeoWeb. To be clear:  add a "
> geomap" tag to html. Browsers already have a contract with html.  In 
> order to create a GeoWeb, we need to change html and concommitantly, 
> browsers, to a new version of that contract.   We need to specify a 
> browser-provided (js) API for maps around a "geomap" tag.
> > 
> > The interface is http.  Browsers are not going to implement your 
> interface.  The only interface they're going to implement is GET.  
> Browsers are not going to guess / build URI from component 
> hierarchies.
>   They want links, preferably fully formed.
> > 
> > The service format consumed by the html map client: the only 
> practical way to do this is with hypertext.  The service format(s) 
> must start with hypertext.  I suggest Atom, because it is a  
> widespread (community) standard hypertext base, having (appropriate) 
> collection/member semantics.  GeoRSS(Atom)-GML would be an excellent 
> extensible starting point for a geo service format.    It is already 
> gaining traction in the OGC.  I am not a tiling expert, but my 
> instinct tells me that tilesets/tiles would have good collection/
> member semantics.  What would be needed would be suitable hypermedia 
> constructs for map navigation: link relations (e.g. "east", 
> "west", (c.
> f. Allan Doyle geo-web-rest)..., "zoomin", "zoomout" etc). Possibly 
> URI templates (they are hypertext too, if the client reads them).
> > 
> > Regarding the contract between servers and format. Web servers 
> already serve arbitrary html.  So that is no problem.  But for Web 
> scale, I suggest an actual "mod_geomap" for apache, which could serve 
> the contents of a tiled filesystem as feeds.  The feed format is the 
> contract for both the server *and* the html client.  That's not to say
>  there could not be a plethora of servers.  There could be, just as 
> there are tomcats, jettys, etc. there will be geoservers, mapservers, 
> arcgis servers, whatever.  Respect the contract and you get to play!
> > 
> > That's my view of the needs for (+/- open source) geo software and 
> open standards.  
> > 
> > Regards, and thanks for any feedback,
> > Peter Rushforth
> > 
> > N.B. I made a presentation on this topic to the OGC Mass Market DWG 
> in Dec 2009, but the artifacts seem to be read-protected.  If anyone 
> is interested let me know. 
> > P.S. If you reply I may not (be able to) respond until tomorrow.
> > 
> > 
> > _______________________________________________
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> > Standards at lists.osgeo.org
> > http://lists.osgeo.org/mailman/listinfo/standards
> > 

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